Forced Air Heating Blower short cycles


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Old 02-08-16, 01:54 PM
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Forced Air Heating Blower short cycles

I have an oil fired furnace hydronic forced air heating system. The second floor zone blower unit constantly short-cycles. It will run for about 30 seconds then shut off for a minute or two and then run for about 30 seconds again and so on. This keeps happening until the t'stat is satisfied. What would be causing this?
 
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Old 02-08-16, 05:27 PM
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There are several possible reasons depending on the control scheme. Has it always done this or is this a recent development? Has any work been done on any part of the system recently?
 
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Old 02-08-16, 06:09 PM
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We recently had one zone eliminated, old hot water heater replaced with new propane fired unit. But it is something that's been happening for some time now.
 
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Old 02-08-16, 06:56 PM
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Often the fans on hydronic fan coils are controlled by water temperature. If the sensor is not tight against the pipe, you will get erratic fan operation. Another possibility is the sensor itself could be the source of the trouble. Still another is the water actually cooling faster than it used to maybe due to insulation on the pipes being lost. A problem like this can take a lot of investigation.
 
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Old 02-09-16, 06:04 AM
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I haven't forgotten you but it may be a few days before I can make much of a response. Grady has given you some things to check.
 
 

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