|
|
|
Geothermal Bid Sanity Check
|
Sort:
|
|
 Prev Next |
You are not authorized to post a reply. |
|
buckybanjo
New Member
Posts:12
 |
| 06 Apr 2008 05:35 PM |
|
This is a great forum that I'm glad I've found. We're trying to build a net zero energy/sustainable 2000 sq ft home in upstate (Hudson Valley) NY (meant to be a weekend home). I really want to use geothermal as I'm putting in a sizable PV array which I believe can handle the geothermal and I don't want any fossil fuels on site. I'm close to getting there but I just received my geothermal bid and, as I suspected, its 3x higher then even the best radiant/munchkin system I had spec'ed before.
I would appreciate if the pros on here could take a look at this bid and tell me if this sounds like a reasonable number. I am told this is one of the most reputable geothermal people in the area but that they aren't the cheapest. They have designed for a 10 ton system (yes, I was surprised as well at how large this was but it is a modern house with glass and concrete) so let's assume their sizing is accurate. Their bid is $53k which does not include well drilling and radiant floor installation. Here's the breakdown I've come up with (from my own research and some detail they gave me on the bid):
- Water-to-water heat pump: most estimates seem to be $2500 per ton so that's $25k
- Desuperheater: don't know how much this adds
- 4 in-wall condensing AC units (we aren't having duct work for AC so this was the only option): $1800 ea so round to $8000
- Hot air recirculator: $5k
- 80 gallon tank for radiant storage: negligent cost
- 40 gallon tank for desuperheater storage: negligent cost
- Labor, piping, etc.
My costs add up to about $40k. I was told that with this system I didn't need a DHW water heater except for backup as the two tanks combined would serve domestic hot water. That's a nice feature but I might still get a medium sized electric tankless DHW (only about $500).
So w/o well drilling (told me I need 1200' of vertical) and radiant in-floor install does $53k sound reasonable?
Thanks. I'm really trying to make this work and right now its a budget buster so at least if I know I'm paying a reasonable rate its just a discussion of making the budget work.
|
|
|
|
|
|
|
Palace Geothermal
Veteran Member
Posts:1609
|
| 06 Apr 2008 06:58 PM |
|
10 Tons seems way too high to me unless you have zero insulation in your house. I have a 3500 sq ft home and a 4.5 ton heat pump.
What is an in-wall condensing unit? Is this an air handler?
What is a hot air recirculator? Why does it cost $5000?
Usually you need about 200' of bore hole per ton. This would be 2000' in your case.
They sure do thing different in NY than UT!
I really can't say what labor costs in your area, but in UT the price would be a lot less.
The most suspect number is 10 tons of heat pump.
Ask them for a detailed heat load analysis. We can learn a lot from it. |
|
Dewayne Dean
<br>www.PalaceGeothermal.com<br>Why settle for 90% when you can have 400%<br>We heat and cool with dirt!<br>visit- http://welserver.com/WEL0114/- to see my system |
|
|
Eric D
Basic Member
Posts:104
|
| 06 Apr 2008 07:35 PM |
|
BuckyBanjo,
Dewayne is spot on with the question as to why they believe you need a 10 ton unit. Is there something unique with the ground in your area?
I have a friend here in Michigan that has a 5000 sq ft home that makes use of radiant in floor heating. A 5 ton water to water that more then meet the heating needs. Something is way off in the calculations. Maybe they mistakingly added a zero to the square feet of your home.
At minimum get a couple more quotes.
Please keep us posted on what you find out.
Regards, |
|
| Eric D<br>Southern Michigan |
|
|
cnygeo
Basic Member
Posts:170
|
| 06 Apr 2008 09:05 PM |
|
I'm not in the install business so I can't comment on cost (which also varies hugely by region) but here are a few thoughts:
1. I second the suggestion to check the load calc - unless your house is ALL glass that sounds extremely high. That's 60btu/ft2. My drafty poorly insulated victorian in a slightly colder climate is only 20-25btu/ft2. Note that you may not even be able to meet that entire load with radiant floor if it is true - you would need floor temps of over 100F assuming you utilize every available square foot of floor space. This would likely require water temps higher than what most geo units can comfortably produce.
