Weil McClain boiler (GV-5, Series 4) "Puffs" on start

jy001

I have a Weil McClain boiler (GV-5, Series 4) with operational issues. When it tries to start it takes an extended period of time. I have the panels off the boiler and can hear the flame "puff" 4 or 5 times before it lights.


This “puffing” is a concern since a month ago the boiler would also puff a few times, try to light and then stop. It would never start. In that scenario the troubleshooting chart, based on the fault lights on the boiler, in the manual, indicated it could be a voltage issue, ignitor or gas valve. Voltages were in spec, and I replaced the ignitor, still didn’t fire but it DID puff until it timed out


Before I ordered a gas valve, I took the entire boiler apart all the way down to the orifice that converts the natural gas unit to propane. I cleaned everything and blew out the orifice inlet with compressed air. Put it all back together and it worked for over a month without any puff until this morning when it wasn’t running. It is running now, however, with the extended puff mentioned earlier.


Just curious if this fault scenario is familiar, common, etc. Hoping to figure out the issue before it dies completely in the middle of Winter.

hot_rod

Do you have a way to check gas pressure, before and after the gas valve? You want to see static pressure, nothing running, then check pressures as the boiler fires and also at high fire.

Jamie Hall

You also need to check the draughts on the unit and make sure that the cleaning really cleaned the heat exchanger and that the breeching and flue are clear.

EdTheHeaterMan

The trouble shooting guide has to many options to look thru without knowing some answers to what the conditions of the lights on the mater control are.
Trouble shooting starts on page 66 of this book https://www.weil-mclain.com/sites/default/files/field-file/gv-series-4-manual_1.pdf. Observing the conditions of the control at the time of the failure, will point you in a direction to look. Without knowing answers to questions like: "are certain lights on, off, or flashing" when the sound or puffing happens we can only guess and use the parts cannon. Eventually you will find a part that will fix the problem. You may have to rebuild the entire boiler a piece at a time, but with unlimited funds, and being in no hurry you can eventually get it right.

I would suggest using standard logical diagnosing to rule out what is not broke, until you get the the part that is broke or dirty or out of adjustment.

JUGHNE

Does the exhaust exit the lower part of the boiler?
Did you take that apart where it connects to the CI section?

There should be a drain tee/hose on the exhaust pipe right at the boiler, that needs to be clear.

EBEBRATT-Ed

I would check the gas pressures as others have mentioned. You need to check the gas pressures at the gas valve inlet and outlet.. Usually 12-14" wc at valve inlet and 9-11" outlet but follow what the boiler manual says

Since you mentioned propane do you have any other propane appliances and are they working ok??

It almost sounds like a sticking regulator. Could be the one in the gas valve, at the tank or at the inlet to the house. Chek to see if the regulator vent openings are clear. Spiders and bees like to get in there.

Did you pull the burners out and clean them?

HVACNUT

Check intake and exhaust and make sure both are clear.
It's a negative pressure gas valve and should read -0.2" wc manifold.

jy001

hot_rod said:

Do you have a way to check gas pressure, before and after the gas valve? You want to see static pressure, nothing running, then check pressures as the boiler fires and also at high fire.

No, I dont. I will likely have to purchase a Manometer.

jy001

Jamie Hall said:

You also need to check the draughts on the unit and make sure that the cleaning really cleaned the heat exchanger and that the breeching and flue are clear.

I checked for air flow blockages when it stopped working a month ago. I have not cleaned the heat exchanger though, I'll do that the next time I take everything apart.

jy001

JUGHNE said:

Does the exhaust exit the lower part of the boiler?
Did you take that apart where it connects to the CI section?

There should be a drain tee/hose on the exhaust pipe right at the boiler, that needs to be clear.

Are you referring to the condensate drain...??

jy001

EBEBRATT-Ed said:

I would check the gas pressures as others have mentioned. You need to check the gas pressures at the gas valve inlet and outlet.. Usually 12-14" wc at valve inlet and 9-11" outlet but follow what the boiler manual says

Since you mentioned propane do you have any other propane appliances and are they working ok??

It almost sounds like a sticking regulator. Could be the one in the gas valve, at the tank or at the inlet to the house. Chek to see if the regulator vent openings are clear. Spiders and bees like to get in there.

Did you pull the burners out and clean them?

I will be purchasing a Manometer to check pressures. All my propane appliances are working fine...

I like the idea of checking the regulator at the inlet to the house, I'll look at that today. Burners were not removed.

jy001

EdTheHeaterMan said:

The trouble shooting guide has to many options to look thru without knowing some answers to what the conditions of the lights on the mater control are.
Trouble shooting starts on page 66 of this book https://www.weil-mclain.com/sites/default/files/field-file/gv-series-4-manual_1.pdf. Observing the conditions of the control at the time of the failure, will point you in a direction to look. Without knowing answers to questions like: "are certain lights on, off, or flashing" when the sound or puffing happens we can only guess and use the parts cannon. Eventually you will find a part that will fix the problem. You may have to rebuild the entire boiler a piece at a time, but with unlimited funds, and being in no hurry you can eventually get it right.

I would suggest using standard logical diagnosing to rule out what is not broke, until you get the the part that is broke or dirty or out of adjustment.

Thanks for the link, that's the same manual I have been using for months. That's how I even got to this point, running through troubleshooting, diagnostic flow charts, specifications, etc. Thats also how I came to the conclusion that the controller is functioning, the ignitor was faulty and that the gas valve was potentially faulty. All of those decisions were made based on review of the diagnostic flow charts in the manual. It is a very well written and detailed. I don't feel as though I am using a "parts cannon" at this point.

If I had unlimited funds I would have purchased a new boiler by now.

JUGHNE

If this is the boiler design I am thinking of, take off the front panel and find where the exhaust connects to the cast iron.
If you look in there you may see some blockage from condensation/soot preventing smooth operation.

A picture would help.

pjc_2

Check the burner cone shown in figure 32 on page 65. These cones can develop holes over time and can cause rough ignition. We have replaced many on these gv's that had rough starts.

jy001

JUGHNE said:

If this is the boiler design I am thinking of, take off the front panel and find where the exhaust connects to the cast iron.
If you look in there you may see some blockage from condensation/soot preventing smooth operation.

A picture would help.

I had previously checked for blockages, etc.

jy001

pjc_2 said:

Check the burner cone shown in figure 32 on page 65. These cones can develop holes over time and can cause rough ignition. We have replaced many on these gv's that had rough starts.

I should have thought of this myself, considering I already had the cone off... It was definitely worn and after having read your comment I will likely remove it again and give it a closer look.

jy001

jy001 said:

pjc_2 said:

Check the burner cone shown in figure 32 on page 65. These cones can develop holes over time and can cause rough ignition. We have replaced many on these gv's that had rough starts.

I haven't gotten to taking the boiler apart to inspect the cone, however, I did tap the gas valve with a rubber mallet this morning as it was starting/puffing. It started after a few more puffs, however, the next time there was a call for heat, it fired without any puffing and I did not tap the valve that time.... First time in weeks no puffing, quite a coincidence considering I had just tapped the valve the previous fire. What is your opinion on the issue potentially being a sticky valve...? Just curious... Thanks...