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Hayward H400 series heater

Get SF and H5 message. Occasionally see 103F or 104F before SF kicks in. Heater has not run, so water temp is likely in the low 60s. sf is sensor failure replace

Posted by Bill Casswell on


5 Related Answers


  • 11 Answers

SOURCE: Hayward H400 heater problem

LO usually indicates low water pressure. Check the pressure in your filter. You may need to backwash. If the filter is to clogged then the water pressure in the heater is so low that it won't activate the pressure switch. While checking the pressure turn the pump off and then on to make sure the pressure gauge is actually working. Also check the pressure coming out of the inlets into the pool. You should be able to tell if you have sufficient water pressure.

Posted on Jan 28, 2009



  • 14 Answers

SOURCE: Hauward H400 heater won't turn on

check pressure switch operation most heaters will not operate without sufficient water flow/pressure. You can use a multimeter to troubleshoot the wiring using the schematic. If its induced draft milivolt ignition verify there is suffiecient gas flow to the unit

Posted on May 26, 2009



  • 760 Answers

SOURCE: Our Hayward gas heater keeps giving us a H5 error

Could the Error code be HS? That is high temperature limit. Perhaps you' don't have enough flow, allowing the heater to heat the water to a temperature higher, than the thermostat setting. Make sure your bypass valve is closed, allowing full flow through the heater. Check your filter pressure differential , and skimmer baskets.
You didn't give your model number, and there are many models. You can go the Hayward website below and select your exact model number and download the manual. The manual will explain each error code.

Posted on Jul 05, 2010


  • 760 Answers

SOURCE: ao error message in Hayward heaters

You didn't indicate exatctly which model you have. But on most the AO error code is :Blower vacuum switch
open error If the blower prover switch does not close after the blower starts the control will
stop the ignition trial go into lockout. The blower will continue to run. Automatic reset is immediate after the switch closes.Check to be sure combustion blower starts
If you don't have your manual you can download one for your exact model at :

Posted on Jul 29, 2010


bonifacio gomez

  • 1238 Answers

SOURCE: H400 Hayward Pool Heater keeps

Good day!

This are the codes for your hayward machine:

LED Diagnostics Codes Description of Error Codes IF Ignition Failure SF Temperature Sensor Input Failure HS Max. Return Water Temp. Exceeded HF Flame Present with Gas Valve Not Energized LO Temp. Limit Switch Fault or Water Pressure Switch Fault or Vent Pressure Switch Fault AC Blower Vacuum Switch Closed AO Blower Vacuum Switch Open Additional Codes for IDL2 series BD Bad Board or Secondary High-Voltage Fault EE Bad Board CE Communication error (between module and display interface assembly) IO Ignitor Failure SB Keypad Failure

Posted on Jun 05, 2011

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2 Answers

What if code sf and h5 comes up

The two may be related? If the right problems are present...
HS = High Limit Sensor
SF = Temperature Sensor or Thermistor
Heaters Maximum Water Temperature has been Exceeded.
Heaters Set temperature not in line with actual water temperature.

A few reasons this occurs...
  • Low water flow thru heater, check :
    • Dirty Filter
    • Opened By Pass Valves
    • Plugged pump impeller
    • Dirty/Full baskets at skimmer or pump
    • Anything that may reduce water flow
  • Sensor could actually be doing its job, in a different aspect, Thermostat failure, and water is overheating in spa or pool?
But anyway, your heaters fault code you asked about is does not necessarily mean they failed. They are informing of a problem.

May 25, 2014 | Hayward H-series Electronic Gas Pool...

1 Answer

Water temp is 140 degrees, motor running and display shows code Sn

I'm not sure which system you have but if your water temp sensor is accurate you have a runaway heater. There are several safeguards internal to the heater that are supposed to prevent this from happening. Max water temp should be 104F. So if your low limit, high limit, redundant limit (if one), and t-stat were working ANY ONE of them should have shut down the heat. Get a qualified tech out to troubleshoot it. This heater has either been rigged at some point, or the gas valve is defective. In either case it is in a very hazardous condition and should not be used!

Dec 29, 2012 | Pool & Spa

1 Answer

Get several codes , when i turn it on all the lights come on and display has a 888, then a 180. all goes off, receive a code sf 1, then an r4

Check your stack flu sensor. Sensor can not be jumped. As soon as the heater fires hold down the pool or spa button until the stack temp appears. At 500 degrees the heater will shut off giving a code. The heater should not restart. I would also check for wire damage based on the description of your issue and the board restarting on it own. You may also have damage to the "user interface board" , hard to say with out on site trouble shooting.

Jun 04, 2017 | Sta Rite Sta-Rite Max-E-Therm High...

1 Answer


The code SF indicates there is either a bad temperature sensor or the input to heater is faulty. I would buy a temperature sensor from a pool supply suppilier and install it. That solution has a very high likelihood of being successful. If you have a few tools and a little mechanical ability installation should be easy. I hope this helps

Aug 13, 2011 | Hayward H-series Electronic Gas Pool...

2 Answers

Heater has a clonking sound when running ans the

SF is a code for excessive temp difference of water coming in and going out. The banging or clonking you here is the water in the heater overheating and boiling. You have a problem with your internal by-pass. It is broken or stuck open and letting most of the water go past the heater and the water in the heater is not moving so it can overheat. This is located inside the water manifold on the side of the heater. If you spin the two big nuts off the water pipes their are twelve nuts holding the manifold on. The by-pass and thermal valve are both inside and since you have it open you should replace both as the thermal valve has probally been hurt from the excessive heat. Then just put it back together and you should be all set. Good luck.

Feb 28, 2010 | Hayward H Series Pool & Spa Heater 400k...

1 Answer


H5-01 means that you have 5 continous paper jamm in the machine. Try to rest by pressing C INTERUPT 0 INTERUPT 14 START.

If problem still occur, check the paper detection sensor by pressing C INTERUPT 0 INTERUPT 30 START 1 START. and manually activate the sensors and look at the display.

May 27, 2009 | Sharp SF 2540 Copier

3 Answers

Sharp sf.2540

Press C - interrupt - 0 - interrupt - flash
and then
14 and press start
Good luck!

Feb 26, 2008 | Toshiba e-Studio65 Copier

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