2. I've posted before about the poor economics (in most cases) of coupling geo with solar. Unless you are already installing a vastly oversized solar system for other reasons, it really doesn't make sense. You can replace some of your PV space with solar hot water collectors and get the same amount of energy at a much, much lower up front cost. A 10-ton system will be drawing up to 12kW average when it is running at full load - that's a pretty big solar array in these parts!
3. Not sure why they'd use individual condensors in the walls - if you are using a hot water system hydronic fan coils would be a lot cheaper for the AC. No need to be running refrigerant all over the place.
4. As others have said the bore length sounds a little on the low side, but this varies greatly with local conditions and the exact load balance etc, so it might be fine. Jus tmake sure they've actually done the required analysis and aren't just using a rule of thumb.
|
|
|
|
|
buckybanjo
New Member
Posts:12
|
| 07 Apr 2008 08:13 AM |
|
Thanks to all for the quick feedback. Yes, I was surprised at the 10 ton assessment as well. I had read the general guideline of 1 ton per 500 sq ft and knew you had to make climate and house adjustments from there but this was a big difference. I pressed them on this and I was told that since my house has a lot of glazing and concrete floors this significantly increases the heating needs. This even though we are incorporating several other techniques to better the efficiency situation: triple paned glass, wall of windows facing south onto thermal mass for passive solar, a special roof system that's super insulated, etc. Since some of these are not the "norm" I suspect we didn't get much credit for those. And just from talking with them I think they size for the worst case scenario (it can stay near zero in this area for a week or two in Jan/Feb). For me, I will have a woodburning stove as backup so I think we can handle that case. Plus, this is only a weekend house so if its that cold I'll be elsewhere most likely.
Anyway, I have asked for their heat load analysis which I'll share if I get it. I am seeking other bids but was told this installer was the best in the area. If there are any other recommendations for one in the central Hudson Valley NY (Woodstock area) please send them over. I'll update when I know more.
|
|
|
|
|
buckybanjo
New Member
Posts:12
|
| 07 Apr 2008 09:01 AM |
|
Posted By cnygeo on 04/06/2008 9:05 PM I'm not in the install business so I can't comment on cost (which also varies hugely by region) but here are a few thoughts:
1. I second the suggestion to check the load calc - unless your house is ALL glass that sounds extremely high. That's 60btu/ft2. My drafty poorly insulated victorian in a slightly colder climate is only 20-25btu/ft2. Note that you may not even be able to meet that entire load with radiant floor if it is true - you would need floor temps of over 100F assuming you utilize every available square foot of floor space. This would likely require water temps higher than what most geo units can comfortably produce.
2. I've posted before about the poor economics (in most cases) of coupling geo with solar. Unless you are already installing a vastly oversized solar system for other reasons, it really doesn't make sense. You can replace some of your PV space with solar hot water collectors and get the same amount of energy at a much, much lower up front cost. A 10-ton system will be drawing up to 12kW average when it is running at full load - that's a pretty big solar array in these parts!
3. Not sure why they'd use individual condensors in the walls - if you are using a hot water system hydronic fan coils would be a lot cheaper for the AC. No need to be running refrigerant all over the place.
4. As others have said the bore length sounds a little on the low side, but this varies greatly with local conditions and the exact load balance etc, so it might be fine. Jus tmake sure they've actually done the required analysis and aren't just using a rule of thumb.
cnygeo,
Thanks for your comments. Answers to a few of your questions:
1. See my update post as I'm trying to get that further assessment. 2. I know that PV is not the optimal source (in all cases) for geothermal. However, there are broader considerations here including the principles I'm trying to achieve (no fossile fuels on site, a weekend home that has zero operating costs, future safe as energy prices continue to rise). I have considered solar hot water but that's not practical for several reasons: a) I have yet to see a design where solar hot water is a source for both radiant heating and DHW. I've been told it really is only for DHW so, for me, that is very little bang for the buck since it is a weekend house and DHW demand will be minimal. If you have a design that solar hot water can be the source for radiant or both please point me to it. b) PV generating electricity has utility beyond geothermal in powering my house. In addition, since solar hot water (sourcing to DHW and radiant) would mostly be in demand in the winter its a half-year system where PV has utility all year (more generation and less demand in summer makes up for winter demand with utility net-metering). 3. They spec'ed in wall condesors because we do not have duct work and cannot add it given the design of the house. The only way to get AC (was not a priority for us) was these units. At $1800 each they are a small part of the cost here. 4. Given how conservative they are on other things I'm guessing they are doing it appropriately for local conditions but will double check that with another bid. Thanks.
