HTP Elite XL ELX-400 Installation manual

Elite XL®
Volume Water Heaters
Installation
Start-Up
Maintenance
Parts
Warranty
ELX-400 / 500 / 650 / 800 / 1000 / 1500 / 2000
Models*
*”VWH” Denotes Volume Water Heater Models,
”N” Denotes Natural Gas,“LP” Denotes Propane,
and “F” Denotes Floor Mount Models
Example Model: ELX-1000FVWHN
DANGER
!
This manual must only be used by a qualied installer / service technician. Read all instructions in this manual before installing.
Perform steps in the given order. Failure to do so could result in substantial property damage, severe personal injury, or death.
NOTICE
HTP reserves the right to make product changes or updates without notice and will not be held liable for typographical errors
in literature.
NOTE TO CONSUMER: PLEASE KEEP ALL INSTRUCTIONS FOR FUTURE REFERENCE.
272 Duchaine Blvd. New Bedford, MA 02745 www.htproducts.com
lp-701 Rev. 000 Rel. 003 Date 6.29.20
WARNING
!
Improper installation, adjustment, alteration, service, or maintenance could void product warranty and cause property
damage, severe personal injury, or death.
Heat Exchanger Bears the ASME “H”
Stamp
California Proposition 65 Warning: This product contains chemicals known to the State of California to cause cancer, birth
defects, or other reproductive harm.

lp-701 Rev. 000 Rel. 003 Date 6.29.20
2
WARNING
!
WARNING: If the information in these instructions is not followed exactly, a re or explosion may result causing property
damage, personal injury or death.
• Do not store or use gasoline or other ammable vapors and liquids in the vicinity of this or any other appliance.
WHAT TO DO IF YOU SMELL GAS
• Do not try to light any appliance.
• Do not touch any electrical switch; do not use any phone in your building.
• Immediately call your gas supplier from a neighbor’s phone. Follow the gas supplier’s instructions.
• If you cannot reach your gas supplier, call the re department.
• Installation and service must be provided by a qualied installer, service agency or the gas supplier.
Improper installation, adjustment, alteration, service, or maintenance can cause injury, property damage, or death.
Refer to this manual. Installation and service must be performed by a qualied installer, service agency, or gas supplier.

lp-701 Rev. 000 Rel. 003 Date 6.29.20
3
SPECIAL ATTENTION BOXES
The following dened terms are used throughout this manual to
bring attention to the presence of hazards of various risk levels or
to important product information.
DANGER
!
DANGER indicates an imminently hazardous situation which, if
not avoided, will result in serious personal injury or death.
WARNING
!
WARNING indicates a potentially hazardous situation which, if not
avoided, could result in personal injury or death.
CAUTION
!
CAUTION indicates a potentially hazardous situation which, if not
avoided, may result in moderate or minor personal injury.
CAUTION
CAUTION used without the safety alert symbol indicates a
potentially hazardous situation which, if not avoided, may result
in property damage.
NOTICE
NOTICE is used to address practices not related to personal injury.
Foreword
This manual is intended to be used in conjunction with other
literature provided with the volume water heater (VWH). This
includes all related control information. It is important that this
manual, all other documents included in this system, and additional
publications including the National Fuel Gas Code - ANSI Z223.1
(latest versions), be reviewed in their entirety before beginning any
work.
Installation should be made in accordance with the regulations of
the Authority Having Jurisdiction, local code authorities, and utility
companies which pertain to this type of water heating equipment.
For the Installer
This VWH must be installed by qualied and licensed personnel. The
installer should be guided by the instructions furnished with the VWH,
and by local codes and utility company requirements. In the absence
of local codes, preference should be given to the National Fuel Gas
Code - ANSI Z223.1, latest version.
Installations Must Comply With:
Local, state, provincial, and national codes, laws, regulations, and
ordinances.
The latest version of the National Fuel Gas Code, ANSI Z223.1, from
American Gas Association Laboratories, 8501 East Pleasant Valley
Road, Cleveland, OH 44131.
In Canada - CGA No. B149 (latest version), from Canadian Gas
Association Laboratories, 55 Scarsdale Road, Don Mills, Ontario,
Canada M3B 2R3. Also, Canadian Electrical Code, C 22.1, from Canadian
Standards Association, 5060 Spectrum Way, Suite 100, Mississauga,
Ontario, Canada L4W 5N6.
The latest version of the National Electrical Code, NFPA No. 70.
NOTE: The gas manifold and controls met safe lighting and other
performance criteria when undergoing tests specied in ANSI Z21.13
- latest edition.
Authority Having Jurisdiction (AHJ) – The AHJ may be a federal, state,
local government, or individual such as a re chief, re marshal, chief
of a re prevention bureau, labor department or health department,
building ocial or electrical inspector, or others having statutory
authority. In some circumstances, the property owner or his/her agent
assumes the role, and at government installations, the commanding
ocer or departmental ocial may be the AHJ.
NOTE: HTP reserves the right to modify product technical specications
and components without prior notice.

lp-701 Rev. 000 Rel. 003 Date 6.29.20
4
Table of Contents
Foreword 3
For the Installer 3
Part 1 - General Safety Information 5
A. Improper Combustion 5
B. Gas 5
C. When Servicing the VWH 5
D. System Water 5
E. Freeze Protection 5
F. Water Temperature Adjustment 6
G. High Elevation Installations 6
Part 2 - Before You Start 7
A. What’s in the Box 8
B. How the VWH Operates 8
C. Optional Equipment 9
Part 3 - Prepare the VWH 9
A. Locating the VWH 9
B. Flooring 10
C. Leveling 10
D. Clearances for Service Access 11
E. Residential Garage and Closet Installations 12
F. Exhaust Vent and Intake Pipe 12
1. Direct Vent of Exhaust and Intake 12
2. Power Venting, Indoor Combustion Air in Conned or Unconned Space
12
G. Carbon Monoxide Detectors 13
H. Prevent Combustion Air Contamination 13
I. Removing an Appliance from a Common Vent System 14
J. Water Chemistry Requirements* 14
K. Technical Specications 17
Part 4 - Piping 18
A. General Plumbing Information 18
B. Relief Valve 18
C. Backow Preventer 19
D. Expansion Tank 19
E. Circulators 19
F. Scalding 19
G. High Velocity Circulator Pump 19
H. Check / Control Water Chemistry 21
I. Plumbing 21
J. Applications 22
NOTICE
The CSD-1 ASME Code, Section CW-400 requires that hot water
heating and supply boilers have a) a UL 353 temperature control
device, b) at least one (1) temperature-actuated control to shut
o the fuel supply when system water reaches a preset operating
temperature, c) a high temperature limit control that prevents
the water temperature from exceeding the maximum allowable
temperature by causing a safety shutdown and lockout, and d) its
own sensing element and operating switch.
The temperature control system integrated into the 928 control
provided with this heating appliance complies with the requirements
of CSD-1 Section CW-400 as a temperature operation control. The
control monitors the temperature dierence between the inlet
and the outlet sensor, which is aected by VWH water ow. If this
temperature dierence exceeds 55°F (typically because of low water
ow or very low heat load), the control will reduce the maximum fan
speed. If the temperature dierence exceeds 60°F, the control will
eectively sense there is little or no water ow or heat load and shut
the VWH down. The controller will restart automatically once the
temperature dierence has dropped below 55°F and the minimum
o time (anti-cycle time) has expired. In addition, if the control senses
that the outlet water temperature has reached 210°F, the VWH is put
into a hard lockout and requires manual reset to restart.
Part 5 - Venting 24
A. General 24
B. Approved Materials for Exhaust Vent and Intake Pipe 25
C. Additional Requirements for Installation in Canada 25
D. Exhaust Vent and Intake Pipe Location 26
E. Exhaust Vent and Intake Pipe Sizing 27
F. Exhaust Vent and Intake Pipe Installation 27
G. Applications 28
1. Direct Vent Installation of Exhaust and Intake 28
2. Power Venting, Room and Indoor Combustion Ventilation
Requirements 30
Part 6 - Condensate Removal 31
Part 7 - Wiring - 400 - 1500 Models 32
A. Installation Must Comply With 32
B. Field Wiring 32
C. Line Voltage Wiring for Standard VWH 33
D. Alarm Connections 33
E. Low Voltage Connections for Standard VWH 33
F. Tank Sensor or Mechanical Control 33
G. System / Pipe Sensor 33
H. UL 353 Internal Low Water Cut-O (Factory Installed) 33
I. Wiring of Cascade System Communication Bus 33
J. Cascade Master Pump and Sensor Wiring 34
K. Cascade Follower Pump and Sensor Wiring 34
L. Variable Speed Pumping 34
M. Optional 0-10 Volt Building Control Signal 34
N. Optional High Gas Pressure Switch 34
O. Optional Low Gas Pressure Switch 34
P. Optional High Limit Manual Reset 34
Part 8 - Wiring - 2000 Models 37
A. Installation Must Comply With 37
B. Field Wiring 37
C. Line Voltage Wiring for Standard VWH 37
D. Alarm Connections 37
E. Low Voltage Connections for Standard VWH 37
F. Tank Sensor or Mechanical Control 37
G. System / Pipe Sensor 38
H. UL 353 Internal Low Water Cut-O (Factory Installed) 38
I. Wiring of Cascade System Communication Bus 38
J. Cascade Master Pump and Sensor Wiring 38
K. Cascade Follower Pump and Sensor Wiring 38
L. Variable Speed Pumping 39
M. Optional 0-10 Volt Building Control Signal 39
N. Optional High Gas Pressure Switch 39
O. Optional Low Gas Pressure Switch 39
P. Optional High Limit Manual Reset 39
Part 9 - Gas Connections 43
A. Gas Piping 43
B. Gas Table 43
C. Check Inlet Gas Pressure 44
D. VWH Gas Valve 45
Part 10 - Start-Up Preparation 46
A. Check / Control Water Chemistry 46
B. Check for Gas Leaks 46
C. Condensate Removal 46
D. Filling and Testing the VWH System 46
E. Final Checks Before Starting VWH 47
Part 11 - Start-Up Procedure 47
A. Control Overview 47
B. Navigation of the Touch Screen Display 48
C. Single VWH Initial Start-Up and Operation 49
D. Cascaded System Initial Start-Up and Operation 49
E. Lockout Condition - Cascade System 49
F. Cascade System Programming 49
G. Operating Instructions 50
H. Programming User Settings 50
I. Programming Installer Settings 52
J. Resetting the Maintenance Schedule 55

