Hi, just had a complete system installed yesterday. I live in dallas where cooling means more than heating. cost 7k even for everything. here is a list of what was installed. Trane XR13 4 ton AC condenser. Trane XR80 5 ton 1 stage with 4 speed blower. New matching evaporator coil with the new R-410A refrigerant. New return and supply plenums, all sheet metal construction with exterior wrapped insulation. New manual air dampers at each supply duct. Added an extra return air duct, grill and filter in double existing volume of return. New drip pan with overflow float switch (cut off system if drainage get blocked - keeps ceiling from getting water damage). New electrical disconnect and wiring (located outside by the condenser). New concrete pad. New programmable thermostat. Did all the work required to rid and clean system of old coolant, hauled away old system and did a relatively good job cleaning up. This new system is so much cooler and better airflow than the old one and should be more efficient. I really wanted the sheet metal plenums with EXTERIOR insulation and the manual dampers. This should really pay off in the long run for comfort and health. Next time I should just have to replace the AC condenser. Furnace later. All in all I think I got a good deal and I'm pretty sure the work is A+. I paid a little extra for the plenums, dampers and for Trane products.

So yesterday buddy comes over to look over things with the a/c system and I think we've got things nailed down properly now. The superheat for the given ambient temperature and heat loading from the indoor coil was way off (5F) vs. the 14-15F that it was supposed to be so he had to remove some of the refrigerant (I was quite surprised how little he had to remove to get the superheat up) and we even went as far as measuring the furnace's CFM flow rating using a differential manometer. I'm pushing roughly 1000CFM across a 2 ton coil so which is a tad bit on the high side but my colleauge says it's a margin of safety for the a/c to not freeze over as we have relatively little humidity in the air would means that on the cooler days we wouldn't be heat loading the coil enough which could lead to freeze up. I personally would like to try running my furnace on the lowest speed to get the 855 CFM but I'm not sure how that will affect the superheat. Presumably I would imagine that if a system is charged properly using the superheat method for fixed orifice systems that blower speed shouldn't dramatically impact the superheat values to the point where they're completely out of whack. I would guess that superheat would rise but isn't that sort of a given? I mean hotter days for example would increase loading so therefore superheat should rise no? For the record the pressure reading on the manometer with the furnace on medium low with a 3M 1500 series filter installed has a -0.44 in wg static pressure difference. With no filter the static pressure diff changes to -0.55. Humidity was still somewhat of an issue yesterday night when it was raining but it was quite cool outside. I had to drop the tstat to 21C to force start the a/c on but after just 20 minutes the house was nice and dry and less stuffy. Just for the sake of my understanding does TXV technically do any better or worse job of temperature/humidity control over a fixed orifice system IF both systems were installed properly and charged to near perfection? I have a friend that is looking to install a/c and his contractor insists on having TXV and says that fixed orifice is evil and should never be used. I find that rather extreme to make a claim like that. I've tried to do my own research online and although it's a given that TXV is the way to go I think it has a lot to do with the fact that it will better protect the compressor from liquid flooding + it's more forgiving for techs that do an incorrect charge on the system - critical charge isn't nearly as important on a TXV system vs. fixed orifice. Thanks,

Thanks, I was thinking that that price was a little high too, but I'm not in the business. FYI: The price includes: 1yr labor,10yr parts warranty,city inspection,secondary drain pan/float switch, freon filter, sealing... My guess is that all of those items are standard with any company replacing the coil. I'm hoping to get the home warranty company just to agree that there is a leak in the evaporator coil and give me a "cash out" option so I can have a good contractor do the repair. My guess is that I will not get anywhere close to the cost of the repair from them, but something is better than nothing. I didn't actually pay for the warranty, the seller did, so I am not as concerned about getting them to pay for it, as I am about getting a good system. In a year, I will not renew the home warranty, but I will have to live with my system. I am leaning toward replacing the whole thing with American Standard. I don't mind paying more to have it done right, I just don't want to get gouged. Do you think the complete system price is fair?

Your AC company is correct about the return size, although I think you could get away with your present 800 sq in if it were't for the master bedroom issue. While adjusting dampers to provide more airflow to the master might do the trick, you may still need another return in the MBR to get the temperatures evened out. You should have 1000 sq in of filter for a 5ton AC so a 20x20 in the MBR would be more than adequate. A two stage unit would be nice for a couple of reasons: the first stage airflows (supply and return) would likely be inaudible in the MBR and would dehumidify the air better as the run times on first stage tend to be longer. And on those rare occasions you kick into 2nd stage, the 1200 sq in of return with your existing supplies shouldn't be distracting while you sleep. Prices are regional but your estimate doesn't appear too outrageous, especially seeing that they appear to have done their homework on sizing and ducting. A two stage system should add about $1000 on up (depending on the level of system you upgrade to).