HVAC refrigerant lines under rigid insulation on top of roof deck?
lc
3 years ago
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Comments (27)Having worked for companies that have installed all of the brands listed here, and having worked on all of the brands listed here (and then some), I thought Id like to weigh in on this discussion. My experience with Goodman is that anything manufactured prior to 2003 (or around there) is absolutely junk. Before then, Goodman units were nothing more than a builder's dream, dirt cheap. I recently installed several Goodman systems and found that they have made many improvemtents in the quality of their systems. I would attribute this to the fact that they now own Amana, and many of the attributes of the Amana systems have been applied to the Goodman systems. I particularly like the Goodman 96% 2 stage Variable speed model which features one of the best heat exchangers on the market (tubular stainless steel design) As far as Carrier goes, I suppose their split systems are OK, but their package systems are pathetic, and no matter what you buy from them, you are going to pay much more than you should for what you are getting (ironically, I work for a company that sells Carrier now). Their Package systems are way overpriced and commonly leak air so badly that we have to re-seal them in order for them to comply with Title 24 (california) duct leakage requirements. The split systems are decent, but for the money you might as well buy a Goodman. I dont mind trane equipment. Ive only had a few problems with their systems, and they seem to be well designed. I have had a couple package units that had no freon in them, and we had a compressor that was DOA once, but overall, I really like their design. I did hear that they were thinking about putting their spine fin coil on the package units in order to increase efficiency, but I think that's a bad idea, because that would mean the coil would have to be wrapped around the top of the unit, making it very difficult to install. My last employer was a Maytag dealer. I despise Maytag heating and cooling equipment. Maytag is manufactured by Nordyne....which also manufactures Gibson, Westinghouse, and several other such brands. They are all junk. But the Maytag is especially bad because they are far more expensive. As a service technician, half of my service calls were for newly installed Maytag junk equipment that was constantly having problems with sensors, bad motors, bad TXV's, and other such problems. I would never purchase this equipment...ever. Nor would I ever purchase a Lennox system...way overpriced and very expensive and difficult to repair....See MoreAttic w/ HVAC Conditioning ?s
Comments (17)"I can't grasp the all or none concept from Billl though. Basically how is creating a mini attic (still equalizing intake soffit sq inches to gable vent exhaust square inches) devaluing the effectiveness of the insulation? " Mini-attics don't work. All the batt types of insulation are mostly air. They only work as insulation if air is not flowing through them. If you are going to use them in a vented situation, you want to keep them away from major air movement. You don't want to create a tiny channel 1-2" directly next to them where all the air currents in the entire attic will need to flow. So, your effective options are to use a venting system so air can flow through the space but then keep the insulation by the floor so air isn't rushing by it OR insulate and seal off the rafters so there is no air movement. Trying to pick something halfway between the two just doesn't work....See MoreDesigning HVAC for super insulated home
Comments (11)Congrats on doing your homework well! A couple of things to ponder. The heat load numbers you list may be correct, but are extremely low at around 2600 sq. ft. per ton. Again, your numbers may be correct. I've never used coolcalc and it may be right, but before the plunge, it might be a good idea to have someone with a very comprehensive Manual J software to just double check, just for fun. That said, a full basement is NICE and makes a conventional system really tempting. A package unit would make a nice install and offer cost savings, noise reduction, and reliability all in one box. Just a thought. I think you're right about the first floor and the two ductless split systems. This should give you good coverage. Remember though, the supply air will exit through the bottom of the front of the air handler. Make sure the airflow doesn't interfere with curtains or window treatments and the drain is properly run so you don't end up with condensate in a window header. Fujitsu makes an excellent product and is cost efficient. For the second floor, I would recommend a 16 SEER conventional split system. I agree, the second floor is too cut up for a ductless system. The reason for a 16 SEER conventional system is cost per energy savings and reliability. I'm not sure about your area but technical talent in West Tennessee can sometimes be a challenge. Make sure that whatever system you choose, you will be able to find qualified service contractors to help when needed. The last thing you want is Bubba's second cousin learning on your new $10,000 AC. Just sayin... Once again, you have done an excellent job of researching your project and have come up with great ideas. I have written several articles on heat load calculations and energy efficient HVAC on my blog. If you would like to check it out, the link is HERE. One more thing. If you have a certified infrared thermographer, please consider taking advantage of this valuable technology. This is great for validating what you believe about your home's energy efficiency and for checking behind contractors. The picture below is from a construction job I was called in to verify. You can clearly see four bays of insulation missing. The insulators just didn't think these bays were important enough to insulate. The sheetrock guys just walled over the empty bays. Thermal imaging will save money. Please feel free to check out this information also HERE. Once again, GREAT JOB! Please let me know if I can help....See MoreIs this normal HVAC operation?
Comments (14)Thanks, Kevin for your input. In answer to #2, I watched while the vacuum pump was running and they let it run 20 minutes before adding refrigerant. I have used this company a few times before. they are factory authorized service for Carrier in my area and actually did the original installation. I have never had a problem and the techs always seem knowledgeable and they pay attention to detail. You're comment about the TXV bulb was similar to one of my thoughts on the situation. I will wait for cooler weather to check it. The house was built in 1991 by a custom builder. The attic is well insulated with blown in fiberglass and the ducts are covered with insulation. I have read several articles by HVAC companies that HVAC systems are not efficient around 100F and are optimized for the average summer temperature range in the area. The articles say that if the outside temp is 100F and the HVAC system is keeping the temperature at 80F or lower, you have a good system. I am using a Honeywell programmable thermostat and when the outside temp is 100F the system maintains 78F inside easily with only a 9 degree delta from inlet to outlet. It usually runs about 5 minutes until the thermostat turns it off and then comes back on 15-25 minutes later at those temperatures so the house is comfortable, but not cold like in an industrial building or retail store. As the outside cools, the system comes on less often and the delta increases to a max of 18F. The only issue I am still concerned about is the condensate line. I was only able to catch about 2-3 tablespoons of water over two days where the RH was 18-25% which is quite dry heat. I'm not sure there is an obstruction since I hooked a strong shop vac up to the outside line and sealed the connection well with duct tape. After 5 minutes where I could feel the PVC pipe get colder than the outside air, all I got was some debris and a few drops of water. I'll wait for a more humid day to check again....See Morelc
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