duct heater

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direwolf
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Joined: Sat Feb 02, 2013 2:53 am

duct heater

Post by direwolf » Sat Feb 02, 2013 3:03 am

Hello, I have a question that has been puzzling me. I have been given the task to figure out how to make a duct heater blower fan run after the thermostat has stopped calling. What I have is a 480V 3phase unit that is working off of a 24V transformer to feed my thermostat and my airflow sensor, which then goes to my 2 contacts. What I want to do is after the blower fan kicks off, the airflow sensor stops sensing air, and the coil turns off I want the blower fan to keep running for a minute or two. I can't seem to figure out how to get around the air flow sensor. If the sensor is closing then the coil will come on. I want to get the residule heat out of the duct basically. Anyone have any ideas. thanks

mikejacobson
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Joined: Sun Feb 10, 2013 10:57 am

- duct heater

Post by mikejacobson » Sun Feb 10, 2013 12:17 pm

I recently had this issue but a little different. What is starting the fan on a call for heat? the stat or some type of fan relay in unit? In some cases I've had to upgrade thermostat and change set up to electric heat mode, which keeps fan on for short time after satisfied. You also could use a fan time delay relay (solid state) that is used for a little better seer rating on a/c units when furnaces were old school.

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