The old line set (copper tubing) can be reused assuming it is the correct size of the new system. If not then it needs to be replaced. It is not the preferred method, but it is done where replacing the line set is difficult. The new refrigerant will be R410. The old refrigerant (R22) must be flushed out of the old line set otherwise you have a contamination problem. This is another reason why it is good practice to replace the line set. FYI - we can talk about prices all day long on this forum. Be warned the lowest bid usually comes with the highest risk. Finally this has been beaten to death, but let's make sure you understand the concept. You can use a 3.5 ton air handler with a 3 ton condenser. The important thing is the air flow is adjusted to the correct speed. The 3.5 ton rating is the maximum air flow, not the minimum. In turns out in this case the 3.5 ton air handler has better efficiency numbers than the 3 ton air handler. If the bigger handler can physically fit in the space, then you can use it. You have to then decide if the extra efficiency is worth the extra upfront cost of the equipment.

pricing vaires, mary. you may want to look at trane's sister company american standard, if trane pricing is too high. same stuff..different label. I find 15-17 SEER to be good efficiency. good savings over minimum efficiency allowed by law..decent payback period. pairing 15 SEER (for example) with a variable speed air handler unit will give you control over humidity. this upgrade will cost about $500-$700 depending on costs in your area. but it is worth every penny because of removal of humidity that it provides. In La. like Fla. high RH(relative humidity) is what makes us uncomfortable when summer temps are 90 degrees & RH is 90%. controling RH to maintain 50% RH is what makes us comfortable. when RH is lowered, the air is colder, so t-stat can be raised and you still be comfortable. staging the heat strips will save you $$ in heating season by not engaging full stips unless needed. most of the time you'll be using heat of heat pump, not emergency heat. while 2 tons for 1,008 sq ft is a lot of a/c, the cost is the same for 1.5 tons as it is for 2 tons. at the end of the day...most companies will sell you 2 tons. to overcome this oversizing, you need the ability to slow the air speed, so that relative humidity is controlled. thus the variable speed ahu. I'm in a small home also. Over the years I've learned a lot about hvac, due to the type of work I do. when I got ready to put a central system in my house (980 sq ft) I installed a two ton heat pump, 15 SEER with a variable speed air handler, staged heat strips. in the summer..my utility bills are $60 at hottest months (aug, sept) winter...$40. don't think emergency heat has come on this mild winter at all. I planned my system to remove humidity, and have been pleased with the success. in August my indoor RH was 50-55% even on rainy days. having gotten a steal of a deal on a whole house dehumdifier I can lower RH to 40-45% and turn temp at tstat higher. If I hadn't gotten the dehumidifier at such a good price..I'd still be ok, because I planned to dehumidify with vs air handler. without dehumidifier RH is still in acceptable range & comfort is great! lowering the speed of the air removes more humidity and air gets colder. cold..in august..heavenly! don't get hung up on name brands. for each big name is a sister company with same equipment with different label. shop around, get bids that give you good...13 SEER better 14 SEER and best...15-17 SEER bids. get at least 3 bids, then compare. tell hvac companies of any issues...excess dust, hot/cold spots, condensating supply grills etc while they bid your job. then share this info with us, & we will advise you & explain any questions you have. make sure they know that all ducts are to be mastic sealed...not duct or foil tape. duct leakage is a huge problem that isn't often addressed. if you are paying to condition the air..it should all come inside the house.. not leak out in unconditioned space. install trumps brand in my book. making sure that ducts are mastic sealed, and in good shape is often over looked as is the air sealing of return. I test homes for air leakage & ducts for duct leakage, so knowing how much these things leak..and how much it costs for these leaks..it is a worth while investment to seal them, this type of sealing is a quick payback, inexpensive materials, and noticable improvement to do these types of sealing. best of luck.

I have r-13 walls with 3 sides brick. If your house is framed, then the duct location is probably too late. Custom in the area is ducts in the attic for the upstairs and then basement and 1st floor above the basement. If you have an open web floor system between the 1st and 2nd floor, then you can put the ducts there. It is pretty hard to do with a large house though - mainly because of returns. Ducts in conditioned space costs less than 2x6 construction and saves more money. But in the end a tight house with modern equipment doesn't really cost a lot. We spend about $500 on a/c and $500 on heat a year. 2x6 walls should save about $70 of that. That is one of the reasons I don't have them - it cost over $2000 - so 30 yr payback. I have seer 15/16 heat pumps and 90% furnace serving the basement and 1st floor.

This is my first post on TGW. I will be the first to say that my experience with Trane is very subjective and anecdotal, but the following experience is mine nonetheless. We bought an existing single story 2280 sq. ft. home in Auburn, AL in May of 2012 (15 months ago). One thing that sold me on the home was the presence of a Trane 14SEER HP with variable speed blower installed in 2007. In June, one month after purchasing the home, we had to call the local Trane company to come out for a non-cooling situation. By August, we had replaced (due to actual failures, not just "failing") the compressor, the blower motor, the blower motor circuit board. All but the circuit board were under a part warranty. However, with labor, freon recharging, etc. We shelled out over $2600 in 2012 alone. In March of 2013 we had to replace a startup capacitor, not under warranty, for $400.00. All told, since June of 2012 (this post is made in early Sep 2013) we have spent well above $3,000.00 on this Trane HVAC system. In that time, I have learned (from an independent, well respected local HVAC guy) that our system is woefully OVERsized. We have a 5 ton unit in a space that, I believe, calls for a 3.5 ton unit. We have $500 power bills in the summer months. In general, I think Trane makes a great product like BMW makes a great car. You should just know what you are getting into. The most urgent comment I would make to anyone buying a Trane is to DEFINITELY get the maximum parts and labor warranty you can get and make sure it's transferrable to a new seller. PW This post was edited by PecanWaffle on Tue, Sep 3, 13 at 10:49