Any HVAC experts Here?

Have been told by an hvac guy here to watch that they dont hook the thermostat up such that the emergency heat comes on every time the regular heat does. He claims the TVA encourages this to make up for the efficiency loans and rebates they do. It's easy to check for if you look at the diagram in the cover of the unit it will usually show the correct hookup.

Here's something most people don't know about, and HVAC installers seem reluctant to bring up (maybe they don't know about it, either). You DO NOT have to use electric resistance heat for your supplimental heat source! You can add a "fossil fuel kit" (basically just another thermostat) and use your EXISTING heat source for supplimental heat (LP, nat. gas, etc.). Electrical resistance heat is THE MOST EXPENSIVE way to heat in most areas, unless your power company cuts you a mother of a deal on cost per KWH. Check into it before you let them talk you into electrical resistance back-up heat.

Ron

My system is a 3 stage setup. HP - 5KW Strip - #2 oil burner FA furnace. 7.1 cent/KW electric cost but the HP gets a 3.7 cent/KW credit from that for being "switchable" from the elec company. 1800 sf two story, bad windows, little insulation, $100 heats the house for 6 months in a normal year. Jan and Feb are the killer months.

A friend has the geo therm looped, with a LP furnace back up, furnace fires up once a year when he manually kicks it in at the beginning of the year to check it out.

If you live in a cold climnate then a HP efficency is greatly reduced. The ideal HP temp is 45�. So when temps fall towards 0� to 10� then your HP isn't going to satisfy heating demand so you add electric strip heating elements, relays and two stage thermostat.

With a two stage thermostat, the first stage calls for heat from the HP. When the HP can not satisfiy the heating demand then the thermostat calls for stage two, the strip heaters.

As the room demad is nearly satisfied , stage two shuts off, then stage one finishs the heating demand then shuts off.

The strip heaters work just like a all electric furances, very expensive. Natural gas is still the cheapest commericaly supplied heating fuel with HP next cheapest in the correct climante.

Do a search on this fourm for, ground source HP, as those are alot more efficent for cold climnates.

T_Bone

Yes heating elements and related componets can be added at any time although more expensive that mfg supplied units.

On my first post I stated 45� is the most efficent tempature for a HP. Since ground temperature doesn't change but a couple degrees over a year at 8ft down (52� average) then a correctly sized/installed HP for your building demand would not need any additonal heating sources.

T_Bone