Raypak 503A Manual

INSTALLATI N & PERATING
INSTRUCTI NS
CATALOG NO. 3400.531A Effective: 10-03-13 Replaces: 04-09-13 P/N 241511 Rev. 2
WARNING: Improper installation, adjustment, alteration, service or maintenance can
cause property damage, personal injury, exposure to hazardous materials* or loss of
life. Review the information in this manual carefully. *This unit contains materials that
have been identified as carcinogenic, or possibly carcinogenic, to humans.
F R Y UR SAFETY: Do not store or use gasoline or other flammable vapors and
liquids or other combustible materials in the vicinity of this or any other appliance. To
do so may result in an explosion or fire.
WHAT T D IF Y U 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 fire department.
Installation and service must be performed by a qualified installer, service agency or
the gas supplier.
This manual should be maintained in legible condition and kept adjacent to the heater or in a safe place for future
reference.
Models 503A–2003A
Types H & WH

2
Rev. 2 reflects the following:
Changes to: Table A on page 8, Table I on page 20, “Electrical Power Connections” on page 20, Table J on page 27,
Table K on page 29, Table M on page 32, Wiring Diagram on page 43, “ lower Check” on page 46, Table T on page 46,
“Manifold Check” on page 46, “Filter Maintenance” on page 54
Additions: “Motorized Combustion Air Dampers or Louvers” on page 11, “Extractors, draft inducers, and motorized flue
dampers” on page 27, Fig. 28 on page 29, Fig. 45 on page 45
Deletions: None

WARNINGS 4
BEF RE INSTALLATI N 5
Product Receipt 5
Model Identification 5
Ratings and Certifications 5
Installations at Elevation 5
Component Locations 6
General Information 6
GENERAL SAFETY 7
Time/Temperature Relationships in
Scalds 7
INSTALLATI N 8
Installation Codes 8
Equipment ase 8
Clearances 8
Combustion and Ventilation Air 9
Conventional Combustion Air Supply 11
Water Piping 12
Hydronic Heating 14
Applications & Modes 15
Domestic Hot Water 17
Gas Supply 19
Electrical Power Connections 20
Field Wiring Connection 21
Venting 26
Venting Installation Tips 28
Venting Configurations 28
Outdoor Installation 33
Controls 34
User Interface 36
WIRING DIAGRAMS 43
START-UP 44
Pre Start-up 44
Start-Up 45
PERATI N 49
Lighting Instructions 49
To Turn Off Gas To Appliance 49
TR UBLESH TING 49
MAINTENANCE 52
Suggested Minimum
Maintenance Schedule 52
Preventative Maintenance Schedule 53
Filter Maintenance 54
Filter Replacement 54
APPENDIX 55
Inside Air Contamination 55
IMP RTANT INSTRUCTI NS F R
THE C MM NWEALTH F
MASSACHUSETTS 56
WARRANTY 57
START-UP CHECKLIST 58
C NTENTS
3

4
DANGER: Indicates the presence of immediate hazards which will cause severe
personal injury, death or substantial property damage if ignored.
WARNING: Indicates the presence of hazards or unsafe practices which could cause
severe personal injury, death or substantial property damage if ignored.
CAUTI N: Indicates the presence of hazards or unsafe practices which could cause
minor personal injury or product or property damage if ignored.
N TE: Indicates special instructions on installation, operation, or maintenance which
are important but not related to personal injury hazards.
DANGER: Make sure the gas on which the heater
will operate is the same type as that specified on the
heater rating plate.
WARNING: Should overheating occur or the gas
supply valve fail to shut, do not turn off or disconnect
the electrical supply to the heater. Instead, shut off
the gas supply at a location external to the heater.
WARNING: Do not use this heater if any part has
been under water. Immediately call a qualified
service technician to inspect the heater and to
replace any part of the control system and any gas
control which has been under water.
WARNING: To minimize the possibility of improper
operation, serious personal injury, fire, or damage to
the heater:
• Always keep the area around the heater free of
combustible materials, gasoline, and other
flammable liquids and vapors.
• Heater should never be covered or have any
blockage to the flow of fresh air to the heater.
WARNING - CALIF RNIA PR P SITI N
65: This product contains chemicals known to the
State of California to cause cancer, birth defects or
other reproductive harm.
WARNING: Risk of electrical shock. More than one
disconnect switch may be required to de-energize
the equipment before servicing.
CAUTI N: This heater requires forced water
circulation when the burner is operating. See
minimum and maximum flow rates. Severe damage
will occur if the heater is operated without proper
water flow circulation.
CAUTI N: Operation of this heater in low
temperature systems requires special piping.
Harmful internal condensation will occur if the inlet
water temperature does not exceed 120°F. Warranty
claims will be denied when condensation occurs.
CAUTI N: If this heater is to be installed above
radiation level, it must be provided with a low water
cut-off device at the time of heater installation.
CAUTI N: If this heater is to be installed in a
negative or positive pressure equipment room, there
are special installation requirements. Consult factory
for details.
WARNINGS
Pay Attention to These Terms
WARNING: UL recognized fuel gas detectors are
recommended in all enclosed propane and natural
gas applications wherein there is a potential for an
explosive mixture of fuel gas to accumulate and their
installation should be in accordance with the
detector manufacturer's recommendations and/or
local laws, rules, regulations, or customs.
WARNING: oth natural gas and propane have an
odorant added to aid in detecting a gas leak. Some
people may not physically be able to smell or
recognize this odorant. If you are unsure or
unfamiliar with the smell of natural gas or propane,
ask your local gas supplier. Other conditions, such
as "odorant fade," which causes the odorant to
diminish in intensity, can also hide, camouflage, or
otherwise make detecting a gas leak by smell more
difficult.

