Pentair MiniMax 525 User manual

1
Rev. K 5-31-06 P/N 470880
MiniMax®, PowerMax™ , Low NOx™ &
MiniMax®with CSD-1 Option
COMMERCIAL SERIES POOL HEATERS
OPERATION & INSTALLATION MANUAL
U.S. Patent Numbers
6,295,980
5,318,007 - 5,228,618
5,201,307 - 4,595,825
Pentair Water Pool and Spa, Inc.
1620 Hawkins Ave., Sanford, NC 27330 •[phone]
10951 West Los Angeles Ave., Moorpark, CA 93021 •[phone]
— Do not store or use gasoline or other flammable vapors and liquids in the
vicinity of this or other appliances.
— 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.
— Installation and service must be performed by a licensed qualified installer,
service agency or the gas supplier.
WARNING
If the information in these instructions are not followed exactly, a fire or
explosion may result, causing property damage, personal injury or death.
For additional free copies of this manual; call [phone].
To
Consumer
Retain For
Future
Reference
SERVCEI
SPA
COLD
OFF
POOLTEMP
COLD HOT
SPATEMP
HOT
THERMOSTAT
TSTAT
AUX.
PRESS
HEAT
POOL
SELECT
POWER
MiniMax
HighPerformanceCommercialElectronicIgnitionHeater
POOLTEMPSPATEMP
THERMOSTAT
SELECT
OFF
COLD
AUX.
COLD
HEAT
PRESS
HOT
POOL
TSTAT
SERVICE
POWER
HOT
SPA
MiniMax
HighPerformanceCommercialElectronicIgnitionHeater

2
P/N 470880 Rev. K 5-31-06
Table of Contents
Introduction ............................................................................................................... 3
Codes ................................................................................................................................................................. 3
Pool Heater Description ...................................................................................................................................... 3
Warranty Information .......................................................................................................................................... 3
Pool Heater Identification .................................................................................................................................... 4
Product Identification .......................................................................................................................................... 4
Operation .................................................................................................................... 4
Safety Rules ....................................................................................................................................................... 4
Electronic Ignition Lighting/Operation - Natural & Propane .................................................................................. 5
Operating Instructions ......................................................................................................................................... 5
Operating (Controls) ........................................................................................................................................... 6-7
Trouble Shooting (Controls) ............................................................................................................................... 7-8
Maintenance (Standard Heater) ................................................................................ 9
Maintenance Instructions .................................................................................................................................... 9
Common Causes of Sooting ............................................................................................................................... 9-10
Pressure Switch .................................................................................................................................................. 11
Relief Valve ......................................................................................................................................................... 11
Vent Test ............................................................................................................................................................ 11
Energy Saving Tips ............................................................................................................................................. 12
Spring and Fall Operation ................................................................................................................................... 12
Winter Operation ................................................................................................................................................ 12
Chemical Balance ...............................................................................................................................................12-13
Installation Instructions ............................................................................................. 14
Specifications ........................................................................................................ 14
Outdoor & Indoor Installations ............................................................................................................................ 14
Ventilation .............................................................................................................. 15
Indoor Installation ............................................................................................................................................... 15
Indoor Draft Hood....................................................................................................................................... 16
Outdoor Installation ............................................................................................................................................. 16
Outdoor Stack & Outdoor Vent Cap Installation ........................................................................................... 16
Gas Connections ................................................................................................... 17
Gas Line/Installation ............................................................................................................................................ 17
Pipe Sizing Chart/Gas Pressure Requirements ................................................................................................... 17
Regulated Manifold Pressure Test ...................................................................................................................... 17
Water Connections ................................................................................................ 18
Valves ................................................................................................................................................................. 18
Water Supply Connections .................................................................................................................................. 18
Installation & Operation of External By-Pass Valve .............................................................................................. 18
Adjusting & Setting of the Manual By-Pass Valve ................................................................................................. 18
Below Pool Installation ........................................................................................................................................ 18
Electrical ................................................................................................................ 19
Transformer Wiring Instruction ........................................................................................................................... 19
Electrical Wiring Diagram, Commercial 525 & 750 .............................................................................................. 20
Electrical Wiring Diagram, Commercial 900......................................................................................................... 21
Trouble Shooting (General) ....................................................................................... 22
MiniMax Commercial Heater Parts List & Exploded View....................................... 23-24
CSD-1 Controls Addenda .......................................................................................... A1-A7
PowerMax Commercial Addendum .......................................................................... A8-A18
Low NOx Commercial Appendix ............................................................................... A19-A27

