Is the sequencer to blame?

Old 01-21-09, 01:03 PM
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Join Date: Oct 2008
Location: Upper Marlboro, MD
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Is the sequencer to blame?

Need some clarification on how sequencers are suppose to work.

My air handler heating coils where not coming on, called two technicians and both of them told me that my unit was so old parts where not made anymore. and that the heating package was burnt, and that i needed a whole new system. $5000. I did some online research and decided to mess with it my self. I went to attic and observed that both sequencers were not burnt but the little pin inside was loose. I disconnected them and dusted them off connected them again to my surprise the heating coils came on full force.

my basic understanding is that they are suppose to come on for a certain interval and turn off at certain intervals. like the follwing

so to give a little example.
I tell my t-stat to heat up my house to 75. the air handler unit along with heat pump turn on. aux heat comes on at intervals and helps heat pump heat up the house all while being controled by the sequencers?

Right now my heating coils come on when my unit is off, (stay warm, not on full) when the system turns on they stay this way and do not turn bright orange.

are the heating coils suppose to stay warm to the touch the whole time? if not will replacing the sequencers help me out in this? or is my t-stat wired wrong?

Thank you in advance.
Old 01-21-09, 06:12 PM
Join Date: Jan 2009
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The sequencer just turns on the heating elements whenever there is a call for aux heating. They are called sequencers because they have bi-metal strips inside them that heat up and close contacts that turn on a heating element in a specified amount of time. If your sequencer controls two heaters it will turn one heater on and then wait say 30 seconds to turn on the second heater. This is so there won't be a surge of power if all would come at once. Your heating element should not be on at all if the system isn't calling for them to be on. This can make the limit trip on the heating element and wear it out. There must be something sticking on or wired wrong. The heating element heats up extremely fast and therefore it does not have to be constantly on.

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