air source heat pump question

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I have an air source heat pump with electric furnace backup. I love the heat pump especially in the face of the rising gas prices.
I have what I think is a problem...or maybe its normal. Once in a great while, and this will be when its in the mid-30's so I'm not running when its below 28, after the heat pump has kicked on and brought the temp in the house up to the set point, the furnace fan continues to run, cold air comes out, and the heat pump's compressor seems to still be running but the heat pumps external fan isn't on.
Any ideas??
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wrote:

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On Sat, 24 Dec 2005 15:32:00 GMT, .p.jm@see_my_sig_for_address.com wrote:

I have an air source heat pump with electric furnace backup. I love the heat pump especially in the face of the rising gas prices.
I have what I think is a problem...or maybe its normal. Once in a great while, and this will be when its in the mid-30's so I'm not running when its below 28, after the heat pump has kicked on and brought the temp in the house up to the set point, the furnace fan continues to run, cold air comes out, and the heat pump's compressor seems to still be running but the heat pumps external fan isn't on.
Any ideas??

Pj has to be a bot...
There can be no other explanation. No one in their right mind would sit all day and all night every day and every night posting "alt.home.repair, not here" within seconds of a target post.
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The heat pump is going into defrost mode. It is drawing heat from the house and pumping it into the outside coils to burn off any frost that may have formed. Some units even go into the resistance heat mode to make the process work. It is a normal function of a heat pump.
BTW depending on your heat pump model it can run as low as zero degrees. I had a GE unit for 18 years and it ran OK (although not very efficient) down to zero.
ftwhd wrote:

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It probably goes into hesistance heat mode during defrost to avoid a cold draft in the house.
Bob
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Is "hesistance heat mode" related to the heating delay mode?
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No. It's related to typeing incompetence. "resistance"
Bob
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Kind of like spelling "TYPING" ? Bubba
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When your air source heat pump goes into defrost, three things happen:
1) Reversing valve switches to cool position.
2) Resistance heat comes on to temper the indoor discharge air so it doesn't blow cold.
3) Outdoor fan shuts off so the outdoor coils thaw faster.
After 10 minutes or after the outdoor coil warms to 70 degrees, the defrost mode terminates. NOTE: during defrost you may notice white vapor coming from outdoor unit. This is water vapor, NOT smoke! You will also see water running out of the outdoor unit. This is normal.
Stretch
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Yup...thats exactly what is happening...except the backup electric furnace is not kicking on. I bought this house this year and the previous owners put all this in and have an extended warranty past this year...get this...they require 2 paid visits a year for 5 years to keep the warranty...what a load of crap especially considering they didn't install it correctly to begin with. So this is the last "free" visit before having to pay, and they better fix it...or I could care less about their rip-off "warranty" requirements.
Thanks for the reply.
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Most manufacturers residential *minimum* warrantys are 1 year parts *and* labor, 5 years on *all* the parts, and 5 or 10 years parts warranty on the compressor. It sounds like the installers are trying to load you like a shotgun. Got make/model/serial number?
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The tech came out and it was exactly what the decent ppl in this forum were saying...it wasn't wired correctly.
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Without getting too technical:
There is one wire on the outdoor unit that is used to send a signal to your resistance heat telling it to come on when it is going through defrost. A lot of the manufacturers state in their install instructions: "Leave this wire off for best economical performance" (or something like that).. It could be that it was never hooked up. 9 times out of 10 it's the white wire, but you have to be color blind and not always go by the color wire. Especially if it's a Lennox.....
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Especially if it's a Lennox.....
Dr. Hardcrab,
You are out of date. Lennox has used industry standard wire color coding for at least 15 years. On a Lennox, the strip heat is brought on with the white wire in the thermostat cable.
Stretch
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just curious here Stretch, but does lennox still use their own terminal designations, such as V-Vr for 24v, M for compressor, R for reversing valve, F for fan, etc?
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wrote:

The ahu I got here uses "3" as terminal designation for common...est. year 1996 unit or so.
The rest are standard, excepting I seem to recall maybe there's an "X" on the condensor schematic...aux call on defrost.
--
SVL





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Fish wrote,
just curious here Stretch, but does lennox still use their own terminal designations, such as V-Vr for 24v, M for compressor, R for reversing valve, F for fan, etc?
Fish, not for the last 15 years. R$V hot, C$V common, YCompressor, O=reversing Valve, W=strip heat, etc. Just like everyone else. They are also using industry standard size desigignations, eg. 036 = 3-tons.
Stretch
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Not out of date here, son. There are a lot of people that still have out of date units out there.
Cut that white wire and the strip heat WON'T come on (during defrost).
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I thought it was related to his inability to count....(another post...hes worked on thousands, and THOUSANDS of oil units)
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Sorry. You've got the wrong guy on that one.
I can't spell. I can't type. What do you expect from an engineer?
Bob
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