|
|
|
|
|
Eric D
Basic Member
Posts:104
|
| 07 Apr 2008 09:40 AM |
|
Bucky,
After rereading your post I think maybe I now understand where the company that gave you the quote for 10 ton may be coming up with the numbers. Did you suggest that the geo system would be used part time? In other words, did you tell them it would be shut down when you're not there, and when you get there expect it to bring the house up to temp? They may have sized it for a reasonable recovery time, like an hour or two. Taking the concrete slabs from zero and bring them up to livable temps would take a huge amount of time with a normally sized system. You would most likely be dollars ahead of the game to have the home very well insolated and live with the fact that you will leave heat on, even while you are not there.
Regards, |
|
| Eric D<br>Southern Michigan |
|
|
buckybanjo
New Member
Posts:12
|
| 07 Apr 2008 09:56 AM |
|
Posted By Eric D on 04/07/2008 9:40 AM Bucky,
After rereading your post I think maybe I now understand where the company that gave you the quote for 10 ton may be coming up with the numbers. Did you suggest that the geo system would be used part time? In other words, did you tell them it would be shut down when you're not there, and when you get there expect it to bring the house up to temp? They may have sized it for a reasonable recovery time, like an hour or two. Taking the concrete slabs from zero and bring them up to livable temps would take a huge amount of time with a normally sized system. You would most likely be dollars ahead of the game to have to place very well insolated and live with the fact that you will leave heat on, even while you are not there.
Regards, Eric, You raise a good point. I did tell them it was a weekend house (thus the assumption is the thermostat is set to 50 degrees the majority of the time when we're not there) but did not put on any requirements for how fast it has to come up to 68 degrees. I did already know that radiant systems take some time to come up no matter what the heat source is. As a side note I'm planning on an Internet connected thermostat so I can turn it on a few hours before we go up. When I discussed the matter of a weekend house with them responding to the 10 ton figure they basically said that wouldn't make a difference as they sized it as a fulltime house. Their reasoning was that if we were to move there fulltime or go to resell it we'd have a problem otherwise. This is a reasonable argument so I can't counter them there. However, I will double check that they haven't "oversized" the system so that it comes up more quickly.
|
|
|
|
|
cnygeo
Basic Member
Posts:170
|
| 07 Apr 2008 10:09 AM |
|
Good point - heating up a large slab rapidly in the winter would require a lot more capacity. If this is the case, there might be ways around this like insulating between the slab and heated space and using a sleeper or warmboard-type product - try to take the big thermal mass out of the picture. Or set it up with a remote thermostat so the heat can be turned up a day or two before it is needed.
I also hadn't considered the effect of part-time occupancy on the loop design - it would probably mean that the peak load rather than the seasonal load would be driving the length requirement and might mean shorter loops than normal. Is there any possibility of doing horizontal loops? Again this varies greatly by region, but in my area horizontal loops are 1/2 the cost or less than vertical.
Getting back to your solar philosophy - it does make more sense if you're using net metering to match the annual load rather than the peak loads - around here a 12kW PV system would probably be well over 6 figures even after tax credits. When you say you can't find a design to combine solar DHW and radiant, I'm curious where the difficulty lies? The actual mechanics and controls would be pretty straightforward, there may not be "off-the-shelf" systems but I would think an engineer familiar with solar DHW could put something together fairly easily. The major problem that I see in our region would be sizing the system - the peak heating load corresponds with the lowest solar availibility, so the system would be grossly oversized in the summer months when it is needed for DHW only. Depending on the type of collector you might need some sort of dump load. This is where the PV with net metering has the advantage as you say - you can essentially use the electric grid to "store" your summer excess production for use in the winter. Still, from what I've seen of solar PV and geo costs, my gut still tells me you'd be ahead using solar hot water for at least some portion of the heating load. It is a pretty complex analysis with lots of factors I don't know about so it's purely a guess.
