geothermal ground loop systems

[toplessHO]

with open loop it was pretty easy to get water temps,I have a spigot right next to the cycling valve
I can test water temp at after it goes thru system.
My thought on monitoring of loop returns is sensors at the inlet to manifold.
doing each loop will tell me if theres a problem.

Ive never used Petes plugs but have used drywells for temp
Unit here is geared towards cooling,has a heat recovery unit factory installed for domestic hot water

 

[My Old Tools]

My geothermal Waterfurnace uses our 50 acre lake. Yes, it approaches 90 degrees in summer and 40 in winter. It's still much more effective than air. Think about a red hot piece of steel. Would you rather blow cool air on it or dunk it in 90 degree water? My system uses a stainless steel lake plate for the heat exchanger. Bill's are $200+ a month cheaper than last year.

 

[Fav Onefour]

Interesting idea to check each loop. It might nice to know. I've never really worried about it much. My main house has the manifold buried nine feet down, so that isn't even an option.
Quite a few of the horizontal fields run the loops all the way into the home. Out of curiosity, I have used an IR reader to see on some just to compare. Unfortunately, the loops are usually not labeled. Most of the horizontal slinky systems are laid in one big open trench. There would not be much fixing if one loop is acting up.

Honestly, the loop field isn't something that even crosses my mind very often. With a proper manifold, there isn't much to monitor. The Pete's plug readings are used to see how well the system is extracting temp differential. With open loops, I'm guessing you always have a rough idea of the inflow temp. The spigot reading would give you the differential.

 

[toplessHO]

just talked to factory for design of the loops
It says 77* closed loop only needs 9 GPM for my 4 ton unit.

 

[toplessHO]

If you have a pond, why not drop a plate in it and do a closed loop system that way?

lake next door is spring fed
Son checked the surface temp yday 91* at about 1 ft down in middle of lake above the spring.
Its Hot!

 

[toplessHO]

I did some test bores down by the pond
50 ft away from water I went 2 ft down and got wet sand.
If I start at that area and work back towards house at a depth of 6 ft
I should stay in wet sandy soil for at least the 80ft for a slinky.
Im toying with the idea of a vertical slinky using a trencher.
2 other options are 2 ft wide ditch with a slinky on both walls
and the open pit with wall to wall slinkys.For that I would need a big loader.
Now looking for a source of 600 or 800 ft rolls of HDPE SDR-11.

 

[bb29510]

i saw one where they had two wells, one pump out and then went through sytem and pump back into second well

 

[toplessHO]

thats the most eco friendly solution but you still have a large pump in the equation

 

[Fav Onefour]

i saw one where they had two wells, one pump out and then went through sytem and pump back into second well

I've heard of that style. I wonder if they are using cased wells? Not aware of any being used in our area. I'm not sure why, but I have some guesses.

Good water flow depths vary a lot around here. Most of the shallow wells tend to have hard water and that would probably be a deal breaker. It's not uncommon to see two sites within a mile vary by a few hundred feet in well depth to reach good water flow. Our farm has two hard water sixty footers while a bunch of neighbors were drilling over three hundred and still running dry. They had good soft water, but poor supply. Quite a few of the deep wells hit a granite layer. Drilling with casing could be a **** shoot and multiple wells might get crazy. In fact, I bet regs wouldn't allow backflow below the granite. We have to do a lot of fancy stuff around wells if we punch through granite.

@toplessHO , Your idea of using a two foot wide ditch with vertical slinky is interesting. How well does your sandy soil hold a wall? Backfilling without collapsing and kinking the loop might be an interesting challenge.
Our most common method is the open pit in wet soils. With high demand for heat loads, we dig big pits at eight feet depth. It's not uncommon to run 800 ft per ton.

 

[toplessHO]

we are geared towards cooling
about 10 months a year the ac IS ON.

Yea the thought of cave ins has crossed my mind
I may need to do the open pit for the slinky and backhoe for the return and supply lines going to the loops.

Backfilling the vertical slinkys is done with washing the sand in between the tubing

 

[Fav Onefour]

Thanks for clairification on the process backfilling vertical slinkys. We don't often deal with large quantities of sand soil. Our area is primarily glacial outwash and the sand is in pockets often on hill tops. It's a bad combo for conductive drain fields. In fact, there is a large system in our area that was installed on a sand hill that has been a nightmare. They have been running sprinklers on the field to keep moisture in the sand.

 

[toplessHO]

consider using the septic drainfield to keep the moisture in

Maybe a clay mix was needed on that sand hill.