View Full Version : Need furnace/heat pump advice
08-19-2006, 03:55 PM
I live in metro Atlanta. My GE furnace is 28 years old and on its last leg; my Trane condenser unit is 12 years old. My house has 3 floors, including a finished basement, for a total of approx 3200 sf. I want to replace the single existing system with 2 new systems: one for the main floor & basement, and one for the upstairs bedrooms. I have had two contractors perform load calculations, and both proposed a 2.5 ton system to replace my existing funace in the basement, and a 2.0 ton system to be installed in the attic.
Both contractors have proposed Trane systems. One recomends a traditional gas furnace (XR80) and A/C condenser (XR13) for both systems (80,000 BTU in basement, 60,000 BTU in attic), while the other recommends a heat pump (XR 13) and 48,000 BTU duel fuel furnace (XR80) for the basement plus a heat pump (XR13) and 2.0 ton air handler for the attic. I am considering upgrading to an XV80 furnace based on discussion I've seen on this web site.
I have no experience with a heat pump system. One contractor swears by them and the other does not recommend them. It seems like a wise investment for the duel fuel option, particularly the way gas prices have skyrocketed. One concern is with the all-electric air handler for the attic. Sometimes the temperature in Atlanta can dip to 10 degrees during the winter, and I've heard that electric systems are not very efficient below 35 degrees. Will the warm air from the main floor (gas furnace) keep the upstairs comfortable in these extreme conditions?
Any input from you experts would be greatly appreciated.
08-19-2006, 05:23 PM
I'd sure want heat pumps outside. Since 10 above is very rare for Atlanta, upstairs a heat pump with electric strip backup is probably all you need. Cheaper than piping gas upstairs and running a flue unless you don't have the electrical capability on adding a heat strip. Won't take much. The heat pump alone should keep you warm down below freezing. In the rare even it gets colder, a 5kw strip should take the edge off. Since heat rises, most of the heat for upstairs will come from the main gas furnace anyway.
08-22-2006, 12:10 AM
I've now had a 3rd contractor give me an estimate, and he was not endorsing a heat pump. He said the warm air from the heat pump (105-110 deg) wasn't as comforting as the hot air (130-140 deg) from a gas furnace. Of course, with the duel fuel system, that wouldn't be an issue. How would the air blown from an air handler compare?
Also, the first 2 contractors recommended Trane systems, but this latest one sells American Standard. I know A.S. owns Trane; are their systems comparable? Are there other comparable brands to the Trane XV80 furnace & XR13 AC/Heat Pump and their A.S. equivalents?
08-22-2006, 01:38 AM
The heat from a heat pump via the air handler or via the furnace is less hot but not less comforting. Also Your duel fuel systems would run heat from your heat pump most of the time. the furnace would not run while the h.p. was running. but seperately depending on outside temp. or by choice of Emergency Heat on your T-Stat. A variable speed unit, A.H. or Furnace, can over come some duct work problems and can increase efficiency and control humidity.
08-22-2006, 06:09 AM
I've put dual fuel in for 2 ladies I know would have my hide of they weren't perfectly comfortable. Fortunately my hide is still intact!
Yes, A-S and Trane are the same machines. Some cosmetic changes to the outdoor units, furnaces are identical.
08-22-2006, 08:55 AM
Are there models from Carrier/Bryant, Rheem/Ruud, or others that are comparable to the Trane/American Standard models listed above? Also, I've heard of Trane forever, but I was unfamiliar with A.S. until yesterday. Will parts availability be an issue if I have an A.S. system installed?
08-22-2006, 09:08 AM
With the price of gas, why have they not suggested a 90% plus gas furnace. Rheem/Ruud and other make comparable equipment. Availability of parts depends on the distributor who sales the equipent to the installing contractor. Proper installation is the key to any equipment. Variable speed is better than standard if you can. Do not use the VS to overcome a bad duct system.
08-22-2006, 09:37 AM
Thanks for the input. My duct system is fine, although 2 of the contractors have suggested the addition one additional supply and return upstairs to address a hot spot in one of the bedrooms.
My research has indicated that a 90% furnace is not worth the investment in Atlanta. I plan to install a VS furnace in the basement, but I understand a single speed furnace/air handler (still deciding on this) would be sufficient for the attic. Your thoughts?
