2manyrocks
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It would be great to see a geothermal system figured out here on TBN that beats the contractor's design. Even better if the homeowner installs the ground piping with photos here, too.
HVAC II, which one?
- Thread starter Richard
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buckeyefarmer
Super Star Member
You will when I get mine done. Although the same principal, each design is almost unique. Look on youtube for some nice geo videos. Also one of the HVAC Boards has documented installs that people have done themselves..
one is www.ricksgeo.com
2manyrocks
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That's a good read on that link. If he had his own backhoe to work at his own pace, I think he could have saved himself some of the headaches he mentions. But it's a very good link. thanks.
I've had a water-source (what geothermal used to be called) heat pump in my house since its construction in 1986. It's still ticking away, and has saved gobs of money over its life. I'm currently researching some on replacements, as it may be coming to the end of its useful time....
When mine was installed, it was originally going to be a pump and dump system, but I really didn't feel good about that, for all the reasons stated already. The designers of the system, a couple of NH engineers, then came up with an elegant solution:
1. They created a manifold with an on-site PVC (?) welder that split the 2" line coming from the house into two 3/4" loops, with welded return bends on the ends of each.
2. They fashioned a large wire spool (4' diameter) on a stand so it could rotate.
3. Using the spool, they wound up my well pipe, with pump on the end, and removed all the plastic spacers I had so carefully positioned when I put it in.
4. They then fed the four 3/4" lines (2 loops) back down the well hole (std. 6"), along with the pump and water line. The loops effectively replaced the plastic spacers. They weren't able to get it back down as far as it had been, but still got about 200' of loop into the well (with the water pump below that); static's at 80'.
5. Welded up the manifold to the two loops, connected to the 2" lines going back into the house, installed two Grundfos circulators in series, and I then had an 8-1/2 gpm recirculating loop. All lines were 8' or more below the surface, so it's all just water, no need for A-F.
As it was a closed system, the water in the loop was filtered well and then treated. It's hooked up to a valve inside so I can replace and/or flush the loop when needed. Twenty-three years and counting.... Still has the original Grundfos pumps, still runs @ 8.5gpm with a 6 degree+/- TD on the loop. I do augment with a wood stove; we have the coldest tap water in the state, I think, in the winter!
It ain't real pretty sitting in my basement, but it sure does work. I envy you guys who have the newer systems-- mine uses R-22 and has a 3.25 COP; I'm drooling over the new ones with a COP of 5!!
In all those years, I've replaced both TXVs, all 3 check-valves ("cheap" Singers/Gemlines), one reversing valve, and repaired a couple of leaks. Not bad, methinks. Oh- it also makes hot water... and in the summer can take house heat and put it directly into DHW. Clever, those NH engineers.
When mine was installed, it was originally going to be a pump and dump system, but I really didn't feel good about that, for all the reasons stated already. The designers of the system, a couple of NH engineers, then came up with an elegant solution:
1. They created a manifold with an on-site PVC (?) welder that split the 2" line coming from the house into two 3/4" loops, with welded return bends on the ends of each.
2. They fashioned a large wire spool (4' diameter) on a stand so it could rotate.
3. Using the spool, they wound up my well pipe, with pump on the end, and removed all the plastic spacers I had so carefully positioned when I put it in.
4. They then fed the four 3/4" lines (2 loops) back down the well hole (std. 6"), along with the pump and water line. The loops effectively replaced the plastic spacers. They weren't able to get it back down as far as it had been, but still got about 200' of loop into the well (with the water pump below that); static's at 80'.
5. Welded up the manifold to the two loops, connected to the 2" lines going back into the house, installed two Grundfos circulators in series, and I then had an 8-1/2 gpm recirculating loop.
All lines were 8' or more below the surface, so it's all just water, no need for A-F.As it was a closed system, the water in the loop was filtered well and then treated. It's hooked up to a valve inside so I can replace and/or flush the loop when needed. Twenty-three years and counting.... Still has the original Grundfos pumps, still runs @ 8.5gpm with a 6 degree+/- TD on the loop. I do augment with a wood stove; we have the coldest tap water in the state, I think, in the winter!
It ain't real pretty sitting in my basement, but it sure does work. I envy you guys who have the newer systems-- mine uses R-22 and has a 3.25 COP; I'm drooling over the new ones with a COP of 5!!
In all those years, I've replaced both TXVs, all 3 check-valves ("cheap" Singers/Gemlines), one reversing valve, and repaired a couple of leaks. Not bad, methinks. Oh- it also makes hot water... and in the summer can take house heat and put it directly into DHW.
Clever, those NH engineers.Attachments
2manyrocks
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irvingj, how many square feet does your unit serve and BTU capacity does your unit have? I am curious what size you have because your system has successfully run on a 200' loop in your well?
buckeyefarmer
Super Star Member
Thanks for sharing your experience!
You've done good. I know a guy who got over 30 yrs with his homemade Geo system. He just replaced it with a new waterfurnace, only because of the age and the rebates.
