Thread: Anyone know HVAC?
10-16-2006, 11:07 AM #1
Anyone know HVAC?
I have electric heat with a heat pump and this morning i awoke to cold air blowing out of my vents with the heat turned on. I turned the thermostat off and left it alone for an hour. i turned it back on and the display on the thermostat said auxillary heat and proceeded to pump out nice warm air. Next time it kicked on the diplay read heat on like normal but the air blowing out was only slightly warm. If anyone has a clue that would save me from having to call someone to look at it i would greatly appreciate it. Money is tight right now and it figures something always goes wrong.
10-16-2006, 12:29 PM #2
well, I can tell you that aux. heat means the hot air is coming from the backup electric coils in the airhandler(part inside the house).
This could happen if it is too cold outside for the heat pump to handle it.
another thing to check: there should be a little red reset button on the outside unit. Should be near where the electric enters the unit.
If your inside air handler is working but the outside part is not running at the same time, check to see if it needs reset from there.
Also check your main electric box fuses to see if the out side unit breaker is popped. That one should be a double breaker because it is 220 volt.
Check those things and report back. I am not an a/c guy but I work warranty department for Ryland homes and have some experience troubleshooting.
10-16-2006, 12:48 PM #3
Thanks for your input. Im a first time homeowner and am not familiar with heat pumps. The outside unit is working, however it is making some strange noises from time to time.
10-16-2006, 01:18 PM #4
10-16-2006, 05:53 PM #5
I'm no HVAC mechanic, but living in the desert, heat pumps are the norm. I've spent a ton of time and money repairing mine, until finaly replacing it.
Probably thermostat... but heat pumps are dependant on a device called a "reversing valve." Once they stop functioning correctly, you will have very strange behevior from your unit.
10-16-2006, 06:10 PM #6
- Join Date
- Jul 2006
how cold was it? also the rev. valve might be stuck on a/c. also using the aux. heat / heat strips your light bill will be high compared to the norm. i will also ask my buddy at work and be back...worke for a/c comp. or you can get some PROPANE.... ....thought about something is the unit outside workin....also is it package unit or a split system......
Last edited by YJSONLY; 10-16-2006 at 06:18 PM.
10-16-2006, 06:13 PM #7
All good advice. I have an AC unit with a heat pump feature. The one time it didn't heat the house it was due to a tripped breaker.
Let us know how u make out. Running the elec strips can be pricey.
10-16-2006, 07:06 PM #8
it's working fine now, brand new digital thermostat 3 months old. It was only 38 degrees which is why i was amazed it was running on auxillary. I think it may be running low on R 22 since i had it freeze upo on me this summer. i'm gonna check that out and the reversing valve.
10-16-2006, 07:54 PM #9
How old of a unit are we talking about? If your not sure post up the serial number and I can help you. These units typically only last about 10-15 years for a heat pump for a decent one and 8-12 for the el' cheapo's.
All a heat pump does is run your AC in reverse. Thats what the reverse valve is for.
Figure that when you run the AC in the summer the cool air is inside and the warm air is outside. In the winter the reversing valve reverses the flow and the warm air is inside and the cold is outside.
Anytime you use the aux heat your electric bill will crank! Think of it as hair dryer coils....
If the unit is freezing up it may be an air flow issue, clogged line or failing compressor as well. It can be an impropperly wired thermostat that is not allowing the system to go into the defrost cycle.
They should never ice up
10-16-2006, 08:48 PM #10
- Join Date
- May 2005
The heat pump comes on first on a call for first stage heat along wth the fan in your air-handler (furnace). When the heat pump is running with no auxilliary electric heat you should have approx. a 20 degree temperature rise across the air-handler. Example: If it's 70 degrees in the home, the temperature of air coming out of the registers should be around 90 degrees, which will feel cool to your hand. When the heat pump alone can't satisfy the thermostat the thermostat will call for second stage heat (aux. heat) and bring on the electric heating elements in the air handler. You should now have approx. a 50 -60 degree rise across the air-handler. The outdoor coil is the condenser in the summer but the evaporator coil in the winter. The outdoor coil will get cold because we are cooling the outdoor air in the winter. Because the outdoor coil will get below freezing in the winter frost will form on the coil. When this frost gets to a point where it will affect the efficiency of the system the heat pump will go into a defrost cycle for 2-5 minutes. When this happens you will hear a whooshing noise outside, the condenser fan will stop and the unit will go into air conditioning mode, making the outdoor coil warm enough to melt the frost. The system can be installed with electric heat coming on when in defrost or not. If the electric heat does not come on in defrost you will feel cold air coming out of the registers because it is in air conditioning mode. This is likely what you were experiencing when you felt cold air coming out of the registers, but then the system appeared to be working fine. You will also notice steam coming from the heat pump when in defrost, nothing to worry aboiut, it's normal from the frost melting. Hope that helps. Should give you some insight into the operation of a heat pump system. And yes, I am in the hvac business.
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