1 MiniMax NT Low NOx Series ® POOL & SPA HEATERS OPERATION & INSTALLATION MANUAL WARNING 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 (800) 831-7133. To Consumer Retain For Future Reference U.S.
Table of Contents Introduction ............................................................................................................... 3 Important Notices ...................................................................................................................................................................... 3 Code Requirements ...........................................................................................................................................................
Introduction 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.
Operation 4 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.
Operation (Lighting) 5 MINIMAX NT LOW NOx HSI ELECTRONIC IGNITION LIGHTING/OPERATION - NATURAL GAS FOR YOUR SAFETY: READ BEFORE LIGHTING WARNING 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. A.
Installation Instructions SPECIFICATIONS 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. OUTDOOR VENTILATION 15.50 7.35 2 in. SOCKET 24.05 30.63 LEG 3.50 14.50 Figure 2. LEG "A" DIM. 21.63 250 24.
Installation (Electrical) 7 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 connecting 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.
Installation (Remotes) 8 TWO-WIRE OR THREE-WIRE REMOTE HOOK-UP 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.
Installation (Remotes) 9 TWO-WIRE OR THREE-WIRE REMOTE HOOK-UP, (cont’d.) • 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.
B NEU 120 VAC (ONLY) HOT ORG WHT SWITCH LOW GAS PRES. ORG SWITCH HI AIR PRES. ORG 2 1 AUX2 10A 250V RELAY 10A 250V RELAY BLOWER REMOTE AIR PR SW. TPROBE TEMPERATURE PROBE WHT ORG LIMITS 6 5 4 3 2 1 POWER 2 1 P7 P4 WHT 1 2 ORG BLK BLK GRN WATER PRESSURE SWITCH W2 WHT RED RED 1 2 3 4 5 6 SWITCH ORG W1 EXHAUST HIGH LIMIT THERMAL SWITCHES 3 2 1 G VALVE P10 1 2 3 LOW AIR PRES.
ORG ORG 2 1 BLK BLK AUX2 10A 250V RELAY 10A 250V RELAY BLOWER REMOTE AIR PR SW. GRN WATER PRESSURE SWITCH WHT TPROBE LIMITS 6 5 4 3 2 1 2 1 P7 P4 RED POWER ORG TEMPERATURE PROBE W2 WHT WHT 1 2 WHT W1 RED 1 2 3 4 5 6 LOW GAS PRES. SWITCH HI AIR PRES.
EXTERNAL BOND LUG ORG AIR PRESSURE SW. 1 2 RELAY WHT AUX2 10A 250V RELAY 10A 250V RELAY BLOWER REMOTE AIR PRESS SW. GRN WATER PRESSURE SWITCH RED TPROBE TEMPERATURE PROBE WHT WHT WHT GAS VALVE 6 5 4 3 2 1 POWER 2 1 3 2 1 P10 P7 P4 RED RED TFUSE LIMITS ORG WHT WHT EXHAUST HIGH LIMIT THERMAL SWITCHES 1 2 GRN ORG WHT HIGH LIMIT THERMAL SWITCHES 1 2 3 4 5 6 WHT GAS PRESSURE SW.
Installation (Plumbing) 13 WATER CONNECTIONS Reversible Inlet/Outlet Connection The MiniMax NT Low NOx heater is factory assembled with right side inlet/outlet water connections. The inlet/outlet header can be reversed for left side water connections without removing the heat exchanger. Reversing Water Connections Tools required: 1/4 in. Screw Driver 9/16 in. Socket and Wrench 1/2 in. & 9/16 in. Open Wrench 1. Remove the right and left large inspection plates. 2.
Installation (Gas Line) GAS CONNECTIONS 14 Pipe Sized For Length Of Run In Equivalent Feet GAS LINE INSTALLATIONS Model Before installing the gas line, be sure to 200 check which gas the heater has been 250 designed to burn. This is important 300 because different types of gas require 400 different gas pipe sizes. The rating plate on the heater will indicate which gas the heater is designed to burn. Table 1, shows which size pipe is required for the distance from the gas meter to the heater.
Installation (Indoor) 15 INDOOR VENTING—General Requirements The vent pipe must be the same size or larger. The MiniMax NT Low NOx heaters are capable of a 360-degree discharge rotation and operate with a positive vent static pressure and with a vent gas temperature less than 400° F. The total length of the horizontal run must not exceed the length that is listed below in the tables. Please note the allowable vent runs for each stack pipe diameter are different and can not be exceeded.