Sounds like a fun project - keep us posted with your progress!
|
|
|
|
|
buckybanjo
New Member
Posts:12
|
| 07 Apr 2008 10:35 AM |
|
Posted By cnygeo on 04/07/2008 10:09 AM
Good point - heating up a large slab rapidly in the winter would require a lot more capacity. If this is the case, there might be ways around this like insulating between the slab and heated space and using a sleeper or warmboard-type product - try to take the big thermal mass out of the picture. Or set it up with a remote thermostat so the heat can be turned up a day or two before it is needed.
I also hadn't considered the effect of part-time occupancy on the loop design - it would probably mean that the peak load rather than the seasonal load would be driving the length requirement and might mean shorter loops than normal. Is there any possibility of doing horizontal loops? Again this varies greatly by region, but in my area horizontal loops are 1/2 the cost or less than vertical.
Getting back to your solar philosophy - it does make more sense if you're using net metering to match the annual load rather than the peak loads - around here a 12kW PV system would probably be well over 6 figures even after tax credits. When you say you can't find a design to combine solar DHW and radiant, I'm curious where the difficulty lies? The actual mechanics and controls would be pretty straightforward, there may not be "off-the-shelf" systems but I would think an engineer familiar with solar DHW could put something together fairly easily. The major problem that I see in our region would be sizing the system - the peak heating load corresponds with the lowest solar availibility, so the system would be grossly oversized in the summer months when it is needed for DHW only. Depending on the type of collector you might need some sort of dump load. This is where the PV with net metering has the advantage as you say - you can essentially use the electric grid to "store" your summer excess production for use in the winter. Still, from what I've seen of solar PV and geo costs, my gut still tells me you'd be ahead using solar hot water for at least some portion of the heating load. It is a pretty complex analysis with lots of factors I don't know about so it's purely a guess.
Sounds like a fun project - keep us posted with your progress!
cnygeo, I will explore the heating of the thermal concrete mass with them as stated above in response to Eric. That got me thinking back to my conversation with the installer about the "why 10 tons". He said the larger sizing was due to significant glazing (understandable) and the concrete mass. At first I didn't quite "get" why the concrete mass was a negative here but now I understand better. I'm going to go back to them and say my expectation is not that the mass will be heated up to living temp in a couple of hours since we'll control that with a remote thermostat so that might lower the tonnage. In regard to the solar HW, radiant, and DHW I imagine that it could be figured out engineering wise but no one I've talked to nor anywhere online can I find that kind of setup. The installers I've talked to pretty much pair solar HW with DHW (which makes sense) but in my case the net benefit is minimal. Its also difficult to get installers to try "outside-the-box" things like this and I don't have the background to do it so if you have a reference I'd appreciate it. Finally, in regard to the PV and geothermal, yes, you picked up the salient point: I don't have to size PV for the heaviest load from the geothermal only the average case because of net metering. The grid is, in fact, my electricity store and I'm going to buy wind power from my utility. I've modeled this out and this is what I have: - During the winter when we are there we will be net negative (peak heating loads and less sun for PV) - Winter when we're not there we should be roughly even to slighly negative (less load because house at 50 degrees; less sun for PV) - Summer when we're there we should be slighly net positive (no heating; minimal AC; lots of sun) - Summer when we're not there we should be very net positive (practially no electrical load; lots of sun) This last case is the big winner as the house should have practially no electricity draw in the summer when we're not there. It'll be a mini power generator and sell back all I took up in the winter. This works mostly because it is a weekend house so the electrical and heating loads are significantly lower then a full time house. In fact, my calcs tell me that I actually might be generating more on an annual basis than I'm using so the utililty will owe me money. Unfortunately, they don't write checks around here just net to zero at year's end but I'm ok with oversizing just in case I missed something or we do spend more time up there then just weekends (fulltime my calcs tell me I'd be generating 75% of energy needs from PV). I am very energy conscious using various strategies to eliminate phantom loads. In our current place we only average about 9kwh per day over the year even though I work from home full time. Granted, this is an apartment and does not include heating/HW but does include a decent amount of AC in the summer. I'll keep you updated on progress.
