Pentair Pool Products MiniMax 250 Manual

Rev. C 11-1-01 P/N 471593
1
1
FOR YOUR SAFETY - READ BEFORE OPERATING
Warning: If you do not follow these instructions exactly, a fire or explosion may
result, causing property damage, personal injury or loss of life.
For additional free copies of this manual; call [phone].
Do not store or use gasoline or other flammable vapors and
liquids in the vicinity of this or other appliances.
For Your
Safety
Warning: Improper installation, adjustment, alteration, service or maintenance can
cause property damage, personal injury or death. Installation and service must be
performed by a qualified installer, service agency or the gas supplier.
MiniMax®NT Low NOx Series
POOL & SPA HEATERS
OPERATION & INSTALLATION MANUAL
WARNING
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 fire department.
WARNING
U.S. Patent Numbers
5,318,007 - 5,228,618
5,201,307 - 4,595,825
Pentair Pool Products, Inc.
1620 Hawkins Ave., Sanford, NC 27330 •[phone]
10951 W. Los Angeles Ave., Moorpark, CA 93021 •[phone]
1
To
Consumer
Retain For
Future
Reference

P/N 471593 Rev. C 11-1-01
2
Table of Contents
Introduction ............................................................................................................... 3
Important Notices ...................................................................................................................................................................... 3
Code Requirements ................................................................................................................................................................... 3
Warranty Information ................................................................................................................................................................. 4
Operation .................................................................................................................... 4
Safety Rules .............................................................................................................................................................................. 4
HSI (Hot-Surface Ignition) Lighting/Operation - Natural Gas ..................................................................................................... 5
Installation Instructions—Specifications................................................................. 6
Installation — Electrical ............................................................................................................................................................. 7
Installation — Remotes (2 and 3 Wire) ...................................................................................................................................... 8 - 9
Installation — Wiring Diagram ................................................................................................................................................... 10 - 12
Installation — Water Connections.............................................................................................................................................. 13
Installation — Plumbing ............................................................................................................................................................. 13
Installation — Gas Line ............................................................................................................................................................. 14
Pipe Sizing Chart/Gas Pressure Requirements ......................................................................................................................... 14
Regulated Manifold Pressure Test ............................................................................................................................................. 14
Venting — Indoor Installations ................................................................................................................................................... 15 - 18
Venting — Outdoor Installations ................................................................................................................................................ 19
Basic Operation — General Description .................................................................................................................................... 20
Basic Operation — Safety Controls ...........................................................................................................................................21 - 22
Basic Operation — HSI Ignition Module .................................................................................................................................... 22
Thermostat (Programming & Layout) ........................................................................................................................................ 23
Temperature & Time Setting (Programming) .............................................................................................................................24 - 25
Maintenance ............................................................................................................................ 26
Maintenance Instructions ........................................................................................................................................................... 26
Pressure Relief Valve ................................................................................................................................................................ 26
Maintenance (Water Treatment) ................................................................................................................................................ 27
Trouble Shooting ....................................................................................................... 28
Normal Operation Sequence ..................................................................................................................................................... 28 - 29
Troubleshooting & Service ......................................................................................................................................................... 30 - 31
Troubleshooting (General) ......................................................................................................................................................... 32
MiniMax NT Low NOx Parts List & Exploded View (Single Voltage) ......................................... 33-34
MiniMax NT Low NOx Parts List & Exploded View (Dual Voltage) ............................................ 35-36
Warranty Information ................................................................................................. Back Cover

