duel fuel heat pump the way to go in nw GA?

I live in Dallas, GA (nw GA) and about to replace the original 17 yo Ruud a/c unit and 3 ton furnace simultaneously. An American Standard owner/operator/installer is suggesting a duel-fuel heat pump w/variable speed blower/furnace. I hesitate to consider a heat pump only because we lived in an apartment 18 yrs ago with a heat pump that ran all of the time and never seemed to bring the heat up to a temp that was comfortable. I know technology has changed but is the added expense of the heat pump worth it and will it keep the house just as warm as a gas furnace? The A.S. owner tells me that there is an outside temp adjustment that can be made on the unit that kicks the gas furnace on at the preset temp (i.e. 20-30 F).

Good way to go. Your backup would seldom run in your part of the country. Even up here where it is cold, we install quite a few with the gas prices through the roof and electric rates good. We use the Honeywell Vision Pro thermostat which has the interface between a gas furnace & the outdoor unit. The old mechanical controls with outdoor stat were less than reliable.

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Originally posted by quickone
I live in Dallas, GA (nw GA) and about to replace the original 17 yo Ruud a/c unit and 3 ton furnace simultaneously. An American Standard owner/operator/installer is suggesting a duel-fuel heat pump w/variable speed blower/furnace. I hesitate to consider a heat pump only because we lived in an apartment 18 yrs ago with a heat pump that ran all of the time and never seemed to bring the heat up to a temp that was comfortable. I know technology has changed but is the added expense of the heat pump worth it and will it keep the house just as warm as a gas furnace? The A.S. owner tells me that there is an outside temp adjustment that can be made on the unit that kicks the gas furnace on at the preset temp (i.e. 20-30 F).

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I would use hydronic water coil as back up. Put a 40000btu coil in front of the heat pump. Connect it to a 60000btu 90% efficient water and let the second stage heat call on the pump to circulate hot water to the coil. There will be no lag time in changing and you keep the efficiency of the heat pump as well. Works with any heat pump Use the highest efficient HP as possible. GEOthermo heating needs no back up in your area.

Dual fuel works VERY well in Georgia (I have had it in two houses in Atlanta over the years). In the last case, I replaced a vintage 1981 gas furnace with a new 80% variable speed unit and a mid-range heat pump (as installed, 13 SEER and 8.0 HSPF). My gas consumption halved, and my winter electric bills only went up $15 a month to feed the heat pump. It turned out to be a tidy savings.

Assuming we're talking Georgia Power and natural gas, it's good stuff. If you get a variable speed furnace and a proper dual fuel thermostat (Carrier makes a good one, too, but the Honeywell VisionPro is the top choice right now), you will have no complaints at all about it feeling drafty or failing to maintain your temperature setting. This is top quality equipment, not the bargain basement stuff you find in apartments. I've been there, done that, and didn't like it either.

I don't recommend the dual fuel setup where you just use a two-stage thermostat and let an outdoor thermostat regulate fuel selection; you won't get the same kind of results (as far as comfort), especially if you don't maintain a constant temperature in the house all winter long.

If by chance you have propane, consider dropping it completely and going to a heat pump with electric backup. With our electric rates, it's cheaper that way. For that matter, in many cases operating costs to be all-electric are lower in Georgia than they are to have natural gas service at all. The monthly charges we pay for the privelege of having a gas meter are awfully steep. The difference generally isn't enough to justify the up-front cost of ripping out flues and doing major electrical work to switch to all-electric, though, so if you've already got natural gas, dual fuel is a good solution. By cutting way back on your gas consumption, you can at least pay less for the energy itself. There's also some savings available on the monthly base charges if you drastically cut your gas consumption like this will generally do, but there can be a tremendous time lag before that savings shows up. The price you pay for your share of the distribution network is calculated each April, based on the previous year's consumption, and takes effect each August, so it typically takes about 15 months for that savings to even start.

By the way, here's the scoop on getting good natural gas rates in Georgia's (competitive) market, from somebody who has taken a class on this exact topic: Check out http://www.psc.state.ga.us/gas/gas.asp. You can compare gas rates from all the providers on one sheet (see the Natural Gas Marketers' Prices section), and (hint hint) if you want the best rates overall on natural gas service, get a fixed rate from whichever gas provider is lowest in the fixed rate category in April. That has historically been the best time of year to have your contract roll over (though May is usually decent too), and fixed rates are the only way to avoid getting screwed by the variable rates (which change every month and always spike when cold weather hits). Walton EMC has been the cheapest available almost every month since they started selling natural gas; they have good service and anyone with Atlanta Gas Light distribution service can use them. They (or possibly the other EMC in the gas market), on next month's fixed rate, will probably have the lowest gas price offered this year for a typical consumer. So far I've managed to lock in the best rate offered by anyone each year, every year, since 2000. :D

[Edited by wyounger on 03-21-2005 at 10:21 AM]