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Size of Geothermal Unit

Posted by JessicaV (My Page) on
Thu, Jun 2, 05 at 8:04

I'm in the process of selecting a company to install a geothermal unit, but we've received contradictory information. I'm hoping this group can shed some light on the situation.

We've had 2 companies come out and give estimates with 2 more lined up. Interestingly enough one company based the size of the unit on cooling demands, while the other based the unit on heating demands. If we go with cooling it will be equvilent to 3.5 tons, whereas heating is 5 tons. I"m not sure who to believe. Does anyone have any advice or experience?

Jessica


Follow-Up Postings:

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RE: Size of Geothermal Unit

Hi Jessica,

The contractor who is sizing the system based on your cooling needs got it right. Heres why. A system sized for 100% of your heating capacity will be over sized for your cooling needs. That means, that in the cooling mode, your unit will be cycling on and off many more times than a system sized to meet 80% of your heating demand. This results in premature wear of the compressor due to unnecessary cycling, but even more importantly, the larger unit will cool your home to the set point before it has lowered the humidity sufficiently. Its the lowering of the humidity that can have an even greater effect on comfort level than a lower temperature.
A unit sized to 80% of the heating capacity is properly sized. The other 20% will come from cooking, lighting, appliances, people, etc; you get the picture. A force air heat pump should also be backed up by about 15 kilowatts of resistance heating elements mounted in the plenum. This serves two functions. First, should you experience severe heat loss in your home due to cold temperatures and high winds, your heat pump is backed up by an additional 50,000 BTUs, more than enough to meet your worst case demands. In our home this only happens when the temperature has dropped to 13 degrees below zero Fahrenheit or below, for more than 24 hours solid - with high winds! The second reason for the back-up plenum heater is so that you have a Plan B should your compressor fail on a long, holiday weekend.
The smaller system will also be substantially less expensive, considering the major cost of any geothermal installation is drilling.
After extensive research of this subject, and after owning a geothermal heat pump through two heating seasons in Montreal Canada, one of the coldest cities in North America, I strongly urge you to research and install ONLY a DX geothermal type heat pump as these are the least expensive to install, operate, and maintain. They are the most reliable as they have fewer parts, pumps, and motors. Their boreholes are half the diameter and 40% shallower than any vertical liquid system.
Our heat pumps computer is capable of monitoring the efficiency of the heat transfer in the boreholes. Should efficiency drops due to dry weather, this is detected and corrected by a soaker pipe installed deep into the borehole. The computer opens a solenoid valve sending in water to flood the boreholes thus re-hydrating the ground back to optimal efficiency. I mention this because others have mentioned that soil conditions may affect efficiency. A properly designed system will even mitigate ground conditions in all but perhaps the worst sandy, desert conditions.
Please continue to do your own research. Who you get to install your system is at least as important as what you buy and install. Its a complex installation. Done right its magic!

This link may provide more useful information:

http://www.how-efficient-is-it-magazine.com

S.R.

Here is a link that might be useful: how-efficient-is-it-magazine.com


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RE: Size of Geothermal Unit

Thank you so much for all the good information! We were debating between a waterfurnance horizontal loop, and a trane veritical loop. How do I know if it is a DX geothermal heat pump type?


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RE: Size of Geothermal Unit

Hi Jessica,

Neither system youre looking at is a DX geothermal system. What differentiates a DX system is that the pipes in the ground are all and only copper not plastic, not high-density polyethylene. Any system employing any form of plastic pipes and circulating a fluid in the ground has to use two heat exchangers. The first exchange is between the fluid and a shorter (than a DX) copper system, which houses the compressible gas. The second exchanger is like a car radiator between the copper system and the air. These systems also use circulating pumps for the liquid in the plastic pipes. These are complications that are not necessary. Every time there is an extra heat exchange step there are heat losses, which translate into inefficiencies. Your whole system goes down if theres a failure with the circulating pump or its motor. Why pay for electricity for fluid circulating pumps when theres a simpler system? The DX system has only one heat exchanger by extending the copper pipes from the compressor right through the entire loop. The compressor does all the circulating. Its there anyways. Besides, whats a better (economical) conductor than copper, certainly not plastic? Thats why plastic has to be at least 40% longer. Plastic is basically an insulator. What transfers heat better and gets hotter in a cup of coffee, a plastic spoon or a metal spoon?
When you hear plastic, high-density polyethylene, or fluid, think loops 40% deeper, twice the diameter MUCH MORE EXPENSIVE, AFTER TAX DOLLARS! DX (Direct Expansion, copper), vertical closed loops are almost always the best way to go.
Please continue researching the subject. The more you know the less likely you are to make a mistake. Ask for references and visit these people if possible. Satisfied clients will be thrilled to have you over and return your call if theyre not home. Prepare a detailed list of questions. Take notes.
Should you need more specifics on brand/model of what weve installed in our home, I can be e-mailed at:

