Best setup for NC? \"Dual fuel?\"

Wayco Wayne_2

a heat Pump outside and a fossel fuel furnace inside. She may be confused and if not let us know. If it's something new we should know about we'd want to know. WW

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Gene Davis_2

In a phone conversation with the wife of a residential HVAC contractor in Flat Rock, NC, I was told that the premium HVAC package for a new custom home there be, in her words, a "dual fuel" setup. Two units, mounted side by side on a slab, near an outside wall of the house. One unit operating with natural gas, the other all-electric.

Please describe what is going on with one of these arrangements. How is the heat exchange conducted inside the house, with the units outside? Does electric-resistance heating take place?

Or was she all wrong?

Alex_6

Dual fuel

Dual fuel usually refers to Heat pump backed up with fossil fuel


H/P operates until (1) preset outdoor temp is reached and controller lets fuel engage and drops H/P out..........or (2) H/P can't satisfy load and fuel takes over via second bulb on T-stat

Gene Davis_2

But she said that typically two units are employed. I should say that the plan was for a two story house with finished space in the basement.

I had heard this story before, from a local builder, about systems for heating and cooling homes typically employing two units, one one kind and the other another.

Gene Davis_2

I got some further information on what these systems are about. Most all the big guns in HVAC make "packaged" dual-fuel systems, half the package being an electric heat pump used for cooling and heating down to maybe 35 degrees outside air, then a gasfired heating unit, the other half of the package, takes over. An example is the Lennox Elite Series 13GCSX. The package sits on a pad adjacent an outside wall of the house, and insulated ducting runs right through the wall.

Now, my question is this: relatively speaking, what would by the installed system cost be for such a system, all ducted, controls, etc., versus a gas-fired hydronic infloor heating (no a/c) system, for the same 3000 sf house?

mtfallsmikey

Unless it's something new and improved,

It sounds like a self-contained heat pump (typically used for manufactured housing)with oil/gas furnace. I've done some of these back in the late 80's with conventional split systems, mfr. usually had a kit which contained a primitive outdoor reset control. Works ok for baked air.

Gene Davis_2

Specify something better?

How would we specify something better? We want to conditon 4000 sf of living space, consisting of 1000 sf in finished basement, 2200 on main floor above, and 800 of upstairs. Location is Flat Rock, NC, halfway between Asheville, NC and Greenville, SC. 90 degree summer highs, 10 degree minimums (very occasional zero) wintertime, long temperate springs and falls.

John_102

local conditions

Hey -

I'm no pro & not quite in your climate (northern Greenville, not Hendersonville). While I generally agree with your characterization of the weather:

1.) What does 'very occasional zero' mean? We've had a run of warm weather lately, but prior decades were colder, especially in the January - March period. (I used to live up the street in Arden.)

2.) What about the humidity of our dear, green land? Seems like it's chillier than the thermometer says.

3.) (Or maybe #2, continued) Personal experience with heat pumps was disappointing.

Don't mean to stick my nose in, rather to nod to a neighbor. These observations have little or no statistical basis.

Good luck & peace.