Pentair 250, 300 Troubleshooting General, Heater Short Cycling Rapid On and Off Operation

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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.
Pump not running	Place pump in operation
Pump air locked	Check for leaks
Filter dirty	Clean filter
Pump strainer clogged	Clean strainer
Defective wiring or connection	Repair or replace wires
Defective pressure switch	Replace switch
Defective gas controls	Call serviceperson
On-Off switch in "OFF" position	Turn switch to "ON"
Heater Short Cycling (Rapid On and Off Operation)

Insufficient water flow	Clean filter and pump strainer
Defective wiring	Repair or replace wiring
Defective flow valve or out of adjustment	Call serviceperson
Defective hi-limit and/or thermostat	Call serviceperson

Heater Makes Knocking Noises,

Make sure all valves on system are open

Heater operating after pump has shut off	Shut off gas supply and call serviceperson
Heater exchanger scaled	Shut off gas supply and call serviceperson

CAUTION

Please consult the latest edition of the “MiniMax NT Low NOx Service Manual” for complete service and repair instructions. Repairs should only be attempted by properly trained service personnel.

P/N 471593

Rev. C 11-1-01

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Contents MiniMax NT Low NOx Series For additional free copies of this manual call 800Table of Contents MiniMax NT Low NOx Code RequirementsOperation Warranty InformationSafety Rules For Your Safety Read Before Lighting Operation LightingInstallation Instructions SpecificationsInstallation Electrical ELECTRICAL, ALL HSI UnitsInstallation Remotes TWO-WIRE or THREE-WIRE Remote HOOK-UPWire Remote Three-wire remote Installation Single Voltage WiringInstallation Single VoltageCode or Superceding Local Wiring Codes MiniMax NTLowPlumbing Connections Water ConnectionsPlumbing GAS Connections Installation Indoor Indoor VENTING-General RequirementsSee page 17 for Indoor Vent Adaptors Indoor Vent Adaptors Fits ALL Models Installation IndoorInstallation Outdoor VentilationBasic Operation General DescriptionBasic System Operation Safety Controls AIR Pressure FAN SwitchWater Pressure Switch Typical Water Pressure SwitchOperation of Ignition Module Pentair Temperature Controller 7800 Layout GeneralBasic Thermostat Operation Normal Operation no RemoteTemperature & Time Setting Programming To Change the Factory Temperature SettingsTime Setting Time SETTING, cont’d Time Setting ProgrammingMaintenance Instructions MaintenanceEnergy Saving Tips Spring and Fall OperationMaintenance Water Treatment Chemical BalancePool and SPA Water If pH becomes too high over alkaline, it has these effectsTroubleshooting-Normal Operation Sequence of Heater Normal Operation SequenceTroubleshooting-Normal Operation of Heater Power Service Current Temp SET TEMP/TIMETroubleshooting & Service Flame Sensor Current Check Service CHECKS-IGNITION ModuleService Checks Troubleshooting General Heater Short Cycling Rapid On and Off OperationMinimax NT LOW NOx Heater Single Voltage Description QTY Minimax NT LOW NOx Heater Dual Voltage MiniMax NT Low NOx Dual Voltage Replacement parts Rev. C Rev. C Rev. C MiniMax NT Low NOx Heaters Limited Warranty