Rev. C 11-1-01 P/N 471593
3
MiniMax NT Low NOx
Pool and Spa Heaters
Congratulations on your purchase of a MiniMax NT Low NOx high performance heating system. Proper
installation and service of your new heating system and correct chemical maintenance of the water will
ensure years of enjoyment. The MiniMax NT Low NOx is a compact, lightweight, efficient, induced-draft,
gas fired high performance pool and spa heater that can be directly connected to schedule 40 PVC pipe. The
MiniMax NT Low NOx, also comes equipped with the Pentair multifunction temperature controller 7800
which shows, at a glance, the proper functioning of the heater. All HSI (hot-surface ignition) MiniMax NT
Low NOx heaters are designed with a direct ignition device (HSI) which eliminates the need for a standing
pilot. The MiniMax NT Low NOx requires an external power source (120/240 VAC 50/60 Hz) to operate.
IMPORTANT NOTICES
...For the installer and operator of the MiniMax NT Low NOx pool and spa heater. The manufacturer’s
warranty may be void if, for any reason, the heater is improperly installed and/or operated. Be sure to follow
the instructions set forth in this manual. If you need any more information, or if you have any questions
regarding to this pool heater, please contact Pentair Pool Products, Inc. at [phone].
These heaters are designed for the heating of swimming pools and spas, and should never be employed for
use as space heating boilers, general purpose water heaters, in non-stationary installations, or for the heating
of salt water.
Do not use the heater to protect pools or spas from freezing if the final maintenance temperature desired is
below 60° F. as this will cause condensation related problems.
CODE REQUIREMENTS
The installation must conform with local codes or in the absence of local codes with the latest National Fuel
Gas Code, ANSI Z223.1, and the latest edition of the National Electrical Code, NFPA 70.
Installation in Canada to be made in accordance with the latest CAN/CGA-B149.1 or .2 and CSA C22.1
Canadian Electric Code, part 1.
Introduction

P/N 471593 Rev. C 11-1-01
4
Operation
This instruction manual provides operating
instructions, installation and service information
for the MiniMax NT Low NOx high performance
heater. The information in this manual applies to
the MiniMax NT Low NOx 200, 250, 300, and
400 natural gas models.
It is very important that the owner/installer read
and understand the section covering installation
instructions, and recognize the local and state codes
before installing the MiniMax NT Low NOx.
History and experience has shown that most heater
damage is caused by improper installation practices.
SAFETY RULES
1. Spa or hot tub water temperatures should never
exceed 104° F. A temperature of 100° F. is
considered safe for a healthy adult. Special
caution is suggested for young children.
2. Drinking of alcoholic beverages before or during
spa or hot tub use can cause drowsiness which
could lead to unconsciousness and subsequently
result in drowning.
3. Pregnant women beware! Soaking in water
above 100° F. can cause fetal damage during the
first three months of pregnancy (resulting in the
birth of a brain-damaged or deformed child).
Pregnant women should stick to the 100° F.
maximum rule.
4. Before entering the spa or hot tub, the user
should check the water temperature with an
accurate thermometer. Spa or hot tub
thermostats may err in regulating water
temperatures by as much as 4° F.
5. Persons with a medical history of heart disease,
circulatory problems, diabetes or blood pressure
problems should obtain their physician's advice
before using spas or hot tubs.
6. Persons taking medication which induce
drowsiness, such as tranquilizers, antihistamines
or anticoagulants should not use spas or hot
tubs.
Should overheating occur or the gas supply fail to shut off, turn off the manual gas control valve to the
appliance. 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 control system and gas control which has been
under water.
WARNING
WARRANTY INFORMATION
The MiniMax NT Low NOx pool heater is sold
with a limited factory warranty. Specific details are
described on the back cover of this manual and a
copy of the warranty and warranty registration
card are included with the product.Return the
warranty registration card after filling in the serial
number from the rating plate inside the heater.
Pentair Pool Products’ high standards of excellence
include a policy of continuous product improvement
resulting in your state-of-the-art heater. We reserve
the right to make improvements which change the
specifications of the heater without incurring an
obligation to update the current heater equipment.
Operation