|
|
|
|
|
tuffluckdriller
Advanced Member
Posts:630
|
| 07 Apr 2008 11:02 AM |
|
Bucky, Is this home slab on grade? If so, why not use "black max" (www.general-plastics.com) under slab duct for your A/C? Also, you should check out EarthLinked DX geothermal. I'd bet the installed price is lower than your water-to-water system quote. the ground loop requirements would be a little less, too. Check with Mel Hensch. His email is: [email protected], or call him at 508-328-4735. He'll know who a good installer is. |
|
| Clark Timothy ([email protected])<br>Geothermal Heat Pumps: Heating and Cooling that's Dirt Cheap!<br>www.pinksgeothermal.com |
|
|
buckybanjo
New Member
Posts:12
|
| 07 Apr 2008 11:39 AM |
|
Posted By tuffluckdriller on 04/07/2008 11:02 AM Bucky, Is this home slab on grade? If so, why not use "black max" (www.general-plastics.com) under slab duct for your A/C? Also, you should check out EarthLinked DX geothermal. I'd bet the installed price is lower than your water-to-water system quote. the ground loop requirements would be a little less, too. Check with Mel Hensch. His email is: [email protected], or call him at 508-328-4735. He'll know who a good installer is. The house is not slab on grade. The site is actually quite sloped in the woods and the house actually projects off a hill and rests on piers so its like a slab raised in the air (with significant insulation below the slab). There is a small basement in a tower part that will house the mechanicals and storage but that's adjascent rather then underneath the main part so nowhere to run ducts. We chose this design partially for aesthetics but also to minimize inpact on the land in digging it out too much for a basement or trying to grade it for a slab. Thanks for the EarthLinked DX reference. I'll take a look and contact Mel.
|
|
|
|
|
gregj
Basic Member
Posts:326
|
| 07 Apr 2008 12:39 PM |
|
Bucky, I applaud your efforts to build a netzero energy home but urge you to reconsider your design. A 2000 ft house that requires a 10 ton unit is quite wastefull. Your large windows and other construction features are obviously not providing an energy savings benefit, in fact they must be dramatically hurting your efforts to conserve. The other alternative is, of course, that your HVAC contractor has no clue as to how your home design works.
If it trully requires a 10 ton unit then I would guess that the cost quoted for the 10 ton setup is probably quite small compared to what it will cost for a PV array that could run it. How much juice does it take to start up a 10 ton unit?Where will this PV array actually be installed? Wouldn't it need to be considerably larger than your roof? Again, I encourage you to look at your home design, it is far cheaper to design a home to use less energy than to design off grid energy supplies. |
|
|
|
|
buckybanjo
New Member
Posts:12
|
| 07 Apr 2008 12:57 PM |
|
Posted By gregj on 04/07/2008 12:39 PM
Bucky, I applaud your efforts to build a netzero energy home but urge you to reconsider your design. A 2000 ft house that requires a 10 ton unit is quite wastefull. Your large windows and other construction features are obviously not providing an energy savings benefit, in fact they must be dramatically hurting your efforts to conserve. The other alternative is, of course, that your HVAC contractor has no clue as to how your home design works.
