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12-03-2008, 02:11 AM #1
Using Gas as Aux heat witha heat Pump
Whats any ones thoughts on using a gas fired furnace as Aux Heat with a Heat Pump? Do not have the ac power to run Aux electric heat strip.. located East Texas. Could one put a short time delay on the defrost to give the furnace time or whats your thoughts on just doing it..AllTemp Heating & Cooling
12-03-2008, 05:52 AM #2
I think I would hook it up , throw the thing in test mode for defrost and see exactly what happens while im standing there... have your guages on to see what the pressures do with the furnace heat blowing directly on the coil during 2nd stage heating as well.
Last edited by Snapperhead; 12-03-2008 at 06:11 AM.
12-03-2008, 07:16 AM #3New Guest
- Join Date
- Nov 2008
- Tranas, Sweden
What system are being used to transport the heat? -Water and radiators?
We use additional heaters such as theese all the time with heat pumps.
We heat up the return from the radiators through the heat pump, then we run it through a valve that returns it out to the radiators.
If there's a higher demand than the heat pump can satisfy the add.heater is started and once it is warm the valve will open slowly to the add.heater and some of the flow from the heat pump will go through the add.heater.
There's an extra circulation pump over the add.heater to prevent boiling points.
Once the valve is fully closed the add.heater is timed out and turned off.
Hope this was to assistance
12-03-2008, 08:40 AM #4Professional Member
- Join Date
- Mar 2007
looks like you just want forced hot air type of system. We do these sometimes depending on what the customer wants.
It works just fine, BUT it doesn't work like you are thinking. The strip heat will come on while the compressor is still on (unless its in defrost mode). On a gas heat type system the heatpump is off while the gas furnace is on. Most people use a duel fuel kit to accomplish this, but the honeywell t-stats will do a better job instead of the dual fuel kit. You just have to use an outdoor t-stat to go with it.
12-03-2008, 10:08 AM #5
don't know how other manufacturers do it but Lennox uses a thermostat between the gas furnace and hp coil to temper the air out of the furnace when hp is in defrost.
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12-03-2008, 03:52 PM #7
Hybrid systems are the best IMHO....
Just use a Honeywell IAQ stat and you are good to go....
You can't have the heat pump and the gas furnace firing together....
The IAQ stat has the ability to serve as your dual fuel stat....
For this application you will also need an outdoor sensor....I need a new signature.....