Help with Hayward 400k ng btu heater (H400FDN)

[New Pool in Houston]

Hey guys long time reader, but just getting frustrated trying to find the right steps/diagnostics for my issue.

I have an 11year old Hayward (H400FDN) heater, 2 years ago I replaced all the boards. The heater has worked like a champ since. This past week we were using the heater quit and started throwing the IF code.

The heater worked fine at first, and warmed the pool to the correct temp, however the IF code started while it was maintaining the temp of the pool, I'm not sure if it's relevant or not, however it was raining on and off while we were using the heater.

What I've tested so far -- The ignitor is getting glowing red, the fan is kicking on and off properly, the gas tubes don't appear to be clogged (cleared them with a pick)

I think the issue is related to the power signal to the gas valve. The gas valve makes a hollow sound like it's operating, but I don't smell gas. In testing the gas valve, I see 19 Vac being sent to the valve briefly, like a second or less then kicks back to very low to no voltage.

What should I be looking at next? The Power control board again? The transformer? How do I test these to narrow down the solution?

Thank you,
Chris

________________________________________________________________________________________________________________________________________
EDIT and FINAL UPDATE:
The voltage was actually 24 volts, my multi meter was giving me bad readings (it's now been replaced with a fluke) the issue was actually the gas valve failed.

Thank you all for your help!
________________________________________________________________________________________________________________________________________

 

[ajw22]

Welcome to TFP.

What specific model number heater are we discussing?

Help with Hayward 400k ng btu heater (H400FDN)

Hey guys long time reader, but just getting frustrated trying to find the right steps/diagnostics for my issue. I have an 11year old Hayward (H400FDN) heater, 2 years ago I replaced all the boards. The heater has worked like a champ since. This past week we were using the heater quit and...

www.troublefreepool.com

 

[New Pool in Houston]

Welcome to TFP.

What specific model number heater are we discussing?

Help with Hayward 400k ng btu heater (H400FDN)

Hey guys long time reader, but just getting frustrated trying to find the right steps/diagnostics for my issue. I have an 11year old Hayward (H400FDN) heater, 2 years ago I replaced all the boards. The heater has worked like a champ since. This past week we were using the heater quit and...

www.troublefreepool.com

Sorry, I've updated, it's the H400FDN

 

[ajw22]

Did you clean the flame sensor?

How much corrosion do you have in the heater?

Hayward H-Series Heaters - Further Reading

www.troublefreepool.com

The flame sensor should be cleaned with steel wool or a small steel/diamond file because cleaning with sandpaper or emery cloth can leave residue that will impede conductance. On the other side (ground side) all surfaces from the burner back to case ground must be clean bare metal (as the flame signal is sensed through the flame). This includes the burners and burner slots which can be cleaned with a wire brush and any other metal to metal surfaces back to case ground which may have lost conductance due to dirt/corrosion/oxidation. This would include orifices ( if the burners are hung directly on the orifices ), burner brackets and any other metal to metal breaks that occur between the burners and the case ground.

Post pics of the insides of the heater.

 

[New Pool in Houston]

Did you clean the flame sensor?

How much corrosion do you have in the heater?

Hayward H-Series Heaters - Further Reading

www.troublefreepool.com

The flame sensor should be cleaned with steel wool or a small steel/diamond file because cleaning with sandpaper or emery cloth can leave residue that will impede conductance. On the other side (ground side) all surfaces from the burner back to case ground must be clean bare metal (as the flame signal is sensed through the flame). This includes the burners and burner slots which can be cleaned with a wire brush and any other metal to metal surfaces back to case ground which may have lost conductance due to dirt/corrosion/oxidation. This would include orifices ( if the burners are hung directly on the orifices ), burner brackets and any other metal to metal breaks that occur between the burners and the case ground.

Post pics of the insides of the heater.

Flame sensor is about 2 years old as well....I will go get some internal pictures. There's certainly corrosion around bolt holes but it's not rusted out by any means. The wires look good and clean, no scoring or breaks. That said i'm not hearing combustion, I don't think it's getting gas to give the flame sensor a chance to work.

