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acinsa
07-04-2006, 01:28 PM
I am in the midst of having several contractors come out to my home and provide estimates on repairing or replacing my current system. I'm more confused now than when I started this excercise and this forum looks to be my best bet for great advice. Any help would be much appreciated.

I have a seven year old AC system (Carrier variable speed blower and Carrier Tech 2000 5 ton compressor) cooling my 3000 sq ft, 2 story home in San Antonio Texas. My regular AC guy came out last week and told me that I've got a leak and he had to put 5 pounds of freon in the system (last checkup was in Dec). He says that the coils in the blower unit are leaking and will cost around $xxxx to replace the coils. This seems to be a fair price for coil replacement as all 5 bids I have so far are around that price. Although everyone recommends replacement of the unit at around 50% more than the coil replacement. My normal AC guy is pushing Trane and recommended that I consider replacing both the blower and the compressor. His quote is a hair less than $xxxxx to go with the Trane xL19i (5 ton unit) with Trane variable speed blower. He also recommends multi-zoning (three zones) which brings the cost to around 20% more. That gave me a heart attack. I've gotten a few other complete system quotes (most not recommending the multi-zone) but all are within a couple of thousand on the price. I'm defintely interested in the 10 year P&L warranty since my current system couldn't make it 7 years (very disappointing). One of the contractors I was speaking with mentioned going with two American standard 15 seer units (one 3 ton, one 3.5 ton) for a bit less than $xxxxx (one to cool each story). This seems to make sense and the price seems good but I have no idea if this is better than a two stage compressor (or two compressors like in the 19i). I also noticed that everyone seemed to say that I needed a 5 ton system and nobody did any Manual J calcs. I know from reading through posts that SIZING is VERY important. The gentleman who recommended two units did look at my square footage (about 3200 sq ft under the roof, 1800 up, 1400 down) to come up with his calcs. Any advice on how to approach this problem would be much appreciated. I paid big bucks for the Carrier unit when I built the home (supposedly their best) and after it failed after 7 years I don't want to be going through this again.

Thanks,
Alan

[Edited by acinsa on 07-04-2006 at 11:27 PM]

4l530
07-04-2006, 02:32 PM
...is an awful lot.
I don't think you're supposed to post pricing here. See Rule #3.
I will say I've never charged over $XXX to repair or replace an evaporator.
Maybe $XXXX is a reasonable price for your neck of the woods.
I'm tempted to think those contractors may be smelling blood?? :)

[Edited by 4l530 on 07-04-2006 at 02:37 PM]

joken
07-04-2006, 04:45 PM
What reason was given for not repairing the leak. Is it not accessible?

beenthere
07-04-2006, 05:22 PM
Edit out the prices, or a mod will soon.

2 systems can be sized closer to you homes load

esigler
07-04-2006, 05:56 PM
You will Love the 19I, I love mine with varible furnace and the zones will be worth it.

acinsa
07-04-2006, 11:34 PM
So which would you guys recommend? The two 15 seer American Standard Units or the Trane XL19I? Both seem like good ideas but two units sound better than one to me, especially if the prices are about the same.

One other thing. One of the contractors mentioned to me that the copper tubing between my compressor and my blower was too small to run R-22 efficiently (it's 7/8 " OD) and that I should run R410a on whatever unit I choose to go with. The Home Depot guy said that R22 was the ONLY way to go. Any advice on this?

Thanks,
Alan

beenthere
07-04-2006, 11:53 PM
If you get a 5 ton r22 unit then the 7/8 will be too small, and you'll lose capacity.

R410a is here to stay, so the home cheapo guy doesn't know what he's talking about.

esigler
07-05-2006, 05:49 PM
Unless the lines are impossible to replace I would want a new line set anyway. I also like 410A a Trane 16I or American Standard Allegiance (4A7A6060B1000A) woul be a great way to go.

acinsa
07-05-2006, 08:07 PM
Thanks guys! I'm still getting quotes and I the last quote on my house the guy did a load calc on my home. He came up with a sensible load of 72,000 BTUs and recommends 6 tons of cooling (I currently have a five ton unit). He mentioned that I could keep my five ton outdoor unit if I went multizone in my two story. I'm really leaning towards the two systems now that I know five tons is undersized for my house. Multizoning sounds interesting, but for two smaller units for the same price as the zoning sounds better to me. Am I on track here?

beenthere
07-05-2006, 08:17 PM
I would go witrh 2 systems.

This last guy came up with 72,000 sensible?

So the current system has never been able to maintain temp?

acinsa
07-05-2006, 10:50 PM
That's what seems weird about him saying my current unit was undersized. In the past (until the leak), my unit maintained temp just fine. I never really noticed whether it was running a bunch or not, it just seemed to cool fine. I was thinking about buying the homeowner version of the HVAC Tool listed on this site and calculate the load myself. Just wasn't certain if I'd have the required knowledge to run the tool properly.

Thanks,
Alan

man from trane
07-06-2006, 12:24 AM
410A may be here to stay, but I would stick with R22 for as long as I could. It will still be around for a long time for repair of existing systems. R22 is simply the best regrigerant ever made. It is easier to work with and if you get a leak on the low side with 410A, since it's a cocktail all the ingredients don't leak out at the same rate, so you have to evac the whole system and start over, instead of just pumping it down. Just my 2 cents.

rclaoac
07-06-2006, 12:47 AM
From what I told at a R410a training sessions from a major equipment manufacturer, if there is a leak, the change in the composition of 410a is not substancial. I've been installing 410a systems and am satisfied so far.

perel
07-06-2006, 01:13 AM
Originally posted by man from trane
R22 is simply the best regrigerant ever made.
I thought R11/R12 had that honor? (not counting environmental impact, just performance)

beenthere
07-06-2006, 05:23 AM
Originally posted by man from trane
It is easier to work with and if you get a leak on the low side with 410A, since it's a cocktail all the ingredients don't leak out at the same rate, so you have to evac the whole system and start over, instead of just pumping it down. Just my 2 cents.

Thats a wives tell.
You can top off the charge the same as 22.

beenthere
07-06-2006, 05:24 AM
Originally posted by acinsa
That's what seems weird about him saying my current unit was undersized. In the past (until the leak), my unit maintained temp just fine. I never really noticed whether it was running a bunch or not, it just seemed to cool fine. I was thinking about buying the homeowner version of the HVAC Tool listed on this site and calculate the load myself. Just wasn't certain if I'd have the required knowledge to run the tool properly.

Thanks,
Alan

I think it will be worth it for you to do your own.
Its not hard to do.

mjk_na
07-06-2006, 08:53 AM
Originally posted by perel

Originally posted by man from trane
R22 is simply the best regrigerant ever made.
I thought R11/R12 had that honor? (not counting environmental impact, just performance)

Nope. A study proven that the performance is about the same as R-410a

mjk_na
07-06-2006, 08:56 AM
Originally posted by man from trane
It is easier to work with and if you get a leak on the low side with 410A, since it's a cocktail all the ingredients don't leak out at the same rate, so you have to evac the whole system and start over, instead of just pumping it down. Just my 2 cents.

R-410a acts like a single refrigerant since it is a near azeotropic refrigerant blend. The composition will evaporate very much at the same rate in case of leakage. So, you can top up if leaked.