Geothermal Open Loop Water Quality

[marcusj]

I recently discovered this forum and am learning a lot. Thanks to all who contribute here!

I have a 15 year old house in western Michigan that I would live to convert to geothermal. Propane prices are horrible and the deliveries are a nuisance due to a long, hilly drive and lake effect snow. I have lots of land for a closed loop, and tons of water for an open loop.

I would like to try an open loop system to keep my initial costs down. I could potentially convert it to a closed loop in a year or two if it proved problematic. The biggest obstacle I have is water quality. We have tannins in the water and a modest amount of iron.

My question is whether there is something that could be done to improve my water quality. I recently met someone that was running their geothermal unit through their water softener. This sounded nuts to me, but it did cause me to wonder whether there is a compromise here. Assuming I only want to improve the water enough to avoid scaling (not necessarily drinking quality), is there a cost-effective way to do so? Is there another out-of-the-box approach that I might be missing?

[fsq4cw]

I would suggest installing a closed loop system from the outset – particularly if your water quality is questionable. Look for a design that will likely be the most trouble free from the start. This is an expensive project to revisit – especially when you’re freezing!

Calculated over a 20-year life cycle, closed loop usually works out to be the most economical, all things considered.

IMO

SR

[marcusj]

Thanks for the reply. I am not opposed to a closed loop system, but it's really not in the budget right now (perhaps a year or two). However, due to a failure, we need to replace at least part of our current system now so I thought it might be a good time to take the plunge. Has anyone made an effort to try and improve water quality for an open loop?

[deaner]

The open loop with improved water quality would be very expensive and the quality may change at a lter date. The open loop is the best and it can be cheaper only if you have a manner of disposal, such as a pond. A closed loop can be less painful down the road. I have researched this and asked a lot of questions to make a determination. I still do not have geo thermal.

[marcusj]

I can dump water very conveniently. We have a high water table and soil is all sand. Even if I dumped it behind the house in the woods, it would disappear almost immediately and go right back to the same aquafier.

I see systems such as http://www.easywater.com/ which claim to eliminate scaling without using salt. I am skeptical, but the parent company at http://www.freije.com/ claims to be doing this commercially as well. If something like this could cause the water to pass through without scaling, then maybe open loop could work for me.

[heatpumpguru]

I had a PUMP and DUMP in my home in a GEO,and I did it due to LOOP costs.I spent more money in well pumps and valves and my wife nagging,I swore I would never do for another customer!! DO NOT MAKE the same mistake.

[marcusj]

I appreciate the warnings about open loop and water quality. Let me ask a different question. Is it possible to add a plate and frame heat exchanger to the setup to isolate the well water from the system? I know this is done commercially. Are there residential versions of these that might be cost effective and would do the job?

[tecman]

I appreciate the warnings about open loop and water quality. Let me ask a different question. Is it possible to add a plate and frame heat exchanger to the setup to isolate the well water from the system? I know this is done commercially. Are there residential versions of these that might be cost effective and would do the job?

This is one solution, but remember you will have an additional pump and the associated power, small loss in efficiency due to thermal loss in the exchanger and you will still need to be concerned over water quality since it is in the primary side of the heat exchanger. Sediment and corrosives can be as big a factor in the heat exchanger as with the heat pump. Only advantage is that your costly heat pump will be isolated from potential costly repairs due to the water quality.

paul

[marcusj]

Tecman: thanks for the feedback. My hope was that a plate and frame heat exchanger would not only isolate the geothermal system, but also be substantially easier to clean. I just don't know if they make one that is practical for a residential setting.

