heat pump split install

JohnEd · August 26, 2007, 10:18:27 PM

Nick I hope and others,

I am installing a heatpump in my house and I have a dilema that I think will apply to a bus install also. My return line (the big tube) is insulated with foam rubber hose. The good stuff. It was provided with the install "kit". Should I also insulate the small hose as well. I guess it will be warm from the condensor unit. Also, I have run everything up through the wall. Is the wall installation going to have any complications?

I think this topic will cross corelate for us.

Thanks,

John

Nick Badame Refrig/ACC · August 27, 2007, 04:16:36 AM

Hi John,

No, the [small] liquid line should not be insulated. The liquid line needs to disapate heat that didn't transfer at the condencer, as it reaches the evaporator coil.

Running through the wall has no effect on proformance of the system. Running too long of a lineset will.

Also, as a heatpump, the [large] suction line that is insulated, will carry the hot discharge gas to the inside coil in heat mode.

Good Luck
Nick-

Jerry Liebler · August 27, 2007, 07:47:43 AM

John,
On this one I've got to disagree with Nick. Insulate both. remember it's a heat pump so the function of the lines is interchanged when it's heating. The designers made the condenser big enough that you don't need additional heat dissipation from the line set. My install kit had insulation on both.
Regards
Jerry 4107 1120

Nick Badame Refrig/ACC · August 27, 2007, 09:19:47 AM

Quote from: Jerry Liebler on August 27, 2007, 07:47:43 AM
John,
On this one I've got to disagree with Nick. Insulate both. remember it's a heat pump so the function of the lines is interchanged when it's heating. The designers made the condenser big enough that you don't need additional heat dissipation from the line set. My install kit had insulation on both.
Regards
Jerry 4107 1120

Hi Jerry,

John and I are talking about a conventional system which has a true reversing valve that carrys the hot gas via the suction line, and not a Ductless Split that uses the liquid line to carry the discharge gas in heat mode.

Reguards
Nick-

JohnEd · August 27, 2007, 10:17:43 AM

Guys,

I have a follow on....The Goodman system I purchased comes fully charged if your lineset is less than 50 feet. Mine is 22 feet long and I assume I won't need to add any freon. My question is: is it absolutely neccessary to "pump down" that 22 feet of line to get the moisture out? I have done a whole lot of auto systems where I replaced the compressor or condensor and I never pumped them down and never had a problem. I think I have just been lucky in that regard. Still? The local AC guys are nuts here. One wanted $400 to braze the lines and pump it down. Another wanted $180 to "only" pump it down. I was going to farm out some of this stuff to them but they seemed so greedy I decided to do it "all" and have purchased the acet/ox tanks to even do the brazing myself. I will come out ahead even paying the labor I hired at $12 and hour and purchasing new tools. So far I have paid him $800 and he has been well worth it.

If I REALLY need to pump it down, where can I buy the vac pump? I will use it on the bus for the over the road and house systems. I was going to wait on that one but maybe I NEED it now. Thanks for your help and both of your opinions and the spirit in which you offer your good council.

Your appreciative fellow bus nut,

John

Jerry Liebler · August 27, 2007, 10:18:28 AM

Nick,
In any case the whole idea of an air conditioner or heat pump is to move heat from evaporator to condenser, and not leave some along the way through the lines. Best practice is to insulate both.
Regards
Jerry 4107 1120

Jerry Liebler · August 27, 2007, 10:22:57 AM

John,
Yes you really need to pull a good vacuum and be sure there is a 'filter/dryer in the system. You can get appropriate rebuilt vacuum pumps on Ebay for about $200. Not doing these things will severely shorten the system's life.
Regards
Jerry 4107 1120

Nick Badame Refrig/ACC · August 27, 2007, 10:32:57 AM

Hi John,

Yes you need to use a vac pump as Jerry stated to you.

Some reasons...

To remove non condencibles, [air], air in the system will give you fulse readings on your guages,
remove moisture [slightest bit of moisture will freeze in the TX valve and clog your system],
to also remove particals from the soldering process [scaleing] .

If theese reasons arn't enough for you, I can type a couple more...lol

Good Luck
Nick-

JohnEd · August 27, 2007, 10:59:08 AM

OK! OK! I give up....I'm coming out with my hands up....don't shoot! I will pump it down.

They wanted $7,000 to put this system in so I still have some "wiggle room" with the budget. My appreciate your being patient with me here. Ignorance is bliss and I be very happy.

I thought the moisture concern was the entire thing. Did not know that air would affect the system adversly. Many thanks for the info. It turned me around.

John