lp-701 Rev. 000 Rel. 003 Date 6.29.20
5
Part 1 - General Safety Information
ThisVWH is approved for indoor installations only and is not intended
for use as a pool heater. Clearance to combustible materials: 0” top,
bottom, sides, and back. The VWH must have room for service: 24”
front, 24” right side, and 18” left side are minimum recommended
service clearances. (A combustible door or removable panel is
acceptable front clearance.) 400 - 1000 Models have been approved
for installation on combustible ooring. Do not install on carpeting.
1500 - 2000 MODELS ARE NOT APPROVED FOR INSTALLATION
ON COMBUSTIBLE FLOORING. Install the VWH in a location where
temperature and pressure relief valve discharge or a leak will not
result in damage to the surrounding area. If such a location is not
available, install an auxiliary catch pan. Use only Category IV vent
systems.
WARNING
!
Installer - Read all instructions in this manual before installing.
Perform steps in the given order.
User - This manual is for use only by a qualied heating installer /
service technician. Have this VWH serviced / inspected annually by
a qualied service technician.
FAILURE TO ADHERE TO THE GUIDELINES ON THIS PAGE
CAN RESULT IN SUBSTANTIAL PROPERTY DAMAGE, SEVERE
PERSONAL INJURY, OR DEATH.
DO NOT USE THIS VWH IF ANY PART HAS BEEN SUBMERGED
IN WATER. Immediately call a qualied service technician. The
VWH MUST BE replaced if it has been submerged. Attempting to
operate a VWH that has been submerged could create numerous
harmful conditions, such as a potential gas leakage causing a re
and/or explosion, or the release of mold, bacteria, or other harmful
particulates into the air. Operating a previously submerged VWH
could result in property damage, severe personal injury, or death.
NOTE: VWH damage due to ood or submersion is considered an
Act of God, and IS NOT covered under product warranty.
NOTE: Obey all local codes. Obtain all applicable permits before
installing the VWH.
NOTE: Install all system components and piping in such a manner
that does not reduce the performance of any re rated assembly.
NOTE: If the VWH is exposed to the following, do not operate.
Immediately call a qualied service technician.
1. Fire
2. Damage
3. Water
Failure to follow this information could result in property damage,
severe personal injury, or death.
K. Service Mode - Setting and Verifying the Combustion Setting -
Testing the Internal LWCO 55
Part 12 - VWH Monitoring 56
A. Status Screens 56
B. History Screens 59
C. Graphics Screen 61
D. Cascade Screen 61
Part 13 - Troubleshooting 63
A. Blocking 63
B. Fault (Lockout) 63
C. User Interface Display 63
Part 14 - Maintenance 69
A. Procedures 69
B. Combustion Chamber Coil Cleaning Instructions 69
Part 15 - Shutdown 71
A. Shutdown Procedure 71
B. Failure to Operate 71
Part 16 - Replacement Parts 72
Part 17 - Installation Checklist 79
Part 18 - Maintenance Report 79
VWH Limited Warranty 81
Maintenance Notes 83
Customer Installation Record Form 84
Altering any HTP VWH with parts not manufactured by HTP WILL
INSTANTLY VOID the VWH warranty and could result in property
damage, personal injury, or death.
A. Improper Combustion
WARNING
!
Do not obstruct the ow of combustion and ventilating air. Adequate
air is necessary for safe operation. Failure to keep the exhaust vent
and combustion air intake clear of ice, snow, or other debris could
result in property damage, serious personal injury, or death.
B. Gas
Should overheating or gas supply fail to shut o, turn o the manual
gas control valve to the VWH.
Do not use this VWH for anything other than its intended purpose (as
described in this manual). Doing so could result in property damage
and WILL VOID product warranty.
CAUTION
High heat sources (sources generating heat 100oF / 37oC or greater,
such as stove pipes, space heaters, etc.) may damage plastic
components of the VWH as well as plastic vent pipe materials. Such
damages ARE NOT covered by warranty. It is recommended to keep
a minimum clearance of 8” from high heat sources. Observe heat
source manufacturer instructions, as well as local, state, provincial,
and national codes, laws, regulations and ordinances when installing
this VWH and related components near high heat sources.
C. When Servicing the VWH
To avoid electric shock, disconnect electrical supply before performing
maintenance.
NOTE: When inquiring about service or troubleshooting, reference
the model and serial numbers from the VWH rating label.
To avoid severe burns, allow the VWH and associated equipment to
cool before servicing.
WARNING
!
Be sure to disconnect electrical power before opening the VWH
cabinet or performing service. Failure to do so could result in
electrical shock, property damage, serious personal injury, or death.
This VWH has been designed to heat potable water ONLY. Using
the VWH to heat non-potable uid WILL VOID product warranty,
and could result in property damage, personal injury, or death.
WARNING
!
D. System Water
• Do not use petroleum-based cleaning or sealing compounds
in a VWH system. Gaskets and seals in the system may be
damaged, possibly resulting in substantial property damage.
• Do not use “homemade cures” or “patent medicines”.
Substantial property damage, damage to the VWH, and/or
serious personal injury may result.
CAUTION
Failure of the VWH due to freeze related damage IS NOT covered by
product warranty.
E. Freeze Protection
NOTE: Consider piping and installation when determining VWH
location.