08-22-2006, 09:53 AM
Baldloonie has given you excellent advice. Since you live in an area/climate with low electric rates, I would put in heat pumps with var speed air handlers. If you do want a gas furnace, then install an 80% AFUE var speed model paired with a high eff heat pump. For the upstairs, a high eff heat pump with var speed air handler would be fine. Make certain ductwork is sized properly for both systems, insulation checked, supply/returns balanced, leak check, etc. Also, you do not want to undersize upstairs system because of those very hot Atlanta summer days.
I personally think Trane/AmStd have the best heat pumps but Carrier/Bryant's Infinity/Evolution models have the best and most sophisticated systems control.
My starting suggestions for downstairs would be Trane's XV80 var spd gas furnace paired with either XL16i or XL14i heat pump depending upon whether you want a 2 stg or sgl stg heat pump(2 stg gives better dehumidification). For upstairs, the XL14i heat pump with var speed air handler would be just fine. And of course you need to consider an air cleaner cabinet for both systems along with appropriate thermostat.
08-22-2006, 10:01 AM
I would use more efficient unit for the upper level since it could possibly see more run time on air conditioning. Also a more efficient unit for the upper level will generally have a better HSPF (Heating Seasonal Performance Factor). HSPF for heating is what SEER is to air conditioning. Like MPG for a car. But nothing wrong with the most you can afford.
08-22-2006, 12:19 PM
Thanks for the input everyone. Now I have another question: what about Freon vs Puron? Is there any reason to buy a Freon A/C or heat pump, since this will be phased out of new systems in 2010?
08-22-2006, 12:29 PM
i personally like the R-410a(Puron) over the R-22 but really would not turn around for the difference and definitely would not pay a premium for the R-410a equipment. While R-22 refrigerant will be around for many yrs, it is being phased out and the R-410a will become the standard and will be the dominant refrigerant in a few yrs. Yes. R-410a frig costs more right now but this situation will flipflop sooner rather than later.
Some dealers don't care for the changeover as it involves new equipment as well as new training for their techs.
There will be varying opinions but the above is mine.
08-22-2006, 03:09 PM
Two years ago I would not consider 410. I still lean toward 22 but I think the manufactures have made improvements. I would not worry either way. I would not pay more for either.
08-24-2006, 06:26 PM
Gas heat is hotter, but it's only an advantage if you can afford to run it. Cold-blooded sorts can be perfectly happy with the warm (not hot) heat from heat pumps, especially in areas like Atlanta where heat pumps are so much cheaper a way to heat a home. Variable speed blowers do go a long way toward making heat pump heating more comfortable, I will grant, and you wouldn't want to set up the supply registers where they were blowing with much velocity (it feels drafty that way). It's easy to set up a heat pump in ways that don't produce good comfort, though, so it's no wonder they get a bad rap.
In my experience in metro Atlanta a home using a heat pump as the primary heat source, regardless of whether the auxiliary heat is gas or electric, costs 50-70% less to heat over the course of a year than a house with an 80% efficient gas furnace alone. The local climate just doesn't require much backup heat beyond what a heat pump can provide.
Georgia Power doesn't offer special rates for those with heat pumps, but have fairly low winter electric rates, and heavy users of electricity in the winter get a bit of a "bulk discount" in the rate structure. Since the vast majority of electric production in the region is nuclear and coal-fired, the recent increases in the cost of oil and natural gas are not affecting our electric rates the way they have in areas that use natural gas to make electricity.
If anything I find the slow-and-steady warm heat from a good heat pump at least as comfortable as the on and off cycling of a furnace.
08-24-2006, 07:53 PM
I got an Amana 92% (I think) Eff. furnace back in 2000. It's a dual fuel system and it runs on electricity until it drops below 40 degress or so outside, then switches to gas. It's been a pretty good unit. No problems at all.
08-24-2006, 11:21 PM
Good information guys. I am becoming more confident in the merits of a duel fuel furnace in the basement, but I'm a bit concerned about wyounger's statement that "It's easy to set up a heat pump in ways that don't produce good comfort, though, so it's no wonder they get a bad rap". Can you explain this further?
I'm still apprehensive about an all-electric air handler in the attic. As stated above, I currently have one system controlling all 3 levels of of my home. If I install a duel fuel furnace in the basement with a heat pump condenser, then a new all-electric air handler in the attic with another heat pump, will the system produce good comfort? The only duct work changes suggested so far are adding another supply in an upstairs bedroom (hot spot) and a return in the upstairs hallway (of course the chase will be closed off between the main floor and attic). I'd hate to regret not installing a gas furnace in the attic. Any further words of wisdom?
Powered by vBulletin® Version 4.2.0 Copyright © 2013 vBulletin Solutions, Inc. All rights reserved.