Placing the PEX for radiant heating is relatively easy. What's not so easy is determining if this is a waste of money for you. It was for us. 1.)We live in the South, where the cooling season is longer than the heating season. Very little chance of payback unless you operate the system for longer periods. The smart boilers needed to accurately control a system in a temperate climate are pretty spendy and complicated and not very DIYable. 2.)We have wide temperature swings, sometimes daily, which magnifies the slowness of the "thermal mass pendulum." We see this just with our heated bathroom floors (separate system). It's going to be 42° tonight, so turning on the heated floors will feel good. You have to think about that a couple of hours in advance, because it takes that long to warm up. By the time they're warm, they're too warm for most of the timeframe except for that brief period that was 42°. The next day when the swing is back up to 60° and the floors are still 80°, the bathroom is too hot and needs a window opened for comfort. 3.) We insulated the new addition so well that a plain 110 volt 1500 w spaceheater can keep it 60° in the winter, and a 2 ton AC in the summer. If we'd put the money we spent on PEX towards additional insulation (we just used 2x6 construction with "standard" type insulation instead of the new high tech products) then the simple addition of the forced air furnace would have been more than sufficient for truly comfortable heating in the winter. For many people who have a long heating season and awkward spaces that forced air isn't comfortable for, radiant heating can work "miracles". For people in warmer climates, or in climates with great daily temperature fluctuations, a radiant system is very often not the best choice for either comfort or the pocketbook. Do your research well, and don't get caught up in the hype thinking it's a "must have". It isn't. And, it's sometimes even a drawback to comfort. We've never fired up the radiant in the addition. We've never needed to, even in 0° weather. And the bathrooms do work wonderfully well (imagine 6 cats lying on their backs in bliss!) but are also inefficient monetarily and for true comfort when confronted with wide temperature swings in a day. They are great when the temps say in the 40's and below for extended periods of time, but that't not how our winters here operate. It's 40 for a couple of days, then back up to 55°, then down to the high 20's, then 70° (must be Christmas day!) and then you have a 50° drop into the teens and on down to 0°. Radiant isn't very efficient or comfortable with weather like that.

A lot of the pricing is determined by the area and the company. Sears and Home Depot may be household names, but I would look elsewhere for HVAC services as I believe both use subs. Those big stores need to make their profit. Look for reputable dealers from the manufacturer's website, or ask for personal references. Bryant and Carrier are the same product. Rheem and Ruud are the same product. Trane and American Standard are the same product. There are minor differences, mostly having to do with cabinet look. You need to get a contractor who can do a load calculation to determine sizing and look at all of your ductwork. Did any contractor do this? How did they determine sizing? Did they examine the ductwork to ensure ample supply and return? Regarding brands... I really don't see a huge difference between any of them. Most use similar if not identical parts. Think about who is installing it more. All of them break.

Our 11 Yr old 3.5 ton RUUD Silouhette II AC for the upstairs (2000 sq. ft.) stopped cooling Monday and DH discovered that the evaporator coils were coated in ice. Shut off AC and fan which is always ON was used to thaw out. But although the drip line was clear (DH opens the evap. cabinet and pours bleach/water mix down the line to condensate pump every 3 months and had installed new condensate pump last year) it turned out that the horizontal cold air return cabinet had 10 inches of stagnant rusty water sitting under the air handler. The blower motor had died of rust! We've never had a service contract on our HVAC but have had whoever was available check freon every other year. Last check was in June by Service Magic and he only suggested cleaning the outdoor units which we did following instructions in a Family Handyman article. But DH admits that though he vacuumed the evap coils he never looked into the furnace blower cabinet below the burner in 11 years so we've likely had that water sitting there for 7 years. 7 years ago we noticed dripping and repairman said he had to correct the "tilt" of the evaporator coil to have water drain to the drain line. Apparently either that didn't work or he cracked the drip pan. The coils are very much tilted toward the drain, but the original installer who came out yesterday says that the drip pan was cracked allowing the unseen drip onto the blower and into the rusty lake below. He's saying that the cracked drip pan and coils are no longer available and therefore we have to change to new coil, matching condensor, and put in new blower for airhandler so we probably should go with new efficient units especially as DH and 2 of the kids have asthma so we run fans on always thru the HP electric air cleaners. Strangely even though they are Rheem/Ruud Top Contractors, they spec'd all Lennox equipment. DH told them he didn't want Lennox but that was the only type the fellow would quote, saying call the office for Rheen/Ruud pricing. Rheem is higher quality right??? He's quoted 3.5 ton 2 Stage 14SEER Lennox AC and 90,000 BTU 80AFUE variable speed Lennox Air Handler Furnace for $6820 w/ Honeywell 2 Stage Thermostat. This is Princeton, NJ does that seem right for Lennox??? House is 4400sqft. with underconstruction basement adding another 1800sqft. We had assumed larger first floor unit was sized for a finished basement but having read many pages of this forum we are now no longer certain???? Existing contractor grade Ruuds are 82% AFUE original equipment for home built in 1997. We pay $0.20KWh from Jersey CPL. (Princeton). We have Home Depot (Trane) and 2 other Trane contractors coming today to get competitive bids. We can't find a Ruud contractor who will show up in less than 2 weeks so will have American Standard bids also if possible. I see they are Trane equivalents. The original installer said no to our request to have a 90% AFUE quoted. He says that the chimney flue would have to be changed, PVC exhaust run to side of house, condesate drip to sump run, gas water heaters replaced because exhaust vents would no longer work. Is that all true???? We have a 3 year old and intend to see him through high school so at least till then or death of DH (go go arsenic!), we'll be here. So really thought we should step up to 90%AFUE. Absent that should we think heat pump? We used 2800KWH and electric bill avg. $600 during summer months at $0.20/KWH. It appears to be flat rate on current bill but I thought it ramped up to 0.34/KWH before. So is central NJ too cold for a heat pump to be effective???

Texas there are three equally important components-quality HVAC, the install by dealer, and probably the most overlooked and disregarded is the ductwork system. these are my minimum specs for a new HP system. both outside and inside units should be replaced to have a properly matched system. 15 SEER, 12.5+ EER, 9 HSPF best matching VS air handler full BTUs in both cooling and heating for your rated size R-410a refrigerant(same as Puron) scroll compressor preferred electronic demand defrost preferred thermostat with "dehumidify on demand" feature staged backup heat strips new and correctly sized refrigerant lineset 10 yr warranty compressor and parts you want a thorough inspection of your ductwork system. size, overall condition, supply and return lines, insulation qualities, leak test, etc. any hot/cold spot issues in your home should be addressed. I would only use authorized dealers for the various brands that provide quotes. see mfg websites. I would look at Trane/AmStd,Rheem/Rudd,Carrier/Bryant. I would not purchase a new HP system that did not have electronic demand defrost. IMO