CT Droid
CT Bot
So I guess some background, as I don't think I gave much....
We have a 3200 sq ft house, not counting the unfinished basement, that we want the unit to be able to heat. We currently have a 4 ton air exchange heat pump, and I'm dis-satisfied with its heating capabilities. Our duct work is more than sufficient for a new geo furnace, so really it's just a device swap out.
There are 4 basic ways to go with geothermal, and I won't go into great detail here...there's much better sites out there for describing the differences.
Pond/Lake exchange - Can't, there ain't one near.
Horizontal Looops - Can't, not enough cleared land (and I won't kill our trees to accomplish the least efficient method)
Vertical Loops - Definitely a contender
Open Loop (well) - Preferred method.
The main things they say about doing open loop, with your existing water well, is that the water has to be sufficient quality and quantity. Well, quality basically revolves around if there is iron and/or sulfur in the water. Having lived with this water for 2 years, if we had an iron problem sufficient to be a problem with geothermal, then we would have seen the red results in our sinks and toilets by now. So, iron isn't a problem. With sulfur, the water quality test guy told me "If you can't smell it, then you don't have it". And we've been rotten egg smell-free, so no issues there either.
As to quantity...from what our well contractor told us, there is PLENTY of water in the ground for the having. We basically can't pump our well dry through normal usage.
Now, once you pump that water into your house, it's got to go out somewhere. If you had a lake nearby, you could probably dump it there. Streams are also a candidate, though I understand you might run into environmental regulations if you do that. *shrug* Doesn't really matter, neither of those are an option for me. So, the other way to get rid of that water is to put it right back into the ground. You have to dig another well, and hope to heck that at some point in the drilling process, they find a crevasse or cavern....something where their air doesn't return to the surface. That's where you know you can dump water and it will go away. It's not completley hopeless, since our well contractor lost his air return when drilling our water well....so we can hope he'll do that again, and not too far down from the surface. It's still one rather large gamble, though.
Finally, your existing well pump has to be of sufficient size to handle the load. And you'll usually need a bigger pressure tank. Turns out we don't need a larger one because we opted to go with a constant pressure pump system, instead of the on/off type. So, it uses just enough pump power to maintain the pressure, instead of bringing on the full power to reach the set point and cutting off. So that's good at least. So the remaining question was....can our pump meet the needs of the geothermal unit at max capacity, AND our normal household needs too. And today I learned that it is a most highly probably NOT.
First, I wanted to see what our theorhetical max gpm was. I turned on the outside hose and set it to full open. That produced just about 12 gpm. I then went inside and turned on the kitchen sink. I already noticed a decrease in pressure. The sink was giving just about 1 gpm. I went and checked the water pressure, and it was holding steady at 38 psi, and the well pump was steady at 2500 watts. Our normal water pressure is 55 psi, so I knew the pump was already giving all it could. So basically, it could do 13 gpm, and at that point, well be noticing a definite decrease in water pressure.
I then wanted to see what the max gpm was at a pressure we would consider reasonable. So I adjust the hose outside to 8 gpm, and the pump was bouncing between 1800 and 2500, as was the water pressure reading (52 to 55). So I opened the kitchen sink again, and measured 1.5 gpm. Pump was still slightly oscillating in power usage, so I opened another sink and got 1.5 gpm out of that too. Now the pump was going full out at 2500 watts, and the pressure was holding rock steady at 50 psi. So I decided that was the max rate at a pressure were used to....11 gpm @ 50 psi.
Water Furnace says that for their 4 ton systems, it is just under 2 gpm per ton....so that's 8 gpm if the thing is using both stages (2 tons per stage). That means, should it be running full speed, that we'll only have 3 gpm left to use in household type situations before we start losing pressure. That's 2 sinks, or 2 showers, or probably 1 laundry machine....in other words, that's an uncomfortable margin for me.
So this is the first bummer about all this....its bad enough we're replacing a perfectly fine air exchange heat pump (and still paying for it in our mortgage), but if we have to start replacing well pump components too, this is going to spiral out of range real quickly. If enough gets replaced, then we'll begin to move into the realm where closed loop vertical wells is more cost effective for installation. I really won't know until the well driller comes out and we discuss the situation.
