# Heat Pump vs Gas Furnance and AC **URL:** \ **Category:** In My Humble Opinion\ **Created:** [March 23, 2011, 4:13pm UTC](https://boards.straightdope.com/t/heat-pump-vs-gas-furnance-and-ac/575726 "2011-03-23T16:13:23Z")\ **Posts on this page:** 11\ **Page:** 2
**Author:** ![cmosdes](https://avatars.discourse-cdn.com/v4/letter/c/a587f6/32.png) [@cmosdes](https://boards.straightdope.com/u/cmosdes)\ **Post date:** [March 23, 2011, 10:49pm UTC](https://boards.straightdope.com/t/heat-pump-vs-gas-furnance-and-ac/575726/21 "2011-03-23T22:49:03Z")
Can anyone help me decipher this spreadsheet found [here](http://www.diychatroom.com/f17/heatpump-vs-natural-gas-energy-cost-spreadsheet-62047/). If you look at the section for “house load”, I assume the 791.66667 number comes from his sq\_ft, times the BTU/sq\_ft/Deg F/Day and divided by 24. But I don’t see where the numbers for the Heating Output HP (kBTU) and Heating Input Power HP (kW) come from. Heating Output Power HP (kW) is simply Heating Output HP (kBTU)/3.41. So right now I’m really stumped on the first two items. I’m hoping I can figure out the test if I knew where those are coming from. Anyone know? ---
**Author:** ![cmosdes](https://avatars.discourse-cdn.com/v4/letter/c/a587f6/32.png) [@cmosdes](https://boards.straightdope.com/u/cmosdes)\ **Post date:** [March 23, 2011, 10:50pm UTC](https://boards.straightdope.com/t/heat-pump-vs-gas-furnance-and-ac/575726/22 "2011-03-23T22:50:04Z")
> [@TravisFromOR](#): > > I’m not impressed with heat pumps. > > I recommend a gas furnace and a swamp (evaporative) cooler. I have a swamp cooler–it’s virtually free to operate in the summer. What is it about heat pumps you don’t like? ---
**Author:** ![Magiver](https://avatars.discourse-cdn.com/v4/letter/m/4491bb/32.png) [@Magiver](https://boards.straightdope.com/u/Magiver)\ **Post date:** [March 24, 2011, 12:21am UTC](https://boards.straightdope.com/t/heat-pump-vs-gas-furnance-and-ac/575726/23 "2011-03-24T00:21:28Z")
> [@raindog](#): > > We install geos and that has been our experience as well. Geos are a good thing for the environment and for the homeowner. > > The only drawback is that they can be expensive------expensive enough that it might make it hard to make sense of the additional investment in moderate climates. > > We’ve had people make the investment because of social concerns. (often they’re also driving hybrid cars) > > But if the OP has no large social concern and if economics are sole criteria, it _may_ be harder to make sense of it. Most of the cost seems to be in the well. Otherwise, it’s just any other exchanger with a compressor unit. The rate of return is in relation to the sources of energy available. I don’t understand why the closed loop system uses antifreeze but I could certainly trench my hard for almost nothing to install the lines for it. That’s got to be a lot cheaper than drilling a well. I’m getting ready to help someone install a well type system. We already moved the exchanger. It was heavy as hell. It’s the type with an electric backup heater for forced air. ---
**Author:** ![Balthisar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/balthisar/32/2825_2.png) [@Balthisar](https://boards.straightdope.com/u/Balthisar)\ **Post date:** [March 24, 2011, 1:57am UTC](https://boards.straightdope.com/t/heat-pump-vs-gas-furnance-and-ac/575726/24 "2011-03-24T01:57:51Z")
My complete geo system was $4000 more than the average quotes from other companies’ super-high efficient gas systems. I attribute that to the labor and materials involved in the ground loop, with a slight premium for a system that doesn’t have the sales volumes of traditional systems. On the other hand I have a nice desuperheater described in another thread that’s not part of traditional systems. And… The power costs (i.e., consumption but not distribution) is at 50% because it’s a “green” system. That means that all things being equal (they’re better, in fact), my A/C operating costs are only half of what they were with the old HVAC system. I didn’t do it for any social concerns nor do I drive a hybrid; rather the ROI was fast and the long term savings were obvious (as I said, it makes me feel morally okay to drive what I want to drive). The ROI was key; it made perfect sense. ---