lp-701 Rev. 000 Rel. 003 Date 6.29.20
6
WARNING
!
NEVER use any toxic chemical, including automotive, standard glycol
antifreeze, or ethylene glycol made for hydronic (non-potable)
systems. These chemicals can attack gaskets and seals in water
systems, are poisonous if consumed, and can cause personal injury
or death.
G. High Elevation Installations
WARNING
!
Natural gas at high elevation might contain less heating value than
typical 1,000 BTU/cu ft and therefore can cause improper air / gas
mix leading to improper combustion. For natural gas installations
above 3,000 ft, call your gas provider to determine the heating value
of the supplied natural gas.
F. Water Temperature Adjustment
Households with small children, disabled, or elderly persons may
require a 120oF or lower temperature setting to prevent severe
personal injury or death due to scalding.
If the VWH is going to have a set temperature above 120oF, you must
use an ASSE 1017 rated mixing valve to avoid severe burns or death
from scalding temperatures.
Approximate Time / Temperature Relationships in Scalds
120oF More than 5 minutes
125oF 1 1/2 to 2 minutes
130oF About 30 seconds
135oF About 10 seconds
140oF Less than 5 seconds
145oF Less than 3 seconds
150oF About 1 1/2 seconds
155oF About 1 second
Table 1 - Approximate Time / Temperature Relationships in Scalds

lp-701 Rev. 000 Rel. 003 Date 6.29.20
7
Part 2 - Before You Start
∆T
(Delta T)
(oF)
400VWH
Continuous
Draw
Gallons
Per Hour
(GPH)*
Storage Tank Gallon Size
and First Hour Rating
80 119 175
40o1176 1236 1266 1308
50o941 1001 1030 1072
60o784 844 873 915
70o672 732 761 803
80o588 648 677 719
90o523 583 612 654
100o471 531 560 602
110o428 488 517 559
120o392 452 481 523
130o362 422 451 493
140o336 396 425 467
Table 2 - VWH Ratings with Storage Tanks - *NOTE: Continuous Draw Does Not Take a Storage Tank into Account
∆T
(Delta T)
(oF)
500VWH 650VWH 800VWH
Continuous
Draw
Gallons
Per Hour
(GPH)*
Storage Tank Gallon Size
and First Hour Rating
Continuous
Draw
Gallons
Per Hour
(GPH)*
Storage Tank Gallon Size
and First Hour Rating
Continuous
Draw
Gallons
Per Hour
(GPH)*
Storage Tank Gallon Size
and First Hour Rating
119 175 200 119 175 200 175 200 300
40o1474 1563 1605 1624 1916 2006 2048 2066 2359 2490 2509 2584
50o1179 1269 1311 1329 1533 1622 1664 1683 1887 2018 2037 2112
60o983 1072 1114 1133 1278 1367 1409 1428 1572 1704 1722 1797
70o842 932 974 992 1095 1184 1226 1245 1348 1479 1498 1573
80o737 826 868 887 958 1047 1089 1108 1179 1311 1329 1404
90o655 744 786 805 852 941 983 1002 1048 1180 1198 1273
100o590 679 721 740 767 856 898 917 943 1075 1093 1168
110o536 625 667 686 697 786 828 847 858 989 1008 1083
120o491 581 623 641 639 728 770 789 786 917 936 1011
130o454 543 585 604 590 679 721 740 726 857 876 951
140o421 510 552 571 548 637 679 698 674 805 824 899
CAUTION
These VWH units must be connected to a storage tank. You must not
have a direct connection of the potable water system into the heat
exchanger. This could cause ow issues, short cycling, and an increase of
mineral build-up in the unit. This system is designed to have incoming
potable water ow through the storage tank rst, then through the
heat exchanger. Failure to connect the VWH to a storage tank will result
in property damage and/or premature VWH failure. Damages resulting
from incorrect installation or from use of products not approved by HTP
ARE NOT covered by warranty.
∆T
(Delta T)
(oF)
1000VWH 1500VWH 2000VWH
Continuous
Draw
Gallons
Per Hour
(GPH)*
Storage Tank Gallon Size
and First Hour Rating
Continuous
Draw
Gallons
Per Hour
(GPH)*
Storage Tank Gallon Size
and First Hour Rating
Continuous
Draw
Gallons
Per Hour
(GPH)*
Storage Tank Gallon Size and
First Hour Rating
200 350 500 350 500 750 350 500 750
40o2948 3098 3211 3323 4422 4647 4797 4985 5897 6159 6272 6459
50o2359 2509 2621 2734 3538 3763 3913 4100 4717 4980 5092 5280
60o1966 2116 2228 2341 2948 3173 3323 3511 3931 4194 4306 4494
70o1685 1835 1947 2060 2527 2752 2902 3090 3369 3632 3744 3932
80o1474 1624 1737 1849 2211 2436 2586 2774 2948 3211 3323 3511
90o1310 1460 1573 1685 1966 2191 2341 2528 2621 2883 2996 3183
100o1179 1329 1442 1554 1769 1994 2144 2331 2359 2621 2734 2921
110o1072 1222 1335 1447 1608 1833 1983 2171 2144 2407 2519 2707
120o983 1133 1245 1358 1474 1699 1849 2037 1966 2228 2341 2528
130o907 1057 1170 1282 1361 1586 1736 1923 1814 2077 2189 2377
140o842 992 1105 1217 1264 1489 1639 1826 1685 1947 2060 2247
Contact HTP for Available Storage Tanks

lp-701 Rev. 000 Rel. 003 Date 6.29.20
8
NOTE: First Hour Rating can be increased by using an external mixing valve and increasing tank setpoint temperature.
Example: If installation requires 120oF from mixing valve, set the tank at 140oF to increase First Hour Rating.
First Hour Rating (FHR) = __Total Input Rate X Thermal Eciency _ + .75 X Total Storage
(VWH Outlet Temp - Inlet Temp) X 8.31
Example:
2 500VWHs = Total Output = 1,000,000 BTU
Thermal Eciency = 98% Eciency
VWH Outlet Temp = 140oF - Inlet Temp = 40oF
2 Storage Tanks (119 Gallons Each) = 238 Gallons Total Storage
FHR = 1,000,000 X .98 + .75 X 238
(140 - 40) X 8.31
FHR = 980,000 + 179
831
FHR = 1,179 + 179
FHR = 1,358 Gallons
Peak Hour Demand / First Hour Rating*
Use Average Gallons of
Hot Water Per Usage
Times Used
During One Hour
Gallons Used
in One Hour
Shower 20
X
1
=
20
Bath 20 1 20
Shavings 2 1 2
Hands and Face Washing 4 1 4
Hair Shampoo 4 1 4
Hand Dishwashing 4 1 4
Automatic Dishwasher 14 1 14
Food Preparation 5 1 5
Wringer Clothes Washer 26 1 26
Automatic Clothes Washer 32 1 32
Total Peak Hour Demand (FHR) 131
Table 3 - Peak Hour Demand / First Hour Rating - NOTE: The above table assumes no water
conservation measures. - *For Reference Use ONLY.
UNCRATING THE VWH - Any claims for damage or shortage in
shipment must be led immediately against the transportation
company by the consignee.
NOTICE
Remove all sides of the shipping crate of the VWH.
Components included with the VWH:
• Intake / Exhaust Screens (400 - 500 Models [7550P-995], 650
- 1000 Models [7550P-996], 1500 - 2000 Models [7550P-997])
• Installation Manual and Warranty
• User’s Information Manual
• CSD-1 Form
• H-3 Data Sheet
A. What’s in the Box
B. How the VWH Operates
Condensing technology intelligently delivers highly ecient hydronic
heating while maximizing eciency by measuring data from the
heating system. The following are features of the system and how they
operate.
Stainless Steel / Steel Heat Exchanger
The highly ecient heat exchanger is designed to use the cold water
return from the system and extract the last bit of heat before it is
exhausted.
Modulating Combustion System
The combustion system modulates the output of the burner during
operation to match system demand and achieve the control set point
while in operation. The set point can change by internal or external
signals to enhance the overall performance of the system.
Control
The integrated control system monitors the system and regulates fan
speed to control VWH output. This allows the VWH to deliver only the
amount of heat energy required and nothing more.
The control can regulate the output of multiple VWHs through
its cascade system function. The cascade system is capable of
connecting up to eight VWHs together in such a way that they
function as one VWH system. This allows for greater turn down
ratios and provides systematic control of the multiple VWHs in an
installation to minimize downtime and maximize eciency.
The master VWH requires a sensor to provide feedback on set point
temperature in order to adjust heating input from the connected
VWHs. Each cascaded VWH will have its own pump to provide
maximum ow and control heat exchanger ow rate.
Electronic Touchscreen Display with Status Indicators
Digital controls with full color resistive touchscreen technology. The
display allows the user to change system parameters and monitor
system operation.
Gas Valve
The gas valve senses suction from the blower, allowing gas to ow
only if powered and combustion air is owing.
Integrated Venturi
Controls air and gas ow into the burner.
Burner
The high grade stainless steel burner uses premixed air and gas to
provide a wide range of ring rates.
Spark Ignition
The burner is ignited by applying high voltage through the system
spark electrode. The spark from the electrode ignites mixed gas o
of the burner.
Dual Supply Water Temperature Sensor / High Limit Water ECO
This dual sensor monitors the VWH outlet water temperature
(System Supply). The control adjusts VWH ring rate so the supply
temperature will match the VWH set point. The dual sensor in
combination with the 928 control meets all requirements of a UL
353 water limiting control, eliminating the mechanical ECO and
increasing safety and reliability.