geothermal@how-efficient-is-it-magazine.com

S.R.


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RE: Size of Geothermal Unit

Jessica,

Unless you have a written specification to hand each contractor to bid on you will have to weigh the unequal merits of each submission. Beyond the actual mechanical equipment installed, consider warrantees, service contracts, construction requirements, land use and access, household disruption time, variance issues, well (slinky) requirements, HASMAT issues with refrigerant/antifreeze in the ground, use of existing infrastructure, equipment space needs within the home, and the like.

Request and obtain supporting evidence for what each contractor suggests. Some would require a Manual J, or equivalent heat loss calculation to size heating/cooling equipment. Old houses and renovations require more guesswork/assumptions since many materials may be unknown.

Understand, or try to, the technology being proposed and how it will be used. Some ground source systems transfer the ground fluid heat/cool to air directly after the compressor and broadcast heat/cooling into the home, "water-to-air". Others transfer to water circulated inside the home through piping to air-handlers, hydro-air.

Some will say the equipment is secondary to who installs/services the system. A key point here is that what is installed should be a system that can be run by the homeowner, and serviced by skilled yet unknowing contractors. Your installer may move on at some point and leave the homeowner to fend for themselves come service time.

How will you generate domestic hot water? If the heat pump is undersized how will you generate additional heat/cooling when it gets below/above the design temperature? Is the system adaptable to existing ductwork/piping?
If the heat pump fails, how will I survive the current weather conditions until service can be performed?

What size the unit is only scratches the surface of the many aspects that are involved with this type of system. I hope some of this helps, as I am a soon to be user.


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RE: Size of Geothermal Unit

Just curious what your estimates were for how many square foot home?
We are looking to install a Geothermal heat/cooling system in our two year old modular home. The system is estimated to cost us in excess of $20000.
We now heat our 2800 sq ft. home with forced air gas. Our high gas bill was $240 month (not too bad) but gas prices may increase to over 70% more. According to the installer we should almost eliminate our monthly gas bill. The electric bill should rise slightly. We still would need some gas for the dryer and stove. Hot water can be produced by the geothermal heat pump.

I am in a delema as I will be retiring in 9 years and would like to be debt free.
Your experience and expertise with these systems would be appreciated.
There are some gov incentives, such as paying 4% of a loan (NYS). Have you used any?

Thank you
Kevin


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RE: Size of Geothermal Unit

Re: KaptainK

"Our high gas bill was $240 month (not too bad) but gas prices may increase to over 70% more.

I am in a dilemma as I will be retiring in 9 years and would like to be debt free."

I would hope not, but the dilemma may be being retired and facing ever-higher bills for fossil fuels.

Your monthly bill of $240.00 represents less than half our total annual heating bill for a house almost the same sq. ft. of yours. Our winters are likely more severe than yours as well as we live in Canada.

I would encourage you to continue researching geothermal heat pumps so as to have your costs of home ownership as low as possible in preparation for retirement.

SR

Here is a link that might be useful: how-efficient-is-it-magazine.com


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RE: Size of Geothermal Unit

I have been looking at the Trane Geothermal system (22 seer)
and am also looking at all long term options. I am currently heating my home with a single catalyzed wood stove. However with the nights in the teens, and around freezing during the days, I am going through oak like crazy.
My second system is an older NG boiler (not efficient) with a 30 gal Superstor for DHW. I have hepex plus radiant floor
heat, including transfer plates and reflectix insulation (efficient). I have been looking at wall mounted condensing
boilers (Trinity makes a nice one, 95% aefu) however it's cost ($2500) has me looking at instant hot water heaters. The only problem is that I'll need a seperate on for DHW,
and with the price of the vent kits the trinty is about the same cost.
Any input here is appreciated as we have probably the highest (Keyspam energy) NG prices in the US, $2.80/therm currently.