;;; ;;; ;;; Installation (Indoor) 16 INDOOR INSTALLATION (USA ONLY) OUTDOOR SHELTER INSTALLATION (CANADA) See page 17 for (Indoor) Vent Adaptors 10 ft. Ridge Vent Cap 2 ft. min. All products of combustion and vent gases must be completely removed to the outside atmosphere through a vent pipe which is connected to the stack adaptor.
Installation (Indoor) 17 NOTE The heater requires two uninterrupted air supply openings; one for ventilation and one to supply oxygen for proper gas combustion. The air supply openings should be sized according to Table 2. b) Construct a non-combustible base from masonry blocks as illustrated, see Figure 14. BASE FOR USE ON COMBUSTIBLE FLOORS Air supply requirements below apply to all MiniMax NT Low NOx heaters*. . in REQUIRED AIR SUPPLY 6" M . in Model Air for Combustion Sq. In.
P/N 471593 Detail H Chimney 3 ft. min. L K J ;; ;; 2 ft. min. Vent Cap may use a single wall vent pipe with permanently sealed seams and joints. must be suitable for use with category III appliances which have flue gas temperatures of less than 400 deg. F. must be the same diameter as the vent connector. Vent pipe extension: L must terminate with an approved (listed) roof jack, storm collar, and vent/weather cap. K must use a double-wall vent pipe through the roof penetration.
Installation (Outdoor) 19 VENTILATION OUTDOOR INSTALLATION ONLY (Outdoor Shelter Installation in Canada, see page 16) For outdoor installation with built in vent, the heater must be placed in a suitable area on a level, noncombustible surface. Do not install the heater under an overhang with clearances less than 3 feet from the top of the heater. The area under an overhang must be open on three sides. Maintain minimum clearances as indicated below.
Basic Operation 20 GENERAL DESCRIPTION The MiniMax NT Low NOx Pool and Spa Heater is a fan-assisted induced draft appliance. The MiniMax NT Low NOx is available in 200,000, 250,000, 300,000 and 400,000 btu/hr. capacities and are certified for both indoor and outdoor installations. The MiniMax NT Low NOx version natural gas pool heater must be used for installations in the South Coast Air Quality Management District (SCAQMD)—these heaters are certified to comply with SCAQMD Rule 1146.
Basic Operation 21 SAFETY CONTROLS AIR PRESSURE (FAN) SWITCH The air pressure switch is a safety device used to insure that the blower (fan) is operating and has been designed to monitor the vacuum (negative) pressure within the blower housing. The air pressures switch is factory set and is in the ignition module circuit— the ignition module does not operate unless the air pressure switch and all safety switches are closed.
Basic Operation 22 SAFETY CONTROLS, (cont’d.) IGNITION MODULE The Ignition Module is microprocessor based and operates on 24 VAC supplied by the transformer. The control utilizes a microprocessor to continually and safely monitor, analyze, and control the proper operation of the gas burners. The module with the presence of the flame sensor/ignitor or remote sensor, using flame rectification, allows the heater to operate.
Thermostat (Programming & Layout) 23 MINIMAX NT LOW NOx PENTAIR TEMPERATURE CONTROLLER 7800 (See Figure 21, for keypad and Pentair Temperature Controller layout details.) GENERAL The MiniMax NT Low NOx Pentair Temperature Controller 7800 is the heart of the control system. It controls all functions of the heater after first verifying that all safety controls are functioning normally.
Temperature & Time Setting (Programming) 24 TO CHANGE THE FACTORY TEMPERATURE SETTINGS: 1. Before changing the temperature, make sure the “Temperature” is in the right window, see pages 24 and 25, if “Time” is displayed, press the MODE key to change to the “Temperature Mode”. SET PROGRAM MODE 2. To change the Pool Temperature setting, press the POOL key. POOL OFF SPA 3. To Raise or Lower the Pool Temperature setting, press the proper TEMP key until the desired setting is displayed.
Time Setting (Programming) 25 TIME SETTING, (cont’d.) 3. The first setting, once you enter the Programming Mode, will be the Day. The Day icon will be flashing. Use the UP or DOWN arrow TEMP keys to locate the appropriate day, then press the SET key. The Day is now set and the Hour Time icon will start to flash. TEMP STEP TEMP SET PROGRAM MODE 4. With Hour Time icon flashing, use the UP/DOWN arrow TEMP keys. Set the Hour to the proper time, “P” will show to the right for PM, and blank for AM.
Maintenance 26 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 hot surface ignitor. The normal color of the flame is blue. When flame appears yellow, burners should be inspected and cleaned. Check ignitor for damage. 3.