lp-701 Rev. 000 Rel. 003 Date 6.29.20
9
Return Water Temperature Sensor
This sensor monitors VWH return water temperature (System
Return).
Temperature and Pressure Gauge
Allows the user to monitor system temperature and pressure.
Electrical eld connections with terminal strips
The electrical cover allows easy access to the clearly marked line
voltage and low voltage terminal strips to facilitate wiring the VWH.
Supplied Condensate Collection System with Clean Out
This VWH is a high eciency appliance and will produce condensate.
The condensate collection system has a oat switch which monitors
condensate level and prevents condensate from backing up into
the combustion system. Inside the collection system is a built in trap
which seals the combustion system from the connected drain. This
condensate should be neutralized to avoid damage to the drainage
system or piping.
Flow Protection
The ow switch is designed to protect the VWH during low ow
conditions. The VWH control also monitors ow through the heat
exchanger by monitoring the return and supply sensors and will
shut down the burner before overheating occurs. The ow switch
activates at 4 GPM for 400 - 1000 Models; 9 GPM for 1500 - 2000
Models.
0-10 Volt Input
Allows the installer to connect a BMS (Building Management
System) to control the VWH.
0-10 Volt Output A (Congured through Control System)
0-10 Volt Output A is congured through the VWH control system.
0-10 Volt Output A is related to one of the following values: VWH
power, cascade power, fan speed, alarm status, temperature setting
based on outdoor reset curve, ame, or pump.
0-10 Volt Output B (Congured through Control System)
0-10 Volt Output B is congured through the VWH control system,
and is related to one of the following values: VWH power, cascade
power, fan speed, alarm status, temperature setting based on
outdoor reset curve, or ame.
UL 353 Internal Low Water Cuto (LWCO)
The supplied internal Low Water Cuto in conjunction with the 928
control meets UL 353 requirements to function as a safety, locking
out the VWH when water level is inadequate for safe operation. See
Service Mode, this manual, to test LWCO function.
Flue Temperature Modulation
As an additional safety feature, if the ue temperature exceeds
200oF, the control will modulate the VWH down based on the
vent temperature, rather than the supply temperature. If the ue
temperature exceeds 210oF the control will lock out the VWH.
HTP Link
HTP Link allows the installer to connect the VWH to WiFi, providing
the user / installer with tools to remotely monitor the system,
optimize eciency, and aid in troubleshooting.
System Sensor (Optional)
This sensor is designed to be used in a cascade system. The
system pipe sensor measures the temperature of return water and
communicates with the control system to modulate the ring rate of
the connected VWHs.
NOTE: When using a system sensor, pipe insulation must be
wrapped around it to improve temperature measurement accuracy
and increase overall system eciency.
C. Optional Equipment
Optional equipment available from HTP (and Part #):
• System Sensor (7250P-324)
• Indirect Tank Sensor (7250P-325)
• High and Low Gas Pressure Switch Kit with Manual Reset
(500 Model [7550P-999], 650 - 2000 Models [7550P-988])
• 4” Stainless Steel Vent Termination Kit (V2000)
• 6” Stainless Steel Outside Termination Vent Kit (V3000)
• 8” Stainless Steel Elbow (7550P-067)
• 8” Stainless Steel to PVC / CPVC Vent Pipe Adapter (7550P-064)
• Mechanical Manual Reset High Temperature Limit (6300P-998)
• Alarm System Kit (to monitor any failure) (7350P-602)
• 928 PC Connection Kit (7450P-330)
• Condensate Neutralizer (7350P-611)
• Condensate Removal Pump (554200)
• Glass-Lined Storage Tanks (GL-80, GL-119, GL-175)
• Stainless Steel Storage Tank (SSU-80CB, SSU-119CB)
NOTE: When using an optional system sensor, pipe insulation must be
wrapped around it to improve temperature measurement accuracy
and increase overall system eciency.
Part 3 - Prepare the VWH
Remove all sides of the shipping crate to allow the VWH to be moved
into its installation location. The VWH is heavy. At least two individuals
and special equipment (pallet jack, forklift, etc.) are needed to properly
handle the VWH. If surface ooring is rough, take care not to damage
the VWH when moving it into position.
COLD WEATHER HANDLING - If the VWH has been stored in a very
cold location (BELOW 0oF) before installation, handle with care until
the components come to room temperature. Failure to do so could
result in damage to the VWH.
CAUTION
Carefully consider installation when determining VWH location.
Please read the entire manual before attempting installation. Failure
to properly take factors such as VWH venting, piping, condensate
removal, and wiring into account before installation could result in
wasted time, money, and possible property damage and personal
injury.
Figure 1 - Moving the ELX - 1500 - 2000 Models Shown
WARNING
!
This VWH is certied for indoor use only as shipped. DO NOT INSTALL
OUTDOORS without an optional Outdoor Installation Kit. Follow the
instructions included with the optional Outdoor Installation Kit when
installing the VWH outdoors. Installing the VWH outdoors without an
optional Outdoor Installation Kit WILL VOID the warranty, and could
result in property damage, severe personal injury, or death.
A. Locating the VWH
Incorrect ambient conditions can lead to damage to the heating
system and put safe operation at risk. Ensure that the installation
location adheres to the information included in this manual. Failure
to do so could result in property damage, serious personal injury, or
death. Failure of the VWH or components due to incorrect operating
conditions IS NOT covered by product warranty.

lp-701 Rev. 000 Rel. 003 Date 6.29.20
10
This VWH must be installed upright in the vertical position as
described in this manual. DO NOT attempt to install this VWH in any
other orientation. Doing so will result in improper VWH operation
and property damage, and could result in serious personal injury or
death.
1. Installation Area (Mechanical Room) Operating Conditions
• Ensure ambient temperatures are higher than 32oF / 0oC and
lower than 104oF / 40oC
• Prevent the air from becoming contaminated by the products,
places, and conditions listed in this manual
• Avoid continuously high levels of humidity
• Never close existing ventilation openings
• Ensure a minimum 1” clearance around hot water and exhaust
vent pipes
• NOTE: To prevent condensing in the fan, it is recommended to
avoid prolonged exposure to temperatures below 45oF
WARNING
!
This VWH has a condensate disposal system that may freeze if
exposed to sustained temperatures below 32oF. Precautions should
be taken to protect the condensate trap and drain lines from
sustained freezing conditions. Failure to take precautions could
result in property damage, severe personal injury, or death.
2. Check for nearby connections to:
• System water piping
• Venting connections
• Gas supply piping
• Electrical power
• Condensate drain
3. Check area around the VWH. Remove any combustible materials,
gasoline, and other ammable liquids.
WARNING
!
Failure to keep the VWH area clear and free of combustible materials,
liquids, and vapors can result in substantial property damage, severe
personal injury, or death.
High heat sources (generating heat 100oF / 37oC or greater, such as
VWH ue pipes, space heaters, etc.) may damage plastic components
of the VWH as well as plastic vent pipe materials. Such damages ARE
NOT covered by warranty. It is recommended to keep a minimum
clearance of 8” from high heat sources. Observe heat source
manufacturer instructions, as well as local, state, provincial, and
national codes, laws, regulations, and ordinances when installing
this VWH and related components near high heat sources.
CAUTION
The service life of the VWH’s exposed metallic surfaces, such as
the casing, as well as internal surfaces, such as the heat exchanger,
are directly inuenced by proximity to damp and salty marine
environments. In such areas higher concentration levels of
chlorides from sea spray coupled with relative humidity can lead
to degradation of VWH components. In these environments, VWHs
must not be installed using direct vent systems which draw outdoor
air for combustion. Such VWHs must be installed using room air for
combustion. Indoor air will have a much lower relative humidity, and
hence potential corrosion will be minimized.
Failure of the VWH or components due to incorrect operating
conditions IS NOT covered by product warranty.
4. Gas control system components must be protected from dripping
water during operation and service.
5. If the VWH is to replace an existing VWH, check for and correct any
existing system problems, such as:
• System leaks
• Location that could cause the system and VWH to freeze and
leak
• Incorrectly sized expansion tank
6. Clean and ush system when reinstalling a VWH.
NOTE: When installing in a minimum clearance location, it may
not be possible to read or view some product labeling. It is
recommended to make note of the VWH model and serial number.
WARNING
!
Use extreme care not to drop the VWH or cause bodily injury while
lifting the VWH. Failure to follow these instructions could result in
property damage, severe personal injury, or death.
WARNING
!
400 - 1000 Models ONLY are approved for installation on
combustible ooring, but must never be installed on carpeting.
1500 - 2000 MODELS ARE NOT APPROVED FOR INSTALLATION
ON COMBUSTIBLE FLOORING. Failure to follow these instructions
could result in re, property damage, severe personal injury, or
death.
B. Flooring
C. Leveling
CAUTION
!
In order for the condensate to properly ow out of the collection
system, the area where you locate the VWH must be level. Location
must also fully support the weight of the lled VWH. See Figure 2.
Ensure that the oor and structure of the installation location
are sucient to support the full installed weight of the VWH,
including water content of the heat exchanger and related piping.
Failure to ensure the oor and structure of the installation location
are structurally sound before installation of the VWH can result in
structural failure, substantial property damage, severe personal
injury, or death.
LP-666-R
01/03/19
INCORRECT CORRECT
Figure 2 - Leveling - 400 - 1000 Models
WARNING
!

