Hayward Heater - Pilot light won't stay lit

[skeleton-man]

I have a Hayward H250 millivolt heater (natural gas), and the pilot won't stay lit when the button is released.

Two things I noticed:
1) The thermopile seems to be putting out very little voltage - when first lit it starts around 8mv, and after 2 minutes only reaches 18mv.
2) The pilot is a bright orange flame, like a candle, not blue as I suspect it should be.

I had a technician come out to do the initial install, and they claim the thermopile is fine, and that I actually have a faultly gas valve ($300+ part!). How can I argue with a professional, even if I took readings myself ?

Any advice ?

Chris R

 

[danpik]

I have a Hayward H250 millivolt heater (natural gas), and the pilot won't stay lit when the button is released.

Two things I noticed:
1) The thermopile seems to be putting out very little voltage - when first lit it starts around 8mv, and after 2 minutes only reaches 18mv.

Ideally a thermopile should be putting out 750 mv. Most heaters will work down as low as the 350-400mv range.

2) The pilot is a bright orange flame, like a candle, not blue as I suspect it should be.

The pilot should be a bright blue flame and a lot bigger than that. I would suspect a clogged up orifice.

I had a technician come out to do the initial install, and they claim the thermopile is fine, and that I actually have a faultly gas valve ($300+ part!). How can I argue with a professional, even if I took readings myself ?

what was the initial install? Is this a new unit?

Any advice ?

Find a different tech. I am not saying the gas valve is good or bad at this point, but I would suspect the gas valve is fine at this point. But then, I don't replace parts until I find the problem, I measure and find the guilty component and then replace it. Fortunately, like Paul, I do have spare parts that I can swap in sometimes to find the guilty component If I need to do that.

 

[ps0303]

I would replace the entire pilot assembly. The thermopile is bad and the flame isn't right so just replace the entire thing. The pilot tube might be partially clogged causing the incorrect flame. You could try using compressed air to clear it out but there is a possibility it still won't be right.

 

[skeleton-man]

Thanks, I'll try cleaning it, then replacing the pilot. The heater is about 8 years old (bought it used from kijiji) - I had to get a gas line run from the meter to the pool (60ft), so I had the technician hookup the heater. I was hoping to get even just 2 more seasons out of this heater (paid $350). I was hoping not to fork out $2,000+ for a brand new heater this year, since the new gas line cost me $1,300+tax (60ft 1 1/4" gastite flex line).

 

[skeleton-man]

Update: I tried connecting an external thermopile (spare parts I had from another heater), and heating it with a torch. I got it up to 760mv and still the pilot light won't stay lit if I release the button.

Maybe the technician tried this same test and it really is a faulty valve ?

 

[ps0303]

Sure heating with a "blow" torch will do it but that's not a good way of testing. I know you didn't use a blow torch as I was just being funny. Sort of.

 

[danpik]

Are e wires on the gas valve on the proper terminals

 

[skeleton-man]

Are e wires on the gas valve on the proper terminals

Red (from thermopile) = TH-PG
White (from thermopile) = PG
Safety circuit (t-stat, limit/pressure switches, etc) = TH and TH-PG

The valve has a symbol of a coil going between TH and PG. I'll get another picture after.

- - - Updated - - -

Sure heating with a "blow" torch will do it but that's not a good way of testing. I know you didn't use a blow torch as I was just being funny. Sort of.

I just wanted to see if once it got the full voltage, it would keep the pilot open, but it doesn't seem to be doing that.

 

[skeleton-man]

Update, the pilot magnet was NOT wired correctly. Upon closer inspection, it was connected to TH instead of TH-PG!

It now WILL light and even run with an external t-pile, but still no dice with the existing one. Going to swap out the t-pile and pilot light to see if that fixes it!

 

[ps0303]

Hmm, so this used heater came from where?

 

[skeleton-man]

I'm in a small town in Ontario, the heater came from a few hours away down by Toronto. I found it on kijiji (Canadian version of Craigslist).

What's puzzling me, is how the technician missed that wiring problem ? and the pilot issue..

Starting it with an external thermopile, it runs and stays running - I guess the burners put out enough heat to run the thermopile.

The issue appears to be the pilot itself - I had everything apart and there was a brand new TP fitted, but the pilot light was clogged with cobwebs. I used fine wire and compressed air, it looked clean but when re-assembled I still get a weak, flickering pilot.

Fyi, I DID leak-test before attempting to light anything after re-assembly, and can confidently say there were no leaks.

 

[ps0303]

You should remove the tubing starting from the gas valve and then once off the heater blow it out with a little compressed air. If you still have a weak lazy flame, replace the entire assembly. The flame on the pilot is what has enough heat to generate the 450+/- MV to keep the unit running.

 

[skeleton-man]

You should remove the tubing starting from the gas valve and then once off the heater blow it out with a little compressed air. If you still have a weak lazy flame, replace the entire assembly. The flame on the pilot is what has enough heat to generate the 450+/- MV to keep the unit running.

So replace the pilot tubing also ? I'll give it a shot

 

[ps0303]

I would clean it out with air, use a can of air used to spray out computers, first and then see if it's any better. If not, then replace the entire pilot assembly.

Here is the entire part I suggest you replace. Parts4heating.com: Hayward HAXPLT1931 PILOT, NA MV

 

[danpik]

Be careful of the orifice hole when doing this too. The hole is very tiny and can be damaged easily if you pick at it with something sharp. I have used a strand of wire from a CAT 5 data cable to clean them out with in the past.

 

[skeleton-man]

Update: I blew out the line with compressed air, backed the pilot adj screw open more, and was able to get a blue flame with 350mv output. This is enough to keep the pilot open, but just shy of the 400mv needed to open the main valve. I'm wondering if the thermopile is sitting too high and not getting enough flame ?

 

[ps0303]

You shouldn't have to adjust anything with regards to the positioning of the thermopile. Post a picture of it.

 

[Hayward Pool]

Reading down through all the post I have to agree with most of the posts. Not a gas valve but a bad pilot generator(thermopile) Replace the pilot generator first. Less costly and you will know for sure. Remember when the pilot is lit and there is a call for gas the MV reading will drop.