Is the defrost cycle length adjustable?


Old 01-05-09, 12:32 PM
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Join Date: Jul 2008
Location: johnson county, ks
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Is the defrost cycle length adjustable?

I want to change my defrost cycle on my heat pump so that when it does go into defrost, that it waits at least 5 or 10 min before turning the auxiliary heat back off.

The reason is I have a NG furnace and sometimes the defrost cycle lasts 2min and the NG furnace pretty much just wastes gas since it doesn't have time to heat up the exchanger properly.
Old 01-05-09, 06:47 PM
Join Date: Jan 2008
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I don't think you can change the defrost cycle length.

I had a worse problem along those lines with my NG furnace. On short defrost cycles the furnace could not finish its startup routine - air intake, ignition, warm up, then blower -and when this happened the logic board would get confused and shut the furnace down until it was manually reset. It took a while for me to figure out this was the problem because it only occurred on short defrost cycles - ARGH! Anway, I just disconnected the wire to call the furnace on defrost. The HP blows cold air in defrost, but it doesn't bother me enough to do anything about it.

Anyway, there is a solution to your problem! Buy a off delay timer relay and connect it to the HP defrost output to the furnace! It will allow the furnace to run for a few extra minutes (or whatever you set it for) after the defrost cycle ends.


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