Boiler cycling on and off continuously

[Sequoia]

Just got a call-- apparently the boiler that does the floor heat is "clicking" and cycling on and off. The description that I heard was "it seems like it is trying to light but can't. Then it does it again, and again ...."

I'm heading that way later today to look at it, but I know *zero* about doing maintenance on boilers. Can you suggest anything for me to check on it?

 

[Waxman]

Check the flow switch. Mine has a cover on it. Under the cover you can manually depress the flow switch and make it ignite.

 

[MEP001]

It can be a problem with the pilot getting "sucked out" when the boiler lights - dirty injectors or heavy winds causing excessive updrafts can cause it. See if you can tell if the pilot remains lit when the boiler goes out and comes back on.

 

[Rudy]

I had a floor heat boiler do something somewhat similar once. After hours, and hours of troubleshooting (at 11pm), I finally hit the main gas valve with the handle of a ball peen hammer in frustration.

Whoosh.... We've got flames.

It turns out that sometimes, the main gas valve can stick closed. What you hear is the ignition module trying to "fire", but it quits after a certain amount of time without ignition.

That was ten years ago. It's happened twice since. It's been repaired twice with the same hammer handle.....

Merry Christmas

 

[Sequoia]

Hammer

Veeeeeeerrrrrrryyyyy interesting responses.

I glanced at the boiler today but was busy with other things. I'll be prepared to tackle it first thing tomorrow- with hammer and all!

 

[dogwasher]

If the clicking noise is the main gas valve opening (you will then have flame) and then shutting off after about 3 seconds then you may have a dirty sensor.(this sensor verifys flame and sends the signal to the main control board) If you look at the burners the sensor may be mounted in the flame on the opposite side of the ignitor, clean off the sensor with a brillow pad of some sort.

Or as others mentioned make sure its not a flow switch cutting out the ignition source. Please give more details

 

[acbruno]

I had the same problem last year...

Cleaning the flame sensor worked for a little while but days later I had to have the entire pilot assembly replaced. That fixed it instantly.

 

[Sequoia]

Boiler

I looked at the boiler and the automatic ignitor for the pilot is constantly cycling. I did see the pilot flame light ... repeatedly ... but it instantly goes out, waits a couple of seconds, and repeats.

It's a weben jarco ajh350 unit and to my surprise there don't seem to be any access panels on the side of it or anywhere on it. At the very bottom of the unit I can manually lift up the metal ring that encompasses the burner, but I have to be laying on the floor to do that and its pretty tight. I'll look at it again and see if I can clean the thermocouple or sensor-- or maybe I'll have to pull it out, clean or replace it, and then reinstall it.

 

[Rudy]

FWIW....I've also had the solid state ignition module go out and do similar things.

If the module does not sense "pilot" (either because of a bad sensor, or because of an internal fault of the module), it will NOT signal the main gas valve to open.

If both of the above are OK, then the main gas valve may be sticking.