lp-701 Rev. 000 Rel. 003 Date 6.29.20
11
Figure 3 - Caster Wheel Adjustment - 400 - 1000 Models ONLY
LOWER
TURN WHEEL TO THE
RIGHT TO LOWER
RUBBER FOOT
TURN WHEEL
TO THE LEFT TO RAISE
RUBBER FOOT
RAISE01/24/19
LP-517-W
Figure 5 - 1500 - 2000 Models - Installing Decorative Skirts
CORRECT
INCORRECT
1
2
Figure 6 - Recommended Service Clearances
1500 - 2000 Models ONLY - After the VWH has been installed level
in the nal location the decorative skirts may be installed. These
can be found in the VWH cabinet. Use the included bolts to install
the front skirt (1) before proceeding to the side skirts (2). See Figure
5.
D. Clearances for Service Access
WARNING
!
The space must be provided with combustion / ventilation air
openings correctly sized for all other appliances located in the
same space as the VWH. The VWH cover must be securely fastened
to prevent the VWH from drawing air from the VWH room. This is
particularly important if the VWH is in a room with other appliances.
Failure to comply with the above warnings could result in substantial
property damage, severe personal injury, or death.
NOTE: If you do not provide the minimum clearances shown in Figure
6 it might not be possible to service the VWH without removing it from
the space.
NOTE: A combustible door or removable panel is acceptable front
clearance.
NOTE: In multiple VWH installations, ensure an 18”minimum clearance
is maintained between VWHs.
24”
6"
10/31/18
LP-666-M
24"24"
18"
Figure 4 - Leveling - 1500 - 2000 Models
All VWHs eventually leak. Locate the VWH where any leakage from
the relief valve, related piping, tank, or connections will not result
in damage to surrounding areas or lower oors of the building. Any
VWH should be installed in such a manner that if it should leak the
resulting ow of water will not cause damage to the area in which
it is installed. If the VWH is installed in a location where a leak could
cause damage, it is required to provide containment measures.
Such measures include but are not limited to: a properly sized drain
pan installed beneath the VWH and piped to an open drain line, or
installing the VWH on a concrete oor pitched to a free owing drain.
Failure to provide containment measures is the sole responsibility of
the owner and/or installer. Leakage damages ARE NOT covered by
warranty.
In addition, water leak detection devices and automatic water shuto
valves are readily available at plumbing supply houses. IT IS HIGHLY
RECOMMENDED BY THE MANUFACTURER TO INSTALL WATER LEAK
DETECTION DEVICES AND AUTOMATIC SHUTOFF VALVES IN ANY
VWH INSTALLATION WHERE A LEAKAGE OF WATER COULD RESULT IN
PROPERTY DAMAGES.
CAUTION

lp-701 Rev. 000 Rel. 003 Date 6.29.20
12
E. Residential Garage and Closet Installations
Check with your local Authority Having Jurisdiction for requirements
when installing the VWH in a garage or closet. Please read the entire
manual before attempting installation. Failure to properly take
factors such as venting, piping, condensate removal, and wiring into
account before installation could result in wasted time, money, and
possible property damage and personal injury.
CAUTION
Precautions
If the VWH is located in a residential garage, per ANSI Z223.1:
• Install the VWH burner and ignition devices a minimum of 18”
above the oor of the garage. This will ensure the burner and
ignition devices are well o the oor.
• When raising the VWH ensure the entire bottom and fully lled
weight of the VWH are fully supported.
• Locate or protect the VWH so it cannot be damaged by a
moving vehicle.
WARNING
!
The space must be provided with correctly sized combustion/
ventilation air openings for all other appliances located in the
space with the VWH. For power venting installations using room
air for combustion, refer to the venting section, this manual, for
descriptions of conned and unconned spaces. Do not install the
VWH in an attic. Failure to comply with these warnings could result in
substantial property damage, severe personal injury, or death.
F. Exhaust Vent and Intake Pipe
The VWH is rated ANSI Z21.13 Category IV (pressurized vent, likely
to form condensate in the vent) and requires a special vent system
designed for pressurized venting.
NOTE: The venting options described here (and further detailed
in the Venting section, this manual) are the lone venting options
approved for this VWH. Failure to vent the VWH in accordance
with the provided venting instructions will void the warranty.
WARNING
!
Do not attempt to vent this VWH by any means other than those
described in this manual. Doing so will void the warranty and may
result in severe personal injury or death.
The exhaust discharged by thisVWH may be very hot. Avoid touching
or other direct contact with the exhaust gases of the vent termination
assembly. Doing so could result in severe personal injury or death.
Vents must be properly supported. VWH exhaust and intake
connections are not designed to carry heavy weight. Vent support
brackets must be within 1’of the VWH and the balance at 4’ intervals.
VWH must be readily accessible for visual inspection for rst 3’ from
the VWH. Failure to properly support vents could result in property
damage, severe personal injury, or death.
1. Direct Vent of Exhaust and Intake
If installing a direct vent option, combustion air must be drawn from
the outdoors directly into the VWH intake and exhaust must terminate
outdoors. There are three basic direct vent options detailed in this
manual: 1. Side Wall Venting, 2. Roof Venting, and 3. Unbalanced
Venting.
2. Power Venting, Indoor Combustion Air in Conned or
Unconned Space
This VWH requires fresh, uncontaminated air for safe operation and
must be installed in a mechanical room where there is adequate
combustion and ventilating air. NOTE: To prevent combustion air
contamination, see Table 1.
Combustion air from the indoor space can be used if the space has
adequate area or when air is provided through a duct or louver to
supply sucient combustion air based on the VWH input. Never
obstruct the supply of combustion air to the VWH. If the VWH is
installed in areas where indoor air is contaminated (see Table 1)
it is imperative that the VWH be installed as direct vent so that all
combustion air is taken directly from the outdoors into the VWH
intake connection.
Unconned space is space with volume greater than 50 cubic feet
per 1,000 BTU/hr (4.8 cubic meters per kW) of the total input rating of
all fuel-burning appliances installed in that space. Rooms connected
directly to this space through openings not furnished with doors are
considered part of the space. See Venting Section for details.
Conned space is space with volume less than 50 cubic feet per
1,000 BTU/hr (4.8 cubic meters per kW) of the total input rating of all
fuel-burning appliances installed in that space. Rooms connected
directly to this space through openings not furnished with doors are
considered part of the space.
When drawing combustion air from inside a conventionally
constructed building to a conned space, such space should be
provided with two permanent openings: one located 6” (15 cm)
below the space ceiling, the other 6” (15cm) above the space oor.
Each opening should have a free area of one square inch per 1,000
BTU/hr (22cm2/kW) of the total input of all appliances in the space,
but not less than 100 square inches (645cm2).
If the conned space is within a building of tight construction, air for
combustion must be obtained from the outdoors as outlined in the
Venting section of this manual.
DANGER
!
Failure to vent the VWH properly will result in serious personal injury
or death.
Be sure to locate the VWH such that the exhaust vent and intake
piping can be routed through the building and properly terminated.
Dierent vent terminals can be used to simplify and eliminate
multiple penetrations in the building structure (see Optional
Equipment in Venting Section). The exhaust vent and intake piping
lengths, routing, and termination methods must all comply with the
methods and limits given in the Venting Section, this manual.
When installing a combustion air intake from outdoors, care must
be taken to utilize uncontaminated combustion air. To prevent
combustion air contamination, see Table 1.
CAUTION
When drawing combustion air from the outside into the
mechanical room, care must be taken to provide adequate freeze
protection.
WARNING
!
Failure to provide an adequate supply of fresh combustion air can
cause poisonous ue gases to enter the living space, resulting
in severe personal injury or death. To prevent combustion air
contamination, see Table 1.