3
Rev. K 5-31-06 P/N 470880
Introduction
MiniMax®, MiniMax®with CSD-1 Options, PowerMax™& Low NOx™
525 - 750 - 900
POOL AND SPA HEATERS
This operation and installation manual contains useful and important information for the correct operation of the
Pentair Water Pool and Spa gas fired pool heater for the healing of swimming pools and spas.
Read these instructions carefully before putting the heater into operation. The manufacturer’s warranty may be void if,
for any reason, the heater is improperly installed and/or operated. If you need any more information, or if you have any
questions regarding to this pool heater, please contact Pentair Water Pool and Spa at [phone].
All the information in this operation and installation manual is based on the latest information and is subject to revision.
We reserve the right to modify the design/or construction of our products at any time without being obliged to adjust
earlier accordingly. Unit should be inspected for possible damage upon delivery. If observed damage on heater, inform the
carrier at time of delivery or as soon as possible. Carrier is responsible for the shortage and damage not the shipper.
WARNING
OPERATING THIS HEATER CONTINUOUSLY AT WATER TEMPERATURE BELOW 68° F. WILL CAUSE
HARMFUL CONDENSATION AND WILL DESTROY THE HEATER AND WILL VOID THE WARRANTY.
CODES
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.
The MiniMax Commerical pool heaters are design certified by CSA (Canadian Standard Assocation) as complying
with the latest edition of ANSI (American National Standard Insititute) Z21.56.CSA 4.7-M98 in the USA and Canada
for both indoor and out installations.
POOL HEATER DESCRIPTION
The heater is supplied entirely assembled and ready for installation. Every heater is tested before shipping to insure
proper operation.
WARRANTY INFORMATION
The MiniMax pool heater is sold with a limited factory warranty. Specific details are described on the warranty
registration card which is included with the product. Return the warranty registration card after filling in the serial
number from the rating plate inside the heater. For ordering parts, you should indicate model and serial numbers of the
heater. If the parts are requested for warranty, you must also indicate the date of installation.

4
P/N 470880 Rev. K 5-31-06
SAFETY RULES
1. Spa or hot tub water temperatures should never
exceed 104° F (40° C). A temperature of 100° F
(38° C) 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
102° F (39° C) 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 (38° C) maximum rule.
Operation
POOL HEATER IDENTIFICATION
Pool heater models 525, 750 and 900, are designed for
indoor and outdoor installation. All these models are
operating with electronic ignition for natural gas or
propane fuel. Standard ratings for these heaters has
been set for elevation from sea level up to 2000 feet.
For elevation above 2000 feet, rating must be reduced
at the rate of 4% for each 1000 feet above sea level. It
is required to change the orifices on the main manifold
to reduced input in the heater for the specific installation
elevation. Please indicate the model number and the
altitude of the location where the unit will be installed
when you place an order for items required to convert
to a higher elevation.
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
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
(2.2° C).
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.
PRODUCT IDENTIFICATION
To identify the heater, see rating plate on the inner front panel of the
heater. There are two designators for each heater, one is the Model
Number and the other is the Heater Identification Number (HIN).
a. Model Number:
Example: 525
1st through 3rd character indicated: Input rating (Btu/hr) X 1000
b. Heater Identification Number (HIN):
The following example simplifies the identification system.
123456
RTH5251-DSCknalBINEMSA
1) HTR : Heater
2) (525, 750 & 900) : Input rating (Btu/hr) X 1000
3) SCD-1 : Commercial MiniMax w/CSD-1*Controls
4) Blank : Standard Model
5) N I : Gas type (Natural gas) & Intermediate Ignition Device
6) Options :
Blank: Standard Model
ASME: ASME Certified (Bronze Headers)
ASHI: ASME Certified Bronze Header & High Altitude Rating
HALT: High Altitude Rating
CAN: Canadian Compliance
CANH: Canadian Compliance and High Altitude
*CSD-1 Controls apply only to the MiniMax Commercial Heater

