Geothermal Estimate and possible Plan B

14 years ago

I have a question about a geothermal quote and a possibly alternative. As one other poster put it, please treat me like a rather slow, but sweet, child in this matter.

So we're planning a build in upstate NY and we are hoping to use Geothermal for our 2,000 sq ft - 2 floor - 2x6 - w/Spray Foam - ICF foundation house. We have an initial quote back from a geothermal guy that we've worked with before (servicing a system in a house we bought) that came back with this for an initial estimate:

1 - Heat Controller Geothermal heating and cooling unit ( 3.25 Ton cooling capacity, should supply 90% of your heat and 100% of your air conditioning )

( AHRI performance certified & Energy Star Listed )

1 - Supplemental heat coil and high capacity circulator

( to distribute supplemental gas heat to air stream, above geothermal unit )

1 - Jackson Systems Zone Control System -

3 - Independent digital Heating & Cooling zone control thermostats

Z1- Main Floor Living Areas - beige 4 x 10 floor supply registers

Z2 -Main Floor Bedroom & Bath - beige 4 x 10 floor supply registers

Z3 - Second Floor - white bulls-eye type ceiling supply registers

( 13" O.D. trunk to attic for distribution of Z3 )

( over insulated to R-30 minimum, by others )

Â Â Â Â Z4 - Lower Level ( spare for future use )

1 - 1 sq.ft. central floor return - toward central part of main floor

3 - zone control damper drives

6 - ALLERGY/DUST/ANIMAL DANDER/ POLLEN stop air filters

* - Misc ducts, control interface, pipes, control wires, etc. to complete within the home

$ 22,000 - $ 24,000

Not included in estimate but required

1 - Bradford White gas heat source and DHW tank ( 90+ % AFUE efficient / 3" PVC vented )

Â Â Â Â ( 50 gallon storage / 60,000 BTUH burner capacity )

Â Â Â Â ( should supply the other 10 % of your heat and 100% of your domestic hot water )

Now I fully understand why the system is sized for 90% heating and I'm even okay with the price tag (though I was hoping for $15-$18 before the tax break). Does this sound like a reasonable quote?

The next part of the question is, the system is an open-loop system so it obviously has well water requirements. If my well does not meet those requirements, I'm not going to have a second well dug, I'm going to go with a non-geothermal system. Is the following a reasonable option, or the ponderings of a non-HVAC person over his head (or both):

Get the supplemental heat coil and high capacity distributor from above with the Bradford White propane water heater and buy a wood furnace. The wood furnace would provide the majority of my heat but the propane water heater + heat exchanger would provide the 'keep it above 60 when the fire goes out at night' amount of heat (or if we're out of town / out of the house / etc.).

Would I just be better off getting an oil furnace / wood furnace combo and a water heater? I like the idea of the propane water heater because I could power vent it out the side instead of needing ANOTHER chimney (I'm going to have a woodstove on the main floor with either option, so I would prefer to have only 2 stacks, not 3)

Obviously using propane to heat water and then change it back to air heat is less efficient that oil, but if it's good enough for the backup/supplement on my geo-thermal system, is it good enough for the backup/supplement of a wood furnace?

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Comments (12)

baldloonie
14 years ago
last modified: 9 years ago
Which heat pump? Model #?

What zone panel? Model #?

How did they arrive at sizing? Do they know how to size for an extremely tight house like foam insulation? Seems like a lot of capacity for the size of house in upstate NY. If they oversize the cooling, could be humidity issues as the unit may not run enough to dry the house. Tight houses have a higher humidity load. May need a whole house ventilating dehumidifier.