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RE: Size of Geothermal Unit

Avoid the Waterfurnace unit!

We put a Waterfurnace unit with a closed loop lake system when we built our house in Southern Illinois in 1992. Our average January heating bills have been $550-800/month. We have had numerous repair bills over the years. I have had the unit looked at by numerous HVAC contractors with multiple opinions. The newest opinion is that the heat exchanger freon side has a leak and the whole unit may need to be reploaced. (estimate for new E-series Waterfurnace unit is $9114). I have had multiple computer boards replaced in the unit also. Waterfurnace refuses to admit that there is a problem with the unit.


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RE: Size of Geothermal Unit

Re: pjuer,

Im not defending Waterfurnace. I am in no way connected to them, Im just raising questions that I dont know the answer to. Is the problem with the Waterfurnace unit or are they related to an improper installation? Who designed and installed your system and what certification or accreditation did they have?

Energy bills in the range of $550. - $800./Mo. are more than likely the hallmark of a poorly conceived design, unless your home is HUGE! Did your system ever perform satisfactorily? How big is it? How big is your home? Were calculations made to determine, among other things, the design loads, energy loads, and ground loads? It sounds like it could be undersized and that your back-up heating is running excessively; but your home would still have to be HUGE!

SR


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RE: Size of Geothermal Unit

The unit was installed by a local waterfurnace dealer. I thought they did the appropriate calculations at the time (via computer). the house is approx 6000 ft2. There is a 4 ton unit and a 2.5 ton unit. The system never seemed to perform correctly, the lowest electric bills were in the $200 + range in the more temperate months, and have only got worse. repairs have totaled $5420 over the years.


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RE: Size of Geothermal Unit

Re: pjuer

Im very sorry to learn of your dissatisfaction with your system. My best advice, if I may offer any, would be to locate an IGSHPA certified GeoExchange Designer in your area. This person will likely be a professional mechanical engineer with a specialty in designing complex geothermal systems.

Its not enough to size the system correctly and choose the right matching components. They must be INSTALLED CORRECTLY - AND STARTED UP CORRECTLY or else it will NEVER deliver! A detailed log of this procedure may tell the whole story if you have one!

Please let us know how things turn out. Best of luck.

SR

Here is a link that might be useful: IGSHPA - Certified GeoExchange Designer


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RE: Size of Geothermal Unit

Jessica,

Listen to S.R. Waterfurnce is way to difficult to size and install. A closed loop system is the worst one. DX, or at least Open Loop, is the way to go.

Our Waterfurnace, installed by a Waterfurnace-recommended dealer, turns out to be undersized, has only half of the loop length it needs, and yield a year-round average electric bill of $350/month.

Waterfurnace as a company will never talk to you, the owner. The literature that they provide is not sufficient for me, as an engineer, to diagnose the problems that I have.

The technology of geoexchange is the future, so don't give up. Take SR advice and get a certified geo mechanical engineer. The closest person I found, in New Jersey, to an expert told me that he won't get involved in a geo project unless it comes out to around $40K for a 3000 sq ft house.


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RE: Size of Geothermal Unit

Re: geosaves

I'm sorry to hear of all these Waterfurnace issues- especially since we just installed 2 Envisions in new construction. Problem is that the first 20 days electric average 60kw/day - and we're not even living in the house. How do we tell if that's normal or if it's high? If I turn the thermostat temps down to 45, usage is 2kw/day. All I have to compare to is our old house - smaller in size, uses propane heat, but electric bills are 25kw/day. Of course, I'm not factoring in the cost of the propane. But we have no way to tell whether the unit is working correctly. House is near Lancaster PA, 3500sqf, with a 4-ton for downstairs and a split 2-ton for upstairs. There are 3 geothermal bores @ 300ft depths. The large unit uses 2 loops, and the smaller unit uses one. We invested in the geothermal (to the tune of about 30k) so I hope it really will be efficient - but I'm nervous that I have no way to tell.


