Understanding evaporator sizing

[jeff520]

I recently had a 3 ton Trane XL19i installed and the contractor sized it with a 3.5 ton evaporator with a TXV.

What are the benefits/disadvantages of oversizing the evaporator coil, and what is the effect when the XL19i is running only its first stage, when there will be only 1.5 tons of condenser feeding the 3.5 ton evaporator?

I live in the hot and dry SouthWest, so sensible cooling is more important than dehumidification most of the time.

[classical]

Since you live in a dry environment that coil is a good match if you were in a wet climate like Houston a smaller nominally sized coil would be a better choice.

[Irishmist]

Jeff, if you continue to have doubts about the system compatibility, simply request your contractor to provide you witht the engineering ratings for that condenser - coil match. This should also show you the efficiency ratings as well as the sensible and latent capacities.

With today's systems, (actually for quite some time now) you can't simply assume a 3-ton condenser / 3-ton evaporator match. There are variations on the indoor coils even in the same capacity. Using a TXV versus a fixed-metering device also affects the outcome.

Typically, your larger indoor coil surface will enhance the latent capabilities of the system as has been indicated by the other response.

Not to sound like a smart aleck, but don't be shy about asking your contractor these questions; after all that's who got paid for the work!

all the best, Irish

[second opinion]

With the 040 coil you actually get the 19 seer set up.

[jeff520]

Not sure what you mean by the 040 coil.

The installation is an XL19i 2TTZ9036B10000BA, 2TXCB042BC3HCAA coil and XV80i TUD2B100AFV32AA

I have tried to get an ARI number for this, but it does not come up in the ARI database (that I can find), so I'm not able to get the SEER. After some chasing my contractor came up with an ARI number, but it is for a different coil! Was so hard to do that I have given up chasing them on this particular point. I also tried Trane directly through their Customer Relations line, but they have not got back to me (after a month) with an ARI number. I plan on chasing Trane until they follow through with a Certification Statement for my configuration or tell me that it does not qualify for the Energy Policy Act tax break.

In every other respect the installation was very good, the rebate worked OK, and the house temperature is staying absolutely on the temperature set and the system is so quiet I do not notice when it cycles. Maybe its a marketing buzzword, but "Comfort-R" is wonderful.

I understand that I should be leaning on my contractor and not on this forum for answers, but the contractor has been so good about other issues (which cost him significant $ to fix) that I am hesitant to push this issue on an ARI number which seems to be outside his expertise.

If any of the professionals here are familiar with this configuration and can give an educated guess at the SEER I would sure appreciate it.

[gary_g]

ARI# 1257395.

35,000 btu cooling, 11.5 EER, 16.25 SEER.

Best to you.

[jeff520]

THANK YOU!

Now I can start with the IRS side of this.

[gary_g]

http://www.energystar.gov/index.cfm?...tax_credits#s1

Sorry to tell you that your system does not qualify for the $300 Federal Tax Credit. It must be 12.5 EER and 15 SEER minimum (both must be met).

Take care.

[jeff520]

I thought I was getting a top of the line super efficient installation.

Well, I guess it is reputable equipment, just not efficient enough.

Thanks again, Gary. You posted just as I was coming to to the same conclusion on the irs.gov web site.

[second opinion]

Not sure what you mean by the 040 coil.

The installation is an XL19i 2TTZ9036B10000BA, 2TXCB042BC3HCAA coil and XV80i TUD2B100AFV32AA

I have tried to get an ARI number for this, but it does not come up in the ARI database (that I can find), so I'm not able to get the SEER. After some chasing my contractor came up with an ARI number, but it is for a different coil! Was so hard to do that I have given up chasing them on this particular point. I also tried Trane directly through their Customer Relations line, but they have not got back to me (after a month) with an ARI number. I plan on chasing Trane until they follow through with a Certification Statement for my configuration or tell me that it does not qualify for the Energy Policy Act tax break.

In every other respect the installation was very good, the rebate worked OK, and the house temperature is staying absolutely on the temperature set and the system is so quiet I do not notice when it cycles. Maybe its a marketing buzzword, but "Comfort-R" is wonderful.

I understand that I should be leaning on my contractor and not on this forum for answers, but the contractor has been so good about other issues (which cost him significant $ to fix) that I am hesitant to push this issue on an ARI number which seems to be outside his expertise.

If any of the professionals here are familiar with this configuration and can give an educated guess at the SEER I would sure appreciate it.

Sorry about that I pulled it up with a TWE 040 air handler. With the combination that you have it would be 15.50 SEER.

Your dealer should have this knowledge as part of his expertise he needs to sell you the right combonation for your needs, and then after it is installed verify its performance.

It is not Tranes responsibility to produce this information, it is your dealers. All of the information is available to him to provide to you. If your dealer sold you a combonation that did not meet your criteria I would certainly be asking him for the answers. He profited from the contract.