5
BEF RE INSTALLATI N
Raypak strongly recommends that this manual be re-
viewed thoroughly before installing your MV heater.
Please review the General Safety information before
installing the heater. Factory warranty does not apply
to heaters that have been improperly installed or oper-
ated. (Refer to the warranty at the back of this
manual.) Installation and service must be performed
by a qualified installer, service agency or gas supplier.
If, after reviewing this manual, you still have questions
which this manual does not answer, please contact
your local Raypak representative or visit our website at
www.raypak.com.
Thank you for purchasing a Raypak product. We hope
you will be satisfied with the high quality and durability
of our equipment.
Product Receipt
On receipt of your heater it is suggested that you visu-
ally check for external damage to the shipping crate. If
the crate is damaged, make a note to that effect on the
ill of Lading when signing for the shipment. Next,
remove the heater from the shipping packaging.
Report any damage to the carrier immediately.
On occasion, items are shipped loose. e sure that
you receive the correct number of packages as indi-
cated on the ill of Lading.
Claims for shortages and damages must be filed with
the carrier by consignee. Permission to return goods
must be received from the factory prior to shipping.
Goods returned to the factory without an authorized
Returned Goods Receipt number will not be accepted.
All returned goods are subject to a restocking charge.
When ordering parts, you must specify the model and
serial number of the heater. When ordering under war-
ranty conditions, you must also specify the date of
installation.
Purchased parts are subject to replacement only
under the manufacturer’s warranty. Debits for defec-
tive replacement parts will not be accepted. Parts will
be replaced in kind only per Raypak’s standard war-
ranties.
Model Identification
The model identification number and heater serial
number are found on the heater rating plate located on
the upper rear jacket panel of the heater. The model
number will have the form H7-0503A or similar
depending on the heater size and configuration. The
letter(s) in the first group of characters identifies the
application (H = Hydronic Heating, WH = Domestic
Hot Water (DHW)). The number which follows identi-
fies the firing mode (7 = electronic modulation). The
second group of characters identifies the size of the
heater (the four numbers representing the approxi-
mate M TUH input), and, where applicable, a letter,
indicating the manufacturing series.
Ratings and Certifications
Standards:
• ANSI Z21.13 · CSA 4.9 - latest edition, Gas-Fired
Hot Water oilers
• CAN 3.1 - latest edition, Industrial and
Commercial Gas-Fired Package oilers
• ANSI Z21.10.3 · CSA 4.3 - latest edition, Gas Wa-
ter Heaters
• SCAQMD Rule 1146.2
• Low-lead content (<.25%) CSA-certified
All Raypak heaters are National oard Approved, and
design-certified and tested by the Canadian Standards
Association (CSA) for the U.S. and Canada. Each
heater is constructed in accordance with Section IV of
the American Society of Mechanical Engineers
(ASME) Heater Pressure Vessel Code and bears the
ASME stamp. This heater also complies with the latest
edition of the ASHRAE 90.1 Standard.
Installations at Elevation
Rated inputs are suitable for up to 2,000 ft elevation
without de-rating. Consult your local representative or
the factory for installations at altitudes over 2,000 ft
above sea level. No hardware changes are required to
the heaters for installations up to 10,000 ft (adjust-
ments may be required).
WARNING: Altering any Raypak pressure vessel
by installing replacement heat exchangers, tube
bundle headers, or any ASME parts not
manufactured and/or approved by Raypak will
instantly void the ASME and CSA ratings of the
vessel and any Raypak warranty on the vessel.
Altering the ASME or CSA ratings of the vessel also
violates national, state, and local approval codes.

General Information
Table A: Basic Data
6
Component Locations
Panels omitted for clarity
Fig. 1: Component Locations – Side
Top panel, blower and gas train omitted for clarity
Fig. 4: Component Locations – Top
Fig. 3: Component Locations – Rear
Panels omitted for clarity
Fig. 2: Component Locations – Front
Model
No.
M TUH
Input Water
Conn.
(NPT)
Gas
Conn.
(NPT)
Vent Size
(in.)
Max. Min. N P Flue Intake
503A 500 70 2 1 1 6 6
753A 750 105 2 1 1 6 6
1003A 999 140 2-1/2 1-1/4 1 6 6
1253A 1250 175 2-1/2 1-1/4 1 8 8
1503A 1500 210 2-1/2 1-1/4 1 8 8
1753A 1750 245 2-1/2 2 1 8 8
2003A 1999 280 2-1/2 2 1 8 8

7
GENERAL SAFETY
To meet commercial hot water use needs, the high
limit safety control on this water heater will shut off the
main gas valve before the outlet temperature reaches
210°F. However, water temperatures over 125°F can
cause instant severe burns or death from scalds.
When supplying general purpose hot water, the rec-
ommended initial setting for the temperature control is
125°F.
This section applies to Hot Water Supply oilers and
Hot Water Heaters ONLY. For sanitary rinse applica-
tions where outlet temperatures of 180°F to 195°F are
required, a boiler is recommended since the 210°F
limit on water heaters will NOT allow the heater to
maintain these desired sanitary rinse temperatures.
Safety and energy conservation are factors to be con-
sidered when setting the water temperature on the
thermostat. The most energy-efficient operation will
result when the temperature setting is the lowest that
satisfies the needs of the application.
Water temperature over 125°F can cause instant
severe burns or death from scalds. Children, disabled
and elderly are at highest risk of being scalded.
• Feel water before bathing or showering.
• Temperature limiting valves are available.
Maximum water temperatures occur just after the
heater’s burner has shut off. To determine the water
temperature being delivered, turn on a hot water
faucet and place a thermometer in the hot water
stream and read the thermometer.
N TE: When this water heater is supplying general
purpose hot water for use by individuals, a
thermostatically controlled mixing valve for reducing
point of use water temperature is recommended to
reduce the risk of scald injury. Contact a licensed
plumber or the local plumbing authority for further
information.
Water temperature over 125°F can
cau s e i nsta n t s e v e r e b u r n s o r d eath
from scalds.
Children, disabled, and elderly are
at highest risk of being scalded.
See instruction manual before set-
ting temperature at water heater.
Feel water before bathing or show-
ering.
Temperature limiting valves are
available, see manual.
Time/Temperature
Relationships in Scalds
The following chart 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.
Water
Temp.
Time to Produce Serious
Burn
120°F More than 5 minutes
125°F 1-1/2 to 2 minutes
130°F About 30 seconds
135°F About 10 seconds
140°F Less than 5 seconds
145°F Less than 3 seconds
150°F About 1-1/2 seconds
155°F About 1 second
Table courtesy of The Shriners Burn Institute
Table B: Time to Produce Serious Burn
CAUTI N: Hotter water increases the risk of
scalding! There is a hot water scald potential if the
thermostat is set too high.

