swap Carrier for Trane

[bopa]

My 20+ year old Carrier 2 1/2 ton Hp has a compressor failure.

I woul like to swap a trane XR12 2 1/2 ton HP and keep the existing indoor coil, which is in good shape.

Use all other existing tsat, lines would remain.

Contractor wants to put in matching coil.

I know that he is right to maximize the system, but will the system function fairly well without a new coil?

Is this a minefield that I do not want to enter?

Bob

[Twilly]

Whatever you do don't listen to the contractor, he's just trying to make money off you. Take the cheaper route. You'll save money....

[Special Ed]

Don't listen to Twilli; he's either kidding or he doesn't know what he's talking about.

Now....

If the indoor coil is 12SEER-rated then, yes, get the Trane XR12; if not & if you're still absolutely dead-set against buying a matched indoor coil, then get the XR11. Otherwise you're wasting your money.

[J4]

Compatability issues with mismatched will forever haunt you if you do not match inside coil with heat pump. Lost capacity and improper refrigerant charge between heat and cool cycle.
For a proper operation, change line set as well. Who knows what contamination and condition the lines are in.

[BaldLoonie]

Anything you do with a 20 year old coil is throwing money away. If you insist on reusing it, buy the cheapest POS 10 SEER you can find cuz it won't last long with the crazy pressures it will run year round with that old coil. Don't even think about putting a nice XR12 on a 7 SEER coil meant for the old clunker.

[bopa]

Contractor has 2 left over XR12 from last year and wants rid of them. Cheaper thn replacing the compressor.

[Wild Leg]

What killed the old unit?
It could have been a problem with the indoor section.
A 20 year old indoor unit has seen it's better days.
Spend a few extra $$ up front.
Go with a matched set.
You will save money in the long run.
Warranty will be longer, and there won't be anything to "blame" a problem on.

[mark beiser]

If the old system was one of Carriers high efficiency models, then you could probably get away with an XR11. It would blow cold air in cooling and warm air in heating, but no tellin what the actual capacity or efficiency would be.

The XR12 has a bigger coil in the outdoor unit, wich could cause you some real problems in the heating mode. I wouldn't do it.

If your old system is Carriers standard efficiency or builders grade type equipment, there is no modern outdoor unit, of the same capacity, you can put in that will work anyting even close to correctly.

Bottom line, have the entire system replaced with a matched system.

Generally speaking, if the existing system was built before 1992, and wasn't a manufacturers top of the line equipment, there won't be any modern outdoor units that will work well with the existing indoor coil. This is doubly true for heat pumps.

[t527ed]

change the coil

[beenthere]

If you like the idea of calling your contractor back every week or so, keep the coil.

If you want it to work right, and not damage the new outdoor unit change the coil.

[Twilly]

I guess some people didn't think my advise was correct. It was for the record. They would save money. In fact they would be able to you the money as many of you have suggested to have the charge adjusted each fall and spring.

So my advice wasn't totally faulty, nor incorrect.

The contractor was trying to make more money...not incorrect.

I'm sometimes amazed at the way homeowners want to second guess contractors. My advise to every homeowner is to form a solid relationship with a reputable hvac contractor that you trust and take thier advise. Don't try and nickel and dime them to death.

Actually my advise was tongue in cheek. However I find that homeowners aren't always looking for the best advise, but the cheapest route.

So I'll go with the experts change the coil. I stand corrected.

[heatpumpguru]

We do work in a townhouse community, and it is funny to see all the heat pumps that have mismached outdoor units with frost on them and the one next to them that match clear of frost. The freon charge is always off because they make them work together.Do it once and it will make SEER and BTUS it is designed to produce.i know that it stinks to spend the money, but people say the old lasted 15 years and now the new one is 6 years old and it needs a compressor.Plus mostof the time if the compressor fails under the warranty we wrote down indoor and outdoor to get the claim,they will RED FLAG the claim.

[tinknocker service tech]

dont waist your money it will not qork on a 20 year old coil. get a 10 seer standart eff unit and hope for the best. your system is 20 years old and has 20 years of use on it. you want to realy save money than replace the intire systen. you will benifit in the long term

[wornout]

Change the coil. Most manufactures can, and will void the warranty if they know it's a mismatched system. It's not worth the potenial problem's, to even consider the mismatch. Dust your money off, and do the right thing!!

[bopa]

This is the strength of this discussion board good input and
very valuable.

Thanks

I think, if we go with a HP relacement I will put in the proper coil. But the economics change.

If I give up air conditioning, (don't relly need it), Will
investigate gas. I have an old oil furnace as backup, and the oil tank needs replaced. so have to look at the whole picture
and keep cost reasonable.

Bob

[berad]

Originally posted by J4
Compatability issues with mismatched will forever haunt you if you do not match inside coil with heat pump. Lost capacity and improper refrigerant charge between heat and cool cycle.
For a proper operation, change line set as well. Who knows what contamination and condition the lines are in.

Espeacialy after a compresor failure. You should either change it all or go through a bloody battle against acid and other contaminants. These contaminants are generaly not handled properly by most contractors. Driers installed, acid tests performed, driers replaced, until the acid levels test to acceptable. There are also system flushes available, again they are not generaly used properly.