Boiler Stops Heating Periodically, Power Reset Fixes It

drewak

My boiler stops heating periodically and I'd appreciate some insight on how to address it.

I've got a 3 year old Weil-McLain GV90+ 3 Series 2 boiler. Single zone plus indirect water heat. Taco circulators.

Periodically, like every couple months, our boiler stops making hot water. Thermostat and indirect water heater put in calls at the zone valve, but boiler doesn't respond. Cycling the breaker or the switch at the boiler make everything good as new, until it happens again. I've done the checklist in my manual:
- the breaker isn't tripped
- I don't get 120 VAC across my circulator pins
- I don't have any red lights and the system isn't in lockout
- There is no obvious signs of trouble, though the relief valve is weeping slightly
- The toubleshooting guide concludes to replace the controller board

Any thoughts? It seems that the controller replacement is simple enough for a DIYer, but I'd like to be sure that it is the cause. Thanks.

JUGHNE

Find the install manual if you don't have it already.
You probably have a hot surface igniter, (HSI). It may double as a flame sensor. The igniter part it can do easily but if slightly defective its function as a flame sensor may be affected.

IIWM, I would change the HSI first. It is very fragile to handle so use caution. Check all wiring connections, especially ground wire to burner. Reseat all spade terminals to cut any corrosion that may be there.
HSI is less money than board.

There are probably pressure switches also that could affect this with combustion air in and venting out. But IMO I would start with the HSI.

drewak

Thanks, and you were right. Last night the igniter died and a new one this morning got us back in business. Which is great, because it is getting cold here in Alaska. I hopeful that this fixes our long-term issue as well.

JUGHNE

Good to hear the feedback......if I was in Alaska I would keep an extra igniter on hand.....(maybe a wood burning stove, also )

Please report if there are other issues as well.

drewak

Okay, its me again. I'm not certain that the HSI was the sole issue last time, but it was bad and was replaced. At the moment we have no heat (still January in Alaska) and I can't get the control board to register the thermostat calls from the valve controller. Both indicator lights are on, but the control board doesn't even start the cycle (whereas last time it was stop at the ignition part). Power cycling does not fix it like it has in the past. I'm getting voltage from the valve controller and there is continuity. I'm going to check a few more things tonight, but I think I'm just going to swap out the board in the morning. I'd appreciate any other thoughts.

lchmb

there should be an end switch on the controller that calls the boiler on. A simple jumper of this should tell you if it's the controller or the board...