 

[ajw22]

Flame sensor is about 2 years old as well....I will go get some internal pictures. There's certainly corrosion around bolt holes but it's not rusted out by any means. The wires look good and clean, no scoring or breaks.

That does not mean you have adequate continuity for the flame sensing that runs through the grounds.

 

[1poolman1]

Hey guys long time reader, but just getting frustrated trying to find the right steps/diagnostics for my issue.

I have an 11year old Hayward (H400FDN) heater, 2 years ago I replaced all the boards. The heater has worked like a champ since. This past week we were using the heater quit and started throwing the IF code.

The heater worked fine at first, and warmed the pool to the correct temp, however the IF code started while it was maintaining the temp of the pool, I'm not sure if it's relevant or not, however it was raining on and off while we were using the heater.

What I've tested so far -- The ignitor is getting glowing red, the fan is kicking on and off properly, the gas tubes don't appear to be clogged (cleared them with a pick)

I think the issue is related to the power signal to the gas valve. The gas valve makes a hollow sound like it's operating, but I don't smell gas. In testing the gas valve, I see 19 Vac being sent to the valve briefly, like a second or less then kicks back to very low to no voltage.

What should I be looking at next? The Power control board again? The transformer? How do I test these to narrow down the solution?

Thank you,
Chris

Its that "second or two" that is the key. If you call Hayward they will tell you that one or both boards have gone bad. Unfortunately if you only replace one of the boards the other can cause the new one to fail. Though it is expensive, they both need to be replaced together. Also, voltage to the valve should be in the 24V range.

 

[New Pool in Houston]

Headed to get the internal pictures now. I'm really struggling with throwing $300+ in boards at this thing every few years, is that normal, or am I really end of life and should be looking for a new heater instead? What would have caused the failure of relatively new boards? Bad design, using it in the rain? Is the Pentair heater more reliable?

 

[New Pool in Houston]

Here's some of the pictures from inside, including the flame sensor, and boards

 

[Poolbreh]

Here is the ignition sequence.

Here is the troubleshooting guide that states 22-28v. In my experience the vac at the gas valve is nominal. Maybe @swamprat69 can clarify if I’m wrong. 19vac may be enough to open valve.

Here is how to check the gas WC. Stating the obvious but make sure all gas valves are open there is also a switch under the gas valve.

 

[New Pool in Houston]

I'm reading this trouble shooting as replace ICB, as i'm not seeing a good 22-28vac at the valve.

Alright this would be my 2nd ICB in 2 years, is this normal?

 

[1poolman1]

Here's some of the pictures from inside, including the flame sensor, and boards

Looks like the brown wire in picture 1 and 3 in the 4-wire plug is burned.

 

[New Pool in Houston]

Looks like the brown wire in picture 1 and 3 in the 4-wire plug is burned.

woudl you believe me if I told you mildew? I will check tomorrow, but I don't believe it really is. That said what's the implications if it is, all the fuses are good, I did test those today as well

 

[New Pool in Houston]

Well unfortunately, I replaced both circuit boards and the wiring harness and no luck. If anything the voltage is lower than it was, and it's far from 24vac. So just as a guess I've ordered the transformer next as a guess.

 

[New Pool in Houston]

Alright, here's my final update on this. First of all, thank you for the help you provided.

Long story short, my not so trusty multi-meter that I've been using for the last 15 years let me down.

At initial diagnosing of the unit, I was showing 16-19 volts at the gas valve, I replaced the circuit boards (both) and the wiring harness but was still seeing the 16 - 19volts. I next replaced the transformer but that test too was 16-19 volts, I remembered my new Fluke amp meter could do voltage as well, so figured I'd give it a try, sure enough it was 24 volts on the dot. So that left me with just he gas valve to swap.

I was able to swap the gas valve this morning and the unit fired right up.

At least I now have a ton of spare parts for the unit.

Thanks again y'all!