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RE: Size of Geothermal Unit

whistle

I had a similar question since we had an issue with our geothermal system (since resolved) and the bills were higher than I expected. So I wanted to estimate what it should cost me during peak cold months (when we had our issue) just so I would know it was working right.

My system is a closed horizontal loop and has 2 pumps - only one of them runs the other is backup. The pump draws 7.5 amps - so I converted that to kilowatt hours and found out what we get charged per kilowatt hour from the power company. Turns out that there are 2 rates - one for minmal usage and a different rate when you get above a certian threshold. Since I was interested in worst case - I used the higher rate (2.3 cents per kW Hour). That gave me an estimate for just running the loop pump - it turned out to be 30 dollars per month.

Then I sat around the house and timed how often the GT heat pumps turned on and off - and how long they ran for - during a 1 hour period. During very cold days they would turn on about 4 times per hour for about 5 to 7 minutes each. At night it was 4 to 5 times per hour. I determined the amperage draw for each of the units and converted that all to kWatt Hours. It came to $200. So I expected a total cost of about $230 for the GT system during the peak cold months.

Our first electric bill where we were completely running on the GT system (with no emergency heat needed) was 300 dollars. This covered the GT heating plus all other electric used in the house. In our previous house, we would spend 50 dollars per month in electric - heat was LP gas. Based on this, we concluded that the GT system was cost was around $250 and was working as we should expect. The house is 6000 square feet of finished space on 3 levels (2 floors plus basement). We have Econar GeoSource 2000 heat pumps (one 6 ton and two 3 ton units).


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Re: whistlepigger

I dont think you have anything to worry about regarding your system. Perhaps it could have been designed to consume less pumping power. Are your 4-ton systems ground loops in series or parallel? Judging by the size of your home and your energy consumption (60kW/day avg.) during the winter -you should sleep like a baby!

Your next geothermal hurdle will be during the peak summer heat. Will you be cool enough; has enough of the humidity been removed?

You havent been there long enough but read your utility meter on the 1st of every month and keep a log. There will probably be at least one month where you need neither heating nor cooling. That month is your baseline. You can measure your heating or cooling costs by subtracting your baseline month from any heating or cooling month (kWh and/or $$). Compare this to neighbors costs that are using conventional HVAC in similar sized/designed homes to gauge how youre doing. Your electric utility meter is a very powerful (no pun intended) tool; I would encourage everyone to learn how to read it and use it regularly.

Re: geosaves

WaterFurnace is no more difficult to size than any other GSHP.

A closed loop is not the worst system, in fact a cost analysis over the life of the system usually indicates a closed loop (in a liquid) system has the lowest cost, maintenance and headaches. Its quite a common misconception that an open loop is the cheapest and best. This is not usually so, in fact doing it right can be very complicated. There are a lot of factors to think about and consider, its much more than plunging into the ground till you hit water.

As for DX, thats a whole different animal. DX is the Apple Macintosh of the GSHP world. They have fewer parts, no circulating pump, no circulating water/antifreeze fluids, no water heat exchanger and associated valving to corrode, freeze, or break, 40% less drilling and lowest life cycle cost are just some of the benefits of a properly designed and installed DX GSHP.

Re: sniffdog

While your energy costs may not be out of line, it seems unusual that during the very coldest days that your system would cycle 4 times per hour for 5-7 minutes. A system should run almost continuously or continuously during the very coldest weather, unless your coldest weather is in fact quite mild. Your system needs longer run times to reach maximum efficiency. Expect higher maintenance and repair costs associated with that much cycling wear and tear. You might have benefited from a 2-speed compressor and a variable speed blower if your system is not so equipped.

IMO

SR


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RE: Size of Geothermal Unit

I live in thw Blueridge Mtns in VA, at 1300 ft elevation. The average daytime temp in the month of Feb was in the mid 30's and night was mid 20's - to some that is mild. I do have variable speed blower fans on all 3 heat pumps - I am not sure if we have variable compressor speeds. I asked the people who installed the system about what normal operation for the system is in winter and summer and the system is working as they said it would. I would not have expected each of the heat pumps to run continuously or even close to that length.

The house is well insulated and has energy efficient windows and doors. That must have some positive effect on the cycling of the GT system. Note that each of the 3 heat pumps is cycling 3 - 4 times per hour (usually at different times) for the 5 to 7 minute length. So if you look at it that way - we have at least one heat pump running most of the time over a 1 hour period during peak cold days and nights.