A COP of 3.25 isn't bad. Most will not get 5 out of the new systems. The TT Tranquility 27 spec sheet shows COP's ranging from 3.6 to 4.0 at full load. At partial load, they run from 3.9 to 4.6. They all advertise their best numbers, but actual situation will be a little less most likely.
COP is the performance of the unit for the heat cycle. If you use electric heat, for every 1 KW (3413 btu) of electric used you get 1 KW of heat, or a COP of 1. You will never get better. For Geothermal with a COP of 5, you are using 1 KW of electric to get the equivalent of 4 more KW of heat from the ground, for a total heat output of 5 KW from the 1 KW used.
And all the free hot water you want in the summer with the desuperheater option.
Great systems, can't wait to get mine done.
2manyrocks (sounds like NH!): My house is a post and beam, built like a walk-in cooler; exterior is foam panels with sheathing in & out, foam is 10". R-39 all around, walls & roof.
House is about 1800 sq ft, heat pump is a ... 3 or 3-1/2 ton, if I remember correctly. Design heat loss @ 0 degrees is around 20KBTU. Sounds impossible, but I heated the whole house --and basement-- with an electric 17.5KBTUH heater the first winter when I ran out of wood (heat pump wasn't hooked up yet). Ran pretty much constantly for a few days, but it did the job. The electric bill was horrendous, however!
The heat pump was sort of hand made by these two guys, a one-of-a-kind. Has a desuperheater coil plumbed in to DHW with a single Grundfos, as well as a dedicated DHW heat exchanger, whose extra water line opens via a HP regulator after second reversing valve cuts in. This is in addition to the usual refrigerant-to-water well loop heat exchanger and air coil. The extra DHW refigerant-to-water coil is that "bump" sticking out in the front bottom.
It's complex, but it's held up pretty well. Guess I did also replace a couple of octal-base relays, now that I think about it. It has no electric back-up resistance heat- I didn't want it installed, it's still sitting somewhere in the basement...
Here's a couple of views of the house, south & north sides.
House is about 1800 sq ft, heat pump is a ... 3 or 3-1/2 ton, if I remember correctly. Design heat loss @ 0 degrees is around 20KBTU. Sounds impossible, but I heated the whole house --and basement-- with an electric 17.5KBTUH heater the first winter when I ran out of wood (heat pump wasn't hooked up yet). Ran pretty much constantly for a few days, but it did the job. The electric bill was horrendous, however!
The heat pump was sort of hand made by these two guys, a one-of-a-kind. Has a desuperheater coil plumbed in to DHW with a single Grundfos, as well as a dedicated DHW heat exchanger, whose extra water line opens via a HP regulator after second reversing valve cuts in. This is in addition to the usual refrigerant-to-water well loop heat exchanger and air coil. The extra DHW refigerant-to-water coil is that "bump" sticking out in the front bottom.
It's complex, but it's held up pretty well. Guess I did also replace a couple of octal-base relays, now that I think about it. It has no electric back-up resistance heat- I didn't want it installed, it's still sitting somewhere in the basement...
Here's a couple of views of the house, south & north sides.
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2manyrocks
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thanks a bunch. I'm in middle TN and have no idea why I'm blessed with so many rocks. They ooze out of my garden every time I till it.
The R-39 panels explain a lot of how you're able to heat with only 3-4 tons in NH. You're heating a very tightly insulated house.
Sometimes homeowners think they are heating 1800 SF for example, but their house is so leaky, that they are effectively trying to heat the great outdoors. I remember talking to one engineer who shocked me because he refused to size any structure without running a blower door test to determine how leaky it was before he would size a system.
I'm still amazed that your loop is 200' for your system. What kind of pipe is used in your loop?
Your system appears to have been so well thought out that it may be a challenge to find a replacement. Are those engineers that designed your system still around?
The R-39 panels explain a lot of how you're able to heat with only 3-4 tons in NH. You're heating a very tightly insulated house.
Sometimes homeowners think they are heating 1800 SF for example, but their house is so leaky, that they are effectively trying to heat the great outdoors. I remember talking to one engineer who shocked me because he refused to size any structure without running a blower door test to determine how leaky it was before he would size a system.
I'm still amazed that your loop is 200' for your system. What kind of pipe is used in your loop?
Your system appears to have been so well thought out that it may be a challenge to find a replacement. Are those engineers that designed your system still around?
I don't know where the engineers are now... the heat pump was part of a package deal with a now-defunct outfit called Northern Energy Homes based in Norwich, VT in the 80s.
The house was obviously built to be super insulated and tight; the white PVC pipes visible on the north side of the house are from an air-to-air heat exchanger which was also part of the deal. Incoming outside air is heated (an aluminum heat exchanger) by exhausting air. Efficiency is purported to be in the 95% range, and, assuming I keep it clean (1X per year), it'll bring in fresh outside air at 48-50 when it's -20 outside and indoor ambient is 70. Exhaust air is drawn from the bathroom vents and one between the laundry room & kitchen. Drips water pretty well when it's cold out, and it is equipped with a freeze-stat which turns off the intake fan while leaving the exhaust on for defrosting. I highly recommend it- Boss-Aire is the manufacturer. (Others use a single fan motor on a double-ended shaft, which require a motorized damper for closing off intake during defrost.)