Rev. C 11-1-01 P/N 471593
5
Operation (Lighting)
FOR YOUR SAFETY: READ BEFORE LIGHTING
A. This heater is equipped with an ignition device
which automatically lights the main burners.
Do not try to light the burners by hand.
B. BEFORE OPERATING, smell all around
the heater area for gas. Be sure to smell next
to the floor because some gas is heavier than
air and will settle on the floor.
WHAT TO DO IF YOU SMELL GAS
- Do not try to light any heater.
- 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.
C. Use only your hand to push in or turn the gas
control knob. Never use tools. If the knob will
not push in or turn by hand, don't try to repair it.
Call a qualified service technician. Forced or
attempted repair may result in a fire or explosion.
D. 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.
E. The MiniMax NT Low NOx incorporates the
Pentair temperature controller 7800 to aid you
in the operation of the heater, and to assist in
diagnosing a failure in the heater’s function.
MINIMAX NT LOW NOx HSI ELECTRONIC IGNITION LIGHTING/OPERATION - NATURAL GAS
1.STOP! Read the safety information above.
2. Set the thermostat to the lowest setting.
3. Turn off electric power to the heater.
4. This heater is equipped with an ignition device
which automatically lights main burners. Do
not try to light the burners by hand.
5. Remove the control access door.
6. Push in gas control knob slightly and turn clock-
wise to “OFF”. (If not on “OFF” position.)
7. Wait five (5) minutes to clear out any gas. If you
then smell gas, STOP! Follow "B" in the safety
information above. If you don't smell gas, go to the
next step.
8. Turn knob on gas control counterclockwise
to “ON”; see Figure 1.
If you do not follow these instructions exactly, a fire or explosion may result causing personal injury, loss of life
and property damage.
Do not attempt to light the heater if you suspect a natural gas leak. Lighting the heater can result in a fire or
explosion which can cause personal injury, death, and property damage.
WARNING
9. Replace the control access door.
10. Turn on the electrical power to the heater.
11. Set the thermostat to the desired setting.
12. If the heater will not operate, follow the instruc-
tions "To Turn Off Gas To Heater" and call your
service technician or gas supplier.
OPERATING INSTRUCTIONS
TO TURN OFF GAS TO APPLIANCE
1. Set the thermostat to lowest setting.
2. Turn off all electric power to the heater if
service is to be performed.
3. Remove control access door.
4. Push in gas control knob slightly and turn
clockwise to "OFF". Do not force.
5. Replace control access door.
Gas control knob shown in “ON” position.
Figure 1.
OFF
ON
Gas
Inlet

P/N 471593 Rev. C 11-1-01
6
Installation Instructions
IMPORTANT NOTICE: These installation instructions are designed for use by qualified personnel
only, trained especially for installation of this type of heating equipment and related components. Some
states require installation and repair by licensed personnel. If this applies in your state, be sure your
contractor bears the appropriate license.
SPECIFICATIONS
24.05
2 in. SOCKET
"A" DIM.
8.84
6.64
30.63
LEG
LEG
14.50
3.50
4.875
MODEL
200
250 24.63
21.63
"A" DIM.
15.50
300
400 34.13
27.63
7.35
24.05
"A" DIM.
8.84
6.64
30.63
LEG
LEG
14.50
3.50
4.875
INDOOR VENT ADAPTOR
4 in. Kit
P/N 460506
5 in. Kit
P/N 460507
15.50
7.35
Ø4.88
Ø5.88
4 in. Kit
P/N 460506
2.00
5 in. Kit
P/N 460507
MODEL
200
250 24.63
21.63
"A" DIM.
300
400 34.13
27.63
OUTDOOR VENTILATION
INDOOR VENTILATION
Figure 2.
Figure 3.

Rev. C 11-1-01 P/N 471593
7
Installation (Electrical)
ELECTRICAL, ALL HSI UNITS
Electrical Rating 50/60 Hz 120 V.A.C. ONLY
NOTE
The transformer is pre-wired at the factory for 120 VAC operation ,connect line
supply to the line terminal block inside junction box. Use caution in con-
necting supply to proper Line (L), Neutral (N), and Ground (GND) terminals;
see below, Figure 5.
NOTE
If any of the original wiring supplied with this heater must be replaced, installer must supply
(No. 18 AWG 105° C. U.L. approved AWM low energy stranded) copper wire or it’s equivalent.
In Canada: wires must be CSA approved.
WARNING
The heater must be electrically grounded and bonded in accordance with local codes or, in the absence
of local codes, with the latest national electrical codes ANSI/NFPA No. 70.
In Canada: CSA standard C22.1 Canada Electrical Code Part 1 and/or local codes.
Always use crimp type connectors when connecting two wires.
L
N
GREEN WIRE
WHITE WIRE
BLACK WIRE
GROUND
CONNECTION
NEUTRAL / WHITE 120 VAC
POSITIVE LINE FOR 120 VOLTS AC
INTERNAL
FACTORY WIRES
LINE TERMINAL BLOCK
Figure 5.