Early in the winter we were having issues where the heater packs were turning on when they should not have and that was driving up our costs. This turned out to be two problems probably related. The first was a compressor failure and the second was a problem with the mixture of anti-freeze and improper balancing of the flow rate from the loop field to the 3 heat pumps. During the 2 months when we were trying to fix this we saw electric bills in the $400+ range which seemed high. That is when I did the rough estimate of what we should have expected. Once we got the system fixed and tuned - the electric bills are right in line with expectations.

It would be nice if someone could invent a monitoring system that measured ground temp, loop input and output temp and pressure, and flow rate to let you know that the system is working within spec. Do you know if there is such a system?


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RE: Size of Geothermal Unit

Re: sniffdog

The supply & return run-outs each have a Pete's Valve or 'P/T' (Pressure/Temperature) Port at the HP. This is where those measurements are taken. Consult your manual for further technical details.

SR


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RE: Size of Geothermal Unit

SR

Yes - I have seen the GT service people use those ports to take measurements. What i would like is an automated system where those measurements can be taken continuously and provide an output alarm if something is wrong. Is there such a system?

Thanks


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RE: Size of Geothermal Unit

Re: sniffdog

Im sure your GSHP has a lockout mode if anything goes wrong. Try contacting your contractor or the HP manufacturer; perhaps they have already done this.

SR


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RE: Size of Geothermal Unit

Sniffdog,

If you are interested in a real time monitoring system for your heat pumps, check out this site.

http://www.ourcoolhouse.com/monitor/monitor.htm

The owner of this web site sells data acquisition cards that will get you what you need.

Best regards,

VK


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RE: Size of Geothermal Unit

VK

That is exactly what I was looking for.

Thanks


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RE: Size of Geothermal Unit

Im currently about to break ground on a custom home in Fort Worth Tx.
Ive had the local Trane and geothermal dealers do load analysis on the blue prints. Trane came back with SEER 20 10Ton zoned top of the line with 4 outside units for about $28K and the Geo using 12Tons of water furnace with 12 vert loops at 300ft each for $80k. Both of these quotes were the 1st round so Im waiting to see how much they will reduce if possible.

Id like to go with Geo mostly for the Electrical costs.

The only thing I pointed out to the Geo dealer was that this is a home with walk out basement that will have 1800SF finished underground, 3500SF on the main floor at grade and 600SF top floor for daytime office. 1700SF in the basement is closed off unfinished.

Both quoted the home for 6000SF but with half ( sorta ) being below ground I frankly dont think I will need that much for HVAC.

Basement is 2 bedrooms one of which has west facing windows, The other will have a Below grade Well window so no directly sun. Both bedrooms will have a 9inch thick concrete wall and the other walls are facing to the middle of the basement which will be a rec room also facing west with a 10FT overhang so no direct sun. I really doubt Im going to have any heat building up down here.

The main floor is the balance of a home. The south wall is brick with 2 windows. All outside walls are 2x6 and attic will be foam insulation. Windows are Vinyl Low-E glass, Roof will be radiant barrier. 4 people with 2 energy eff fridges.

Perhaps I just have wish full thinking that I dont need 12Tons of Geo but Im going to install vents in the 1st floor to the basement and use the HVAC fan to move return air at the top of the home down to the basement and vice verses depending on where the heat is trapped and needed.

Any comments?


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RE: Size of Geothermal Unit

II would suggest that you not only calculate the purchase price of your HVAC system but also calculate what it will cost you over its lifetime in energy and maintenance costs as well. You should calculate buying a conventional system twice, once at todays prices and at a future price 10~20 years down the road as this type of system will last, at best, only half as long as a geothermal system.

SR


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michael

My home is 5700 sq feet finished on 2 levels (1st floor is 3900, second is 1800). The basement is a mirror image of the first floor - I will probably finish 2300 sq feet of it to bring the total to 8000 sq ft. I have a 12 ton GT system.

I have one 6 ton unit that services 2/3 of the main level and 2/3 of the basement. I have a 3 ton unit that services the master bedroom/bath suite (also on the main level but in a seperate wing) and 1/3 of the basement below it. And a second 3 ton unit services the entire second level.

