Heat pump

Fast5Frog_2

Hey guys, I'm having a little trouble here and could use some of your help. I just put in a 2-ton Heat Pump for a guy and a few days later now he says its not heating the house at all. He went out and talked to "some service guy" who told him to just get a 3 or 3.5 ton system (now I would take his credible advice, right?) I redid the heat loss calculation and it came out to 2.1 ton of cooling. When we left the install, we did have an issue with the reversing valve, but we checked and double checked it along with the pressure charts on the unit and all pressures were spot on. The house was nice and warm when we left. At this point I am going out there on Monday, but I really think that its a system issue not a sizing issue. Again the guy he talked to on the phone told him "a 1400 sqft. house needs a 3ton unit" pl

Brad White_146

Not a sizing issue

in my opinion. In this weather (wherever you are it is not deep winter yet, right?), heating is binary. Yes or No. You have it or you do not.

If it were a sizing issue, it would be "we have heat but not enough".

Your cooling calculations are not applicable, but your heating calculations are, especially as they relate to the balance point of your system. I assume you have auxilliary heat in any case, so if it is a matter of it being too cold out for refrigerant-based heat, you have heat anyway.

That "some service guy" DID give useful advice but it is not about the system. It is about what service guy not to use, IMHO.

Eugene Silberstein 3

Heat Pump Primer

Since the customer mentioned that the heat pump was not heating at all, he might be comparing this system to a traditional, warm air, fossil-fuel system. Heat pumps, by their very nature operate with lower discharge air temperature than gas or oil-fired heating systems.

For a heat pump system, discharge air temperatures can be in the 100 degree range, which, for some, may seem quite cool when they have been used to feeling the discharge air from other systems.

As Brad mentioned, this does not seem to be a system sizing issue, but may indeed be a customer isssue.

Read more:

http://www.heatinghelp.com/shopcart/product.cfm?category=2-103

joel_19

hp

What heated the house before??? ARe you sure your wiring is corect and briging in the electric heat.

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Fast5Frog_2

They have an oil boiler with baseboard, no electric heat packs...

don_156

Now its

back to being not enough heat.

What is your balance point.And my area I can get down to about 35 before the backup heater start coming on more often.

Now that you mention he has no backup heater but, does have baseboard... you made want to add a outdoor stat and lockout the heat pump system at a certain odt.

No backup heater to take off the chill when its in defrost?
Or when it meets the balance point?

Lock it out at 38 degrees and bring in the baseboard.

Techman

Heat Pump

I thought H.P.'s were sized for their properly sized cooling load and you setteled for your heating BTU's, and adding auxillary heat to fit .Why couldn't use the H.P. as 1st stage and B.B. as 2nd stage/auxillary heat?

mtfallsmikey

What about the ductwork?

Was it new, or tied into old??. Dr. Eugene is right on the mark. And, years ago when these beasts first hit the market in droves, we were taught that a heat pump is a "compromise" system. Not as efficient as straight A.C. or heat. It is easier to install the proper reheats in the air handler than to fab a changeover relay, etc. for BB. All of the controls should be already in the A.H. for it. Pretty much plug and play.

Ken D.

HP

I agree with Professor Silberstein. The Homeowner may not be accustomed to a heat pump. 85 to 100 degree discharge air may not be what he is used to. The cooling load is used to size it. The heating load is used for the balance point. Check the defrost and be sure it works and the back up heat comes on during defrost. In milder temperatures, the thing should cycle off (At or below the balance point it wont, unless it has a low ambient cut off). If it does not, check charge or sizing. Are the indoor and outdoor units and/or coils matched? Is the first stage heat on the t-stat running the HP? Is the ductwork properly sized? Old heat ducts are not adequate for heat pumps. Is the back up heat adequate for the load? Also, an inadequately insulated house is not a good candidate for a heat pump. Oversizing is a no-no as is sizing over the phone. Hope this helps.