P/N 471593 Rev. C 11-1-01
8
TWO-WIRE OR THREE-WIRE REMOTE HOOK-UP
Installation (Remotes)
Before connecting the remote control system please read the following:
1. First turn the gas valve to the "OFF" position and power up the
heater, now using the front buttons on the temperature controller,
set the "SPA" and "POOL" temperature to the maximum setting,
see Page 24.
2. Now turn the heater to the "OFF" mode by using the "OFF" button
on the temperature controller, see Page 24 or by using the main
power switch located on the bottom of the junction box.
3. With the heater in the "OFF" mode, locate the three tabs on the back
of the temperature controller as viewed from the backside,
see Figure 6.
4. • Two-wire remote with temperature control:
a) Using 3/16" female quick disconnect connectors, connect one
wire to the "GND" tab of the temperature controller, then the
second wire to either the "SPA" or "POOL" tab.
b) Now return power to the heater but leaving the temperature controller in the "OFF" position,
see Page 24. (Note: If you used the main power switch to turn off the heater, now turn the main power
switch on.) At this time the remote system has control over the heater, and will turn it on and off when
called for by the remote system thermostat thus keep the pool and spa at the desired temperature.
123
POOL SPA GND
Figure 6.
10 A
25O V
RELAY
5 A
25O V
RELAY
10 A
25O V
RELAY
TPROBE
AUX2
POWERLIMITSG VALVEIGN MODULE
24 VAC
PV PV/MV
MV
PV/MV
PV
MV
24 VAC
H LIMIT
T FUSE
PRESS
BLOWER
A.C LOAD (PUMP/AUX2)
(PILOT DUTY ONLY)
3
4
1234 123 123456 12 12
1
2
3
1
F
2
TEMPERATURE
DISPLAY MODE 3
C
5 A FUSE
FOR AUX2 (PILOT DUTY ONLY)
2
13
(AUX1)
REMOTE
AIR PRESS
POOL SPA GND
BLOWER (POWER) LINE
BLOWER (POWER) LINE
PUMP/AUX2
PURGE PUMP
MODE
135
642
531
246
J1 J2
} NOT USED
SPA GND
REMOTE SWITCH CONTROLLER
2 WIRE REMOTE
Figure 7.
Three-Wire continued on next page.

Rev. C 11-1-01 P/N 471593
9
• Three-wire remote:
a) Using 3/16" female quick disconnect connectors, connect the common wire to the "GND" tab of the
temperature controller, then connect the two remaining wires to the temperature controller
corresponding to the remote control device, pool wire to "POOL" tab, spa wire to "SPA" tab.
b) Now return power to the heater. (Note: If you used the main power switch to turn off the heater, now
turn the main power switch on.) At this time, the remote system has control over the heater and if pool
or spa temperature is below the temperature controller setting, then the heater will try to come on.
c) If you desire to reset the temperature settings of the temperature controller, the remote has to be in the
desired mode for you to change the particular setting. Example: You wish to raise or lower the pool
temperature from the factory setting, you must have the remote system in the pool mode, if you wish to
change the spa temperature, you must have the remote system in the spa mode.
5. Now turn on the gas valve to "OPEN" position, the heater is now ready to
operate.
NOTE
The heater factory settings are 78° F. for the pool and 104° F. for the spa.
When connecting a remote control to the MiniMax, you must install the low
voltage thermostat wires in separate conduit from ANY line voltage wires.
Failure to follow these instructions will cause the thermostat relay to react
erratically. A Remote hook-up deactivates the selector keys on the front
thermostat display panel and gives selection control to the remote.
TWO-WIRE OR THREE-WIRE REMOTE HOOK-UP, (cont’d.)
Installation (Remotes)
10 A
25O V
RELAY
5 A
25O V
RELAY
10 A
25O V
RELAY
TPROBE
AUX2
POWERLIMITSG VALVEIGN MODULE
24 VAC
PV PV/MV
MV
PV/MV
PV
MV
24 VAC
H LIMIT
T FUSE
PRESS
BLOWER
A.C LOAD (PUMP/AUX2)
(PILOT DUTY ONLY)
3
4
1234 123 123456 12 12
1
2
3
1
F
2
TEMPERATURE
DISPLAY MODE
POOL
3
C
5 A FUSE
FOR AUX2 (PILOT DUTY ONLY)
2
13
(AUX1)
REMOTE
AIR PRESS
POOL SPA GND
POOL SPA GND
BLOWER (POWER) LINE
BLOWER (POWER) LINE
PUMP/AUX2
PURGE PUMP
MODE
135
642
531
246
J1 J2
REMOTE POOL/OFF/SPA
THERMOSTAT SELECT SWITCH
}NOT USED
COMMON
SPA
3 WIRE REMOTE
This icon is not a fault icon
but instead indicates a remote
switching device is connected
to the Pentair Temperature
Controller 7800, and has
overriding selection control
of Pentair Temperature
Controller 7800.
Figure 8.