I suggest having them re-calculate the vertical loops. I looked at that - and I needed 12 wells that were 100 feet deep - not 300 feet. I wound up with a horizontal loop system that had 12 loops, each about 100' long. You might want to look at a horizontal loop system if you have the room.

I also got a bid (from the same company that did my GT system) for a 3 HE LP gas heaters and 3 outside A/C units - 12 tons total. The bid was $28K for that (same as yours!). Then to upgrade to the GT heat pumps and add the internal plumbing it was an additional $15K for a total of $43K. The horizontal loop field cost $20K - but I had major rock issues since I live on a mountain side. It should have been around $5 to 7K if we were on flat ground with no rock. That would be a total of around 50K for a 12 ton GT system in my area (Northern VA - a high cost area). The GT heat pumps are Econar Geosource 2000 units.

I suggest getting some other bids. 80K seems a bit high to me.


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RE: Size of Geothermal Unit

I am about to put a 5 ton dual speed envision into a relatively new home (2000). I live in upstate NY and it will be a horizontal install. My home is 2700 sq. ft and has an unfinished basement (that ultimately will be heated). My question is if people think that zoning is necessary -- at least upstairs vs. downstairs. After hearing arguments, I'm still not sure.
Thanks!


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I did zoning in my home - all in the second floor suite. Each bedroom has it's own tstat and it works great. the reasons i added it up there were 1) there were going to be hot and cold spots due to the position of the house and the surroundings, 2) it is much harder to add it in the future in the second floor if the ducts are in the attic, and 3) it was only 1500 dollars for 3 zones which I thought was reasonable. I am very glad I did it - the upstairs suite stays at a constant temp.

After living in the house for 3 months - I plan to add another zone on the main level because there is a 2 degree temp difference between the room where the tstat is located in the main area of the first floor (2 story library) and the family room where we hang out most of the time. It will be very easy to add the zone since all the ducts in the basement are accessible and the ducts were layed out so that zones could be added later. I will also add zones in the basement as I finish that off - probably 2.

A lot of the need for zones is driven by the layout of the house. My house is 2 levels plus a basement and is very long. If i did not have zones, there would be large temp swings between the rooms which I wanted to avoid.

If you have kids and you do zones, you might want to put the tsats in a locked box because then you maintain control of your hvac system and the bills won't go through the roof. I actually found a clear box with breathing holes made for commercial applications to lock up tstats and was going to use it during our build because the subs were driving the hvac to ridiculous levels.


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RE: Size of Geothermal Unit

Thanks sniffdog - that is very helpful information. No children here (yet), just a new Chow puppy. That is more than enough for now :)
Do you mind if I ask a few follow up questions? I'm looking at the contract right now and have to decide in the next day or so. What kind of waterfurnace unit do you have? How large is your house? What state are you located in?
Thanks!
PS Prices haven't gone up that much - I get a 2nd floor thermostat for $1600 and the others apparently are cheap enough to add.


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Thanks All for the info.
I know the 1st quote was zoned and split level verticals

Not sure why they say the loops need to be 300 Ft. Perhaps because this is North Texas. My elevation is about 700ft.
I know they had about 7 zones total with the better stats.
Specs are:
5950' total living
R38 ceilings and walls with 5.5in foam walls/ceiling.
Low E Vinyl windows u-val .37 and coefficient .22
Avg house temp 75-79 summer 103' day
70-72 winter 22' day.
3 Envision water furn units. Vari speed
- 2 units w/desuperheater and cir pump
11 waterfurnace stats TA32E12 ( might be overkill )
4 cir pumps
Unit 1, envi 3 ton - 4 zone
Unit 2, envi 6 ton - 3 zone
Unit 3 envi 3 ton - 4 zone
3 Intellizone damer systems for 11 zones
All foil/metal flex supply Insulated
12 wells 300ft each = 1.0" polyethylene pipe
Headers 1-2"
$81K


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doug

5700' total living on 2 levels
2300 sq feet to be finished in the basement

house is at 1250' elevation in the blueridge mtns, northern VA

3 Econar GeoSource 2000 Vari speed heat pumps
2 cir pumps
Unit 1, 3 ton - 3 zone (second floor)
Unit 2, 6 ton - 1 zone (living space 1st level)
Unit 3 3 ton - 1 zone (master bed/bath suite' 1st level)
1 pit (120' x 48' x 6') 12 loops @115 ft each, 1.0" polyethylene pipe with manifold system

the bid also included the main ducts for all basement space as registers in 1 finished room down there.

the zones cost $1200 for 2, then 300 per additional zone after that. i will be adding zones into the basement as I finish it off.
$46K for everything but the pit
$20K for the pit (boulder problem)

total 66K. it should have cost $51K to $53K - darn boulders!