Also, round diffusers in the ceiling are lousy for heating if that's what is planned upstairs.
vhehn
14 years ago
last modified: 9 years ago
a foam insulated icf house and geothermal is overkill. that combination puts roi far into the future.another problem is open loop systems are problimatic. pumping costs can eat up your geothermal savings.
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Ah CT - here we spent $90 last month for 4000 sq feet - with just ASHP.... but that was mostly A/C (and lights etc). Are you still heating in CT? To respond to the previous poster. Geothermal works great in the South (just like the North) - its just that it is overkill most of the time. My audit suggested I'd save $300 a year with geothermal but that was based on a reference house - it was down to about $100 compared to HE ASHP. Try to get $100 a year to ever payback - sure it saves money but you could save more clipping a coupon a week without the $20k upfront cost. How is this thread still alive? The savings of geothermal compared to oil in the North is amazing. Compared to ASHP in the South - it is pennies. There is an ad line that says installing geo is like taking 2 cars off the road. They must be some pretty efficient cars.... Unless you are comparing to oil in the North. The average car driving 12,000 miles a year costs about $2000 in energy (20 mpg at $3 a gallon). The average house uses less than that for HVAC. Cost is not the only concern but there is nothing clean about gas in a car - at least electricity can be clean.... CONC: Insulate and use geothermal if you can do horizontal loop or live in the North and your alternative is not NG. And drive a hybrid and/or right sized car. And don't use incandescent bulbs for lights on frequently.
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What a timely question. Just this week we submitted a proposal for a 10-ton system using 2- 5-ton Nordic EMDX units or 2-EMW, depending on whether the system will be open loop or DX. I would say your quote does sound high, however, I would not condemn this quote without speaking to your contractor. HereÂs what I would suggest. YouÂre definitely on the right track with the Nordic EMDX unit for all the reasons you already seem to know. Namely a solid reputation for building high-end products and having everything already built and installed in one ÂboxÂ. Keep in mind that these are large and heavy units to install. Be sure your installers can Âget them inÂ. Another reason youÂre on to something is that this (DX) unit will require 300-feet of drilling Â total (3-100 foot boreholes), Ã 3-inches, instead of Ã 6-inches. ThatÂs a difference of 600 feet of drilling - and a lot less debris to deal with! In our case, because of the drill rig we use, we are able to drill boreholes for DX systems on a 30Â° off axis angle, in a radial pattern. What this means is that at the surface the borefield resembles the apex of a pyramid and then spreads out the further into the earth it goes. This technique allows us to drill quite close to the envelope we are space-conditioning (taking up very little real estate!) and requires very little trenching. In many cases trenching is done by one person with a pick and shovel, without having to use a mechanical excavator. I would suggest seeing whether this is a possibility for your installation as conventional geothermal (liquid/HDPE) and drilling techniques may otherwise result in your property resembling World War I France at Vimy Ridge before all is completed. You quote was for 300-ft boreholes per ton. ThatÂs rather a lot by almost any standard. What are your ground conditions like; do you have veins of water flowing through or a high water table (it doesnÂt sound like it)? Anyway, I hope this helps. SR
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brickton
Original Author
14 years ago
last modified: 9 years ago
We're actually trying to budget everything and then pick where we want to save (ie do only 2 of the 3 icf, sprayfoam, geothermal). Right now, I think geothermal is going to be the place we decide to save. It's the most costly, we have the option of doing wood which is nearly as cheap to operate (just a little more time and maintenance work).

The geothermal guy had all of the specs (including orientation, window grade, expected insulation etc.) and floor plans for the quote. I was not going to use the bullseye vents, I agree they are useless.

We've had open loop systems before and the pump cost is not bad (for smaller houses at least), particularly if we spring for a variable speed well pump with manager (which is what our geothermal guy recommended). We won't do a closed loop system due to the possibility of negative environmental impact if a pipe ever were to leak or break. The water table contamination risk is not worth it for us.

So does plan B sound like an option? Is it too gimicky? Should I just do an oil furnace and wood furnace and try and make room for another flue? I like the idea of using propane because we intend to do propane hot water and propane backup generator, so I would rather not have an oil tank AND a propane tank too.

Thanks for the help so far, I appreciate it.
fsq4cw
14 years ago
last modified: 9 years ago
Why all (any) the zoning for a 2-level house thats only 2000sq ft? Why would you go out of your way to design ducts to run through an attic?

