Boiler not coming online when stat say to.

RonG

A friend of mine called me about a month ago and said he lost his pilot on his heater and can't get it lit. So right away I replaced the thermocouple, problem solved. Now today he calls me and says his heater will not come on. He said he has pilot and the thermostat is calling for heat, but the boiler won't kick on.

I'm at work so I don't have the exact model number now, but this is what I remember:

Peerless Cast iron sectional- appx. ten years old.
Natural gas fuel, atmospheric exhaust, forced flow hydronic system.

Things I've checked:
1. Power- fine
2. Thermostat functon- fine
3. Continuity from stat to boiler- fine
4. I checked all sensors and automatice damper function- all fine
5. I check the control transformer- fine

The only thing I think it could be, is a bad relay switch-
If I hold the switch for continuity the boiler lights like a champ, once I let go it opens and the boiler shuts down

Does everyone agree this is the problem?
Is there a way to confirm this?
Anyone now of a cheap source (friend is low on cash) for a new relay?

Thanks Ron

Justin Gavin

did you check all the safety's

Did you check the safety's like the gas pressure switch?
Also is there any kind of positive pressure coming from the flue?

Is there a low water cut off? If so is the water low?

If all that is fine than if you think it is the relay replace it. There is a product called Relay in a Bos RIB and they cost about $25 to the contractor.
http://www.functionaldevices.com/pdf/RIB013P.pdf
start here for starters.

Good Luck

Newbee

peerless problem

I checked his water level (he has no low water cut-off), it was fine. I burned a piece of paper next to the flew, the smoke was sucked right out. I'm going to stop by his house today , and check his gas pressure switch.
Thanks