**Author:** ![Magiver](https://avatars.discourse-cdn.com/v4/letter/m/4491bb/32.png) [@Magiver](https://boards.straightdope.com/u/Magiver)\ **Post date:** [March 24, 2011, 2:44am UTC](https://boards.straightdope.com/t/heat-pump-vs-gas-furnance-and-ac/575726/25 "2011-03-24T02:44:15Z")
> [@Balthisar](#): > > My complete geo system was $4000 more than the average quotes from other companies’ super-high efficient gas systems. I attribute that to the labor and materials involved in the ground loop, with a slight premium for a system that doesn’t have the sales volumes of traditional systems. On the other hand I have a nice desuperheater described in another thread that’s not part of traditional systems. And… > > The power costs (i.e., consumption but not distribution) is at 50% because it’s a “green” system. That means that all things being equal (they’re better, in fact), my A/C operating costs are only half of what they were with the old HVAC system. > > I didn’t do it for any social concerns nor do I drive a hybrid; rather the ROI was fast and the long term savings were obvious (as I said, it makes me feel morally okay to drive what I want to drive). The ROI was key; it made perfect sense. Did the company that built it describe any difference in efficiency between a ground loop and a well system? Is the glycol anything special or was it automotive antifreeze? What was your ROI for the $4000 difference? ---
**Author:** ![China\_Guy](https://avatars.discourse-cdn.com/v4/letter/c/779978/32.png) [@China\_Guy](https://boards.straightdope.com/u/China_Guy)\ **Post date:** [March 24, 2011, 3:21am UTC](https://boards.straightdope.com/t/heat-pump-vs-gas-furnance-and-ac/575726/26 "2011-03-24T03:21:36Z")
I’m in the PNW (Seattle Eastside) and interested in the conclusions of this thread as we’re gonna build pretty soon. ---
**Author:** ![raindog](https://avatars.discourse-cdn.com/v4/letter/r/2bfe46/32.png) [@raindog](https://boards.straightdope.com/u/raindog)\ **Post date:** [March 24, 2011, 4:02am UTC](https://boards.straightdope.com/t/heat-pump-vs-gas-furnance-and-ac/575726/27 "2011-03-24T04:02:30Z")
For those who don’t already know, I’m an HVAC contractor and sell and install geo systems. It is largely true that difference in cost related to a geo is mostly caught up in the cost of the field. There are basically 3 types of “closed loop” systems. My cost for a field runs between $1500-2000 per ton. I don’t mark up the field at all. The HVAC part of the system is comparable to a high seer system, IOW, my costs for the geo system without the loop is comparable to the costs associated with an 18 seer system. My profit margins are about the same. If not for the cost of the field/loop the cost of a geo would be comparable to an 18 seer air source heap pump. By way of example, I’m installing a 3 ton geo next week, and the cost of the HVAC part of the system is around $12K, which is comparable to a high seer air source heat pump. But…there will be an additional $6K for the ground loop. Sop the total cost to the homeowner will be roughly $18K ---
**Author:** ![Magiver](https://avatars.discourse-cdn.com/v4/letter/m/4491bb/32.png) [@Magiver](https://boards.straightdope.com/u/Magiver)\ **Post date:** [March 24, 2011, 4:53am UTC](https://boards.straightdope.com/t/heat-pump-vs-gas-furnance-and-ac/575726/28 "2011-03-24T04:53:23Z")
> [@raindog](#): > > By way of example, I’m installing a 3 ton geo next week, and the cost of the HVAC part of the system is around $12K, which is comparable to a high seer air source heat pump. But…there will be an additional $6K for the ground loop. Sop the total cost to the homeowner will be roughly $18K what would be the cost savings per year for a 3 ton system versus a high efficiency system of similar size? ---
**Author:** ![raindog](https://avatars.discourse-cdn.com/v4/letter/r/2bfe46/32.png) [@raindog](https://boards.straightdope.com/u/raindog)\ **Post date:** [March 24, 2011, 2:15pm UTC](https://boards.straightdope.com/t/heat-pump-vs-gas-furnance-and-ac/575726/29 "2011-03-24T14:15:19Z")
> [@Magiver](#): > > what would be the cost savings per year for a 3 ton system versus a high efficiency system of similar size? We haven’t quite quantified that yet. Its something we’re working on. The manufacturers we work with tell us that they have SEER ratings in the 30ish range, although I haven’t seen any data yet. We hope to have a calculator on our web site within