Oh.. one follow-up. Is this true? (see below):

Another reason he offered up the idea of getting the R-22 system vs. the 401A was that Trane was (or had) changed their warranty on the new 401A units to 5 years. He said that the R-22 units he's selling come with (13 seer) 10 year compressor/10 parts.. and (14 seer) 12 year compressor/10 year parts (if we register it online.. which I would do for her).

Is it true that Trane has lowered their warranty level on the 401A refrig. units because they have been pretty faulty? My HVAC guy says that he's had to work on/replace several units and is really disgusted with them.

EBBQ

Probably why he's figuring 22 is that he is a HACK.

The indoor coil is part of the cooling season. If the outdoor unit "has seen better days" then so has the indoor coil. Probably about ready to leak anyway.

So dispose of this guy and find a professional that does the job right by changing the indoor coil AND running a load calc rather than sizing by what is there. Putting a 13 SEER outdoor unit on an 8 SEER coil probably won't increase the efficiency much and can give some operational issues getting the refrigerant level right.

Trane warranties are the same on 410 as well. He is so full of it. Probably the reason he is disgusted with them is he doesn't know how to work on them. He probably has put them on mismatched coils, dirty linesets, etc. and has problems.

It might be wise to run new copper lines that conform to R410A code as the higher pressure, in some cases, calls for thicker copper tubing.

Don't let them oversize the equipment as you can always do things to reduce the heatload to fit sizing. The ductwork will work better, too.

For example, in Rockford, IL a 2,400 sq./ft home with 600-sq./ft of window area, those using wrong headed 600-sq./ft per-ton, it figures to take 4 tons or so to cool it.

However, a 2-Ton Unit moving 1,000-CFM of air (or 500-cfm per ton of cooling), even at 95 degrees with a blazing sun heat outside and very high humidity the 2-ton cooling equipment system still cycles! It is very comfortable at around 75-F and 50% Relative Humidity or less. Use your own judgment! - udarrell

Here is a link that might be useful: SIZING EQUIPMENT & OPTIMIZING EVAPORATOR LOAD

Thank you for the help folks. I have some follow-up questions now. Really, it's more for education I guess.

1) The inside "furnace".. that's the unit up in the attic that distributes the air to the house... right? There's a "coil" in there that should be considered for replacement as well then? I think you mentioned earlier that having the new outdoor unit on a 1996 "furnace" would negate the electric savings and not really cool the house better.. correct?

2) Another thing I forgot to mention was that my moms old system (or current one for now) is actually a duel-fuel system. The air conditioning is electric.. and during the winter if she puts it on "emergency heat" it uses gas. If she just puts it on "heat" it uses electric. Now in the time she has been in the house she has always used gas heat and electric air conditioning... so, the current dude (known as the HACK) was going to convert the system so that it is only electric for air and gas for heat.. no longer will it be duel fuel... I don't think this is an issue, unless you think this might be another warning sign. My mom did not want to spend the money for a new duel fuel unit... so I don't know if it really matters, but I think I needed to say something just in case.

3) Did we ever resolve the argument over R401 needing to be fully discharged if new fuel is needed? That was a hot topic earlier (2 yrs ago I believe)... that seemed to be one of the arguments for the old R22 system where you can add fuel vs. total replacement. Thanks for the clarification.

EBBQ

PS: My mom lives in a suburb of Fort Worth Texas (hot summers)

The coil in the attic should be changed to match whatever unit is chosen for outdoors. The existing furnace is fine as long as you don't get into really high efficiency units or 2 stage equipment.

So what she has now is a heat pump system and wants to go to straight cooling and use the gas furnace for heating? That's fine, may increase the heating bill a bit. Make sure she gets a new thermostat so she doesn't accidentally put it on the regular heat position and turn on the A/C in the winter.

You do not need to remove 410 from the system, you can add to it. But you don't need to add to any system unless there is a leak. Any leak should be found & fixed. Running a unit low costs quite a bit more $$ and is hard on the compressor. A unit can be low but still cool enough that you don't know it.

Thanks again for the answers!

I'm going to attempt to explain what she has, but I may be confused.. so please forgive me.

What she has right now is a duel fuel system.. she can run either electric heat or gas heat during the winter. She told me that she has never used electric heat. If her system is set on emergency heat it uses gas during the winter.. if she sets it just to heat, she uses electric (but never does). So.. the guy I had price things out said that he would be replacing the thermostat, and making it where the system runs gas for heat during the winter.. and electric for air conditioning during the summer... she will no longer have the choice of gas or electric during the winter. My understanding is that she does not have a heat pump, but straight up electric heat.. no pump.. so expensive city if I'm correct. I believe that's the situation.

I did have her re-read the estimate she got and there was nothing about changing the guts (inside coil) of the equipment. I will call for clarification... but for the 2200 and 2400 figures he's quoting, I be that's not part of his estimate. Doesn't that sound like pricing for an outdoor unit only? Somebody couldn't do the outdoor unit, replace the indoor coil, and haul off the old equip for 2200 to 2400 dollars and make a living, could they?

Plus.. from what people are stating here it sounds like the dude might be atleast questionable, if not a bad dude (even though he's been good for me for about 4 years... but, I haven't had any major issues either)

EBBQ

"So dispose of this guy and find a professional that does the job right by changing the indoor coil AND running a load calc rather than sizing by what is there."

So after having 'run the experiment' with the size of the old unit, in its application, you want to throw away the best data point you probably have for the losses in old construction?

If the old unit has supplied cooling as desired, it WAS sized correctly.

Estimating R values for old construction can cause errors in sizing.
A minor error in the R value of exterior walls and infiltration losses can result in major errors when multiplied by the number of square feet of exterior wall.

While the new system may have a higher SEER rating, it is going to take the same cooling capacity to perform the job.

I would run a manual J, but take the results with a grain of salt if there is a major change in capacity and the old unit has been shown to be adequate.

If the evap coil is not changed it will fail. It will cause the coil to leak and could cause the compressor to fail. More freon passes through the system to gain eff, oldre coils cannot handle it. She has a heat pump- heat pump is the electric heat.