5
Rev. K 5-31-06 P/N 470880
FOR YOUR SAFETY: READ BEFORE LIGHTING
A. This heater is equipped with an ignition device which
automatically lights the pilot. Do not try to light the
pilot 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 electric 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 incorporates six indicator lights to aid
you in the operation of the heater, and to assist in
diagnosing a failure in the heater’s function.
ELECTRONIC IGNITION LIGHTING/OPERATION-NATURAL GAS & PROPANE
Operation (contd.)
OPERATING INSTRUCTIONS
1. STOP! Read the safety information above.
2. Set the thermostat to lowest setting.
3. Turn off electric power to the heater.
4. This heater is equipped with an ignition device which
automatically lights the main burner.
Do not try to light the main burner by hand.
5. Remove the control access door.
6. For models 525 and 750 with Robertshaw gas valve
turn gas control knob clockwise to “OFF”;
see Figure 1.
For model 900 with Honeywell gas valve turn
main gas shut-off and pilot shut-off valves counter
clockwise to “OFF”; see Figure 2.
If you do not follow these instructions exactly, a fire or explosion may result causing personal injury, loss
of life and property damage.
Since propane gas is heavier than air, escaping propane will accumulate and remain at ground level. Do
not attempt to light the heater. If you suspect a propane leak, lighting the heater can result in a fire or
explosion which can cause personal injury, death, and property damage.
WARNING
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. For model 525 and 750 turn knob on gas control
counter clockwise to “ON”.
For model 900 turn main shut-off and pilot cut-off valves
clockwise to “ON”.
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 instructions "To
Turn Off Gas To
Heater" and call
your service
technician or gas
supplier.
Figure 1.
Gas Control Knob
Shown In “OFF” Position
Gas Inlet
Figure 2.
Pilot Shut-Off Valve Control
Shown in the “ON” Position
To Pilot
Main Gas
Shut-Off Valve
Gas
Inlet
(continued on next page)

6
P/N 470880 Rev. K 5-31-06
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.
TO TURN OFF GAS TO HEATER
Operation (contd.)
OPERATING (CONTROLS)
Dual Temperature Control System
For convenience and economy all MiniMax Commer-
cial heaters are equipped with two thermostats on the
front of the heater control panel; see Figure 3.
The Pool/Off/Spa switch allows the heater to be turned
off when heating is not desired.
1. “Pool” position - Maintains selected pool
temperature.
2. “Off” position - Heater will not come on
regardless of drop in pool or spa temperature.
3. “Spa” position - This allows separate control of
spa water temperature.
4. Push in gas control knob slightly and turn clock-
wise to "OFF". Do not force.
5. Replace control access door.
SELECTOR DIALS
The selector dials eliminate constant thermostat
adjustments. Set the spa dial at the desired spa
temperature and the pool dial at the desired pool
temperature. This provides convenient preset
operating temperatures.
THERMOSTAT KNOB STOPPER
Each thermostat is equipped with a mechanical stop
that can be locked or unlocked with use of a
screwdriver to prevent temperatures in excess of
that desired by the user; see Figure 4.
The maximum setting can be adjusted by loosening the
screw "A" and turning the stopper dial to desired
maximum setting. Lock the setting by tightening the
screw.
Figure 3.
INDICATOR LIGHT DESCRIPTION
The MiniMax Pool Heater provides six status indicator lights, seen from the front of the control panel,
which help you understand the operation of the heater. If something should go wrong, the lights will aid in
troubleshooting the problem - additionally three lights can be seen after opening the control panel. These
three lights give the service technician advance troubleshooting capability. All the LED lights are green with
the exception of the red service LED.
Figure 4.
Knob Stopper
Screw A
POWER LIGHT (POWER)
The light is on at all times, in any switch position,
indicating 24 VAC power is being supplied to the
control circuit. If it fails to light, no other light will
be on. Possible causes are: a) external power to the
heater is disconnected, check service panel circuit
breaker or fuses; b) local circuit breaker inside the
heater, at the junction box, has tripped -- investigate
cause before resetting; c) transformer has failed.
THERMOSTAT (TSTAT)
This light is on when the thermostat contacts close,
signaled by the water temperature falling below the
setpoint, calling for the heater to fire to maintain the
desired water temperature.

