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Posted by Harry on March 19, 2006 at 23:44:25:
In Reply to: WhyTwo Pressuretrols? posted by Paul Williams on February 18, 2006 at 11:48:34:
You dont tell me what pressure you are operating at, however the use of 2 controls is a safety feature and it is code....one of them is the actual operating control and the other one is a high-limit control....should the operating control fail then the high limit will shut down the boiler before the safety valve lifts....the hi-limit therefore should be set higher than the operating control...ie if you operate at 5 lbs then the operating control should be set to cut-out at 5 lbs and cut in at whatever the differential is.....the hi-limit in this case should be set about 1 or 2 lbs higher