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Rick, HVAC Supervisor
Category: HVAC
Satisfied Customers: 21387
Experience:  40+ yrs. experience as a licensed oil & gas technician.
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My revolution boiler is about 14 years old. Draft motor

Customer Question

My revolution boiler is about 14 years old. Draft motor turns on but it won't ignite all the time. Draft motor will run indefinitely. If I power down the boiler for a few minutes then turn on it will occasionally ignite. My technician has changed the igniter assembly with the flamed sensor and the pressure switch. When it works, the fan runs and a few seconds later there is a click and it ignites. When it doesn't work there is no "click" at all.
Getting real tired of buying expensive parts and no solution.
Submitted: 1 year ago.
Category: HVAC
Expert:  Rick replied 1 year ago.

Welcome to Just Answer, my name is ***** ***** I will do my best to help you with your issue. If my initial response doesn’t answer your question then let me know and we can continue our conversation.

What you're describing sounds like a probable draft pressure problem. Did your guy ever put a manometer on the exhaust?

Expert:  Rick replied 1 year ago.

The only way to diagnose this problem is when the unit doesn't fire up. If you have a multi-meter I can tell you which terminals to probe to test the voltage

Customer: replied 1 year ago.
I don't believe so. I questioned that because my intake/exhaust is a concentric assembly. He wrapped the exterior in stainless a couple years ago since ii corroded once and was replaced and I wonder if it has corroded inside the stainless and something is obstructing the draft.
Expert:  Rick replied 1 year ago.

That's a distinct possibility. It sounds like your draft may be borderline. Which could be due to a weak fan or an obstruction in the exhaust or intake. The procedure is to probe the NO terminal on the pressure switch and B2 on the L8148 (the aquastat relay). If you don't have 24 vac there then the draft differential pressure must be checked with a manometer.

Expert:  Rick replied 1 year ago.

Do you have any more questions?