Central AC Replacement Question - http://www.hvacmechanic.com/ Forums
Original message
| daveinindy
 |  "Central AC Replacement Question - which unit?"
, posted Sat 19 Jun 10:16:  
I moved into a 16 year old house with the original Whirlpool 5 ton AC unit. It was checked a year ago and everything was okay. While the AC worked fine last year, it never really got that cold. The house is 4400 Sq. Ft. and really should have had two units installed (too late for that now).
Lately the inside evaporator coil and the hose started freezing up due to what I thought was a very dirty filter (it was dirty). I change the filter and things improved for a day or two, but now no cold air is coming out at all. I called a local HVAC repair company and they checked the compressor and it is bad. He did a thorough testing on the unit and I got a second opinion too and they confirmed the compressor is bad. The both removed the quickstart and tried another - no change. One tech checked the Freon and the pressure was okay, but the smell was funky (oily/acidic). Both of the techs suggested I get a new unit and when they install one make sure the lines are cleaned/sucked thoroughly.
Sorry for the long-winded thread. But here is my dilemma. We may be moving from this house at some point and I do believe I probably need a new unit. I have gotten estimates to replace from $1200+ for a 10 seer Goodman to 3000+ for American Standard, Lennox, or Trane. The inside evaporator coil was replaced in 2000. It is a Lennox C23-51/65 and I'm being told I'm probably okay to keep that. Are there any concerns matching up the current coil to other units (they did it with the Whirlpool)? Am I limited to 10 seer? Also, is the Goodman price too good to be true? It seems they have rep for being used in rental units. Should I stay away from them?
[this message was edited by daveinindy on Sat 19 Jun 10:20] |
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| HVAC Doc
| "Re(1):Central AC Replacement Question - which" , posted Sat 19 Jun 11:41
With that coil it is true you cannot achieve more than 10 seer. "Possibly" with a TXV it might do a squeek to the 11 seer but that is a stretch. If you are planning on selling the house soon then you probably are not looking to invest a major chunk of change but remember, a proper installation is the key to ANY brand of units sucess. As for Goodman, yeah they have a bad rep BUT!!!! There are many reputable companies that sell Goodman and have no more problems with the units than any other brand. They have good warrantys and in most areas of the country, good distributors who back their dealers up. The bad rep comes from their "ease of attainability" and hacks who work out the back of a truck just slapping them with no real regard to how they should be sized/installed etc. If Tranes or lennox were that easy to purchase, then they would have the exact same reputation.
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| | backyard mech
| "Re(2):Central AC Replacement Question - which" , posted Sat 19 Jun 11:58
I totally agree with HVAC Doc. The system I installed in my home is a Goodman. It is a good product at a good price. Your main concern should be the installer of this product.
Absolute Tempcontrol
Aurora Colorado
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| | daveinindy
| "Re(3):Central AC Replacement Question - which" , posted Sat 19 Jun 14:16
I want to thank both of you for responding. At this point, I'm close to making a choice and feel this forum and you two are helping me ask the installer the right questions. I would like to avoid installing a new evaporator coil since this was installed in 2000. However, I don't want them using that to void a warranty if there is a problem later. One company said they could not give me the full warranty unless I changed the coil. The other said it was not an issue. If there is any kind of contaminates in the line, are they usually pretty successful in cleaning them out?
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| | HVAC Doc
| "Re(4):Central AC Replacement Question - which" , posted Sat 19 Jun 15:30
If the installation is done properly, there should be no problems with contaminants in the lineset. Good brazing procedures such as running nitrogen through the lineset while brazing and a proper evacuation with a vacuum pump and micron guage will show the installer whether or not he has a leak or contaminants still in the system. Ideally yes you would want to replace a condensing unit both at the same time as a matched set. The units though you are looking at (10 seer) will work fine with that coil as it is a 10 seer unit. Is it possible that a 4 yr. old coil could develop a leak, the unit run low on charge and damage a compressor???........Yes it is POSSIBLE but again, you could have them install a unit with a bad compressor in it right out of the box (it has happened to everyone before). I personally would lean towards the one that seems to be more on the upfront side that is not pushing you with buying a new coil and saying that the warranties are void if you don't. Like I said, you could develop a leak on that coil but I would not myself threaten you with a voided warranty or scare tatics to make you buy one. Keep in mind if you do have a problem with it a year or so down the road that you would not have any kind of a warranty except for the manufacture warranty (if it was still in effect) and that only includes the coil itself. Not labor, recovery, refrigerant or anything else.....just the coil.
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| | daveinindy
| "Re(5):Central AC Replacement Question - which" , posted Sun 20 Jun 11:11
A couple more comments: One of the companies is offering a unit with a scroll compressor (which seems to last longer from what I have read) and a 5 year parts and labor warranty and a 10 year compressor warranty. While the unit is a 12.05 seer rating can I mate it with my Lennox evaporator coil and get some better efficiency or will it still run at the evaporator coil seer rating? I was also told installing a better metering TXV valve may give me better performance with regards to temperature regulation, etc. Is that true? Also, by reading this forum, I may need to install a new line too since the current diameter does not seem to be what is installed for a 5 ton unit now. If some of these items will improve performance (and better cooling) I don’t mind paying for them. I’m just not sure if the return is there.
BTW: I spoke to one of the companies and they said if I did not change the evaporator coil they would still honor any manufacture warranty since they handle it in house and they said they would put that in writing too.
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| | HVAC Doc
| "Re(6):Central AC Replacement Question - which" , posted Sun 20 Jun 14:21
Using a TXV is the only way you will get anything better than 10 seer out of the unit. Just hooking a 12 seer a/c to a 10 seer coil without it will net you 10 seer. A TXV also helps with latent capacity and load changes better. Think of it sort of like a carb on a car, the more gas you need, the more the more it opens up. Samr as a TXV, it opens and closes as demand requires vs. a fixed orfice that just meters in X amount of refrigerant at all times no matter the condition. If your lineset is not the proper size to match the system, you will definately hinder the performance of the system. Remember, ARI ratings tests are done with completely matched equipment and lineset and "ideal" conditions. Although chances are you will never have "ideal" conditions, you can match as much as you can as far as proper linesets, good metering device (TXV), return/supply ductwork is adequate, etc. It is especially good when a company is willing to back their warranty 100% in writing. Sounds like you have done some good homework!
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| | agabril
| "Re(7):Central AC Replacement Question - which" , posted Tue 6 Jul 17:08
I am sorry. I am not professional BUT the same Goodman recommends exactly the same coil for different SEER ratings 10 or 14 - does not matter. What matters is BTU. It looks like the same coil supports all units of the same BTU independent on SEER rating. Where am I wrong?
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| | HVAC Doc
| "Re(8):Central AC Replacement Question - which" , posted Tue 6 Jul 17:28
You are correct. Many manufactures will list same coils for a variety of SEER ratings. You obtain the higher SEER by adding a TXV. Many manufactures also make a line of coils with the TXV already installed so that it is inside the evap. coil cabinet (not external like a field installed one) and to help minimize the chance of leaks as these coils come precharged with Nitrogen from the factory to try to eliminate receiving a bad coil out of the box. With no ARI rating for a Goodman outdoor unit with a Lennox evap coil, the only reasonable guess on SEER would be 10 with a piston and possibly higher with a TXV.
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