Equipment Base
The heater should be mounted on a level, structurally
sound surface. The heater is approved for installation
on a combustible surface but must NEVER be
installed on carpeting. Gas-fueled equipment installed
in enclosed parking garages must be located at least
18 in. above the floor.
In addition, the heater shall be installed such that the
gas ignition system components are protected from
water (dripping, spraying, rain, etc.) during appliance
operation or service (circulator replacement, control
replacement, etc.).
If the heater needs to be secured to the ground, use
the hole pattern shown in Fig. 5, following local codes.
Additional clearance may be required when using the
factory anchor bracket.
Clearances
Indoor Installations
When installed according to the listed minimum clear-
ances from combustible construction, these heaters
can still be serviced without removing permanent
structural construction around the heater. However, for
ease of servicing, a clearance of at least 24 in. in front,
1 in. on the side, at least 24 in. on the rear and 10 in.
above the top of the heater is required. This will allow
8
Table C: Clearances – Indoor Installations
INSTALLATI N
Installation Codes
Installations must follow these codes:
• Local, state, provincial, and national codes, laws,
regulations and ordinances
• National Fuel Gas Code, ANSI Z223.1/NFPA 54 –
latest edition (NFGC)
• National Electrical Code, ANSI/NFPA 70 - latest
edition (NEC)
• Standard for Controls and Safety Devices for
Automatically Fired oilers, ANSI/ASME CSD-1,
(CSD-1) when required
• For Canada only: CAN/CSA 149 Natural Gas
and Propane Installation Code and CSA C22.1
C.E.C. Part 1 (C22.1)
CAUTI N: This heater should be located in an
area where water leakage will not result in damage
to the area adjacent to the appliances or to the
structure. When such locations cannot be avoided, it
is recommended that a suitable catch pan,
adequately drained, be installed under the
appliance. The pan must not restrict air flow.
Fig. 5: Anchor Hole Locations
Heater
Side
Minimum Clearance
from Combustible
Surfaces
Minimum
Service
Clearance
Floor* 0” 0”
Rear 12” 24”
Right Side 1” 1”
Left Side 1” 1”
Top 0” 10”
Front Open 24”
Vent 1” 1”
*DO NOT install on carpeting.

9
Fig. 6: Minimum Clearances from Combustible
Surfaces – Indoor and Outdoor Installations
lation codes and the requirements of the gas supplier.
Three sides must be open in the area under the over-
hang. Roof water drainage must be diverted away
from heaters installed under overhangs.
The combustion air intake elbow MUST be used for
outdoor installations. It is shipped loose to be installed
at the job site on the air filter intake at rear of the
heater. The elbow MUST be oriented with the opening
facing downward.
Table D: Clearances – Outdoor Installations
the heater to be serviced in its installed location with-
out movement or removal of the heater.
Service clearances less than the minimum may
require removal of the heater to service either the heat
exchanger or the burner components. In either case,
the heater must be installed in a manner that will
enable the heater to be serviced without removing any
structure around the heater.
utdoor Installations
These heaters are design-certified for outdoor installa-
tion. Heaters must not be installed under an overhang
unless clearances are in accordance with local instal-
Combustion and Ventilation Air
Indoor Units
This heater must be supplied with sufficient quantities
of non-contaminated air to support proper combustion
and equipment ventilation. Combustion air can be sup-
plied via conventional means where combustion air is
drawn from the area immediately surrounding the
heater, or via direct vent, where combustion air is
drawn directly from outside. All installations must com-
ply with the requirements of the NFGC (U.S.) and
149 (Canada), and all local codes.
N TE: Use of this heater in construction areas
where fine particulate matter, such as concrete or
dry-wall dust, is present may result in damage to the
heater that is not covered by the warranty. If
operated in a construction environment, a clean
source of combustion air must be provided directly to
the heater.
Heater
Side
Min. Clearance
from Combustible
Surfaces
Minimum
Service
Clearance
Rear 12” 24”
Front Open 24”
Right Side 1” 1”
Left Side 1” 1”
Top Unobstructed 10”
Vent
Termination 12” 12”
CAUTI N: Combustion air must not be
contaminated by corrosive chemical fumes which
can damage the heater and void the warranty. (See
the Appendix.)
N TE: It is recommended that the intake vent be
insulated to minimize sweating.

10
U.S. Installations
1 Canadian Installations 2
A Clearance above grade, veranda, porch,
deck, or balcony 1 ft (30 cm) 1 ft (30 cm)
B Clearance to window or door that may be
opened
4 ft (1.2m) below or to side
of opening; 1 foot (30 cm)
above opening
3 ft (91 cm)
C Clearance to permanently closed window * *
D
Vertical clearance to ventilated soffit located
above the terminal within a horizontal dis-
tance of 2 ft (61cm) from the centerline of the
terminal
5 ft (1.5m) *
E Clearance to unventilated soffit * *
F Clearance to outside corner * *
G Clearance to inside corner 6 ft (1.83m) *
H Clearance to each side of center line ex-
tended above meter/regulator assembly *
I Clearance to service regulator vent outlet * 6 ft (1.83m)
J
Clearance to non-mechanical air supply inlet
to building or the combustion air inlet to any
other appliance
4 ft (1.2m) below or to side
of opening; 1 ft (30 cm)
above opening
3 ft (91 cm)
K Clearance to mechanical air supply inlet 3 ft (91 cm) above if within
10 ft (3m) horizontally 6 ft (1.83m)
L Clearance above paved sidewalk or paved
driveway located on public property 7 ft (2.13m) 7 ft (2.13m) t
M Clearance under veranda, porch, deck or
balcony * 12 in. (30 cm) TT
1 In accordance with the current ANSI Z223.1/NFPA 54 National Fuel Gas Code
2 In accordance with the current CAN/CSA-B149 Installation Codes
t Vent terminal shall not terminate directly above sidewalk or paved driveway located between 2 single family dwellings that serves
both dwellings
TT Permittedonly if veranda, porch, deck, or balcony is fully open on a minimum of two sides beneath the floor and top of terminal and
underside of veranda, porch, deck or balcony is greater than 1 ft (30cm)
* Clearancesinaccordance with local installation codes and the requirements of the gas supplier
3 ft (91 cm) within a
height 15 ft above the
meter/regulator assembly
Fig. 7: Minimum Clearances from Vent/Air Inlet Terminations – Indoor and Outdoor Installations
Table E: Vent/Air Inlet Termination Clearances