SR
greenheat
14 years ago
last modified: 9 years ago
Here is an interesting alternative to geo. http://www.daikinaltherma.eu/

It has just arrived in the USA from the UK. I'm very impressed!
brickton
Original Author
14 years ago
last modified: 9 years ago
Are zones overkill in that size house? I've never had the opportunity to have them and I assumed they would be nice to have. I asked about nixing them from the system but was told they would help increase efficiency.

The whole attic run is confusing to me as well. I have a very open first floor so it's possible he was trying to avoid any duct work runs but my architect planned for them, so I would change all the second floor runs to be floor registers.

I guess when I read the bullseye registers on upper walls, I assumed these were returns? But it does call them supplies in the quote...

Does anyone have an opinion on my option B? Has anyone ever done this or heard of it? Again I assume if it's an option for backup for geothermal systems that someone else must have done this. Is it worth exploring it?

greenheat - Why would I be interested in your spam? Air source heat pumps are not an option in the Adirondacks. You just registered today so I'm guessing you haven't had your hand slapped for this type of thing yet, but it's not acceptable.
fsq4cw
14 years ago
last modified: 9 years ago
Why would you think that air-source heat pumps are not an option in the Adirondacks?

SR
brickton
Original Author
14 years ago
last modified: 9 years ago
Because on average we have 30-45 days per year that are below zero (as per Cornell's data here) and because as far as I know air source heat pumps use the ambient temperature of the air. The majority of them will not work below freezing and those that will, will not work below 0. I don't want a system that is not going to function on the coldest days of the year. I'm willing to take a geothermal system that will get me 'most of the way' on the coldest days, because it uses the near constant temperature of ground water. As far as I know an air source heat pump will get me nothing on these days. And I've never heard of anyone recommending ASHP in my area.

If you are a HVAC professional who has experience with ASHP in cold climates, by all means educate me, but I've never heard anyone say they are a good idea up here.
fsq4cw
14 years ago
last modified: 9 years ago
Air-source HP may be useful where you live depending on your electrical rate. I live in Montreal, we use them down to -10°F.

If you were to do an open loop GSHP the 2-choices I would consider are either geo with active heating/passive cooling with electric plenum resistance heating as backup. The advantage is an all-electric system with very inexpensive cooling as the compressor is not required for A/C.

The 2nd open loop geo option would be a hybrid system using a high efficiency gas forced air furnace such as a Carrier Infinity with a split geothermal HP. The advantage of this system would be gas as the backup and the possibility of using a generator to run the furnace during a blackout. A desuperheater with a buffer tank could supply DHW either to an active tank or an instantaneous gas DHW heater.

Your concerns regarding ground water contamination with closed loop systems, when properly installed, are (largely) unfounded.

SR
fsq4cw
14 years ago
last modified: 9 years ago
The above post should be corrected. Should read:

Air-source HP may be useful where you live depending on your electrical rate. I live in Montreal, we use them down to ~+10°F.

SR
brickton
Original Author
14 years ago
last modified: 9 years ago
SR- Thanks so much for writing back. I'm really surprised to hear that someone up North uses an Air Source Heat Pump, literally not a single person I know around here has one, nor have any HVAC people I've talked to installed one.

Our old system was an open loop with active heating / passive cooling with electric resistor backup like you described. It worked fine, but I can't find anyone who installs this type of system. I feel like there aren't enough geothermal contractors around for me to get good options.

I am thinking I am going to go with something more along the lines of my plan B. Of course this means I need to start researching oil vs propane furnaces vs my crazy propane water heater with convertor as well as wood furnaces versus add on furnaces.

Thanks for your help though.
fsq4cw
14 years ago
last modified: 9 years ago
If air-source HPs didnt work, the Canadian Federal government would not be offering $500 rebates for Energy Star 14.5 SEER or higher HPs with no restrictions on how far north you live!

Are you aware of the Mitsubishi Zuba air-source HP that can heat down to -22°F
(-30°C) and beyond?

http://www.mitsubishielectric.ca/en/hvac/zuba-central/index.html

Anyone that can install a conventional open loop GSHP should be able to hook-up a unit with passive cooling; its just plumbing. Theres no mystery, its not rocket science!

SR

Geothermal Estimate and possible Plan B

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