I have combined the following two posts from "Green Building Talk" into this thread in hopes of obtaining some expertise or direction. I am building in the coming months and am willing to experiment IF the science is solid. Proposed is a two well (source and recharge) geo setup.
This is a proposed alternative to the traditional domestic well pump scenario with the associated head lift/high-pressure/energy consumption problem:
Post #1:
[ Since a [submergized] domestic well pump when being used for geo pressurizes the water to 35-50 psi and lifts it to the house with low efficency can the following method be used instead:
1. install a second 3/4 or 1" geo water source pipe in the supply well placed alongside the normal pipe from the submergized water pump. Maybe use a "deep-well jet pump" pitless adaptor (a dual fitting for two pipes) for the casing connection to handle the two pipes...
2. install a check-valve at the bottom of the geo source pipe and drill a smallish "bleed" hole above the valve (for priming purposes).
3. run this second pipe to the house and connect via a "T" to 1) a valve that is connected to the cold domestic water supply (high pressure water) and 2) a small "jet-pump" or simply a normal circulator pump with decent head.
4. this circulator pump (or small jet-pump) feeds the geo exchanger and then the dump side continues via pipe to a second [recharge] well. This return pipe continues via a pitless adaptor and pipe down to somewhere permanently below any static water level in the second well.
5. the valve in the house would be used only to prime the supply pipe and small pump.
The standing water levels in both wells would obviously vary depending on many reasons. However, wouldn't the small water pump only have to overcome the following flow resistances: total pipe length restrictions + geo exchanger head loss + any difference between the standing water levels in the two wells. If the standing water levels are roughly equal then the little pump only needs to overcome pipe and exchanger resistance and would not encounter much lift [gravity] resistance.
If I understand correctly it's a combination of lifting the well water to the surface and pressurizing to a high-level is what uses so much energy. This seems to solve both problems. Would this work better than using a varible frequency motor well pump or a domestic use/pressure adjusting method?
Also it seems this configuration would be free from a flow direction that otherwise would be dictated by the domestic water pump. In otherwords depending on well yields and the static levels maybe we could use one well to supply the geo and dump into the domestic source well. This way the water use load is split between the wells and not all coming from just one well. ]
Post #2:
[ Location is SW Montana; estimated 4 to 5 tons required (sorry, no precise heat calc performed yet for a well-insulated house). Proposed GSHP system type; WaterFurnace Synergy 3D or rough equal for radiant floor (gypcrete thin-slab), forced air AC (electric strip backup), & desuperheater.
There is plenty of flat land to work with so any system type could be installed. My biggest horizontal closed-loop concern: very soft, powdery loamy+fine sandy soil (no rocks at all a good thing), soil will have low conductivity issues and is very dry even at at 8' down (only 10" annual precip)...probably have to use a soaker for a horizontal loop.
A domestic water well will need to be punched anyway and may be upsized for light irrigation purposes and yield boost. Adjacent properties have both residential and some irrigation wells averaging 250' to 275' deep with standing water to 100' of surface. Yields are almost always high: between 25 to 35+ gpm. Precise water quality is unknown but adjacents don't have or need water softening systems (anedotal evidence only, no test data available yet). Bedrock depth is usually between 50 to 120'. Groundwater temp in the area is reported at 55 to 56 degrees.
This is new construction and I am weighing all pros/cons/costs. The cost of the second well is mostly offset by not having to buy and bury a couple of 1000 gallon propane tanks so it would come down to the Geo equipment upgrade costs versus conventional high-eff. propane equipment. For cost estimating I'm also guessing the return well would be drilled down to the same depth and aquafer as the supply well. ]
The last paragraph of post #1 has additional implications. I am considering light irrigation over part of the property. If the geo source well returns [dumps} into the domestic water source well, then in the summer months when both AC and irrigation are both needed then the two wells in essence share the load...thinking of it as a sortof parallel source well arrangement. Can the domestic source well also function as the geo recharge well?
