The way to size a system properly is to have a capable contractor perform a Manual J heat gain/loss calculation on the structure.

The frequency of compressor failure is probably due to poor installation and/or system evacuation/charge procedures.

I would have a new system installed including a matched air handler.

The refrigeration lines would have to be cleaned properly and a new bi-flow filter/drier installed in the liquid line. The old filter drier needs to be removed (it is usually located near the heat pump (outside).

American Standard makes Trane. $4575 looks like a good price. Post the model#s of the condensing unit (outside) and the air handler (inside) and I can verify if it is a matched set and the SEER rating.

You should consider a PARTS AND LABOR warranty for your piece of mind. The manufacturer covers only parts, not labor, as I'm sure you already know.

What is your cost of electricity ($ per kw-hour)?

Best to you.

Thank you for your kind response -

I am really leaning towards the new system, but I want to be sure first that my repairman didn't misdiagnose a more simple problem. Although history has shown these replacement compressors don't last long, I want to be sure before I plunk down several grand on a new system. If it was just the compressor on the heat pump, would the whole thing (fan on HP) be dead? Is there an easy way for me to tell for certain that it's not a contact problem?

As for the quote I got on the American Standard, the HP is the 4A6H4042. He didn't give me the model on the air handler, but said it was a matched pair (I would get this in writing before making any choice.) So far, I like the price on the American Std. but I am concerned about his installation skills. He's been around a long time, lots of experience, but I'm pretty sure he botched a prior installation of my HP - thus the short compressor lives. Upon replacing the compressor the second time, there was a big short problem and he had to come right back and reinstall another... I've already contacted a few different companies for quotes.

I like the idea of a parts/ labor warranty.

I pay around 12-13 cents per KWH here. It's a tiered plan, so it depends on usage. I range from 900 KWH to 1900 KWH per month. My house has terrible builder grade windows. The attic insulation seems ok, but as I've seen elsewhere it's always good to have more...

What about ducting? Should I consider getting that redone? It's builder grade R-6 flex. I only have one return and one side of the house (sun exposure) is naturally warmer. Don't know if the ducting would make much difference without better insulation, windows, etc on the house...

I've got two quotes coming tomorrow. I'll ask for Man J, but from what I've heard, don't expect it in FLA. Thanks for your advice

"If it was just the compressor on the heat pump, would the whole thing (fan on HP) be dead? Is there an easy way for me to tell for certain that it's not a contact problem?"

You bring up a good point. I am just a homeowner like yourself, not an HVAC pro, but here are some possibilities:

- the electrical contacts from the 24 volt side are not closing so 220 volts are not being to supplied to the unit. I think that this would affect both the compressor and fan.

- The run/start capacitor is bad. It is located on the outside unit under the access panel.

- If the compressor is locked up, it will be drawing the Locked Rotor Amps (LRA) listed on the data plate.

- The compressor motor could also be grounded.

Please be extremely careful if you investigate the above with a meter.

The 4A6H4042 is listed on the ARI Directory (link below) as a Heritage 14. In my humble opinion, a 14 SEER system provides the best combination of purchase price and true operating costs. True operating costs are determined by Energy Efficiency Ratio(EER), not SEER, much to the surprise of many people including pros. EER is taken at 95 degrees outside air temps while SEER is taken at 82 degrees outside air temps. Once you provide the model# of the air handler, all performance data will be known.

Replacing a hacked-up 10 SEER system with a matched 14 SEER system should reduce your electricity consumption for cooling by about 25%.

You bring up another good point about ducting. A new system is only as good as the ducting and the installation. Adding another return, sealing up duct leaks, etc. will only make your system better. I have all metal ducts so I can't comment on the R6 flex. Have one of of the contractors take a look at your ducts.

You ask very good questions and have obviously done your homework.

Here is a link that might be useful: American Refrigeration Institute Directory

Thanks GaryG for your reply; I realize you're a homeowner like me, but basing on all of the detailed input you've given to this forum, you've done more than a little homework. Thanks so much!

Ok, so here's my new quote from 10 minutes ago, with a few of my questions at the end:

Trane 3.5 ton condenser 2TWR3042A1000A
Air Handler 2TEE3F40A1000A
New liquid/suction/drain lines
new digital T-stat (no model given...)
Basic warranty
TOTAL INSTALLED: $4854

10 year extended parts and labor: $750

This is a large, reputable dealer in the area. He claims that even though the condernser is the XL13, it provide Seer 14 when used in conjuntion with the variable speed handler (???)

I asked about Man J - he siad it is really not a concern with newer mass produced track homes (such as mine) and AC installed by a large distributor (such as mine which has 600,000 installs in my area...)

I asked about one side of my home being hotter and if the duct work should be redone. He said that it is usually not a concern with newer homes, and that ducting should be good for life. He wouldn't even look. He said the hotter side would be compensated for by the variable speed handler which would "allow the air supply to be slowed down and more evenly distributed" (???) Now, I am a mechanical Engineer, however certainly not a HVAC / flow specialist, but I'm really not sure about that line. What will the variable speed really give me? Is there a downside to it?

It is an R22 system. I'm a little uncomfortable with the changes coming ahead - I wonder what the price of R22 will do - but it's true I'd only have a problem if I had a leak and that would be covered by my 10 year warranty.

