eoz

heat pump all the way with electric strip heat backup.

run the numbers on attached link to fuel comparison calculator.

use COP of 2.75 for HP efficiency which is conservative. you can set the furnace efficiency.

BTW, have you even considered geothermal?

IMO

Here is a link that might be useful: Fuel Comparison Calculator

I haven't seriously investigated geothermal in this area. It's hard to find reliable information on geothermal in the Houston/Conroe area.

Should I be concerned about a heat pump being able to cool effectively in teh summers we have here? Not many people have them in this area and I'm not sure why.

Heat pumps cool just as well as regular A/C's. They are the same except for a reversing valve and some extra controls. They are actually better built then A/C's some say. They have some extra high and low pressure valves.

If your in texas and heatpump wlll serve you well. Especially if your house is well insulated.

eoz3106,

I'm in TX, about 2 hrs from Houston area. Heat pumps are common around here on all-electric constructions. My parents, a sister, and I have had heat pumps for years, we like them. One of my neighbors spent $24,000 (before tax credits) on a 4-ton geothermal system last year, I don't think there'll ever be a payback on that investment.

Eos, we are building a house in Houston right now and need the name of a good Heating and AC sub-contractor to look at the system that has been installed by our builder. We believe he did not choose a good sub-contractor. We have not sheet rocked yet. Can you recommend anyone?

if you plan of being in the house a long time, geo thermal might be worth it. That is assuming you can find good contractors that don't overcharge and have access to good well-drillers.

Geo-thermal will save you alot on cooling too. Which in texas you will be doing alot of.

If you can get a 24,000 4 ton geo-thermal system installed I would do it. If 4 ton is the proper size for your house. AFter the credit its only 16,000++. Geo-thermal systems with closed loop well can last a long time also. Makes alot of sense really. Especially since they plenty of land around your house so it should be no problem for the driller to drive their truck with their rig to drill the wells.

The 30% credit doesn't go away for geo-thermal like the other tax credits do on Jan. 1, 2011 so it gives you extra incentive to spend more for the geo.

I do think $24k is pretty steep but $16k sounds so much better. If you figure $1000 savings a year which maybe right, then in 10 years you are doing fine with a system that should last a realy long time. I think people running the numbers will find the payback is easier with heat than a/c. It is a matter of delta Ts - with a/c there is never a huge delta T - 20 degrees usually whereas with heat there can be 60 degree delta T's. (not technically the best use of "delta T" in this situation but the concept is sound)

It would be helpful to know some average life expectancy for units. I'd guess 15 years for ASHP and 30 years for GSHP. I guess my question would be are there pumps that might go out earlier on GSHP and are they cheap to replace.?

It is unlikely that a 4 ton unit in Texas would save $1000 a year like I stated in the above post.

Extrapolating my numbers (about $1500 a year to run 7 tons of HP with NG in NC) would put 7 tons of heat and a/c at $2000 a year (obviously big guess and assuming $.11KWH). So 4 tons of mostly just a/c would probably only cost $1000 a year so geo savings is probably just $300 a year. That makes payback a really really long time. It becomes realized when you buy your second ASHP unit though.

I got one thing right, geo makes more sense in a heating environment and particularly when NG is not available.

Geothermal may save up to about 45% compared to high efficiency A/C or Air-Source HP. Geothermal makes most sense in regions where climatic conditions are extreme.
BTW: Avg. ground temperature below 10-feet in Houston should be about 76 degrees F.

SR