Maintenance (Water Treatment) 27 CHEMICAL BALANCE RULE: 7.4 to 7.6 is a desirable pH range. It is essential to maintain correct pH, see Table 4. POOL AND SPA WATER If pH becomes too high (over alkaline), it has these effects: Your Pentair Pool Products pool heater was designed specifically for your spa or pool and will give you many years of trouble-free service, provided you keep your water chemistry in proper condition.
Troubleshooting—Normal Operation Sequence of Heater NORMAL OPERATION SEQUENCE (Refer to Figure 21 of Pentair Temperature Controller 7800 keyboard) The heater features a fully automated firing start-up and shutdown sequence under the control of the MiniMax NT Low NOx Pentair Temperature Controller 7800.
Troubleshooting—Normal Operation of Heater 29 3. After normal firing of the heater (main burners) the heater will continue to operate until the temperature setpoint is reached (thermostat satisfied). As the pool/spa loses heat the heater will refire and continue to operate cycling automatically to maintain the selected temperature setpoint for either the pool or spa.
Troubleshooting & Service 30 LEGEND OF FAULT ICONS AND TYPE OF PROBLEMS FLAGGED This fault icon displays whenever there is an unexpected loss of flame. This condition may arise from air in gas supply line or malfunction of flame detection circuit or related hardware.This is a hard lockout condition requiring a manual reset to clear. This fault icon displays whenever one or more of safety temperature limit switches open to flag an excessive temperature condition.
Troubleshooting & Service 31 SERVICE CHECKS—IGNITION MODULE Service Checks Symptom Cause/Cure 1. Dead A. B. C. D. 2. Thermostat on—no ignition A. Miswired B. Bad thermostat no voltage at terminal W 3. Valve on, no ignitor A. Defective ignitor B. Miswired C. Bad control (check voltage at ignitor) 4. Ignitor on, no valve A. Valve coil open B. Open valve wire C. Bad control (check voltage between V1 & V2) 5. Flame okay during TFI, no flame sense (after TFI) A. B. C. D.
Troubleshooting - General Possible Cause Remedy Heater will not come on Automatic ignition system fails Check if electrical connections are correct and securely fastened – If YES, call serviceperson.
MINIMAX NT LOW NOx HEATER - (Single Voltage) MiniMAX NT Low NOx, Single Voltage (Manufactured Date Prior to October 15, 2001) 1 2 3 4 5 6 7 8 9 13 14 24 25 10 15 11 16 12 17 18 26 19 27 20 28 30 29 32 31 21 22 33 23 34 37 35 38 36 39 50 40 49 41 48 Rev.
MiniMax NT Low NOx Single Voltage Replacement parts (Manufactured Date Prior to October 15, 2001) ITEM DESCRIPTION QTY. 250 400 471592 1 Exhaust Grill 1 471701 2 Gasket, Exhaust Grill 1 1 471692 471591 3 Top Cover 471996 1 471995 4 Exhaust Assy. 471714 1 5 Shut-off Safety Switch, Exhaust 471741 6 Blower 1 471610 7 Gasket, Blower 1 1 472007 472005 8 Flue Collector Assy. 471991 1 9 Return Manifold Assy. 471622 16 10 Bolt, Heat Exchanger 072184 16 11 Washer, Heat Exchanger 1 471835 471821 12 Fire box Assy.
MINIMAX NT LOW NOx HEATER - (Dual Voltage) MiniMAX NT Low NOx, Dual Voltage (Manufactured Date After October 15, 2001) 1 2 3 4 5 6 7 8 9 13 14 24 25 10 15 11 16 12 17 18 26 19 27 20 28 30 29 21 32 31 22 33 23 34 37 35 38 36 39 40 41 48 Rev.
ITEM 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 NA NA NA MiniMax NT Low NOx Dual Voltage Replacement parts (Manufactured Date After October 15, 2001) DESCRIPTION QTY. 200 250 300 471592 Exhaust Grill 1 471701 Gasket, Exhaust Grill 1 1 471885 471692 471886 Top Cover 472014 1 Exhaust Assy.
NOTES Rev.
NOTES P/N 471593 Rev.
NOTES Rev.
MiniMax NT Low NOx Heaters Limited Warranty Your MiniMax NT Low NOx pool heater is another quality product from Pentair Pool Products, Inc. and is backed by the following warranty. 1. The following parts are warranted for 5 years from date of purchase: The MiniMax NT Low NOx cabinet and combustion chamber, the main burners and burner manifold, the inlet/outlet header and the return header.