Ancient Hayward H350ED2 Issues

[HeskeyM]

Hi everyone!

EDIT: Wow, I apologize in advance for the wall of text.

We bought a pool equipped house that was in a deep (deep) state of disrepair - pool included. I've been chipping away at issues pretty steadily, making learning and repairing the small pool my hobby. Its a very small unit, more of a sim spa than a pool. By my calculations its only about 2800 gallons. Before I get to the issues, let me try and give an idea of the entire system:

• Rectangular, approx 4 feet deep pool/spa area
• Three pumps (none variable speed).
  • Filter
  • Swim Jets
  • Spa jets
• Cartridge filter
• Easytouch upgrade automation
• One (ancient) Hayward electronic ignition heater. I don't have a date of manufacture, but this thing must be from when the pool was originally installed, which in my estimation was sometime in the mid-90's.

I got the pool pumps running after much troubleshooting. This site helped me learn the chemistry side of pool maintenance and as a result we've actually gotten a lot of good use out of it the past year. The pool heater originally was inop, but I managed to track that down to two issues: broken water temperature and pressure sensors. We got about three good months of use from the repaired heater.

I went to turn it on three days ago and no luck. I've followed what troubleshooting processes I've been able to find, but I do not have an original manual for the unit and it's so old that there don't seem to be copies available online for this specific model/vintage. The reference material I've found is for newer versions of this model and while it helps, it isn't exact. I think the issues this time are rooted in the gas valve, but I'd like to run that by you folks as a bit of a sanity check.

Specifically, the heater igniter sparks, and the pilot lights on a call for heat from the controller. But nothing else happens. When the heater switch is turned on at the control panel I can hear a click from what I suspect is the pilot solenoid, the pilot lights and the igniter begins to spark...and never stops until the heater is disabled.

I checked the flame sensor thermocouple and I'm getting somewhere in the vicinity of 500mV when exposed to a differential, which checks against a brand new unit. I figure the control unit is working fine if the iginiter is sparking in the first place, ditto for the remaining components of the safety loop. I checked the gas valve at terminal TR, looking for 24V and it checks out okay.

In my reading here I've noted that I should get a whiff of natural gas on startup. That definitely doesn't happen. I don't have a manometer to check for gas output pressure, though I suppose that's the next step. By now I think I have enough data points to call the gas valve bad, but its $200 at the cheapest. I'd love a second of opinion if anyone can think of anything else.

This site is awesome.

 

[ajw22]

Welcome to TFP.

@ps0303 @Pool Clown @swamprat69 ideas?

 

[swamprat69]

This might be the manual for your heater, but your description seems to be a cross between the millivolt model and the electronic ignition model??? A close up photo of the pilot assembly and a close up of all sides of the gas valve would be helpful. Also a straight on and 45 degrees above the burner compartment including the gas valve and gas mainifold.

 

[Pool Clown]

Conservatively, mid 90's puts that heater at around 25 years. I would give the heater a good look through. Flashlight, mirror, whatever it takes to give it a good rust and mouse or rat inspection. The results may warrant a new heater as opposed to repair (fiscally speaking).

making learning and repairing the small pool my hobby.

As with all hobby's comes a price...

 

[HeskeyM]

This might be the manual for your heater, but your description seems to be a cross between the millivolt model and the electronic ignition model??? A close up photo of the pilot assembly and a close up of all sides of the gas valve would be helpful. Also a straight on and 45 degrees above the burner compartment including the gas valve and gas mainifold.

Thanks so much for replying!

Actually, that one is close, but I think its one of the newer ones I mentioned above if you can believe it. The heater itself is definitely electronic ignition, the component I was talking about earlier was just the flame sensor.

During this past year I've taken a massive amount of pictures, please see the attachments, hope its what you're looking for. Forgive the horror show of dirt and crud all over. These pictures were taken last year during my initial assessment. Believe me when I say that as bad as they look, the reality was way worse.

I don't have a shot of the entire manifold, but I can get one tomorrow.

 

[HeskeyM]

Conservatively, mid 90's puts that heater at around 25 years. I would give the heater a good look through. Flashlight, mirror, whatever it takes to give it a good rust and mouse or rat inspection. The results may warrant a new heater as opposed to repair (fiscally speaking).