11
Air Filter
An air filter is supplied standard with the heater. This
filter is shipped loose for field installation. Refer to the
Air Filter Kit Installation Instructions (Part No. 241338)
for details.
Direct Vent
If outside air is drawn through the intake pipe directly
to the unit for combustion:
1. Install combustion air direct vent in accordance
with Fig. 33 (horizontal) or Fig. 34 (vertical) of this
manual (pages 31 and 32, respectively).
2. Ventilation of the space occupied by the heater(s)
is recommended and can be provided by an open-
ing(s) for ventilation air at the highest practical
point communicating with the outdoors. The total
cross-sectional areas should be at least 1 in.² of
free area per 20,000 TUH (111 mm² per kW) of
total input rating of all equipment in the room,
when the opening is communicating directly with
the outdoors or through vertical duct(s). The total
cross-sectional area should be at least 1in.² of free
area per 10,000 TUH (222 mm² per kW) of total
input rating of all equipment in the room, when the
opening is communicating with the outdoors
through horizontal duct(s). Damage to the equip-
ment due to inadequate ventilation of the space is
not a warrantable failure.
3. In cold climates, and to mitigate potential freeze-
up, Raypak highly recommends the installation of
a motorized sealed damper to prevent the circula-
tion of cold air through the heater during the
non-operating hours.
Motorized Combustion Air Dampers or
Louvers
When dampers or louvers are communicating directly
with outside combustion air, they must be interlocked
with each appliance in the equipment room, to ensure
proper operation. See field wiring connection section
of this manual for proper wiring instructions, using
Fan/Damper dry contacts and external interlock.
TruSeal™ Combustion Air
In addition to the 3 previous steps, combustion air may
be ducted directly to the heater by using PVC, CPVC
or sealed single-wall galvanized ducting. The duct will
attach directly to the air collar located on the inline Air
Filter ox (shipped loose), using 3-4 sheet metal
screws (not supplied) equally positioned around the
circumference of the duct. The screen assembly
should be removed before attaching any air duct. The
screws and duct connection point must be sealed with
RTV (not supplied). TruSeal is generally used when
damaging contaminants are present in the mechanical
room.
All ducting MUST be self-supported.
Conventional Combustion Air
Supply
U.S. Installations
All Air from Inside the Building
The confined space shall be provided with TWO per-
manent openings communicating directly with an
additional room(s) of sufficient volume so that the com-
bined volume of all spaces meets the criteria for a
room large in comparison (NFGC). The total input of all
gas utilization equipment installed in the combined
space shall be considered in making this determina-
tion. Each opening shall have a minimum free area of
1 in.2 per 1,000 TUH (2,225 mm2per kW) of the total
input rating of all gas utilization equipment in the con-
fined space, but not less than 100 in.2(645 cm2). One
opening shall commence within 12 in. (305 mm) of the
top, and one opening shall commence within 12 in.
(305 mm) of the bottom of the enclosure. The mini-
mum dimension of air openings shall be not less than
3 in. (76 mm) in any direction.
CAUTI N: Use TruSeal combustion air if
damaging airborne contaminants are or may be
present in the heater area. See the Appendix of this
manual regarding air contamination.
Fig. 8: Air Filter Box

All Air from utdoors
The confined space shall communicate with the out-
doors in accordance with one of the methods below.
The minimum dimension of air openings shall not be
less than 3 in. (76 mm) in any direction. Where ducts
are used, they shall be of the same cross-sectional
area as the net free area of the openings to which they
connect.
1. Two permanent openings, one commencing
within 12 in. (305 mm) of the top, and one com-
mencing within 12 in. (305 mm) of the bottom of
the enclosure, shall be provided. The openings
shall communicate directly, or by ducts, with the
outdoors or spaces (crawl or attic) that freely com-
municate with the outdoors.
a. Where directly communicating with the out-
doors or where communicating to the
outdoors through vertical ducts, each open-
ing shall have a minimum free area of 1 in.2
per 4,000 TUH (550 mm2per kW) of total
input rating of all equipment in the enclosure.
b. Where communicating with the outdoors
through horizontal ducts, each opening shall
have a minimum free area of 1 in.2per 2,000
TUH (1,100 mm2per kW) of total input rat-
ing of all equipment in the enclosure.
2. One permanent opening, commencing within 12
in. (305 mm) of the top of the enclosure, shall be
permitted where the equipment has clearances of
at least 1 in. (25 mm) from the sides and back and
6 in. (152 mm) from the front of the appliance. The
opening shall directly communicate with the out-
doors or shall communicate through a vertical or
horizontal duct to the outdoors or spaces that
freely communicate with the outdoors, and shall
have a minimum free area of:
a. 1 in.2per 3,000 TUH (740 mm2per kW) of
the total input rating of all equipment located in
the enclosure, and
b. Not less than the sum of the areas of all vent
connectors in the confined space.
12
WARNING: Do not use the “one permanent
opening” method if the equipment room is under
negative pressure conditions.
Canadian Installations
1. Ventilation of the space occupied by the heater
shall be provided by an opening(s) for ventilation
air at the highest practical point communicating
with the outdoors. The total cross-sectional area of
such an opening(s) shall be at least 10% of the
area required in 2. and 3. (below), but in no case
shall the cross-sectional area be less than 10 in.2
(65 cm2).
2. For heaters using a barometric damper in the vent
system there shall be a permanent air supply
opening(s) having a cross section area of not less
than 1 in.2per 7,000 TUH (320 mm2per kW) up
to and including 1 million TUH, plus 1 in.2per
14,000 TUH (160 mm2per kW) in excess of 1
million TUH. This opening(s) shall be either
located at or ducted to a point not more than 18 in.
(450 mm) nor less than 6 in. (152 mm) above the
floor level. The duct can also “goose neck” through
the roof. The duct is preferred to be straight down
and terminated 18 in. (450 mm) from the floor, but
not near piping. This air supply opening require-
ment shall be in addition to the air opening for
ventilation air required in 1. (above).
3. For heaters not using a barometric damper in the
vent system, and when air supply is provided by
natural air flow from outdoors for a power burner
and there is no draft regulator, drafthood or similar
flue gas dilution device installed in the same
space, in addition to the opening for ventilation air
required in 1., there shall be a permanent air sup-
ply opening(s) having a total cross-sectional area
of not less than 1 in.2for each 30,000 TUH (74
mm2per kW) of total rated input of the burner(s),
and the location of the opening(s) shall not inter-
fere with the intended purpose of the opening(s)
for ventilation air referred to in 1. This opening(s)
can be ducted to a point not more than 18 in. (450
mm) nor less than 6 in. (152 mm) above the floor
level. The duct can also “goose neck” through the
roof. The duct is preferred to be straight down 18
in. (450 mm) from the floor, but not near piping.
WARNING: Care must be taken to ensure that the
equipment room is not under negative pressure
conditions.
CAUTI N: All combustion air must be drawn from
the air outside of the building; the mechanical equip-
ment room must communicate directly with the
outdoors.

