Full or partial AC replacement

[larry128]

Our air conditioning system compressor, Carrier 38TKB (10 SEER 3-ton), seized last fall after 13 years of service in Syracuse, New York. Our dilemma is in selecting 1 of 3 repair options. After reviewing bids and manufacturers (TRANE, Payne, Kenmore, Carrier, & Rheem), we have decided on TRANE for replacement. This decision was based more on our assessment that TRANE was the best product. Now we are struggling with whether to do a partial or full replacement. Efficiency is not important, because of the limited need to use the system in the central New York area, and our conservative use of the system.
Option 1 - Replacing just the compressor unit with the TRANE XR13 (13 SEER & R-22) is the cheapest option. Most of the contractors were not willing to replace just the complete outside compressor unit. They cited incompatibility (10 SEER vs 13 SEER) and need for a hard start option required on the compressor unit due to the SEER rating differential.
Option 2 - Replacing the compressor & evaporator coil units with the TRANE XR13 (R-22), leaving the supply and return lines, costs 55% more than Option 1.
Option 3 - Replacing the whole system with the TRANE XL14i (14 SEER, R-410A) would be more than double the cost of Option 1 and 55% more than Option 2.
Our concerns with Options 1 & 2 would be the availability of R-22 for the life of the unit. The contractors we contacted felt R-22 would be available for the life of these units. A smaller concern would be leaving the existing lines, verses replacing them for less than 10% more.
For Option 1, we have the added concern for the remaining life of the evaporator coil unit and whether it would fail significantly before the replacement compressor unit, and/or its replacement would not be available. Thus, forcing us to replace the whole system at a later date anyway, and money spent now could be fully or partially wasted. Do condenser units fail?? What are the contributing causes?
Option 3 – is just a cost issue.
At present, we are retired, and we have no plans to move.
Is it worth the risk to replace just the compressor unit and bank on the evaporator coil lasting 10 to 15 more years? New compressor is warranted for 10 years. If the coil fails before that, how long will coil replacements be available?
Larry, Syracuse, NY

[dan sw fl]

Condensing unit = Compressor a.k.a. outdoor unit

AHU = Air Handlng Unit = Evaporator

There is not such thing as partial replacement.
It is just a two-phased more expensive decision
to replace one item at a time.

[platchford]

I would recommend you avoid option 1. Not only is there a question of compatibility (and its not recommended by anybody), but you will have a lower SEER rating and the newer coils utilize a better metering device than the old units. Dan said it well "There is not such thing as partial replacement. It is just a two-phased more expensive decision to replace one item at a time."

As far as availability of R22 vs R410a its a bit of a toss-up at the moment. R22 begins to be phased out in 2010. Its already considerably more expensive than it used to be. Not sure why. R410a isn't cheap either compared to the R22 but you can guarantee the price of R22 will skyrocket near the end of the phase-out period. If you can swing it you should probably go with the R410a. There probably is not much of a point to replacing the current line-sets unless the sizes are different than the new equipment.

As far as brand, the installation is more important than the brand name. You will hear this a lot on this forum because it is true. I have nothing against Trane but I don't really believe the better product argument. ;) Whomever you choose I hope they performed a Manual J (load calculation) on your home and didn't just decide to replace the unit with the same size as the original. Who is to say the original unit was sized properly? :cool:

[larry128]

Meant the coil at air handling unit when referencing the condenser. Seems thoughts are that you should not stay will an old coil when the outside compressor requires replacement.

Thanks for the frankness.

[beenthere]

Replace both outdoor unit, and indoor coil.
You get a warranty on the new indoor coil then.
Better safe then sorry. Fewer headaches down the road.

[dan sw fl]

As far as availability of R22 vs R410a its a bit of a toss-up at the moment.
R22 begins to be phased out in 2010.

Its already considerably more expensive than it used to be. Not sure why.

R410a isn't cheap either compared to the R22 but you can guarantee the price of R22 will skyrocket near the end of the phase-out period.

Who is to say the original unit was sized properly?

640 days to end of R-22 for new equipment

[rponson]

I am a big proponent of complete system changeouts. If at all possible (budget wise) it is the best way to get the lowest life cycle cost. I am also a big proponent of 410. r22 cost are going up very rapidly. it won't be long before 410 is less expensive.

I recomend the complete system change out but a better option 2 would be to leave the furnace and change the Condenser and Evaperator using 410 instead of r22. cost should be very similar to your current option 2 and you won't be stuck with the r22

I also take exception to the Statement that "Trane is the Better unit" more than likely you feel that way because they had a, "better dealer" which is the most important part of the system