lp-701 Rev. 000 Rel. 003 Date 6.29.20
13
Figure 8 - Direct Vent Examples
In the Commonwealth of Massachusetts and As Required by State
and Local Codes:
Installation of Carbon Monoxide Detectors: At the time of installation
or replacement of the vented gas fueled appliance, the installing
plumber or gas tter shall observe that a hard wired carbon monoxide
detector with an alarm and battery back-up is installed on the oor
level where the gas appliance is installed, unless the appliance is
located in a detached, uninhabitable structure separate from the
dwelling, building, or structure used in whole or in part for residential
purposes.
In addition, the installing plumber or gas tter shall observe that a hard
wired carbon monoxide detector with an alarm and battery back-up is
installed on each additional level of the dwelling, building, or structure
served by the vented gas appliance. It shall be the responsibility of the
property owner to secure the service of qualied licensed professionals
for the installation of hard wired carbon monoxide detectors.
a. In the event that the vented gas fueled appliance is installed in a
crawl space or attic, the hard wired carbon monoxide detector with
alarm and battery back-up shall be installed on the next adjacent
oor level.
b. In the event that these requirements cannot be met at the time of
completion of installation, the owner shall have a period of thirty (30)
days to comply with the above requirements; provided, however,
that during said thirty (30) day period, a battery operated carbon
monoxide detector with an alarm shall be installed.
G. Carbon Monoxide Detectors
WARNING
!
Do not attempt to vent this appliance by any means other than
those described in this manual. Doing so will void the warranty and
may result in severe personal injury or death.
Approved Carbon Monoxide Detectors: Each carbon monoxide
detector as required in accordance with the above provisions shall
comply with NFPA 70 and be ANSI/UL 2034 listed and IAS certied.
Figure 7 - CO Warning Label
H. Prevent Combustion Air Contamination
Install intake air piping for the VWH as described in the Venting
Section, this manual. Do not terminate exhaust in locations that can
allow contamination of intake air.

lp-701 Rev. 000 Rel. 003 Date 6.29.20
14
Products to Avoid Areas Likely to Have
Contaminants
Spray cans containing
uorocarbons
Dry cleaning / laundry areas
and establishments
Permanent wave solutions Swimming pools
Chlorinated waxes / cleaners Metal fabrication plants
Chlorine-based swimming pool
chemicals Beauty shops
Calcium chloride used for
thawing Refrigeration repair shops
Sodium chloride used for water
softening Photo processing plants
Refrigerant leaks Auto body shops
Paint or varnish removers Plastic manufacturing plants
Hydrochloric or Muriatic acid Furniture renishing areas and
establishments
Cements and glues New building construction
Antistatic fabric softeners used in
clothes dryers Remodeling areas
Chlorine-type bleaches, laundry
detergents, and cleaning
solvents
Garages and workshops
Adhesives used to fasten
building products
Table 4 - Products and Areas Likely to Have Contaminants
NOTE: DAMAGE TO THE VWH CAUSED BY EXPOSURE TO
CORROSIVE VAPORS IS NOT COVERED BY WARRANTY. (Refer to
the limited warranty for complete terms and conditions.)
I. Removing an Appliance from a Common Vent System
WARNING
!
Failure to follow all instructions can result in ue gas spillage and
carbon monoxide emissions, causing severe personal injury or death.
DANGER
!
Do not install the VWH into a common vent with any other appliance.
This will cause ue gas spillage or appliance malfunction, resulting
in possible substantial property damage, severe personal injury, or
death.
When removing an existing appliance, follow the steps below.
1. Seal any unused openings in the common venting system.
2. Visually inspect the venting system for proper size and horizontal
pitch to determine if there is blockage, leakage, corrosion, or other
deciencies that could cause an unsafe condition.
3. If practical, close all building doors, windows, and doors between
the space in which the appliance remains connected to the common
venting system and other spaces in the building. Turn on clothes
dryers and any appliances not connected to the common venting
system. Turn on any exhaust fans, such as range hoods and bathroom
exhausts, at maximum speed. Do not operate a summer exhaust fan.
Close all replace dampers.
J. Water Chemistry Requirements*
The water must be potable, free of corrosive chemicals, sand,
dirt, and other contaminates. It is up to the installer to ensure the
water does not contain corrosive chemicals or elements that can
damage the heat exchanger. Potable water is dened as drinkable
water supplied from utility or well water in compliance with EPA
secondary maximum contaminant levels (40 CFR Part 143.3) as
shown in the table below. If the water contains contaminants higher
than outlined by the EPA, water treatment is recommended and
additional, more frequent maintenance may be required.
If you suspect that your water is contaminated in any way,
discontinue use of the appliance and contact an authorized
technician or licensed professional.
Contaminant
Maximum
Allowable
Level
Contaminant
Maximum
Allowable
Level
Total Hardness
(Commercial
Use - 140oF and
above water
temperature)
120 mg/l
(7 grains/gallon)
pH 6.5-8.5
Sulfate 205 mg/l
Total
Dissolved
Solids (TDS)
500 mg/l
Aluminum 0.05 to 0.2 mg/l Zinc 5 mg/l
Chloride 100 mg/l
Copper 1 mg/l Dissolved
Carbon
Dioxide (CO2)
15 mg/l or
PPM
Iron 0.3 mg/l
Manganese 0.05 mg/l
CAUTION
Chemical imbalance of the water supply may aect eciency
and cause severe damage to the appliance and associated
equipment. It is important that the water chemistry on both the
domestic hot water and central heating sides are checked before
installing the appliance. Water quality must be professionally
analyzed to determine whether it is necessary to treat the water.
Various solutions are available to adjust water quality. Adverse
water quality will aect the reliability of the system. In addition,
operating temperatures above 135oF will accelerate the build-up
of lime scale and possibly shorten appliance service life. Failure of
an appliance due to lime scale build-up, low pH, or other chemical
imbalance IS NOT covered by the warranty.
Table 5 - Water Quality Specications
*NOTE: It is recommended to clean heat exchanger at least once
a year to prevent lime scale buildup. Follow the maintenance
procedure in the Maintenance Section of this manual to clean the
heat exchanger.
WARNING
!
Ensure that the intake air will not contain any of the contaminants in
Table 1. Contaminated air will damage the VWH, resulting in possible
substantial property damage, severe personal injury, or death. For
example, do not pipe intake air near a swimming pool or laundry
facilities. These areas always contain contaminants.
4. Place in operation the appliance being inspected. Follow the
lighting instructions. Adjust the thermostat so the appliance will
operate continuously.
5. Test for spillage at the draft hood relief opening after 5 minutes of
main burner operation. Use the ame of a match or candle or smoke
from a cigarette.
6. After it has been determined that each appliance remaining
connected to the common venting system properly vents when
tested as outlined, return doors, windows, exhaust fans, replace
dampers, and any other gas burning appliances to their previous
condition of use.
7. Any improper operation of the common venting system should
be corrected to conform to the National Fuel Gas Code, ANSI Z223.1.
When resizing any portion of the common venting system, the
system should approach the minimum size as determined using the
appropriate tables in Appendix G of ANSI Z223.1.