4. Refer to the 149 Installation Code for additional
information
Water Piping
General
The heater should be located so that any water leaks
will not cause damage to the adjacent area or struc-
tures.
Relief Valve Piping
Temperature & Pressure Gauge
The temperature and pressure gauge is shipped loose
for field installation and must be installed within 12
inches of the boiler outlet (if possible) in an easily
readable location. Installation must comply with ASME
Section IV as well as all applicable national, state and
local codes.
Hydrostatic Test
Unlike many types of heaters, this heater does not re-
quire hydrostatic testing prior to being placed in
operation. The heat exchanger has already been fac-
tory-tested and is rated for 160 psi operating pressure.
However, Raypak does recommend hydrostatic test-
ing of the piping connections to the heater and the rest
of the system prior to operation. This is particularly
true for hydronic systems using expensive glycol-
based anti-freeze. Raypak recommends conducting
the hydrostatic test before connecting gas piping or
electrical supply.
13
Leaks must be repaired at once to prevent damage to
the heater. NEVER use petroleum-based stop-leak
compounds.
To perform hydrostatic test:
1. Connect fill water supply. Fill heater with water.
Carefully fill the rest of the system, making sure to
eliminate any entrapped air by using high-point
vents. Close feed valve. Test at standard operating
pressure for at least 24 hours.
2. Make sure constant gauge pressure has been
maintained throughout test.
3. Check for leaks. Repair any that are found.
Cold Water peration
This heater is equipped with a proprietary condensate
evaporation system which will evaporate any conden-
sate that may begin to accumulate inside the primary
heat exchanger with water temperatures as low as
120°F (49°C).
Heaters operated with an inlet temperature of less
than 120°F (49°C) MUST have an approved low-tem-
perature operation system (Figs. 10 and 11) to prevent
problems with condensation. Inlet water temperatures
below 120°F (49°C) can excessively cool the products
of combustion, resulting in collection of condensate in
the heat exchanger area beyond the capacity of the
condensate evaporation system.
Failure to reach or exceed 120°F (49°C) may damage
or cause failure of the heat exchanger, combustion
chamber, or other parts within the combustion cham-
ber. It can cause operational problems, bad
combustion, sooting, flue gas leakage and reduced
service life of the appliance and the vent system. A
bypass allows part of the heater discharge water to be
mixed with the cooler water returning to the heater
inlet to increase the heater inlet temperature above
120°F (49°C). This precautionary measure should pre-
vent the products of combustion from condensing
beyond the ability of the condensate management sys-
tem employed in this heater in most installations.
Warranty claims will be denied for damage or fail-
ures caused by condensation.
WARNING: Pressure relief valve discharge piping
must be piped near the floor and close to a drain to
eliminate the potential of severe burns. Do not pipe
to any area where freezing could occur. Refer to
local codes.
CAUTI N: Damage due to internal condensation
may occur if the heater inlet water temperature does
not exceed 120°F (49°C) within 7 minutes of start-
up.
CAUTI N: This heater requires forced water
circulation when the burner is operating. See Table F
and Table G for minimum and maximum flow rates.
The pump must be interlocked with the heater to
prevent heater operation without water circulation.
N TE: Minimum pipe size for in/out connections is
2 in. NPT for 503A and 753A models and 2-1⁄2in NPT
for 1003A–2003A models. Verify proper flow rates
and ∆T as instructed in this manual.