a year that allows a consumer to calculate operating costs and make vis a vis comparisons as well as ROI info. Its worth noting that the legislation that allowed homeowners to take a $1500 direct tax credit for a variety of efficiency improvements (and was scaled way back as of 1/1/11) had an amazing exception for geothermal. The legislation (as I understand it) for geo didn’t semi-end in 2010, but runs through 2016. Even more, the tax credit didn’t cap out at $1500. It was a tax credit for 30% of the installed prices with no limit. So a guy spending $18K on a geo was/is getting a $6k tax credit, which puts the final price close to the cost of an 18 SEER system. That tax credit had the effect of converting high seer buyers to geo buyers. ---
**Author:** ![Balthisar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/balthisar/32/2825_2.png) [@Balthisar](https://boards.straightdope.com/u/Balthisar)\ **Post date:** [March 24, 2011, 2:42pm UTC](https://boards.straightdope.com/t/heat-pump-vs-gas-furnance-and-ac/575726/30 "2011-03-24T14:42:26Z")
> [@raindog](#): > > By way of example, I’m installing a 3 ton geo next week, and the cost of the HVAC part of the system is around $12K, which is comparable to a high seer air source heat pump. But…there will be an additional $6K for the ground loop. Sop the total cost to the homeowner will be roughly $18K This is almost perfectly in line with all on my quotes from a few years ago, except as I said, my ground loop was only about $4K of the price. Mine was a 3.5 ton system, if I recall correctly. > [@Magiver](#): > > Did the company that built it describe any difference in efficiency between a ground loop and a well system? Is the glycol anything special or was it automotive antifreeze? What was your ROI for the $4000 difference? I actually did all my research myself. The technical specs indicate thermal efficiencies based on the ground or well temperature. Wells are _significantly_ more expensive, and I didn’t see a reasonable return for the well. On the other hand, my back yard would still be more intact. The complete ROI versus the original system was originally about nine years, but it’s gotten stretched to 12 years due to so much time leaving the house vacant (i.e., the system running cold in the winter and hot in the summer when I’m on the road for months at a time). It can drop again (or go up) depending on natural gas price fluctuations. I didn’t have enough reliable data on the return versus a high-efficiency gas system. The best I can figure is that I’d probably have saved 20% on natural gas consumption, but with no electrical discount for A/C use in the summer (not a “green” system). > [@raindog](#): > > The legislation (as I understand it) for geo didn’t semi-end in 2010, but runs through 2016. Even more, the tax credit didn’t cap out at $1500. It was a tax credit for 30% of the installed prices with no limit. So a guy spending $18K on a geo was/is getting a $6k tax credit, which puts the final price close to the cost of an 18 SEER system. I think I got a $500 credit the year of installation, and a $4000 deduction (not a credit) the year the installation was completed (“completed” meaning that the property was brought back up to standards, i.e., the grass over my loop field). ---
**Author:** ![luvrbcs](https://avatars.discourse-cdn.com/v4/letter/l/7c8e57/32.png) [@luvrbcs](https://boards.straightdope.com/u/luvrbcs)\ **Post date:** [March 25, 2011, 2:56pm UTC](https://boards.straightdope.com/t/heat-pump-vs-gas-furnance-and-ac/575726/31 "2011-03-25T14:56:39Z")
We have both a high efficiency heat pump and high efficiency variable speed gas furnace. We are in Pittsburgh, PA. area. It works out great. The heat pump runs heat during the spring and fall with occasional bouts in the winter. If it still feels chilly we just set it on emergency heat and let the gas run. Since we were upgrading our system, it was a no brainer (to us) that since we had the unit for A/C, why not use it for heat also. We lived in Maryland for the past 25 years so we are very experienced with heat pumps and feeling cold, but, they do work well on those not quite so cold days. We average our utility bills so I don’t know what the savings are, but we are satisfied. [Previous page](https://boards.straightdope.com/t/heat-pump-vs-gas-furnance-and-ac/575726.md?page=1)