Seems like a pretty good quote to me, and they can install next day. I've got a couple more quotes coming soon. ANy comments would be greatly appreciated. It's still really hot and humid in Florida - 90 and humid this WE... :(

I need to correct in my post - the condenser is the XR13 (not XL)

A 2TWR3042 heat pump combined with a 2TEE3F40 air handler is indeed an XR13 rated at 40,500 btu-hour, 14 SEER, 12 EER, 8.2 HSPF. A little low on HSPF but you are in Florida so no big deal. Otherwise, these are good numbers especially the 12 EER.

I think that it is smart to replace the 2 refrigerant lines. You won't have to worry about any junk from the old lines getting into the new system.

As far as the v-s blower, it is an ECM motor, extremeley quiet, and adjusts it's speed based on constant CFM output. These are the latest and greatest motors. The pros love them because they can adjust their speed based on ductwork conditions and provide a fixed CFM. They are also very expensive to replace. Some poor girl many months ago paid $1000, part-only, for an OEM Bryant ECM motor. My entire Goodman air handler was only $700. There are dip switches in the air handler that have to be set by the installer for the v-s motor to run properly. The v-s blowers are touted to people who like to run the fan all of the time to help circulate air in the home. In this mode, the v-s motor drops to about 30%, and you can't hear it if you are standing next to the air handler.

There is a setting called "Comfort R", offerred by Trane, that slows the air handler down to provide better humidity control when the a/c is running. I am not sure if this is a function of the air handler or t-stat so you should ask Mr Trane.

For pricing comparison, an April 30th quote for a 3-ton XR13 in Baltimore was $4600, different heat pump and air handler. Your performance numbers are much better than what I was quoted. Your pricing looks good.

I wouldn't let the R22 be a major factor in your decision. I just installed a new 3-ton, 14 SEER, 12 EER, Goodman heat pump in June. I chose good old R22 and a fixed speed fan in the air handler. These were my personal choices after many days of research.

I too am I mech engineer employed in the steel industry. This HVAC stuff is side interest to keep my brain cells communicating.

One thing I wonder about with the R22 is the following scenario: If I get a 10 yr. parts/labor warranty and then, after R22 units cease being manufactured (2010?), my outdoor unit dies, will there be enough replacements available for them to honor the warranty? (I suppose that is their problem.)

Also regarding the warranty, I assume that will cover the variable speed blower and would give me peace of mind considering the high repair costs you noted.

Two more quotes coming tomorrow, I'll post the results. Thanks again for your help

"One thing I wonder about with the R22 is the following scenario: If I get a 10 yr. parts/labor warranty and then, after R22 units cease being manufactured (2010?), my outdoor unit dies, will there be enough replacements available for them to honor the warranty? (I suppose that is their problem.)"

- I believe that freon is not covered under any warranty. The R22 freon itself will cease to be produced in the country after 2010, not compressors or other parts. R22 will still be made in other countries. Most systems in use today use R22 so parts should be available.

"Also regarding the warranty, I assume that will cover the variable speed blower and would give me peace of mind considering the high repair costs you noted"

- Yes. The extended parts and labor warranty will cover the ECM motor for 10 years. Trane's standard warranty for the XR13 is 10 years on the compressor and outdoor coil, all other internal functional parts have a 5 year warranty. Parts only, no labor. The installer should provide a 1 year labor warranty if you do not get the extended warranty from Trane.

At some cost, R22 will be available for a long time. Heck, R12 is still available for older cars even if it is expensive.

Well, alot has happened since yesterday - I've got two more quotes and I've been rethinking a couple things.

First off, I did get one of the smaller contractors, who came very highly recommended from coworkers and a neighbor, did a full diagnosis on the condenser unit and it's power supply and did confirm that the compressor is dead. Additionally, the breaker for this outside unit was fried - likely the result of the failing compressor drawing too much current.

Secondly, I am finding that the R410a units are only a little more than a hundred bucks ($146 in my top estimate) more than the equivalent R22. With a little bargaining, this difference is negligible. I will likely go with the R410a.

For some reason I am stuck on the variable speed blower. Everyone says it does a better job on humidity (issue #1 in Florida...) my only concern with this is that the lower velocity air coming out of the vents won't travel as far into my rooms (we have high ceilings) and the mixing with the warmer air might be decreased (?)

I have also re-thought the extended warranty on parts and labor. I know Garyg has been a big proponent for this warranty, and I am certainly sick of high labor bill for replacing compressors..... However, in general, I am not a big fan of extended warranties, etc. and I continue to hear more and more cases of damages that were excluded from such policies due to various reasons: not enough maintenance, lightening strikes, etc. Maybe it is a bit of a gamble, but I could just save that money ($750 in my estimates) and keep it in my account for that day when something does go wrong. Trane still has a very solid base warranty on parts.

My preferred quote at the moment is: SEER 14, EER 11.5 Trane 3.5 ton heat pump #4TWR3042A1000A with variable speed air handler #4TEE3F40B1000A (R410a system), T-stat, 5kW heat strips, all tubing, drains replaced, breaker replaced, pad replaced, etc. $5000. I'll also get $100 back from Progress Energy.

"I know Garyg has been a big proponent for this warranty..."

- I only bring up the warranty because most people don't understand that the mfrs warranties are parts only, no labor. I do not have a parts and labor warranty for my new Goodman heat pump. Trane's base warranty for the XR13 is 10 years on the compressor and outside coil, 5 years on all other functional parts.

Your SEER and EER numbers are correct. I'll add that this sytem is 41,500 btu-hr cooling (a full 3.5 tons - excellent!), 40,000 btu heating at 47 degrees, and 8.5 HSPF. These are solid numbers. Your pricing looks great.

Best to you.