[manx82]

I live in Dorr Michigan and my water is also on the hard side. I used open loop for years without problem, you do want to be sure your well pump can handle cycling more, you should definitely have a large well tank or tanks and install a sediment filter on the inlet to the furnace. True, you may have to run a descaling solution every few years as maintenance and you need to get a unit with cupro nickel. My water table is 4 feet and sandy soil, if I ever go closed loop I will look into a pond with a loop at the bottom. I'm not here to argue with the pros that install this stuff for a living, but I know from my experience an open loop system with careful considerations can be rewarding. Jim

[marcusj]

manx82: I am in Grand Haven - I think about an hour away. We may be dealing with the same contractors. I set my contact info to be visible. Please email me if you would like to compare notes.

[Rickochet]

We have a open loop Water Furnace Geothermal unit that is almost 20 years old. We have used the same well pump with 2 pressure tanks and have never had a well problem. We have only had to replace 1 compressor and do the general yearly maintenance that is recommended. I would not hesitate to go with an open loop system again. Our water quality was not perfect either. I would advice you to talk to different professionals who are reputable and listen closely to what they suggest.

[marcusj]

Rickochet: Thanks. I have received quotes from three professionals. They all seem knowledgeable, but their recommendations on open loop vary widely. Anyway, I'm taking the water to be tested and I'm gonna go from there. It's nice to seem some people with good experiences.

[Eric M]

We all have various experiences but scaling and clogging are only a few of the water quality problems. Hydrogen sulfide...big problem. PH...big problem. My 15 year $12,000.00 investment...down the drain (no pun intended) in 3 years and what installer wants get that bill. Mine doesn't. Water is not always constant either. Installers don't always follow the rules either so be careful.

[marcusj]

Eric: Thanks for the reply. I did go open loop and it has been running for about 4 months. I am keeping a close watch on the performance of the unit through the measurement ports and expect to clean it out annually. I did have the water tested before pulling the trigger. It was not as bad as I expected. I also kept the install cost down by doing all the plumbing and electrical myself. I paid a contractor for the unit and ductwork to hook it up.

[beachtech]

I had a PUMP and DUMP in my home in a GEO,and I did it due to LOOP costs.I spent more money in well pumps and valves and my wife nagging,I swore I would never do for another customer!! DO NOT MAKE the same mistake.

you too lol well i didn't have a nagging wife

[kevink1955]

I built a system for my home in 1980, used a shell and tube condensor with removable end bells on the water side. It's on Long Island and the ground water will turn your sidewalks brown if you use it in a sprinkler system.

Pulled the end bells once about 10 years ago and the only deposits I found where in the end bell gasket passages between tubes, the tubes where still clean.

It,s still runing today, has had 1 compressor replacment and 1 well pump replacment (shallow well jet pump). Both the original compressor and well pump were used when installed and still ran 15 to 18 years before replacment.

This thing runs great, has no restance heat as it never looses efficenty with the incoming water around 58 degrees year round.

The house it's in is now owned by my Ex Wife but I still get to visit once in a while (the heat pump not the Ex )

What type of well and pump are you using, I had a 30 foot stainless steel point driven well and it did bring up some sand that was caught in the inlet strainer the first year it ran but has been clean since.

[jongig]

I know very little about geothermal and am having my own problems but as a licensed wather operator I know a bit about wells. I chose not to use the pump and dump for several reasons.

1. you never know the water in a well and I've had wells within 1 mile be very different. Water quality can ruin everything.
2. If you use one well in a pump and dump think about this. Water in a well in a drought can drop in a well considerably. I've seen the water drop 80 feet in a well. This could cause a sort of short circuit in the water collum.
3. more cost due to pumping instead of circulating.

[marcusj]

jongig: I agree there can be some serious drawbacks to a pump and dump arrangement, but in certain circumstances I think it can be very effective. We have an abundance of water (high water table right next to a blueberry field) and very sandy soil that readily returns water. The well was tested and could deliver 30GPM (way more than I need) indefinitely.

Also, your comment about pumping costs increasing versus circulating costs ignores that open loop arrangements are more efficient. ClimateMaster's own literature gives significantly better efficiencies for open loop versus closed loop.

kevin1955: I don't have my well specs in front of me except that I know it is ~50 ft with a 1HP submersible pump.