7
Rev. K 5-31-06 P/N 470880
Operation (contd.)
AUXILIARY (AUX)
When this light is on it indicates the remote switch
contacts are closed. This allows you to observe if
your remote switch is properly closing the heater
control circuit. When shipped from the factory a
jumper is installed to maintain closed circuit in the
absence of a remote switch.
PRESSURE (PRESS)
This light is on when Spa/Pool Selector switch is
on, indicates the circulation pump is running prop-
erly. If pressure light fails to light, the pump may
have lost its prime or water flow may be restricted
by an inadvertently closed valve or clogged filter or
pump basket. If you have determined that there is no
water flow restriction to the heater, you should call
a qualified serviceman.
HEAT (HEAT)
The heat light is on any time the thermostat has
signaled a call for heat which initializes the ignition
safety firing circuit -- the light comes on to indicate
successful firing of the main burners.
SERVICE (SERVICE)
The service light is off during normal operation of
heater. The light only comes on if a problem with a
control has occurred or when the heater is first
firing. The problem must be investigated by the
serviceman prior to attempts to fire the heater again.
The diagrams that follow give examples of
troubleshooting a malfunctioning heater using the
assistance of the indicator lights.
TROUBLESHOOTING (CONTROLS)
Example of troubleshooting with the assistance of the indicator lights.
PWR TSTAT RMT PRESS
SRVE
HI TEMP TFUSE
GAS VALVE
MV
MV
IGNITION MODULE
IND GND VAL
MV HEAT
CLOSE IF
NO MV
THERMOSTAT
RELAY
REMOTE PRESS TFUSE
HI TEMP
LIMIT SWITCHESBREAKER
CIRCUIT
TRANSFORMER
INCOMING
LINE VOLTAGE
THERMOSTAT CIRCUIT BOARD
LIMIT SWITCHES
HI TEMP
NO MV
CLOSE IF
THERMOSTAT CIRCUIT BOARD
TRANSFORMER
LINE VOLTAGE
INCOMING
PWR
CIRCUIT
BREAKER
TSTAT RMT
RELAY
THERMOSTAT
REMOTE
PRESS
SRVE
PRESS HI TEMP
MVTFUSE
TFUSE
HEAT
IGNITION MODULE
IND GND VAL GAS VALVE
MV
MV
WATER AT SELECTED TEMPERATURE.... NORMAL OPERATION
THERMOSTAT CALLING FOR HEAT - PUMP OFF(NO PRESSURE) BLOCKS FIRING
NORMAL OPERATION
SYMBOL TABLE
LED LIT LED OFF
SWITCH OR DEVICE
OPEN CIRCUIT
(BLOCK CURRENT)
SWITCH OR DEVICE
CLOSED CIRCUIT
(PASS CURRENT)
THERM
AUX
PRESS
HEAT
POWER
SERVICE
FRONT PANEL LEDS
FRONT PANEL LEDS
HEAT
PRESS
AUX
THERM
SERVICE
POWER
OR POOL/OFF/SPA THERMOSTAT SELECT SWITCH OFF.... NORMAL OPERATION

8
P/N 470880 Rev. K 5-31-06
TROUBLESHOOTING SECTION - Continued
(Also see wiring section)
Operation (contd.)
PRESS
PRESS
HEATER FIRING - NORMAL OPERATION
NOTE: SERVICE LED LIT FLAGS PROBLEM, TFUSE LED OFF SHOWS PROBLEM
PRESS
PRESS
THERMOSTAT CALLING FOR HEAT - BLOWN THERMAL FUSE BLOCKS FIRING
FRONT PANEL LEDS
HEAT
PRESS
AUX SERVICE
TRANSFORMER
THERM POWER
INCOMING
LINE VOLTAGE
FRONT PANEL LEDS
PRESS
HEAT
AUX
THERMOSTAT
PWR
CIRCUIT
BREAKER
TSTAT
RELAY
RMT
REMOTE
TRANSFORMER
THERM
INCOMING
LINE VOLTAGE
THERMOSTAT
PWR
BREAKER
CIRCUIT
TSTAT
RELAY RMT
REMOTE
THERMOSTAT CIRCUIT BOARD
NO MV
CLOSE IF
IGNITION MODULE
SRVE
HI TEMP
LIMIT SWITCHES
HI TEMP
TFUSE MV
IND
TFUSE
GND
THERMOSTAT CIRCUIT BOARD
GAS VALVE
HEAT
VAL
MV
MV
IGNITION MODULE
SRVE
CLOSE IF
NO MV
HI TEMP
LIMIT SWITCHES
HI TEMP
TFUSE MV
IND
TFUSE
GND GAS VALVE
HEAT
VAL
MV
MV
POWER
SERVICE
IS IN THERMAL FUSE CIRCUIT
SYMBOL TABLE
LED LIT LED OFF
SWITCH OR DEVICE
OPEN CIRCUIT
(BLOCK CURRENT)
SWITCH OR DEVICE
CLOSED CIRCUIT
(PASS CURRENT)