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I got my first Geothermal estimate for a closed loop system for 5200 sq ft living space with additional unfinished walkout basement 2400 sq ft. Sized 5 tons total, $39k installed incl duct work, dehumidifier,uv light air purifier.
I was browsing the manual J calc he prepared and saw some of the assumptions: walls even though they're icf, he listed r-value as r-36 but the manufacturer lists r-60 with brick veneer. Basement slab he listed as uninsulated but it will be. Would these make a big difference to the J calc and tonnage?
BTW this is about $11k more than a conventional ventilation sytem priced for this house.


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Re doctj:

Providing that the geothermal system is properly designed & installed, at that price and price differential of 1st costs between conventional & geothermal - Id jump o it!

IMO

SR


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RE: Size of Geothermal Unit

SR
The installer has been IGSHPA certified since '94 and he has a lot of references so he seems to be quite qualified. Plus my wife wanted us to add radiant heat to the basement but he said it wouldn't be justified since we reside in a mild climate. In his own words: " I'd love to add another $7-11000 to the job but to be honest it's overkill for your house".


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RE doctj:

Sounds like you found the right installer and he did take the time to do the Manual J calcs.
Its your call regarding radiant in-floor for the basement. Personally, I would do it. Your basement will always be very comfortable and dry. I would sooner spend the money and have something good that adds value to my home and occasionally think I went overboard than kick myself later that I didnt do it while I had the chance. If youre planning an in-ground pool, that part of the radiant in-floor geothermal capacity can, in the summer, heat the pool at a tremendous savings.

Anyways, Id be calling your IGSHPA guy and writing him a cheque.

IMO

SR


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You've got me thinking about radiant heat now. I'm thinking of putting PEX in the slab (buy the materials from radiantec and do a self install)and hooking it up later either to the geothermal system or a separate solar system. Are there any problems with this approach?


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Hi doctj,

My expertise is not in radiant in-floor design (yet-just got all my software last week!).

You would have to make sure your layout design (pipe spacing, flow rate etc.) is matched to the correct design water temperature very important! The other thing to be mindful about is that your PEX tubing should be full of liquid and under pressure when you do your pour so that the PEX tubing does not collapse. Make sure the ground is properly prepared and insulated (crushed stone, vapor barrier & 2in. blue Styrofoam) before the pour you dont want to be sinking your heat straight into the ground.

Please consult an experienced professional and avoid any heartache its worth it!

If youre thinking about it you should probably do it. Not only will you love it but also the next owner will be willing to pay big bucks for it too especially if your open house is during heating season and they have small kids! Take a look at triple function geothermal HPs, full capacity HW for radiant in-floor heating, forced air heating & cooling AND DHW ALL in one unit!

Heres the link:

http://www.nordicghp.com/mg/

Then click Products, then click TF-Series, then download either R410a or R22 Installation Manual pdf for the whole story. They also make DX versions of these GSHPs.

Good Luck Let me know what you think.

Steve


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RE: Size of Geothermal Unit

Steve
Thanks for the advice. We've found a " consultant" who will draw the layouts room by room and guide us on pressurizing the tubes during the pour, etc. He charged us $250 which I think is reasonable as I was nervous doing it solo and my builder hasn't installed one before although now he's really excited about it.
I've already committed to certain gshp model with the hvac contractor. I'm thinking of having the radiant as a separate system hooked up to solar.


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RE: Size of Geothermal Unit

Has anyone used Open Loop ground source from a well?

My basement contractor recommends saving the $35-50K worth of drilling 12 closed loops and just drilling into the water table, running it into the water furnace and dumping into the creek out back.

Cost would be about $4500-6000 complete. Drilled 1hp pump 10-20gpm, bladder tank 40-60gal and filtration for sand.

