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Posted by Vern on February 27, 2005 at 20:44:38:
In Reply to: boiler cold start mystery posted by Susan on February 23, 2005 at 23:59:26:
: Hi, I own a Weil-Mclain HE II natural gas-fired boiler(7 years old)to operate our under-joist radiant heat system and domestic hot water in our house.
: One thing I start to notice is whenever my boiler begins under a 'cold' start in which the boiler temperature is low after a prolonged period of boiler idle, it just keeps on short-cycling on and off, on and off.....(flame won't stay on for more than 10 seconds, then shut off ,then immediately starts the cycle again since thermometer still calls for heat). Because of that, it takes forever to reach the initial first high limit cut-off temperature of 180F. Once it heats up, no short cyclings repeat and it works fine. Flame stays on until reaching the high and re-starts once dropping below the low differential.
: No one can figure it out. One technician said it's the wind draft coming down from the chimney.But it happens on a calm day too! And another company came in and said it must be a faulty aquastat and changed that, but the situation still persists. Please help me and my family!
Does your unit have a flue gas spillage switch located on the stack? If so, has any of the companies you hired checked this? What can happen on a cold start is you don't have enough draft to pull the exhaust gases up the stack and they can spill out of the draft diverter or stack damper and trip the switch. Then when everything calms down the switch can reset if it is an auto reset switch and start all over again. When the chimney gets hot enough for a sufficient draft, the flue gas spillage stops and everything works properly. Hope this helps.