If it trully requires a 10 ton unit then I would guess that the cost quoted for the 10 ton setup is probably quite small compared to what it will cost for a PV array that could run it. How much juice does it take to start up a 10 ton unit?Where will this PV array actually be installed? Wouldn't it need to be considerably larger than your roof? Again, I encourage you to look at your home design, it is far cheaper to design a home to use less energy than to design off grid energy supplies. Greg, Thanks for your comments. First, whether the 10 ton figure is correct or not is something I have to determine by getting other bids. I just talked to another installer and, without seeing my plans, laughed out loud at the 10 ton figure. He now has my plans so let's see what he comes up with. I suspect that the first installer was more being extremely conservative then completely out of whack. I agree that if my house does, in fact, require a 10 ton system we have broader design problems then just the HVAC. I do know that there are design elements we have chosen which are not the most efficient. Heck, if I was just building a house to be max efficiency I would build a mud hut w/o windows and 8' thick walls but aesthetics do matter. We do have a wall of windows but have done other things to help overall efficiency. That wall of windows is directly south facing and the winter sun will fall onto a thermal mass (and be shaded in the summer). I know, not as efficient as a thick, well insulated wall, but its better then a north facing wall of windows (which my neighbor did). Also, the windows we're using are fiberglass triple paned from Manitoba Canada and by far the highest R value on the market. We also have over insulated as much as we can and our roof has a special double layer with an air channel in the middle to vent hot air in the summer (prevents house baking). We easily passed our NY state res check (albeit we did not blow it away) so I know we aren't really bad with efficiency. I just don't think that the calcs that were done to get to the 10 ton system fully took into account all these measures and other "lifestyle" factors such as I don't need my slab heated from 50 to 68 via radiant in 2 hours. Also, our 5kw system easily fits onto our roof. Yes, doing PV to fully supply a 10 ton system at peak load would be huge but we don't have to do that. First, even if we ended up with a 10 ton system, I doubt it would run much at full load. Second, as mentioned in an earlier post, I have net-metering with my utility so I only have to design for average load over the whole year. I don't have much need for AC and its a weekend house so the warmer months will have me net-positive energy-wise. I am not off the grid and we don't need to design for the extreme case scenario as I believe the first installer did.
|
|
|
|
|
Eric D
Basic Member
Posts:104
|
| 07 Apr 2008 01:34 PM |
|
Bucky,
Not that you need any encouragement, but for what it’s worth I think you are going about this in an equable way. You are asking the right kind of questions and taking notes of useful information. I’ll be willing to bet that the bottom line cost when all said and done will be much less then you have currently been quoted and I believe that the size of your home will blend into this outcome very nicely.
From all the information in your postings so far, I would bet a 4 to 5 ton system will cover your needs nicely. If you plan on remotely calling for heat a day before getting there, I would lean in the direction of a 4 ton. It would also cover nicely for DHW with a desuperheater and a good size storage tank.
I'm sure you already know this now, but when asking for a quote, be sure to mention that you will make a remote call for heat and the amount of time you are willing to wait for it to come up to temp. At zero outside temps, it might take a day or two.
Please keep us posted on how you make out…
Regards, |
|
| Eric D<br>Southern Michigan |
|
|
tuffluckdriller
Advanced Member
Posts:630
|
| 07 Apr 2008 06:57 PM |
|
I sized a system for a 2940 sq.ft. house that was on piers, too. It's 20' up in the air. (referred to as the "Jetson house") I had him insulate the structure with foam, so that he could have a smaller tonnage requirement. He used triple pane windows, and has walls of glass. He ended up going with warmboard for the radiant floor. He heats his domestic water and living space with the geothermal. With the characteristics of heating water with geothermal instead of air, his system ended up being 8 tons. Radiant is comfortable at times, but it's not as efficient as air.
At first, I thought 8 tons had to be wrong. I checked and re-checked that load. I had an engineer look at the calculation, and he confirmed my numbers.
My point is, because of the design, even with your 3 pane windows, and good insulation, a suspended home does have a larger heat loss per square foot than a house on an enclosed foundation. I'm not necessarily endorsing the 10 ton design, but it may be correct.
With water source loops, though, I do really question the small amount of loop they are proposing for 10 tons. The LAST thing you should do is short-loop the system. If the house really needs 10 tons, then the loop needs to be sufficient to handle 10 tons. Geodean can attest to this. There is a so-called "geo loop expert" in our state that has given geo-exchange a bad name for years because he short loops the loop field. He even has people put in a boiler to warm up the loop. What's the point of doing geo if you're not going to design and rely on the ground for the complete system? This loop design "guru" somehow still dupes people into believing that he's reputable, and that he really knows his stuff. Just because a company claims a lot, doesn't mean they're doing things right. That's probably one of the benefits of this forum. You're using it how you should be by checking on someone's design/sizing/installation... |
|
| Clark Timothy ([email protected])<br>Geothermal Heat Pumps: Heating and Cooling that's Dirt Cheap!<br>www.pinksgeothermal.com |
|
|
buckybanjo
New Member
Posts:12
|
| 07 Apr 2008 07:08 PM |
|
Posted By tuffluckdriller on 04/07/2008 6:57 PM
I sized a system for a 2940 sq.ft. house that was on piers, too. It's 20' up in the air. (referred to as the "Jetson house") I had him insulate the structure with foam, so that he could have a smaller tonnage requirement. He used triple pane windows, and has walls of glass. He ended up going with warmboard for the radiant floor. He heats his domestic water and living space with the geothermal. With the characteristics of heating water with geothermal instead of air, his system ended up being 8 tons. Radiant is comfortable at times, but it's not as efficient as air.