14
Cold Water Starts
Cold water starts, where the inlet water temperature
remains below 120°F (49°C) must have cold water
start protection. Known protection methods consist
of mixing heated outlet water with the inlet water using
a bypass to raise the inlet to 120°F (49°C) or higher.
Once the system is heated up and has return water
temperatures of 120°F (49°C) or higher, the mixing of
outlet water with inlet water is no longer needed and
the bypass can be shut off. If the bypass is not shut off
as the system heats up, the outlet temperature may
continue to climb and trip the high limit, thereby shut-
ting down the heater. Thus an automatic valve system,
such as a three-way proportional valve to control the
bypass, should be used.
Cold Water Run
Cold water run differs from cold water start in that the
system water entering the heater remains below
120°F (49°C) continuously. Typically, this is the case in
water source heat pump applications as well as some
others. An injector pump arrangement may be used to
keep the heater loop at or above 120°F (49°C). An
injector pump approach has the added value of being
able to adjust automatically to changes in the system
water coming back to the heater.
Hydronic Heating
Pump Selection
In order to ensure proper performance of your heater
system, you must install a correctly-sized pump. Ray-
pak requires designing for a ∆T within the range of
16°F to 39°F (9°C to 22°C). See Table F for accept-
able flow rates for each model (∆T is the temperature
difference between the inlet and outlet water when the
heater is firing at full rate).
Feedwater Regulator
Raypak recommends that a feedwater regulator be in-
stalled and set at 12 psi minimum pressure at the
highest point of the system. Install a check valve or
back flow device upstream of the regulator, with a
manual shut-off valve as required by local codes.
*
Fig. 9: Cold Water Start
*
Fig. 10: Cold Water Run
*Maximum 4 times the pipe diameter or 12”, whichever is less.
*Maximum 4 times the pipe diameter or 12”, whichever is less.

15
Table F: Heater Rates of Flow and Pressure Drops
Notes: asis for minimum flow is ∆T . asis for maximum flow is gpm.
Piping
All high points should be vented. A heater installed
above radiation level must be provided with a low wa-
ter cut-off device (sales order option F-10). This
heater, when used in connection with a refrigeration
system, must be installed so that the chilled medium is
piped in parallel with the heater with appropriate
valves to pre-vent the chilled medium from entering
the heater.
The piping system of a hot water heater connected to
heating coils located in air handling units where they
may be exposed to circulating refrigerated air, must be
equipped with flow control valves or other automatic
means to prevent gravity circulation of the heater
water during the cooling cycle. It is highly recommend-
ed that the piping be insulated.
Air-Separation/Expansion Tank
All heaters should be equipped with a properly sized
expansion tank and air separator fitting as shown in
Fig. 11.
Fig. 11: Air-Separation/Expansion Tank
Three-Way Valves
Three-way valves intended to regulate system water
temperatures by reducing flow in the boiler should not
be used. Raypak heaters are high-recovery, low-mass
heaters which are not subject to thermal shock.
Applications & Modes
The VERSA IC Control system is designed for a wide
range of applications. The installer/design engineer
should refer to the following Modes to determine which
best fits the intended application and functionality for
the unit being installed.
Type H models of MV have three modes available to
them to address the various applications the units can
be applied to. Type WH units will only have the WH
configuration available to them for use with potable
water applications when directly connected to a hot
water storage tank.
N TE: Hot water heating systems all have unique
levels of operating diversity that must be accounted
for in the system design. The system should always
include adequate system flow in excess of the
connected boiler flow for proper operation. Where
the system flow may drop below the connected
boiler flow a buffer/decoupler may be needed.
Failure to design for adequate flow (i.e. bypasses, 3
way control valves, flow limiting balance devices,
buffer tanks, etc.) will result in boiler short cycling
and may reduce boiler life. Always contact your local
Raypak representative for system design assistance
to avoid these issues.
GPM PGPM PGPM PGPM P T GPM P T
503A 44 2.8 29 1.4 N/A N/A 25 1.1 35 100 11.3 9
753A 65 6.4 44 3.1 33 1.9 33 1.9 39 100 13.8 13
1003A 87 12.0 58 6.0 45 3.8 45 3.8 39 113 18.6 15
1253A 109 20.9 73 10.2 56 6.5 56 6.5 39 113 22.2 19
1503A N/A N/A 87 16.0 67 10.0 67 10.0 39 113 25.5 23
1753A N/A N/A 102 22.5 78 14.0 78 14.0 39 113 27.2 27
2003A N/A N/A 116 31.9 89 19.8 89 19.8 39 116 32.0 30
Max Flow
MVB
Model
20° T
30° T
39° T
Min Flow

16
Mode 2 (Type H Units nly)
This mode selection is for hydronic heating systems
with single or multiple boilers (Maximum 4 boilers) in
primary/secondary piping configuration with or without
Outdoor Air Reset (S4) with indirect DHW on the sys-
tem loop (with or without priority). The system
temperature is controlled by the System sensor (S3).
The Indirect DHW sensor (S5) determines the indirect
call/tank setpoint. The system temperature is boosted
to Target Max when using the Indirect DHW sensor
(S5) during an indirect call for heat. Priority mode tog-
gles off the System Pump (P2) when an indirect call for
heat is present. The oiler Pump (P1) runs during any
call for heat. The Indirect DHW Pump (P3) runs during
an indirect call for heat with no “off” delay. The oiler
Pump (P1) and System Pump (P2) delay “off” as user
defined in the ADJUST menu. The System Pump (P2)
runs whenever the system is enabled for heating and
the outdoor air temperature is lower than the WWSD
temperature setting (if utilized) unless an indirect call
for heat is present with priority.
Fig. 12: MODE 1 - Single Boiler with
Primary/Secondary Piping
Fig. 14: MODE 2 - Single Boiler with Indirect
on System Loop
Mode 1 (Type H Units nly)
This mode selection is for hydronic heating systems
with single or multiple boilers (Maximum 4 boilers) in
primary/secondary piping configuration with or without
Outdoor Air Reset (S4). The system temperature is
controlled by the System sensor (S3). The oiler
Pump (P1) runs during any call for heat. The System
Pump (P2) runs whenever the system is enabled for
heating and the outdoor air temperature is lower than
the warm weather shut down (WWSD) temperature
setting (if utilized). The oiler Pump and System Pump
are delayed “off” as user defined in the ADJUST
menu.
NTE: MODE 1 can also be used for process heat-
ing applications in conjunction with a buffer/storage
tank when operating temperatures above 160°F are
required. Care must be given to ensure water hard-
ness is no more than 15 grains per gallon for scale
free operation.
Fig. 13: MODE 1 - Boiler Cascade with
Primary/Secondary Piping