9
Rev. K 5-31-06 P/N 470880
MAINTENANCE INSTRUCTIONS
It is recommended that you check the following items at
least every six months and at the beginning of every
swimming season.
1. Examine the venting system. Make sure there
are no obstructions in the flow of combustion
and ventilation air.
2. Visually inspect the main burner and the pilot burner
flame. The normal color of the flame is blue. When
flame appears yellow, burners should be inspected
and cleaned; see Figure 5.
3. Check the heat exchanger surface for sooting.
For cleaning the burner, the following steps
must be performed by qualified servicemen.
1. Turn off the power to the heater.
2. Shut off the power to the heater.
3. Remove front door.
4. By loosening union disconnect gas train from burner
tray.
5. Remove two screws which secure the burner tray to
the base of heater and pull out the burner tray.
6. Remove screws and burner, hold down bracket and
slide burners out.
7. Clean and remove the soot from burners and orifice
by wire brush or
vacuum cleaner.
8. Remove the pilot
orifice and clean it;
see Figure 6.
Do not use any
sharp object! It will
destroy the designed
orifice size!
9. Reverse above
procedure to reinstall
burner tray.
Maintenance (Standard Heater)
COMMON CAUSES OF SOOTING
1. Low gas pressure.
2. Excessive water flow can cause condensation
which will contribute to sooting.
3. Foreign material in burners and orifices; dirt,
spider webs, etc.
4. Inadequate air supply or inadequate venting.
5. Heater cycling rapidly; fires, shuts down and
refires quickly 30-45 seconds.
To remove a light soot formation without
removing the heater exchanger:
1. Remove burner tray; see
Figure 7.
2. Remove top,
flue collector
and baffles.
3. Using a brush
with plastic or
fiber bristles,
brush the bottom
of the tubes and
then the top of
the tubes.
4. Spray off residue with water. (Repeat steps 3-4
as needed).
5. Brush off burners.
6. Replace burner tray and baffles, then test fire.
7. If flames burn clean, replace baffles, flue
collector, and top.
CAUTION
DO NOT USE WIRE BRUSH!
Figure 6.
Pilot
Figure 7.
Burner Tray
Figure 5.
Blue Flame

10
P/N 470880 Rev. K 5-31-06
Maintenance (contd.)
For heavy soot accumulation which cannot be
successfully removed by merely brushing, the heat
exchanger must be removed from the heater.
1. Disconnect the plumbing at the flanges.
Remove the thermistor, hi-limit wires and
pressure switch tube from the inlet outlet heater.
CAUTION
When lifting the heat exchanger out of the fire box,
use caution so as not to damage the fire wall.
2. Remove the heat exchanger.
3. Place exchanger in an area that won’t be affected
by chemicals or strong detergents.
4. After spraying the exchanger with water, use a
mixture of detergent and water. Pour, spray or
brush on.
5. Rinse the solution off of the tubes and inspect them,
repeat if necessary.
6. Alternate method, have exchanger sand blasted at a
local facility.
Reinstalling Heat Exchanger
1. Inspect fire box for damage or cracks that would
allow heat to leak out into the outer cabinet and
controls.
2. Remove any old sealant from fire box.
3. Apply new sealant to the fire box using a quality
industrial grade R.T.V. or equivalent. The sealant
must completely seal the space between the heat
exchanger and fire box, so that when the heater is
firing, heat does not escape to the outer cabinet.
4. Place heat exchanger into the box and push
down firmly, until the heat exchanger sets
solidly on the fire box.
5. Reconnect the inlet and outlet flange to the headers
(use new flange gaskets), be careful not to move
the heat exchanger and break the seal.
6. Reinstall flue collector, inner panel and top.
CAUTION
Do not store combustible material, gasoline and
other flammable vapor and liquids in the vicinity
of this or any other appliance.
Heat
Exchanger
Flue
Collector
Fire Box