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We have a 3200 sq ft house, not counting the unfinished basement, that we want the unit to be able to heat. We currently have a 4 ton air exchange heat pump, and I'm dis-satisfied with its heating capabilities. Our duct work is more than sufficient for a new geo furnace, so really it's just a device swap out.
There are 4 basic ways to go with geothermal, and I won't go into great detail here...there's much better sites out there for describing the differences.
Pond/Lake exchange - Can't, there ain't one near.
Horizontal Looops - Can't, not enough cleared land (and I won't kill our trees to accomplish the least efficient method)
Vertical Loops - Definitely a contender
Open Loop (well) - Preferred method.
The main things they say about doing open loop, with your existing water well, is that the water has to be sufficient quality and quantity. Well, quality basically revolves around if there is iron and/or sulfur in the water. Having lived with this water for 2 years, if we had an iron problem sufficient to be a problem with geothermal, then we would have seen the red results in our sinks and toilets by now. So, iron isn't a problem. With sulfur, the water quality test guy told me "If you can't smell it, then you don't have it". And we've been rotten egg smell-free, so no issues there either.
As to quantity...from what our well contractor told us, there is PLENTY of water in the ground for the having. We basically can't pump our well dry through normal usage.
Now, once you pump that water into your house, it's got to go out somewhere. If you had a lake nearby, you could probably dump it there. Streams are also a candidate, though I understand you might run into environmental regulations if you do that. *shrug* Doesn't really matter, neither of those are an option for me. So, the other way to get rid of that water is to put it right back into the ground. You have to dig another well, and hope to heck that at some point in the drilling process, they find a crevasse or cavern....something where their air doesn't return to the surface. That's where you know you can dump water and it will go away. It's not completley hopeless, since our well contractor lost his air return when drilling our water well....so we can hope he'll do that again, and not too far down from the surface. It's still one rather large gamble, though.
Finally, your existing well pump has to be of sufficient size to handle the load. And you'll usually need a bigger pressure tank. Turns out we don't need a larger one because we opted to go with a constant pressure pump system, instead of the on/off type. So, it uses just enough pump power to maintain the pressure, instead of bringing on the full power to reach the set point and cutting off. So that's good at least. So the remaining question was....can our pump meet the needs of the geothermal unit at max capacity, AND our normal household needs too. And today I learned that it is a most highly probably NOT.
First, I wanted to see what our theorhetical max gpm was. I turned on the outside hose and set it to full open. That produced just about 12 gpm. I then went inside and turned on the kitchen sink. I already noticed a decrease in pressure. The sink was giving just about 1 gpm. I went and checked the water pressure, and it was holding steady at 38 psi, and the well pump was steady at 2500 watts. Our normal water pressure is 55 psi, so I knew the pump was already giving all it could. So basically, it could do 13 gpm, and at that point, well be noticing a definite decrease in water pressure.
I then wanted to see what the max gpm was at a pressure we would consider reasonable. So I adjust the hose outside to 8 gpm, and the pump was bouncing between 1800 and 2500, as was the water pressure reading (52 to 55). So I opened the kitchen sink again, and measured 1.5 gpm. Pump was still slightly oscillating in power usage, so I opened another sink and got 1.5 gpm out of that too. Now the pump was going full out at 2500 watts, and the pressure was holding rock steady at 50 psi. So I decided that was the max rate at a pressure were used to....11 gpm @ 50 psi.
Water Furnace says that for their 4 ton systems, it is just under 2 gpm per ton....so that's 8 gpm if the thing is using both stages (2 tons per stage). That means, should it be running full speed, that we'll only have 3 gpm left to use in household type situations before we start losing pressure. That's 2 sinks, or 2 showers, or probably 1 laundry machine....in other words, that's an uncomfortable margin for me.
So this is the first bummer about all this....its bad enough we're replacing a perfectly fine air exchange heat pump (and still paying for it in our mortgage), but if we have to start replacing well pump components too, this is going to spiral out of range real quickly. If enough gets replaced, then we'll begin to move into the realm where closed loop vertical wells is more cost effective for installation. I really won't know until the well driller comes out and we discuss the situation.
This thread is not open. If you wish to respond, please respond using the original blog entry link. View the original blog entry
