Geothermal furnace ratings/comparisons

marcrobinsonJanuary 18, 2009

I'm getting bids for a ground source heat pump. It will be 3 tons, vertical closed loops, for an 1800 sq. ft. house in the Kansas City area. The bidders propose different furnaces (Ruud, WaterFurnace). One vendor includes 10 years' maintenance as part of the bid, but they're about $4000 more than another vendor.

I haven't been able to find any info on furnace efficiency and reliability so I can make my decision knowledgeably. Can anyone help me out?

Thanks in advance.

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HereƂs the short answer.

Conventional furnace will have 80 ~ 96% efficiency depending on what you install. The WaterFurnace will have 350 ~ 500% efficiency depending on what you install. The geothermal system requires no maintenance beyond periodic changing of air filters (required on any system).

The conventional furnace will not provide air-conditioning or domestic hot water. The WaterFurnace can and does. The geothermal system will likely last at least twice as long as a conventional system does and add greater resale value to your home. Geo is greener with lower operating & maintenance costs.


    Bookmark   January 19, 2009 at 9:59AM
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Perhaps I wasn't clear. All the vendors are bidding geothermal. All the furnaces are geothermal. I'm trying to compare them. I can't find any rankings on the web, only people pushing their own product. So I'm looking for one of:
* An impersonal, accurate web site (think Consumer Reports)
* Someone knowledgeable (e.g., someone who's exchanged info with other GSHP users on a forum)

    Bookmark   January 19, 2009 at 8:33PM
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Water Furnace has been making heatpumps for a long time and are very well respected in the industry. They are top of the line.

As far as maintenance, there really isn't any like there is with a traditional furnace. What tends to fail if anything is electronics (ie. circuit board) so I personally wouldn't get excited about a maintenance warranty.

Sorry, I'm not aware of a CR testing site for GSHPs.

    Bookmark   January 27, 2009 at 1:49PM
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To date I've been happy with my Climatemaster Tranquility, but, let me say it again, everything depends on the design and installation, no matter what make or model. A properly designed and installed closed loop system will work very well and very economically. We find ourselves comfortable with a three ton open loop system in an old 1200 square foot stucco, poorly insulated, and are saving some money over our old gas forced air unit even though we have to run a well pump for the heatpump also. We're in Montana and the temperatures were in the 0 F range (climbing now) the last day or three.

I'm not all that knowledgeable but I'm not a company flack either! :-) I hope this helps.

Good luck,


    Bookmark   January 28, 2009 at 6:55AM
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Do you have a back up heat system? I've been told that I would need one in my area but you live in a far colder location.

    Bookmark   February 17, 2009 at 9:57PM
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Hi Sunny. We have the backup (electric) heat strips in the unit itself, but I have the breaker to that part turned off. We did not need it at all this winter, and we had an extended period of cold, windy days.

The backup unit adds little to the cost of the heatpump and is cheap insurance. I originally was not going to let them install it, but they urged me to, with the reasoning that I could enable the heat strips in case my well pump failed -the well provides all the water for our open loop system. We would, for example, enable the heat strips and turn the thermostat down to 50 F if we were to leave town for more than a day or two. A well failure would let the house cool, but the heat strips would prevent frozen pipes.

Of course if our electrical service were interrupted we'ed be dead in the water either way, and I'd be running a Buddy heater!


    Bookmark   February 18, 2009 at 6:06AM
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You are in Montana and are able to keep your house warm with a geothermal unit alone? Without a heat strip kicking in? I did not know that was possible.

We too have cold windy days, today being one of them, but they probably are not as cold as yours. I am in a coastal location just below New England and in a very exposed area. When the wind blows, our house can feel chilly to cold with the oil hot air system pounding away.

I am looking into a Waterfurnace system - a tech is coming over shortly, and am getting estimates for wells. All this is such a steep learning curve for me, but I think I am going in the right direction. My husband is not too sure, so I will have to convince him with numbers. The installation cost versus what we would save over using oil, plus the tax credit we would get - 30% now, as of two days ago. Thank you President Obama!!!!

    Bookmark   February 20, 2009 at 12:27PM
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The outside temp doesn't affect geothermal like it does a heat pump. When its zero outside the ground temp is 40-50 degrees so the geothermal is able to use the 40-50 degree dirt to pull heat from. Your heatpump is struggling to pull the heat from zero degree air. Same goes for blistering hot outside, that ground temp is still around 50 instead of 100.

    Bookmark   February 22, 2009 at 12:17AM
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Hi Sunny.

Well, yes, our geothermal unit is managing well without falling back on any other heat, but let me be clear- we're in western Montana, and the climate in eastern Montana is much less forgiving.

Still, had it been necessary it would have been doable to size up to a larger unit, and these things are being installed all over the state for all kinds of buildings: one of the local hospitals, many of the university buildings, private homes large and small. I think the public library is all geothermal.

What countryboymo said is absolutely correct. There's much more energy just a few feet down. I know that 40 degree F water feels cold to you, but it carries a massive amount of energy compared to air at any temperature. You only have to look at how easy it is to heat air (it doesn't take much!) and how hard is is to heat water (just can't get that pot to boil!) It works the other way too. A person might go to bed with a hot water bottle, but a hot air bottle of similar size would be a complete waste, ay?

Good luck,


    Bookmark   February 22, 2009 at 6:05PM
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We live in NW CT, have a 4 ton Tranquility 27 from Climatemaster with electric backup for 2700 sf house. We turn on the breaker in Nov (usually right around Tgiving) and turn it off in early April. 2008 was our first full year in the house (moved in Sept 2007) so I only have 1 year's worth of data. We keep the house 68 in winter and 74ish in summer. Have 2 80-gal stone-lined hot water tanks - first is warmed by geo desuperheater, 2nd is electric and brings the intake water from the geo tank up to 120. Our avg usage is 40 kWh/day May-Oct and then Nov - Apr it jumps - Jan/Feb can be 75-77 kWh/day. But I do on average 7 loads of laundry (electric dryer, non-Energy Star top load washer, both 3 yrs old) a week, run DW (Bosch Energy Star) once a day, and have a 25 cf Energy Star LG fridge (though it's not as good as they claimed - had to retrofit and gave me $43 for last 14 months electric bill).

I haven't tried turning the water heater off during the summer but I think geo nearly gets it to 100 degrees when it's cooling my house. We may try supplementing with solar if incentives are big enough but we have roof facing the wrong away for a bunch of collectors.

We had one contractor who wanted to use a 5 ton unit and another who wanted a 3 ton and a 2 ton (separate units for upstairs and downstairs), I think based on what they thought cooling demands for this size house would be. But we didn't need it 65 in summer, after coming from a 1987 built 2500sf Colonial with a window unit in the kitchen and another in a loft over FR with cathedral ceiling (hated to heat and cool that place!). 4 ton unit does fine job heating this place. Please do your homework and find someone who knows how to properly size the unit for your house and climate. Sorry I can't help there.

    Bookmark   March 10, 2009 at 1:51PM
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Sorry, it was a 3 ton not a 5 ton. So one guy oversized, the other undersized and we picked the one in the middle (hopefully "just right!" says Baby Bear). No ratings/comparisons that I know of, but look at the COP if you're worried about heating, EER if cooling is main concern.

I just remembered website at was a good source of info 2 years ago when I was shopping. HTH

    Bookmark   March 12, 2009 at 2:29PM
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