Hayward H100ID Gas Heater - Cycles Once, Then No Heat

[ronmerk]

I have a Hayward H100ID nat gas pool heater, 2 years old.

In the last couple of days, it's not working as usual - we have it set to auto run 2 hours, 2xs a day. This usually results in water temp of approx 90 degrees. The last couple of day, I noticed the water temp has fallen off dramatically.

The heater was on, but blowing cold air out of the hot air exhaust. By turning off the heater and restarting it, I can get the heater to come on and go through 1 whole complete cycle (5 to 8 minutes). Then the burner shuts off as it should - air fan runs, but the burner never fires up again.

It's like the heater has gone into lock-out mode. By pulling the plug out or turning the heater off/on, I can get it to re-start and go through 1 cycle.

I have checked the following:

• Filter backwashed
  All screens cleaned
  water pressure good
  Following tested with multi meter-
  Air pressure switch is working
  Temp Limiters are working
  water pressure switch working
  Thermostat working

By disconnecting the power connectors anywhere in the "red wire" side of the circuit to the control module, I can simulate the reset of the lock-out and cause the heater to go through one complete cycle.

Ideas?? Suggestions??

Ron

 

[PoolGuyNJ]

How did you test the high limits? Check them right when the heater shuts down. While you are waiting, listen carefully to the fan motor.

Scott

 

[ronmerk]

I actually took the leads off (one sensor at a time) - put a "short" jumper across the leads and then put my ohm meter on the sensor and watched the ohm meter as the heater went through it's cycle.

Each sensor had continuity until they "opened" from the heated water temp -then they closed when the water temp cooled off.

 

[PoolGuyNJ]

They shouldn't ever open. If the the water is getting hot enough to open them, not enough water is going through the heat exchanger or they are shot or the pressure switch is set for too low a flow.

The only time a heater, in normal operation should shut off is when the pump turns off or the the thermostat has sensed the set temp has been reached.

If the high limits are good, then it is also possible that the tubes in the heat exchanger are clogged or the internal water flow bypass is malfunctioning and bypassing too much water. I don't know if the spring in the bypass is still available.

 

[ronmerk]

Hi Scott:

You nailed it!

Thinking about your reply, I went back to the heater and gave the heat exchanger main pipe a rap or two with the handle end of a screw driver. The heater immediately began to make knocking, popping and rattling noises. (water flow problem)

I took off the main water connections to the heater and looked into the inlet end. I could see that the water flow bypass "spring" had broken off at both ends and was jammed downward - causing the water to flow through the main pipe, but not diverting into the heat exchanger. When I touched it with my fingers it was loose and flopping around inside.

The water bypass "spring" looks a lot like a salmon fishing flasher - about 10 inches long, 3inches wide and bent at the ends in opposite directions. Hayward used "epoxy" (not even welded) to attach the both ends to the main copper pipe that makes up the flow-through chamber for the heat exchanger.

Luckily there is 1/4 inch vertical tube that houses a temperature sensor for the thermostat at the inlet end of the main chamber. I was able to put a pipe clamp on this tube and force the water flow bypass spring up into it's proper position. Heater is now working great.

I must say up to now I always though Hayward made a decent product, but "epoxy" to hold this piece in place is ridiculous. If I wasn't doing this repair myself, the cost of a new heat exchanger and labour to install would be as much as the heater cost new.

Thanks to you Scott in leading me in the right direction.

Ron

 

[Brian68]

Hi i have the same heater and it make the same popping banging sounds that you have talked about.i would like to try what you have but i am not sure what you did? is there any way of seeing some pictures or a diagram of what i am looking to fix?

 

[khocke]

+1 on Ron's repair advice. Getting that hose clamp in there was no picnic but it tightened up the entire diverter nicely. Even though the outlet side of the diverter seemed tight after hose clamping the inlet side, I JB welded it too. So far so good.