Any and all constructive thoughts or directions to existing bodies of work on this subject are greatly appricated. Again, I am willing to to pony the $$ to "experiment" with this but I will need to see the science and pitfalls first.
Thump
This is a proposed alternative to the traditional domestic well pump scenario with the associated head lift/high-pressure/energy consumption problem:
Post #1:
[ Since a [submergized] domestic well pump when being used for geo pressurizes the water to 35-50 psi and lifts it to the house with low efficency can the following method be used instead:
1. install a second 3/4 or 1" geo water source pipe in the supply well placed alongside the normal pipe from the submergized water pump. Maybe use a "deep-well jet pump" pitless adaptor (a dual fitting for two pipes) for the casing connection to handle the two pipes...
2. install a check-valve at the bottom of the geo source pipe and drill a smallish "bleed" hole above the valve (for priming purposes).
3. run this second pipe to the house and connect via a "T" to 1) a valve that is connected to the cold domestic water supply (high pressure water) and 2) a small "jet-pump" or simply a normal circulator pump with decent head.
4. this circulator pump (or small jet-pump) feeds the geo exchanger and then the dump side continues via pipe to a second [recharge] well. This return pipe continues via a pitless adaptor and pipe down to somewhere permanently below any static water level in the second well.
5. the valve in the house would be used only to prime the supply pipe and small pump.
The standing water levels in both wells would obviously vary depending on many reasons. However, wouldn't the small water pump only have to overcome the following flow resistances: total pipe length restrictions + geo exchanger head loss + any difference between the standing water levels in the two wells. If the standing water levels are roughly equal then the little pump only needs to overcome pipe and exchanger resistance and would not encounter much lift [gravity] resistance.
If I understand correctly it's a combination of lifting the well water to the surface and pressurizing to a high-level is what uses so much energy. This seems to solve both problems. Would this work better than using a varible frequency motor well pump or a domestic use/pressure adjusting method?
Also it seems this configuration would be free from a flow direction that otherwise would be dictated by the domestic water pump. In otherwords depending on well yields and the static levels maybe we could use one well to supply the geo and dump into the domestic source well. This way the water use load is split between the wells and not all coming from just one well. ]
Post #2:
[ Location is SW Montana; estimated 4 to 5 tons required (sorry, no precise heat calc performed yet for a well-insulated house). Proposed GSHP system type; WaterFurnace Synergy 3D or rough equal for radiant floor (gypcrete thin-slab), forced air AC (electric strip backup), & desuperheater.
There is plenty of flat land to work with so any system type could be installed. My biggest horizontal closed-loop concern: very soft, powdery loamy+fine sandy soil (no rocks at all a good thing), soil will have low conductivity issues and is very dry even at at 8' down (only 10" annual precip)...probably have to use a soaker for a horizontal loop.
A domestic water well will need to be punched anyway and may be upsized for light irrigation purposes and yield boost. Adjacent properties have both residential and some irrigation wells averaging 250' to 275' deep with standing water to 100' of surface. Yields are almost always high: between 25 to 35+ gpm. Precise water quality is unknown but adjacents don't have or need water softening systems (anedotal evidence only, no test data available yet). Bedrock depth is usually between 50 to 120'. Groundwater temp in the area is reported at 55 to 56 degrees.
This is new construction and I am weighing all pros/cons/costs. The cost of the second well is mostly offset by not having to buy and bury a couple of 1000 gallon propane tanks so it would come down to the Geo equipment upgrade costs versus conventional high-eff. propane equipment. For cost estimating I'm also guessing the return well would be drilled down to the same depth and aquafer as the supply well. ]
The last paragraph of post #1 has additional implications. I am considering light irrigation over part of the property. If the geo source well returns [dumps} into the domestic water source well, then in the summer months when both AC and irrigation are both needed then the two wells in essence share the load...thinking of it as a sortof parallel source well arrangement. Can the domestic source well also function as the geo recharge well?
Any and all constructive thoughts or directions to existing bodies of work on this subject are greatly appricated. Again, I am willing to to pony the $$ to "experiment" with this but I will need to see the science and pitfalls first.
Thump
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