I read online that well water has a 118 efficiency which is hands down the best for geo.

Water furnace said I will need 12-18gpm or 1200gal / hr for the 4 units. They got all into the minerals building up and requiring flushing yearly to keep it clean.

I found some geo grade Brazed Heat Exchangers ment for this application thus keeping the water out of the geo unit.

Seems this is the way to go from what I see even if I have to replace the heat exchangers or clean then myself.

Est cost:
1 ground water well $6000 worst case.
12 ground loops $35,000 - $39,000


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RE: Size of Geothermal Unit

Hi Michael.

Yes, we've used Open Loop ground source from a well. It's working pretty well, so far. We drilled into the water table and are able to dump the "used" water into an old dry well, from when it returns to the water table.

However, it is scarcely the most cost-efficient system. our heat pump runs well but for every minute it runs so does the well pump. The cost of lifting all that water severely cuts into the savings. Nevertheless, we think we're saving about 25% over the cost of heating with natural gas.

By the time we had the well drilled and the heat pump installed we had about $12K invested (we had to upgrade the electrical service as well, and so on). As it has worked out we're able to use the well for our sprinkler system, and that has worked out to a significant savings.

If we had to justify the well on the basis of just the heat pump or just the irrigation we could not. But the two of them together actually do pay for the investment.

I am scheduled to do the annual flushing "any minute now" but haven't yet. Thanks for the reminder. It will be my first time and I need to get to it. It's supposed to be straightforward enough and I think I can handle it ... but when I'm 80, instead of 58, I'll probably have to have somebody come in ...

Good luck on your project. I hope you have time to back up, take a long look, and proceed with caution. If everything goes well it could be a good deal, but with a little poor planning it could be an expensive and frustrating experiment. One hopes your contractor is qualified and ethical.

Best wishes,

M


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RE: Size of Geothermal Unit

ohhh i'm just so irritated!! this is exactly what i wanted when i told the dang contractor what i wanted for our heating/ac. instead they put in electric only!!! uhhhh and errr!! of course this was last year!! he had his own people come out and do the work. i shoulda knwn!!! now that i'm reading more i know. what we have don't even work like they said it should. our house is a almost 800 sq ft. and it don't cool it down like its supposed to or heat it up like its supposed to. and i've plasticed all the windows like i do every year, and cover the back door and cover the front door, they put the front door in and it still has a huge gap in!!!


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RE: Size of Geothermal Unit

Hi Doctj

We bought our system from Radiantec and have been very happy with it. The only thing I would have changed was going from a 5 loop manifold with 300' on each loop to a 6 loop manifold with 250' on each loop. You can just feel it in the cement where it looses it's heat on the return lines, numbers look good temp wise, but it's there to the human touch.

We're researching Geothermal energy now to try and tie it into our Radiant floor. Was even looking at the possibility of using the cement floor zone to use instead of running new loops outside since the temperature under our slab never goes below 50 degrees.


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RE: Size of Geothermal Unit

I have a Waterfurnace rep coming from Rochester NY this week to look at my house and options for a GT system. I've read all of the posts thus far, and find similarities to my home, but I'd be interested to have any inputs prior to the gentelman showing up so that I ask the right questions.
I have about 5000ft2 on the main level of my home (includes large garage which is heated but only to 60), 3900ft2 in the basement (only heated by the fact that the furnace is down there and the baseboard pipes for main level - it is great temperature down there year round, and we hope to finish it to about 80% of the footage), and a second story that is like a finished attic of sorts (it is the bar / poker / pool room) that is a little less than 1000ft2. So that makes almost 10,000ft2 of total heated space. Currently I heat with oil (have you checked the current prices?!!) in a System 2000 boiler in the basement and via an 8 zone baseboard system), and have four A/C units outside that drive four air handlers in the attic and all of this ductwork in the attic space.
I think this is probably a unique setup, given the size of the home and the two separate systems.
I am in the Binghamton region of New York State.
Also of note, I have 10' ceilings in the basement, so if the new system requires air ducting, it is almost ideal for it, and still maintain 8-9' ceilings when finished.
I'd really be interested in your suggestions on installation approaches / options... from vertical to horizontal and sizing of units and architecture of the system in general. thanks for all of the good info posted in this forum!
Tim


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