Circulating Pump cycles on and off rapidly


Old 01-01-05, 01:08 PM
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Help-Circulating Pump cycles on and off rapidly

Maybe someone can help me with a question. Gas furnace, honeywell L8148j aquastat, and mech. thermostat.
The circulating pump will turn on and then shut down after a few seconds. This repeats every few minutes and after a while it (could be 20 min or an hour) it will turn on normally and stay on until the thermostat is satisfied.
It started doing this the end of last winter and at first the temp dropped to abut 50. When that happened I called the gas co. Inbetween the time I called the gas Co.and the time the tech arrived, the pump stayed on and brought the house up to temp. The tech adjusted the anticipator to stay on longer. From then on it has been doing the same thing except it, so far, has not let the temp drop more than 8-10 degrees before the pump finally stays on and brings the temp back up.
It will work normally for a couple of days at times and then starts the same symptons again.
Could it be the thermostat or sticky/corroded contacts in the aquastat?
What should I do? I did work as an elec apprentice for 3 years so I know I can fix it, but I know very little about heating system troubleshooting besides hooking up the wiring.
Thanks for any suggestions you can give me as where to begin looking for the trouble,

Last edited by BiGMulli; 01-02-05 at 03:56 AM.
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Old 01-02-05, 05:58 AM
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I would suspect a broken/bad solder joint inside the aquastat. If you are adventurous, you can pull it apart and look for yourself. It is not delicate. It is not too uncommon. What happens is the screw that holds the relay to the board comes loose and the shock of the relay closing evenyuallt breaks the joint. If you can solder, you can fix it good as new if that is the problem. I have seen it many times so I have a fair amount of confidence that you will find it to be your problem. One thing you can try is to leave the cover off of the control and when it is cold in the house, go push on the board inside the control with a screwdriver just enough to flex it and see if the relay pills in. If it does, you know thats the trouble. Good Luck. You can also just replace the control but that sort of takes the fun out of it.

Old 01-05-05, 02:57 PM
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Thanks KField, It was running great the last few days so I did not get to try pushing on the board until today. It did not help. I guess the next step will be to pull the aquastat and give it a closer inspection.
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