Hayward H250DFN IF code problem

[larrymb]

Hello:

This heater has worked fine for 4 years, but now won't stay lit, and displays an "IF" code. The heater lights normally then shuts down after a few seconds. I've done a lot of research so far and checked quite a bit. Here is what I've done so far:

I checked the gas pressure. I have about 7" on the supply side not running, 5" while running, and 2" (exactly on spec.) on the manifold side when running. So I don't see any gas supply problem.

I checked the orifices. I found #4 slightly blocked by spider webs, and cleaned that out. No change. All other's looked fine.

I pulled the burner tubes and checked each one. No blockages or debris.

I checked voltage to the gas valve. 24v, and the gas valve opens immediately when voltage is applied.

I removed the top of the heater, no blockages.

Following some other advice I saw online, I blocked half the holes on the inducer fan with tape. No change, removed the tape.

With the top removed, I can see through the heat exchanger, the flame looks fine (for the few seconds it's on.) and the igniter glows bright. I don't think there is any problem with the flame itself or the igniter.

I cleaned the flame sensor. No change.

After all the above, I replaced the flame sensor. No change.

At this point, I guess the control board is next. But I hate to throw parts at it. Is there anything I missed? Any other tests I can do before buying parts?

Thanks, Larry

 

[DHoover85]

Hello:

I cleaned the flame sensor. No change.

After all the above, I replaced the flame sensor. No change.

At this point, I guess the control board is next. But I hate to throw parts at it. Is there anything I missed? Any other tests I can do before buying parts?

Thanks, Larry

judging by the context you are giving about your problem I'm guessing you have a flame sensor that wires to the control board and some sort of electric/electronic ignition. (as opposed to a thermocouple type with a standing pilot) that being said, handle that type of flame sensing rod carefully, and don't ever touch it with bare hands, use gloves. It is sensitive to skin oil like a halogen bulb. also when cleaning them I only use a piece of steel wool, nothing else. if you replaced it and the new one didn't get contaminated, then I'd agree that the board is probably dead. I remember there was a way to test that sensor electrically, but don't remember exactly. I think it was DC Milliamps you were looking for, but can't be certain.

 

[ps0303]

Usually cleaning the flame sensor doesn't do much. A flame sensor is cheaper than a board so start there first. Now if that doesn't work, the board is next.

 

[Hayward Pool]

Hi This is John the Hayward tech. You have already done everything I would do checking to find out why the FDN will not light. Based on your information I would say it is either the fuse board or most likely the main control board.

 

[larrymb]

Followup: I replaced the control board and the unit works fine now. While I am happy that the unit works, I am frustrated at what looks to me like a design with an overly sensitive calibration. I don't think anything was wrong with the board other than a component drifted a bit, moving the flame sensor calibration out of range.

 

[ps0303]

larrymb, what happened to you has been happening to lots of Hayward customers on this style heater. It has gotten so I no longer recommend these units to customers. It's really a shame as Hayward is such a good company but they drifted way out of wack with this heater. I have also sen these units have leaky heat exchangers after as little as 18 months.