P/N 471593 Rev. C 11-1-01
10
Installation (Single Voltage Wiring)
MiniMax NT Low NOx 400 HSI Electronic Ignition Wiring Diagram
(SINGLE VOLTAGE)
GRN
IGN MODULE
IGNITOR
HOT SURFACE
BURNER
LOW GAS PRES.
SWITCH
GRN VAL TH S2 L2 L1 S1
MiniMax NT 400 LOW NOx WIRING DIAGRAM IF ORIGINAL FACTORY WIRING MUST BE REPLACED, INSTALLER MUST SUPPLY UL OR CSA (IF CANADA) APPROVED WIRE, 18 GAUGE, 600V, 105 C TEMPERATURE RATING. THERMAL FUSE WIRING MUST BE REPLACED WITH UL OR CSA (IF CANADA) APPROVED WIRE, 18 GAUGE, 600V, 125 C TEMPERATURE RATING. INTERCONNECTING WIRING TO APPLIANCE MUST CONFORM TO THE NATIONAL ELECTRICAL CODE OR SUPERCEDING LOCAL (WIRING) CODES.
SHEET METAL
GROUND SCREW WITH PAINT CUTTING WASHER
TERMINATE SUPPLY SAFETY GROUND WIRE (GREEN) HERE
CHASSIS
BOND LUG EXTERNAL
ORG WHT
GRN
2
1
3
2
1
4
3
2
5
1
4
3
6
2
1
W2
W1
F2
F1
P11P10P7P4
ORG
RED
THERMAL FUSE
WHT
BLU
RED
SWITCH
WATER PRESSURE
THERMAL SWITCHES
EXHAUST HIGH LIMIT
NEU
HOT
GAS VALVE
BLU
WHT
RED
432112312345612
10A 250V RELAY RELAY 250V 10A
5A 250V RELAY
LIMITS G VALVE IGN MODULEPOWERTPROBE
REMOTE
AUX2
123
FC
BLOWER 2
1
3
1
2
TEMPERATURE
PROBE
RED
HIGH LIMIT
THERMAL SWITCHES
120 VAC
FROM
(ONLY)
FROM
COM
SPA
POOL
1 2 3 4 5
3 2 1
BTERM
GRN NEU
HOT (ONLY)
SUPPLY 120 VAC
AIR PR SW.
SWITCH
LOW AIR PRES.
SWITCH
HI AIR PRES.
HI SPEED
LOW SPEED
COM
DUAL
SPEED
FAN
HOT SURFACE
IGNITOR
(NEU)
(HOT)
FC FL FH PC PL PH
24VAC
RET
FAN CON. BOARD
ORG
BLU
RED
WHT
BLOCK A
TERM BLOCK
TERM BLOCK
TERM BLOCK
B
B
WHT
BLK
WHT
BLK
BLK
WHT
WHT
ORG
ORG
ORG
ORG
WHT
ORG ORG ORG BLK
BLK
WHT
RED
BLK
ORG
ORG
ORG
BLK
(HOT)
N
WHT
WHT
WHT
WHT
RED