Northern Energy Homes died when the 80s went bust, along with a lot of other companies; last I heard those heat pump designers went to work with one of the major players in the then-new water-source heat pump industry; I certainly hope they did!
The loop pipes are a black plastic, somewhat flexible; I don't know if they're PVC or a polyethylene type. A long length can easily be flexed, but a short piece could be used as a weapon, it's so hard! Pretty tough stuff.
The hope I have is that, when it comes time for replacement, the loop will simply remain intact and be hooked up to the new inside unit. I don't see why that wouldn't work. However, it appears that, other than a desuperheater, I may have to forego a dedicated DHW circuit. I can live with that--- It's really not that effective in the winer heating season anyway, as once the water's up to temp on DHW, when the system switches into house heat the head pressure's low enough that it takes heat OUT of he DHW loop (via the desuperheater)-- condensing temp's around 90, so if the DHW's hotter than that....
What happens is that the machine goes back & forth between DHW and house heat without ever stopping. I've circumvented that by dropping the dedicated DHW t-stat to it's lowest setting (85?) so it never comes on. Because of the desuperheater, however, when it's cold and the unit's cranking for house heat, it'll keep my 80-gallon electric hot water heater right around 90; if I want hot water, I just switch on the upper electric element and I have 125 in about ten minutes or less, then switch off the electric heater after morning showers or laundry.
I grew up in a 200-year-old cape, and lived with that leaky, frosty, drafty, oil-sucking, constantly-in-need-of-repairs behemoth.... decided I didn't want to go through that again! My house was relatively expensive at the time ($120K in 1985), but I bit the bullet and never regretted it. (Well, maybe once or twice in the early years....) Now, it's really nice to "boast" about how efficient it is!
The house was obviously built to be super insulated and tight; the white PVC pipes visible on the north side of the house are from an air-to-air heat exchanger which was also part of the deal. Incoming outside air is heated (an aluminum heat exchanger) by exhausting air. Efficiency is purported to be in the 95% range, and, assuming I keep it clean (1X per year), it'll bring in fresh outside air at 48-50 when it's -20 outside and indoor ambient is 70. Exhaust air is drawn from the bathroom vents and one between the laundry room & kitchen. Drips water pretty well when it's cold out, and it is equipped with a freeze-stat which turns off the intake fan while leaving the exhaust on for defrosting. I highly recommend it- Boss-Aire is the manufacturer. (Others use a single fan motor on a double-ended shaft, which require a motorized damper for closing off intake during defrost.)
Northern Energy Homes died when the 80s went bust, along with a lot of other companies; last I heard those heat pump designers went to work with one of the major players in the then-new water-source heat pump industry; I certainly hope they did!
The loop pipes are a black plastic, somewhat flexible; I don't know if they're PVC or a polyethylene type. A long length can easily be flexed, but a short piece could be used as a weapon, it's so hard! Pretty tough stuff.
The hope I have is that, when it comes time for replacement, the loop will simply remain intact and be hooked up to the new inside unit. I don't see why that wouldn't work. However, it appears that, other than a desuperheater, I may have to forego a dedicated DHW circuit. I can live with that--- It's really not that effective in the winer heating season anyway, as once the water's up to temp on DHW, when the system switches into house heat the head pressure's low enough that it takes heat OUT of he DHW loop (via the desuperheater)-- condensing temp's around 90, so if the DHW's hotter than that....
What happens is that the machine goes back & forth between DHW and house heat without ever stopping. I've circumvented that by dropping the dedicated DHW t-stat to it's lowest setting (85?) so it never comes on. Because of the desuperheater, however, when it's cold and the unit's cranking for house heat, it'll keep my 80-gallon electric hot water heater right around 90; if I want hot water, I just switch on the upper electric element and I have 125 in about ten minutes or less, then switch off the electric heater after morning showers or laundry.
I grew up in a 200-year-old cape, and lived with that leaky, frosty, drafty, oil-sucking, constantly-in-need-of-repairs behemoth.... decided I didn't want to go through that again! My house was relatively expensive at the time ($120K in 1985), but I bit the bullet and never regretted it. (Well, maybe once or twice in the early years....
) Now, it's really nice to "boast" about how efficient it is!
OP
Richard
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Another angle on the ground loop system for a Geothermal setup...
It dawned on me that if I did one of these, there might be some merit in laying one of those magnetic tapes over the top of it so it could be located in the future if need be.
1. Prudent?
2. Where do you get this stuff?
3. If used, what do you use to FIND this stuff once buried?
4. Any other way to mark it better than the magnetic tape?
5. Given the power company uses it, would you be "allowed" to use it since it might imply power is down there instead of water?
It dawned on me that if I did one of these, there might be some merit in laying one of those magnetic tapes over the top of it so it could be located in the future if need be.
1. Prudent?
2. Where do you get this stuff?
3. If used, what do you use to FIND this stuff once buried?
4. Any other way to mark it better than the magnetic tape?
5. Given the power company uses it, would you be "allowed" to use it since it might imply power is down there instead of water?