lp-701 Rev. 000 Rel. 003 Date 6.29.20
15
Closed loop water must be free of corrosive chemicals, sand, dirt,
and other contaminates. It is up to the installer to ensure the water
does not contain corrosive chemicals or elements that can damage
the heat exchanger.
If you suspect that your water is contaminated in any way,
discontinue use of the appliance and contact an authorized
technician or licensed professional.
• Water pH between 6.5 and 8.5
• pH levels below 6.5 can cause an increase in the rate of
corrosion. pH of 8.5 or higher can potentially cause lime
scale build-up.
• Maintain water pH between 6.5 and 8.5. Check with litmus
paper or have it chemically analyzed by a local water treat-
ment company.
• If the pH is not between 6.5 and 8.5, consult a local water
treatment company for solutions.
• Hardness between 5 and 12 grains (71.3 and 205 mg/L)*
• Hardness levels above the required amounts can lead to
lime scale build-up throughout the system. Water below 5
grains/gallon (71.3 mg/L) may be over softened.
• Consult local water treatment companies for unusually
hard water areas (above the required amounts) or for
other treatment solutions if water is being over softened
(below 5 grains/gallon [71.3 mg/L]).
• Chloride concentration less than 150 ppm (mg/L)
• Do not ll appliance or operate with water containing
chlorides in excess of 150 ppm (mg/L).
• Using chlorinated fresh water should be acceptable as
levels are typically less than 5 ppm (mg/L).
• Do not connect the appliance to directly heat swimming
pool or spa water.
• Total Dissolved Solids (TDS) between 100 and 450 ppm
(mg/L)*
• Total dissolved solids are minerals, salts, metals, and
charged particles that are dissolved in water.
• The greater the amounts of TDS present, the higher the
corrosion potential due to increased conductivity in the
water.
• If using softened water to ll the appliance, it is still
possible to have high TDS. This water can be corrosive.
Consult local water treatment companies for other
treatment solutions to reduce this aect.
*NOTE: The amount of Hardness ppm (mg/L) + TDS ppm (mg/L)
must be less than 450 ppm (mg/L) total. For Example:
NOTE: Regularly monitoring pH, chlorides, TDS, and hardness
levels can prolong the life of the appliance by reducing mineral
scale buildup, corrosion, and erosion. Mineral buildup in the heat
exchanger reduces heat transfer, overheats the stainless steel heat
exchanger, and causes failure.

lp-701 Rev. 000 Rel. 003 Date 6.29.20
16
Figure 9 - ELX VWH Specications and Dimensions - NOTE: All Dimensions Are Approximate
Table 6 - ELX VWH Adapter Dimensions and Specications
A
B
C
D
E
L
N
Q
P
O
K
R
H
M
F
G
J
ELX-400-1000
ELX-1500-2000
LP-666-P
04/06/20
WATER SUPPLY WATER RETURN GAS
AIR INTAKE
EXHAUST
CONDENSATE
2" CLEANOUT
A
B
C
R
F
G
K
L
M
E
D
O
N
P
Q
H
J
WATER SUPPLY
GAS
AIR INTAKE
EXHAUST
CONDENSATE
2" CLEANOUT
WATER RETURN
MODEL # A B C D E F G H J K L M N O P Q R
ELX400-500 41.0 26.0 40.7 17.9 35.0 4.1 10.1 10.5 12.6 16.1 20.5 22.0 6.1 8.1 25.8 35.0 2.8*
ELX650-1000 56.5
ELX1500 60.8 31.8 67.5 39.2 44.8 51.2 3.4 7.4 7.5 11.9 14.4 24.4 31.8 4.6 6.5 22.7 39.1
ELX2000 80.0
Model Water Connection Vent Size Air Intake Gas Connection Condensate
400
2" NPT
4" 4" 1"
3/4" PVC
500
650
6" 6"
1"
800 1-1/4"
1000
1500 2 1/2” Flange 8” 8” 1-1/2” 1” PVC
2000 2”

lp-701 Rev. 000 Rel. 003 Date 6.29.20
17
K. Technical Specications
Table 7 - Technical Specications
Model 400 500 650 800 1000 1500 2000
Installation Indoor, Floor Standing, Fully Condensing
Minimum / Maximum Input (Btu/Hr) 39,900 / 399,000 50,000 / 500,000 65,000 / 650,000 80,000 / 800,000 100,000 /
1,000,000
150,000 /
1,500,000
200,000 /
2,000,000
Heating Capacity (MBH) 391 490 637 784 980 1,470 1,960
Flue System Category IV, Sealed Combustion Direct Vent, Power Vent
Minimum Combined Vent Run 10 feet 15 feet
Maximum Combined Vent Run 4” (125 feet) 6” (125 feet) 8” (150 feet)
Approved Exhaust Vent Materials PVC, CPVC, PP, Stainless Steel
Packaging
Dimensions
(in Inches)
W32.25 43.25
H49.625 64.25
D48 64 76 86
Shipping Weight (lbs) 538 545 680 700 745 1400 1750
Gas Supply Pressure 3.5”to 14”WC (NG or LP) 3.5” to 10.5”WC (NG
ONLY)
Manifold Pressure Min / Max NG/LP: -0.08”WC NG: -0.07”WC
Power Supply 120V 60 Hz, 21.3A
208/3PH
WYE, 60Hz,
15A/Leg
Customer Connection Board Fuse
Amperage Ratings 2 Amps 5 Amps
General Operating Conditions Ambient Temperature Range: 33 – 104oF (0.6 – 40oC)
Product Approvals and Requirements: ANSI Z21.13 / CSA 4.9, CSD-1 ASME Code
Ignition System Direct Electronic Spark Ignition / Flame Rectication
Burner System Premixed Fuel Modulation / Stainless Steel Burner
Gas Valve System Pneumatic Gas Valve
Dimensions
(in Inches)
W26 31.8
H41 60.8
D40.7 56.5 66.5 79
VWH Water Content (Gallons) 3.8 4.3 5.6 6.6 8.1 12.9 16.25
Minimum Flow Rate @ 20oF ∆T at
Low Fire (GPM) 4 5 6.5 8 10 15 20
Flow Switch Activation (GPM) 4 9
DHW Indirect Setpoint Temperature
Range 70 – 185oF
Water Pressure
(PSI)
Heat Exchanger
MAWP 160
Relief Valve Temperature: 210F / Pressure: 150
Control Panel 7” Full Color Touch Screen
Main Controller 928 SIT Control
Connection Sizes Supply / Return 2” NPT 2 1/2” Flange
Gas Inlet 1” NPT 1 1/4” NPT 1 1/2” NPT 2” NPT
Materials Cabinet Powder Coated Galvaneal Steel
Heat Exchanger 316L Stainless Steel Water Tube
Safety Devices
Flame Rectier Probe, Dual Water Supply Temperature Sensor / High Limit (210oF), Freeze Protection, Condensate
Trap with Float, Dual Flue Sensor (210oF), Blocked Vent Pressure Switch, Internal UL 353 Approved Low Water
Cut-O (LWCO), High Resolution Flow Switch

