buckeyefarmer
Epic Contributor
When I took my training they said don’t dump it back into aquifer.
geothermal questions and possible DIY
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When I took my training they said don’t dump it back into aquifer.
Valveman
Platinum Member
A lot of open loop heat pumps use an injection well or even inject back into the same well. If heating the water through the heat pump causes any minerals to precipitate out of solution, the solids can plug the injection well. Water test need to be done to make sure there are no solids in the discharge water, and if there are a filter is needed. With a shallow water table an open loop heat pump can be more efficient than a closed loop. But as the water level gets deeper the open loop system requires more energy. A lot of people use a Cycle Stop Valve on their open loop well pump. It doesn't matter how much energy a heap pump can save if it is cycling the well pump to death and causing expensive repairs too often.
Popgadget
Elite Member
The outgoing water from my heat pump is about 45 degrees in heat mode and 65 in AC. Neither is going to precipitate anything out of the water, or cause deposits to form in the heat exchanger. My supply and return wells are over 200 ft deep, but that is inconsequential, because the static water level is not very deep, and that is what determines the load on the pump.
truckdiagnostics
Platinum Member
We are in the process of redoing ours which has been in for 25 years. We have two closed loops burried at 6 feet and for the most part it is sized correctly. One feeds the house the other the shop and office. The loop for the shop and office I have had the water in the spring when the frost goes deep going back into the loop below freezing. It was sized right for the shop then I added an air handler and water coil for the office. Having a good loop is a big deal. Loop used for the house never had issues.
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The unit in the house is a split system it makes domestic hot water then switches to an evaporator for forced air for heating and cooling. In 25 years it has had new compressor and evaporator. Unit in the shop is water to water I got it used out of an apartment building it is bullet proof. All i have put in is a start capacitor. It is 28 years old. IMO you don't want a split system there is a better way to do it. You want to use a water to water.
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When we sized the spit unit we sized it for potable hot water. Then on the AC size it was to large, and it does not like it when you slow the blower down. You don't get the dehumidification, rots out the evap core. don't know what the deal was with the compressor. How they solved the problem is they sell a split system where everything is variable. Well, the problem is everything is variable they are a control and repair nightmare. Don't want one.
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Here is how we are going to get there. Split unit from the house is going to the shop, that gets me AC in my older years and it will be happy running full out on ac and getting the right sized ducts is not an issue. A water coil does not care about the air flow across it. The coil from the office is going to go to the house on top of a forced air gas furnace that we will use as an air handler and back up. I will take the water to water from the shop and move it to the house. Here is the neat part we are going to add another water-to-water unit to the loop for the house.
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We are going to install a loop buffer tank. So the loop will go in and out and two water to water units. Now here is where this pays off in the summer. In theory if you have the same load for hot and cold water you don't need the loop because they are mixing in the buffer tank. Then when the water gets either too cold or hot we run the loop pumps. We then have 4 stages of heating and cooling. It is all plumbing, all the valves are out where you can get too, not in a box the size of a refrigerator.
___________
The unit in the house is a split system it makes domestic hot water then switches to an evaporator for forced air for heating and cooling. In 25 years it has had new compressor and evaporator. Unit in the shop is water to water I got it used out of an apartment building it is bullet proof. All i have put in is a start capacitor. It is 28 years old. IMO you don't want a split system there is a better way to do it. You want to use a water to water.
____________
When we sized the spit unit we sized it for potable hot water. Then on the AC size it was to large, and it does not like it when you slow the blower down. You don't get the dehumidification, rots out the evap core. don't know what the deal was with the compressor. How they solved the problem is they sell a split system where everything is variable. Well, the problem is everything is variable they are a control and repair nightmare. Don't want one.
_____________
Here is how we are going to get there. Split unit from the house is going to the shop, that gets me AC in my older years and it will be happy running full out on ac and getting the right sized ducts is not an issue. A water coil does not care about the air flow across it. The coil from the office is going to go to the house on top of a forced air gas furnace that we will use as an air handler and back up. I will take the water to water from the shop and move it to the house. Here is the neat part we are going to add another water-to-water unit to the loop for the house.
___________________
We are going to install a loop buffer tank. So the loop will go in and out and two water to water units. Now here is where this pays off in the summer. In theory if you have the same load for hot and cold water you don't need the loop because they are mixing in the buffer tank. Then when the water gets either too cold or hot we run the loop pumps. We then have 4 stages of heating and cooling. It is all plumbing, all the valves are out where you can get too, not in a box the size of a refrigerator.
ponytug
Super Member
@truckdiagnostics I like the loop buffer tank idea! Stanford University redid their energy plant awhile back, and put in some monstrous hot and chilled water tanks.
Here is a photo before the insulation went on;
There are a couple of workers on floor (roof) in the lower right below for scale.
All the best,
Peter
Here is a photo before the insulation went on;
There are a couple of workers on floor (roof) in the lower right below for scale.
All the best,
Peter
truckdiagnostics
Platinum Member
With that said on the straight up geo. The correct sized and installed closed loop. Then two water to water reversing heat pumps. Buffer on the loop side. Use a chilled water coil for forced air AC. You will need a buffer here also. Then you can get your in floor from this tank in winter. (remember you have forced air gas, so you can stay on chilled water for those duel heat weeks)Then pipe to an indirect hot water tank for your potable. In our case the loop for the house will support 4 tons no problem. So when the 5 ton from the shop poops out if ever, it will become a 2 ton two stage. (we will have two 2 tons)Near as I can figure that ticks all the boxes. This thing is going to run for 25 years, it needs to be build so it is easy to repair. (its all piping and a lot of glycol)Chances are the guy that put it in won't be fixing it. What i have just described is simple and workable, with the correct shut offs and what not it should be essay to repair. The unit inside a box the size of a frig just is not.
I'll post in the next couple days what we are up too.
I'll post in the next couple days what we are up too.
IXLR8
Veteran Member
I want to redo the heating/cooling system in my house. Researched geothermal, closed loop is not used around here due to all the trees. Open loop is what all the installers are familiar with. I was told they drill one well/ton of cooling, for me that would be 4 wells. Total system cost, just over $40K. Top of the line variable speed air to air system with propane backup was going to run $14K. As much as I like the idea of a geothermal system, I'm not sure I would ever make up that $26K difference.
ponytug
Super Member
This is exactly the issue with geothermal.
Geothermal has some theoretical efficiency advantages, but isn't very much compared to modern air source heat pumps. On a ROI basis, the added cost of a geothermal installation can't come close to making up the lower upfront costs and generally high efficiency of air sourced heat pumps.
Locally, the ROI on geothermal is never.
All the best,
Peter
Popgadget
Elite Member
As a long time geothermal user and advocate, I agree with your assessment. The air to air units have gotten exponentially better over the decades. It is 19 degrees as I type this, and the air to air in my shop is doing fine, has not needed the propane furnace at all.
Of course the open loop geo in the house is also doing well and has no backup heat source, as it is never needed. But it would be hard to justify today.
Of course the open loop geo in the house is also doing well and has no backup heat source, as it is never needed. But it would be hard to justify today.
Grumpycat
Veteran Member
But often it does. It can not when it costs $200/hr to dig a ditch.