As with all hobby's comes a price...

I am 100% that this heater is going to be replaced in the next year. I just hate when machines don't do what I tell them.

 

[swamprat69]

24 volts at TR??? TR is the 24 volt common leg of the transformer. You should have 24 volts between TH and TR at the gas valve. If you do have 24 volts between TH and TR, then the possibities may be a poor electrical connection at TH and TR at the gas valve, an open coil for main gas valve solenoid or a stuck solenoid valve or no gas supply pressure. If you don't have 24 volts between TH and TR at the gas valve what you might try if you are comfortable and feel safe doing it is to pull the pilot assembly. You may have to take the gas valve inlet support bracket off to disconnect the pilot tubing from the gas valve. Be careful of the brass compression nut on the pilot tubing as it tends to round out easily. Remove the pilot assembly from the burner frame. Clean the metal electrode and flame sensor with steel wool being careful not to stress and crack the ceramic insulators on both. Clean the underside of the pilot hood to bare metal with either dental picks or a small metal or diamond file. When you reattach the pilot assembly, clean to bare metal the areas where the pilot assembly bracket and the burner frame touch. Make sure the ground connections from the ignition control to the heater/burner frame are also clean bare metal. The ignition control must recognize that the pilot flame has been established before it puts 24 volts to TH and TR. From the looks of the heater, I would also check for good connections at all of the ignition control connection points and also make sure that the burner slots, inside of burner tubes and gas manifold orifices are clear and clean.

 

[HeskeyM]

Hi @swamprat69, thank you for the suggestions. The pilot lights immediately every time, so I suspect that there is no issue with that side of the valve. That's what led me to suspect the flame sensor and pull it out for testing/cleaning.

What I'm leaning most towards is the main solenoid being bad, but I will double check the presence of 24V between those terminals in a couple of minutes here and report back. Honestly, I suspect that I'll be spending some money today.

 

[HeskeyM]

Quick follow up to this: There is NO voltage between main gas solenoid terminals TH and TR when the heater tries to start. Wouldn't that actually point towards the electronic ignition module?

 

[swamprat69]

If there is no voltage between Th an TR on the gas valve it would point to the ignition control not sensing the pilot flame is there. Follow above instrcutions after "If you don't have 24 volts between TH and TR at the gas valve " if you feel comfortable and safe in doing so.

 

[HeskeyM]

If there is no voltage between Th an TR on the gas valve it would point to the ignition control not sensing the pilot flame is there. Follow above instrcutions after "If you don't have 24 volts between TH and TR at the gas valve " if you feel comfortable and safe in doing so.

Okay, I'm going to try to not leave another wall of text here. TL/DR: I think I've got the issue figured out.

I followed your advice and my hunch that there wasn't anything wrong with the gas valve following the lack of 24V at the main solenoid terminals. The diagram has that signal coming from the ignition module, and it is enabled by the flame sensor. I'd pulled out the flame sensor earlier in the week and cleaned it, followed up by testing it on an oscilloscope and watching the signal change when exposed to a temperature differential, then comparing it to a brand new unit I'd bought on amazon when I'd originally pegged that as the issue. That only leaves the control module. Specifically THIS relay on the control module:


I've dealt with my share of faulty relays in the past and if the code just above it is what I think it is this thing has performed way beyond what most folks would expect, especially being outside and neglected as it has been. I pulled out the board, bench-tested the relay and it was definitely sticky. Putting it back on and attempting to light the heater worked this time, but only after some definite "Please replace me NOW" noises coming from it. But...



Can't argue with that. Now, the relay appears to be discontinued, so i'm in the process of sorting out a replacement. This should cost me less than ten bucks. Which is way better than the $200 I was ready to spend on a new gas valve.

The kid's 3rd birthday party this Saturday may not suck. Thank you all for your help. It was invaluable.

 

[swamprat69]

Your photo of the burners and burner box seem to show excessive yellow tipping and slightly lazy flame from the burners. This would indicate that the that the burners should be cleaned inside and out and possibly use a pipe cleaner to clean the gas manifold orifices.

 

[HeskeyM]

I'll do that! Thanks again!