Weil Mclain Gas Boiler Issue

[Zane Frederick]

Hello,

I'm having an issue with my Weil Mclain Gas Boiler (Heat Only) where it is having trouble kicking on. I came home from the holidays to a very cold house as the heat hadn't seemed to be running for a few days. The thermostat was set to 65, but the house was around 50 when I arrived home. I opened up the boiler to make sure everything looked okay, which it did. Stumped on what the issue could be, I just starting tapping on the components of the boiler and pipes connected to the boiler. Low & behold, when I tapped on the water pipe that's connected to the expansion tank, the boiler kicked on. The boiler had no issues running and getting the house back up to temperature, but it now seems to be a reoccurring problem. The Boiler has no issues when running, but when it shuts off & needs to turn back on, it will not. That is until I go down and tap on the water pipe. What could this be? Would a frozen pipe cause this? Any insight is appreciated.

 

[WorthFlorida]

A few things to check out.

Somewhere near or on the boiler is a control box. Generally where the thermostat wires terminate to. There is a relay in there and it might be hanging up. The next time tap the control box. Or remove the cover and inspect it. Having someone operate the thermostat and you should hear or feel and maybe see if the relay is operating. Note, most thermostats (digital or WiFi) has a built in delay timer between cycles so the unit is not fired up , on-off-on immediately. It might be about a three minute delay. I'm not sure if the boiler itself has its own delay timer in the control box.

Is this a gas or oil fired? What is the model number?

Have you drained the expansion tank lately? A steel tank just empty it. A bladder type drain it and pressure check it that it is at 12PSI. The boiler must be off during the drain procedure. With too high pressure the relief valve should have opened and you would see water somewhere. Note item #2. If this is the case I would suspect that the system would shut down before reaching set temperature.

From a manual for EG Gas Boiler

If boiler doesn’t start . . . Check for:

1. Loose connections, blown fuse or service switch off?
2. High limit switch set below boiler pressure?
3. Thermostat set below room temperature?
4. Gas not turned on at meter or boiler?
5. Incoming gas pressure less than:5” w.c. for natural gas? 11” w.c. for propane gas?
6. If none of the above corrects the problem, see “Troubleshooting” in the Control Supplement.

Does the unit have a motorized damper?

 

[Sponsor]

 

[Fitter30]

Take some pics of the boiler and related piping and controls and model of boiler