Separate 2nd floor HVAC necessary?
cocteau3
| Posted in Energy, Heating & Insulation on
My home is 1980 square feet, with 650 of that upstairs. I’m getting different opinions on whether a separate HVAC is required or even desireable for the upstairs. I would prefer to have a single system that is an electric heat pump. (My area is experiencing massive natural gas cost increases – midsouth, Kentucky). My thoughts are to create one or two return ducts for the upstairs and use one system. Or is this a case for the “micro-vent” or “micro-duct” system that uses 2″ pvc in the walls for ducts? I met someone who owns a three story house in DC who had mixed feelings about their micro-vent system, saying it did not work well. Also, does a heat pump system work when the temp outdoors goes below 25 F?
Thanks,
John
Replies
Get a ground-source (3" well, single-stage sytem) heat pump - I think you're just too cold to keep the toaster strips from running up your electric bill. Ducting for one system shouldn't be a problem. The 2" stuff is really just for tight retrofits, and takes LOTS of design to get good distribution.
Forrest
Actually, my parents have a house with a standard heat pump near Taylorsville. Their electric bills aren't at all outrageous.Ground source makes more sense up here (Minnesota).
If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison
John,
My house is a 2200 sq ft split level I moved into when it was built in 1978. If and when we move, if the house is more than one level I guaranteeeeee you it will have seperate systems. As I type this upstairs in my office it is probably about 80 degrees, but down in the dining room where the thermostat is, its about 75. I like it cool at night and if we keep the bedrooms at about 74 or so, its freezing downstairs.
If you have the choice now, get a split system for sure.
Just my opinion,
Bill Koustenis
Advanced Automotive Machine
Waldorf Md
Another option is a zoned system. Cost is generally less than $1000 over the cost of a unzoned system, though it may be a bit more for a heat pump setup.
You especially want the upper floor zoned separately in cooling season.
Don't know about the micro-vent stuff.
" I'm getting different opinions on whether a separate HVAC "
Absolutely no.
What is needed is a complete calcualtion of the loads for each room and the size of the duct work that is needed to supply that load.
That might mean one system or two systems. The one system might have manual dampners to control the different demands during summer and during winter.
Or they might be an automated zoning system.
My own house is about 1600 sq ft, 800 up and 800 down. I have two furnaces, but only AC on the upstairs.
When I replace it I will probably go with a single system with zoning if it is practical.
The reason for the 2 furnaces was because when it was built in 79 I talked to about 20 HVAC contractors and they all said that they "would stick a couple of vents in the ceiling for the BASEMENT".
The house does not have a basement. The 1st floor is slab on grade and 50% of it is at grade level. Only in the backside is it partialy in the ground. And there is lots of glass on the first floor.