At first, I thought 8 tons had to be wrong. I checked and re-checked that load. I had an engineer look at the calculation, and he confirmed my numbers.
My point is, because of the design, even with your 3 pane windows, and good insulation, a suspended home does have a larger heat loss per square foot than a house on an enclosed foundation. I'm not necessarily endorsing the 10 ton design, but it may be correct.
With water source loops, though, I do really question the small amount of loop they are proposing for 10 tons. The LAST thing you should do is short-loop the system. If the house really needs 10 tons, then the loop needs to be sufficient to handle 10 tons. Geodean can attest to this. There is a so-called "geo loop expert" in our state that has given geo-exchange a bad name for years because he short loops the loop field. He even has people put in a boiler to warm up the loop. What's the point of doing geo if you're not going to design and rely on the ground for the complete system? This loop design "guru" somehow still dupes people into believing that he's reputable, and that he really knows his stuff. Just because a company claims a lot, doesn't mean they're doing things right. That's probably one of the benefits of this forum. You're using it how you should be by checking on someone's design/sizing/installation... Clark, I agree that our house design probably requires a larger design but 2.5x base design parameters (1 ton per 500 sq ft) just seemed excessive to me. I will also look further into to the loop sizing. The installer has agreed to do the detailed design now so I'll get a refinement. I also talked to Mel from Earthlinked who you mentioned earlier today and he laughed when I told him of the 10 ton design. He is putting me in contact with a local installer of their DX system and, at a minimum, I'll get a second assessment on the load. In reading up today on DX I actually think that might work for me and cost savings and other efficiencies are appealing (assuming they are real). Thanks.
|
|
|
|
|
tuffluckdriller
Advanced Member
Posts:630
|
| 07 Apr 2008 10:58 PM |
|
The efficiencies are definitely real. We have a bunch of sub meters on different houses to prove how efficient they are. The sub meters prove that they are even more efficient than expected. By that, I mean we usually see a COP on drilled systems of 4.5-4.7, instead of 4.0-4.2 as ARI tested.
You'll be happy with an EarthLinked DX system. |
|
| Clark Timothy ([email protected])<br>Geothermal Heat Pumps: Heating and Cooling that's Dirt Cheap!<br>www.pinksgeothermal.com |
|
|
geoloopman
New Member
Posts:1
|
| 09 Apr 2008 10:42 AM |
|
Can I ask what company's you have been in contact with? |
|
|
|
|
buckybanjo
New Member
Posts:12
|
| 10 Apr 2008 02:31 PM |
|
Posted By geoloopman on 04/09/2008 10:42 AM
Can I ask what company's you have been in contact with? Given that we're still in the bidding process I don't want to
reveal that information at this time. If you have another recommended
company in the central Hudson Valley NY feel free to post it here.
Also, I'd like to thank all of those who weighed in with their thoughts
on this forum. It helped greatly and certainly influenced what we'll end
up doing but mostly I'm more knowledgeable and able to (hopefully) get
the best and most appropriate system deal. I'll update here once we
make a decision and update as we progress through the project.
|
|
|
|
|
| You are not authorized to post a reply. |
|
Active Forums 4.1
 |
Membership: |
 |
Latest:
Scottnorton |
 |
New Today:
1 |
 |
New Yesterday:
1 |
 |
Overall:
34728 |
 |
People Online: |
 |
Visitors:
103 |
 |
Members:
0 |
 |
Total:
103 |
|
|
|