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Thread: New Construction HVAC
06-27-2005, 12:30 PM #1Regular Guest
- Join Date
- Jun 2005
Hi- I'm building a 2400 sq. ft. home near Lexington,VA. 2 story, 9' ceilings 1st fl, 8 on 2nd, full basement, open floor plan on 1st fl, BR's upstairs. Since I currently live in New England I have no experience with heat pumps. We keep our current house, which has hydro air/oil heat(new construction) at 68-70 in the winter and the a/c at 78-79 in summer. The builder's HVAC person suggests heat pump w/propane backup. I've read a lot on this forum and Fine Homebuilding to get some basic info.
I have 2 questions.
#1 Some people say the air from a heat pump system feels "cooler" than air from an oil heat system and a neighbor in VA who has also used oil heat confirms this. So, is the answer to that to just go to the backup propane sooner as the temp goes down?
Would I be able to use the propane backup system alone if I'm not happy with the heat pump? Or is it sized smaller because it's for backup? I haven't spoken to anyone down there who suggests just doing an oil or propane system alone.
#2 It's clear the installer is critical to getting a good job done. Is NATE certification any indication of a good installer? (The closest co. on the Nate site is 50 miles away) What about sizing using Manual J? The first 3 hvac companies I spoke to said they don't use Manual J for sizing unless there are unusual factors. I can get references but everybody has someone who liked their work. Should I start with people who install good brands (whould you say Rheem/Trane?)?
Any help would be appreciated.
06-27-2005, 02:04 PM #2
Yes supply air temp for a h/p will feel cooler than supply air temp from a fossil fuel
It will still heat your home and probably be more efficient
Request a 2 stage variable speed furnace and request that it be sized to handle the entire home in case of h/p failure or if you just dont like it
Being that it is a fossil fuel furnace it should be sized to handle the whole home anyway because it should not run at same time as h/p
as far as manual j it is the only way to know you are getting the right size equipment, it should be done you can do it yourself to check what they are doing by clicking the bulls eye at the top of the page and buying the software
Nate is not an indication that the install will be done right it is an indication that someone could take and pass the test
Nate shows they should know what they are doing but doesnt mean they will do it right
There are many contractors who do a great job and are not Nate certified
06-27-2005, 05:50 PM #3Member-bad email
- Join Date
- Aug 2003
The key to comfort is not just the HVAC system. That is the biggest mistake people make when building a home. The thermal envelope is just as important. Insulating better than code, air sealing, the right windows, and all the other details effect comfort and utility bills greatly. The better the thermal envelope the smaller the HVAC system. In terms of propane backup--why bother? The temperature coming out of the ducts won't vary much from electric, and the cost is about the same (now-propane will be much more expensive in the future)..
I would check with Dominion Power to find an independant consultant to help with all of this.
If you depend on your builder and HVAC person you will be out of luck!!
06-27-2005, 07:15 PM #4Regular Guest
- Join Date
- Mar 2004
- Vancouver, BC
Exactly. Build a better envelope and save HVAC plant first costs as well as on-going energy costs. Given what will be happening with energy costs even over the next few years, it only makes more and more sense to address the windows and solar control, then the infiltration, and then the thermal bridging details. Lots of good stuff if you do a search for "healthy heating" and other similar keywords.
06-28-2005, 01:22 PM #5Regular Guest
- Join Date
- Jan 2004
If you spend an extra 3 or $4000 for insulation and air sealing over and above the code minimum, the cost of your HVAC system will decrease enough to get most of that money back. Smaller heat pump, smaller ducts, fewer ducts, more comfortable inside, and lower energy bills. You will not regret spending extra for more insulation and better air sealing.