lp-701 Rev. 000 Rel. 003 Date 6.29.20
18
Part 4 - Piping
WARNING
!
Failure to follow the instructions in this section WILL VOID the
warranty and may result in property damage, severe personal injury,
or death.
CAUTION
Dielectric unions or galvanized steel ttings must not be used in a
system with this VWH. Doing so WILL VOID the warranty. Use only
copper, brass, or stainless steel ttings.Teon thread sealant must be
used on all connections.
Plumbing of this product should only be done by a qualied, licensed
plumber in accordance with all local plumbing codes. The VWH is
designed to be connected to a storage tank to supply domestic hot
water. HTP oers 60/80/119/175 gallon storage tanks in either stainless
steel or glass-lined construction. These storage tanks will be directly
connected to the VWH supply and return connections.
A. General Plumbing Information
CAUTION
The building piping system must meet or exceed the piping
requirements in this manual.
NOTE: The addition of a high temperature limiting device is important
if the VWH is connected to a domestic hot water system.
Connect the cold water supply to both the storage tank bottom port
and the supply side of the VWH (shown in Applications, this manual).
It is important that you install a ow check on the supply line of the
VWH BEFORE connecting the feed line to the storage tank. This allows
the cold feed to ow through the storage tank rst. It is recommended
that you install shut o valves on the cold feed line for future ease of
service. If there is a back ow preventer or any type of no return valve
in the system you must install an additional tee for a suitable potable
hot water expansion tank. Connect the storage tank return line to the
return connection located on the VWH (shown in Applications, this
manual). Then connect the storage tank hot water outlet to the hot
water plumbing lines.
B. Relief Valve
WARNING
!
To avoid water damage or scalding due to relief valve operation:
• Discharge line must be connected to relief valve outlet and
run to a safe place of disposal. Terminate the discharge line
in a manner that will prevent possibility of severe burns or
property damage should the relief valve discharge.
• Discharge line must be as short as possible and the same
size as the valve discharge connection throughout its entire
length.
• Discharge line must pitch downward from the valve and
terminate at least 6”above the oor drain, making discharge
clearly visible.
• The discharge line shall terminate plain, not threaded, with
a material serviceable for temperatures of 375oF or greater.
• Do not pipe discharge to any location where freezing could
occur.
• No valve may be installed between the relief valve and
VWH or in the discharge line. Do not plug or place any
obstruction in the discharge line.
• Test the operation of the relief valve after lling and
pressurizing the system by lifting the lever. Make sure the
valve discharges freely. If the valve fails to operate correctly,
immediately replace with a new properly rated relief valve.
• Test relief valve at least once annually to ensure the
waterway is clear. If valve does not operate, turn the VWH
“o” and call a plumber immediately.
• Take care whenever operating relief valve to avoid scalding
injury or property damage.
FAILURE TO COMPLY WITH THE ABOVE GUIDELINES COULD
RESULT IN FAILURE OF RELIEF VALVE OPERATION, RESULTING
IN POSSIBILITY OF SUBSTANTIAL PROPERTY DAMAGE, SEVERE
PERSONAL INJURY, OR DEATH.
Connect discharge piping to a safe disposal location by following
these guidelines.
Use two wrenches when tightening water piping at the VWH. Use
one wrench to prevent the VWH return or supply line from turning.
Failure to prevent piping connections from turning could cause
damage to VWH components.
The control module uses temperature sensors to provide both high
limit protection and modulating temperature control. The control
module also provides low water protection by sensing the water
level in the heat exchanger. Some codes/jurisdictions may require
additional external controls.
RE-INSPECTION OF RELIEF VALVES: Valves should be inspected
AT LEAST ONCE EVERYTHREEYEARS, and replaced if necessary,
by a licensed plumbing contractor or qualied service technician
to ensure that the product has not been aected by corrosive
water conditions and to ensure that the valve and discharge line
have not been altered or tampered with illegally. Certain naturally
occuring conditions may corrode the valve and its components
over time, rendering the valve inoperative. Such conditions can
only be detected if the valve and its components are physically
removed and inspected. Do not attempt to conduct an
inspection on your own. Contact your plumbing contractor for a
re-inspection to assure continued safety.
FAILURE TO RE-INSPECT THE RELIEF VALVE AS DIRECTED
COULD RESULT IN UNSAFE TEMPERATURE AND/OR PRESSURE
BUILD-UP WHICH CAN RESULT IN PROPERTY DAMAGE,
SERIOUS PERSONAL INJURY, OR DEATH.
Do not thread a cap or plug into the relief valve or relief valve line
under any circumstances! Explosion and property damage, serious
injury, or death may result.
DO NOT pipe this VWH with black iron, galvanized steel, steel, or lead
pipe. Doing so will result in premature product failure and property
damage, and WILL VOID the warranty.

lp-701 Rev. 000 Rel. 003 Date 6.29.20
19
C. Backow Preventer
Use a backow preventer specically designed for hot water heater
installations. This valve should be installed on the cold water ll
supply line per local codes.
D. Expansion Tank
Expansion Tank and Make-Up Water
1. Ensure that the expansion tank is sized to correctly handle VWH
and system water volume and temperature.
CAUTION
Undersized expansion tanks cause system water to be lost from
the relief valve, causing make-up water to be added. Eventual
VWH failure can result due to excessive make-up water addition.
SUCH FAILURE IS NOT COVERED BY WARRANTY.
Expansion tanks must be sized according to total system volume.
This includes all length of pipe, all xtures, VWHs, etc. Failure to
properly size for system expansion could result in wasted time,
money, possible property damage, serious injury, or death.
WARNING
!
2. The expansion tank must be located as shown in Applications, this
manual, or following recognized design methods. See expansion
tank manufacturer’s instructions for details.
Table 8 - Heat Exchanger Volume - Add Required Storage Tank Gallon
Size to Heat Exchanger Volume
Model Heat Exchanger Volume (Gallons)
400 3.8
500 4.3
650 5.6
800 6.6
1000 8.1
1500 12.9
2000 16.25
DO NOT install automatic air vents on closed type expansion tank
systems. Air must remain in the system and return to the tank to
provide an air cushion. An automatic air vent would cause air to
leave the system, resulting in improper operation of the expansion
tank.
The expansion tank must be suitable for potable water systems.
E. Circulators
Every VWH system requires special attention to circulator size to
overcome pressure drop through the VWH and its related piping.
All circulators installed on the VWH system must be designed for
potable water installations. VWH pressure drop is detailed in this
manual.
Water temperature above 140oF requires the circulator to run
continuously. Water hardness must be between 5 and 7 grains.
Hardness above 7 grains will damage the heat exchanger and
shorten the service life of the VWH.
DO NOT use the VWH circulator in any location other than the
ones shown in this manual. The VWH circulator location is selected
to ensure adequate ow through the VWH. Failure to comply with
this caution could result in unreliable performance and nuisance
shutdowns from insucient ow.
The risk of scalding increases when raising tank temperature. Use a
water tempering or mixing valve when raising tank temperature to
lessen the chance of scalds. Consult codes for conformance. Failure
to install a temperature limiting or mixing valve and follow these
instructions could result in property damage, severe personal injury,
or death due to scalds.
Approximate Time / Temperature Relationships in Scalds
120oF More than 5 minutes
125oF 1 1/2 to 2 minutes
130oF About 30 seconds
135oF About 10 seconds
140oF Less than 5 seconds
145oF Less than 3 seconds
150oF About 1 1/2 seconds
155oF About 1 second
Table 9 - Approximate Time / Temperature Relationships in Scalds
F. Scalding
This VWH can deliver
scalding water at any faucet
in the system. Be careful
whenever using hot water
to avoid scalding injury.
Certain appliances such as
dishwashers and automatic
clothes washers may require
increased water temperatures.
By setting the thermostat
on this VWH to obtain the
increased water temperature
required by these appliances
you may create the potential
for scald injury.
To protect against injury,
install a mixing valve in the
water system. This valve will
reduce point of use discharge
temperatures by mixing
cold and hot water in branch
supply lines. Such valves are
available from your local
plumbing supplier.
Table 8 details the relationship of water temperature and time with
regard to scald injury and may be used as a guide in determining the
safest water temperature for your applications.
G. High Velocity Circulator Pump
Every VWH system requires special attention to pump size in order
to overcome pressure drop through the VWH and its related piping.
All circulators installed on the VWH system must be designed for a
potable water system.
In addition, the heat exchanger has a minimum ow rate that must
be taken into account when sizing the circulator. Minimum ow
rates are listed in Table 8.

lp-701 Rev. 000 Rel. 003 Date 6.29.20
20
Table 10 - Pressure Drop at Various Temperature Rises
The VWH heat exchanger does have a pressure drop which must be considered in system design.
Table 11 - Multiple VWH Manifold Piping - NOTE: Table based on water velocity less than Five (5) feet per second.
The chart below represents the combined ow rates and pipe sizes when using multiple VWHs to design the manifold system for the primary
circuit. To size, simply add up the number of VWHs and the required ow rates for the system design temperature.
Example: (5) 1000 VWHs with a design of 30oF temperature rise with each VWH having an individual ow rate of 64 GPM. To correctly size the
manifold feeding these VWHs, you would need a pipe size of 6”.
Model 20oF 30oF 40oF
GPM Ft / Hd GPM Ft / Hd GPM Ft / Hd
400 39 12.0 26 7.2 19 4.0
500 48 11.4 32 5.4 24 3.2
650 63 11.5 42 6.2 31 4.0
800 77 12 52 6 39 3
1000 96 14.0 64 7 48 4.7
1500 146 16 97 7.6 73 4.7
2000 200 21 133 11.5 100 6.7
Model Number of Units and Recommended Common Header Pipe Sizes in Inches
2 3 4 5 6 7 8
400 3 3 4 4 5 5 5
500 3 4 4 5 5 5 6
650 4 4 5 5 6 6 6
800 4 5 5 6 6 8 8
1000 4 5 6 6 8 8 8
1500 5 6 8 8 8 10 10
2000 6 6 8 8 10 10 12
ELX-2000
ELX-1500
ELX-1000
ELX-800
ELX-650
ELX-500
ELX-400
0
5
10
15
20
25
30
010 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210
Pressure Loss (Feet of Head) +/-10%
Flow Rate (GPM)
ELX-400 ELX-500 ELX-650 ELX-800 ELX-1000 ELX-1500 ELX-2000
Figure 10 - Pressure Drop through the VWH