17
Mode 3 (Type H Units nly)
This mode selection is for hydronic heating systems
with single or multiple boilers (Maximum 4 boilers) in
primary/secondary piping configuration with or without
Outdoor Air Reset (S4) with indirect DHW on the boil-
er loop (with priority). The system temperature is
controlled by the Supply sensor (S3) whenever the
indirect call for heat is not active. The DHW Supply
sensor (S5) determines the indirect call/tank setpoint.
During an indirect call for heat the boiler firing rate is
determined by the water temperature at the Indirect
Supply sensor (S6) and the Target Max setting when
using the Indirect DHW sensor (S5). The oiler Pump
(P1) runs during all heat calls regardless of priority.
The Indirect DHW Pump (P3) runs during an indirect
call for heat with no “off” delay. The oiler Pump (P1)
and System Pump (P2) delay “off” as user defined in
the ADJUST menu. The system pump (P2) runs
whenever the system is enabled for heating and the
outdoor air temperature is lower than the WWSD tem-
perature setting (if utilized) unless an indirect call for
heat is present.
Fig. 15: MODE 3 - Single Boiler with Indirect
on Boiler Loop
N TE: A Tank Aquastat can be used in lieu of the
Indirect DHW Sensor (S5). See the Versa IC manu-
al for additional details.
Domestic Hot Water
When designing the water piping system for domestic
hot water applications, water hardness should be con-
sidered. Table G indicates the suggested flow rates for
soft, medium and hard water. Water hardness is ex-
pressed in grains per gallon.
Fig. 16: WH Units - Single Water Heater with Tank
H Units - Single Boiler with Process Tank
WH – Direct DHW Configuration
When the unit is ordered as a “WH” configuration the
only application available to it is direct DHW with sin-
gle or multiple heaters (Maximum 4 heaters). The tank
temperature is controlled by the System sensor (S3).
The oiler Pump (P1) runs during any call for heat.
The System Pump (P2) output is active whenever the
system is enabled. The oiler Pump is delayed “off”
after the Tank Target temperature is achieved and as
user defined in the ADJUST menu.
N TE: WH units will operate to a maximum tank
temperature of 160°F. For temperatures required
above 160°F an “H” model boiler must be used and
great care must be given to ensure water hardness
is no more than 15 grains per gallon for scale free
operation. MODE 1 should be used and configured
for setpoint operation for process heating applica-
tions.
N TE: If local codes require a vacuum relief valve,
acquire one locally and install per valve
manufacturer’s instructions.

N TE: Failure of a heat exchanger due to lime
scale build-up on the heating surface, low pH or
other chemical imbalance is non-warrantable.
N TE: High chemical concentrates from feeders
that are out of adjustment will cause rapid corrosion
to the heat exchanger. Such damage is not covered
under the warranty.
18
Potable Water and Space Heating
1. All piping materials and components connected to
the water heater for the space heating application
shall be suitable for use with potable water.
2. Toxic chemicals, such as used for boiler treatment,
shall not be introduced into the potable water used
for space heating.
3. If the heater will be used to supply potable water,
it shall not be connected to any heating system or
components previously used with a non-potable
water heating appliance.
4. When the system requires water for space heating
at temperatures higher than 140°F (60°C), a
means such as a mixing valve shall be installed to
temper the water in order to reduce scald hazard
potential.
CAUTI N: When this heater is used for both
potable water and space heating, observe the
following to ensure proper operation.
∆T = Temperature rise, °F
∆P = Pressure drop through heat exchanger, ft
SHL = System head loss, ft (based on heater and tank connections of no more than 100 eq. ft. of tubing)
gpm = Gallons per minute, flow rate
MTS = Minimum tubing size
*Must utilize optional cupro-nickel tubes. If over 25 grains per gallon, a water softener/treatment system must be utilized.
**Caution: For scale free operation with "Hard Water" (16-25 grains per gallon of total hardness), the operating control must NOT be set
higher than 130 F. For higher than 130 F operation, a water softener/treatment system must be utilized.
***Care should be given to prevent over-softening of the water as over-softened water can become aggressive. Cupro-nickel tubes are
recommended for water softened below 5 grains per gallon.
Table G: Domestic Water Heater Flow Rate Requirements
CAUTI N: Combustion air must not be
contaminated by corrosive chemical fumes which
can damage the heater and void the warranty.
Automatic Chemical Feeders
All chemicals must be introduced and completely dilut-
ed into the water before being circulated through the
heater. High chemical concentrations will result when
the pump is not running (e.g. overnight).
WATER HARDNESS
SOFT* MEDIUM HARD*
3-4 Grains Per Gallon 5-15 Grains Per Gallon 16-25** Grains Per Gallon
MVB
Model
T
(ºF) GPM
P
(ft wc)
MTS
(in)
SHL
(ft wc)
T(ºF) GPM
P
(ft wc)
MTS
(in)
SHL
(ft wc)
T(ºF) GPM
P
(ft wc)
MTS
(in)
SHL
(ft wc)
503A 17 50 3.6 2 8.3 17 50 3.6 2 8.3 9 95 10.4 2 25.7
753A 26 50 4.0 2 8.7 18 73 7.8 2 17.3 15 90 11.4 2 25.3
1003A 20 85 11.5 2 1/2 16.2 20 85 11.5 2 1/2 16.2 15 116 19.6 2 1/2 27.8
1253A 27 80 12.2 2 1/2 16.3 20 109 21.0 2 1/2 28.3 20 109 21.0 2 1/2 28.3
1503A 28 94 18.4 2 1/2 24.0 25 105 22.5 2 1/2 29.3 23 115 26.5 2 1/2 34.6
1753A 29 104 23.6 2 1/2 30.3 27 113 27.4 2 1/2 35.2 27 113 27.4 2 1/2 35.2
2003A 29 118 33.0 2 1/2 41.5 29 118 33.0 2 1/2 41.5 29 118 33.0 2 1/2 41.5

