geothermal questions and possible DIY

[LD1]

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.

That's not open loop. Open loop would only require 1 or 2 wells....depending on where you choose to discharge.

4 vertical wells is still closed loop. They just put the loop vertically in the wells instead of trenched horizontally in the ground.

And $10k per well seems a little steep IMO.

Maybe 10k for one water well I can understand. Because alot of cost to mobilize and ser equipment up. But 4 wells in one location for $40k just don't seem right. But I'm not a water well guy.

For 4-ton worth of horizontal loops, you only need an area to excavate that's about 80' x 120'. So unless you are in a complete dense forest, or on a small city lot.....I'd still look at horizontal loops

 

[Shblack]

Soil conditions are important! We tried the trench / slinky approach, I was going to dig the trench. Soil is gravel (former creek bed) with a water table that can get within 2’ of the surface when wet. It was wet when I dug the trench, water was 2’ down, contractor specified a 5’ deep trench. Sidewalks kept collapsing, trench full of water, ended up being 8’ wide in places. Couldn’t use the trench, unsafe to enter, pipe would have floated during install. Filled it in, went with 2 -300’ wells.

Friend was installing a system at the same time, planned on vertical wells. Site had a thick overburden of broken rock, well driller couldn’t set the casing with the equipment he had, every time he would pull the drill to set the casing the rock would shift and interfere with setting the casing. Ended using a horizontal loop in a trench.

Water furnace series 7, works well even when it got down to -3F in Tennessee this Christmas.

 

[IXLR8]

That's not open loop. Open loop would only require 1 or 2 wells....depending on where you choose to discharge.

4 vertical wells is still closed loop. They just put the loop vertically in the wells instead of trenched horizontally in the ground.

Considering all the discharge was going into the creek behind my house... I would consider that open loop. They were instant that they needed to drill 1 well per ton of cooling. I told them that seemed excessive, their reply was "that is the way we do things". So.. they are not 'doing things'.

 

[Valveman]

One of the good things about open loop geo is that it can utilize an existing water well. You should not need a well for every ton, but rather 1.5 GPM for every ton. If one well can make 6 GPM it will work for a 4 ton unit. If you don't have a good place to dump, you may need to drill an injection well. But many people use what is called a standing column design, which pumps and dumps back to the same well. If you have to drill wells for an open loop geo it can get as expensive as the closed loop designs. But using a well that was already drilled for house water doesn't add any cost to an open loop geo system.

 

[dodge man]

Keep in mind the tax break on geothermal. My opinion is the biggest factor is how easily the horizontal ground loops can be installed that makes geothermal practical.

 

[Popgadget]

Considering all the discharge was going into the creek behind my house...'.

In that case, if your existing well can supply 6-8 gpm in addition to what you use now, you don’t need to drill any well, and geo makes a lot of sense.

 

[Shblack]

One of the good things about open loop geo is that it can utilize an existing water well. You should not need a well for every ton, but rather 1.5 GPM for every ton. If one well can make 6 GPM it will work for a 4 ton unit. If you don't have a good place to dump, you may need to drill an injection well. But many people use what is called a standing column design, which pumps and dumps back to the same well. If you have to drill wells for an open loop geo it can get as expensive as the closed loop designs. But using a well that was already drilled for house water doesn't add any cost to an open loop geo system.

Standing column concept sounds attractive, maybe pull from the bottom, return to the top. Don’t need a lot of flow, larger water volume and far better thermal conductivity to the earth than 1 ½” HDPE / bentonite clay. Down side is minerals / silt in the water damaging the equipment over time. Not sure I would want to share this well with domestic water, though.

 

[IXLR8]

In that case, if your existing well can supply 6-8 gpm in addition to what you use now, you don’t need to drill any well, and geo makes a lot of sense.

I actually have 2 wells on the property. One supplies the house, the other for the irrigation system. We almost never use the irrigation system, but the HVAC tech didn't want to hear about using it. If I had a clue how to install a geothermal system I might try it myself, but I don't have the knowledge or tools. Also, I am a little concerned that the well water is fairly hard and full of minerals. Within 50 miles of me I only have 3 HVAC companies, only 2 of them do Geothermal and one of them installed the HVAC mess I have now and I wouldn't use them again. My options are limited for Geothermal and I am afraid even if I got a system installed, what would it be like to get service if needed. As much as I would like to go Geothermal, I just don't think it is in my future here. My property is also heavily wooded and I don't have an 80' x 120' area clear within 600' of the house.

 

[Popgadget]

A modern open loop is a very easy install. Ductwork, which any HVAC contractor should be familiar with, electrical supply, thermostat, water in and out. The modulating valve for water out to your creek is supplied with the unit, No aux or backup heat.
If you ordered it with a hot water loop for an indirect hot water tank you will have to plumb that loop as well. The variable speed circulator can come preinstalled if ordered with the unit.

 

[LD1]

Considering all the discharge was going into the creek behind my house... I would consider that open loop. They were instant that they needed to drill 1 well per ton of cooling. I told them that seemed excessive, their reply was "that is the way we do things". So.. they are not 'doing things'.

You had a moron for a contractor...plain and simple.

The main benefit of open loop is a single well...and/or already having a well completely eliminating the need for any heavy equipment.

Someone wanting to dri one well per ton....you might as well go closed loop and never have to worry about water quality, discharge water, or runny dry. Or the high amperage a deep well pump pulls.

So your contractor was an idiot.

And if you already have an unused well, a DIY Geo is as easy as it gets. You don't need a manifold or flow center or anything. And geo's....since all the refrigerant is contained within the furnace itself, they come pre charged. Some you don't even need an HVAC license.

It's as simple as setting a furnace, tying in ductwork, supplying electric, and water supply and return.