19
Gas Supply
Gas piping must have a sediment trap ahead of the
heater gas controls, and a manual shut-off valve lo-
cated outside the heater jacket. It is recommended
that a union be installed in the gas supply piping adja-
cent to the heater for servicing. The gas supply
pressure to the heater must not exceed 10.5 in. WC for
natural gas or 13.0 in. WC for propane gas. A pounds-
to-inches regulator must be installed to reduce the gas
supply pressure if it is higher than noted above. This
regulator should be placed a minimum distance of 10
times the pipe diameter upstream of the heater gas
controls. Refer to Table H for maximum pipe lengths.
Gas Supply Connection
The heater must be isolated from the gas supply pip-
ing system by closing the upstream manual shut-off
valve during any pressure testing of the gas supply
piping system at test pressures equal to or less than
1/2 psi (3.45 kPa). Relieve test pressure in the gas
supply line prior to re-connecting the heater and its
manual shut-off valve to the gas supply line. FAILURE
TO FOLLOW THIS PROCEDURE MAY DAMAGE
THE GAS VALVE. Over-pressurized gas valves are
not covered by warranty. The heater and its gas con-
nections shall be leak-tested before placing the
appliance in operation. Use soapy water for leak test.
DO NOT use an open flame.
DANGER: Make sure the gas on which the heater
will operate is the same type as specified on the
heater’s rating plate.
CAUTI N: The heater must be disconnected from
the gas supply during any pressure testing of the gas
supply system at test pressures in excess of 1/2 psi
(3.45 kPa).
Gas Supply Pressure
A minimum of 4.0 in. WC upstream gas pressure
under full load and a maximum gas supply pressure
setpoint of 10.5 in. WC under load and no-load condi-
tions for natural gas. A minimum of 4.0 in. WC
upstream gas pressure under full load and a maximum
gas supply pressure setpoint of 13.0 in. WC is required
for propane gas. The gas pressure regulator(s) sup-
plied on the heater is for low-pressure service. If
upstream pressure exceeds 1/2 psi at any time, an
intermediate gas pressure regulator, of the lockup
type, must be installed. This regulator should be
placed a minimum distance of 10 times the pipe diam-
eter upstream of the heater gas controls.
When connecting additional gas utilization equipment
to the gas piping system, the existing piping must be
checked to determine if it has adequate capacity for
the combined load.
The gas valve pressure regulator on the heater is
nominally preset as noted in Table I.
During normal operation, carbon dioxide should be
9.0% ± 0.2% at full fire for natural gas and
10.2% ± 0.2% for propane gas. Carbon monoxide
should be ‹100ppm at all firing rates, measured at the
test port, 12” above the flue collar.
Fig. 17: Gas Supply Connection
CAUTI N: Do not use Teflon tape on gas line pipe
thread. A pipe compound rated for use with natural
and propane gases is recommended. Apply
sparingly only on male pipe ends, leaving the two
end threads bare.
CAUTI N: Support gas supply piping with
hangers, not by the heater or its accessories. Make
sure the gas piping is protected from physical
damage and freezing, where required.

20
The MV 503A-1503A heaters are wired for 120 VAC,
12 amps while the MV 1753A & 2003A heaters are
wired for 120 VAC, 18 amps. Consult the wiring dia-
gram shipped with the heater. efore starting the
heater, check to ensure proper voltage to the heater
and pump.
Pumps must use a separate power supply and run the
power through the pump contactor, which is located in
the rear wiring box. Use appropriately-sized wire as
defined by NEC, CSA and/or local codes. All primary
wiring should be 125% of minimum rating.
If any of the original wire as supplied with the heater
must be replaced, it must be replaced with 105°C wire
or its equivalent.
All high voltage wiring connections to the MV heater
are made inside the rear wiring box as shown in
Fig. 18. Power for indirect DHW pump not exceeding
5 amps should be taken from terminals 4(Hot), 5
(Com), and 6 (Gnd). Power for system pump not
exceeding 5 amps should be taken from terminals 7
(Hot), 8 (Com), and 9 (Gnd). Power for boiler pumps
3/4 HP and smaller should be taken from terminals 1
(Hot), 2 (Com), and 3 (Gnd), and must be routed
through the pump contactor; 30A supply is required.
Power for pumps larger than 3/4 HP must be a sepa-
rate circuit wired through the pump contactor. Power to
the MV heater should be connected to Terminals 1,
2, and 3 as noted in Fig. 18. All low voltage wiring,
including sensors, interlocks, enable/disable, and var-
ious options are wired into terminals 1–24 on the front
wiring panel as noted in Fig. 23.
Electrical Power Connections
Installations must follow these codes:
• National Electrical Code and any other national,
state, provincial or local codes or regulations hav-
ing jurisdiction.
• Safety wiring must be NEC Class 1.
• Heater must be electrically grounded as required
by the NEC.
• In Canada, CSA C22. 1 C.E.C. Part 1.
Natural Gas – 1,000 TU/ft3, 0.60 specific gravity at 0.5 in. WC pressure drop •
Propane Gas – 2,500 TU/ft3, 1.53 specific gravity at 0.6 in. WC pressure drop•
Table H: Maximum Equivalent Pipe Length
NOTE: Manifold pressures should be ±0.2 in. WC.
Table I: Manifold Gas Pressure Settings
CAUTI N: For proper operation, no more than a
30% drop in gas supply pressure from no-load to full-
load conditions is acceptable. Under no
circumstances should the pressure be outside the
listed operational range.
Model
No.
1 in. NPT 1-1/4 in. NPT 1-1/2 in. NPT 2 in. NPT 2-1/2 in. NPT
N P N P N P N P N P
503A 15 35 65 150 130 360
753A 5 1565100 75180 250
1103A 35 55 35 90 125 300 300
1253A 15 25 25 60 85 225 200 300
1503A 10 15 15 25 60 150 150 275
1753A 45 110 115 230
2003A 35 90 85 210
Model
Manifold Gas Pressure
(High Fire Values)
Natural Gas Propane Gas
503A -4.7 -5.3
753A -4.6 -5.8
1003A -5.9 -7.5
1253A -6.3 -8.3
1503A -8.3 -10.8
1753A -4.5 -7.6
2003A -6.4 -10.4