Hi folks, got a problem we are wrestling with.

We have a geothermal open loop system.  House is 5 years old or so.  Our water is quite hard, and has a lot of iron also (8-10ppm).  Water to the house goes through an iron filter and softener, but the water to the geo is directly from the well (unfiltered and unsoftened).

Over the years, it has become increasingly clear that the iron is causing issues in our system.  It really builds up in the pipes and in the unit itself.  We had the unit flushed with acid at the recommendation of the company that does most of our service.  That's fine, but is just a band-aid.  We want to solve the issue if we can, and not just throw money at temporary fixes.  After we had things cleaned out, it only took a few more months for the flow restrictor (which was new) to get clogged with iron.

We are getting conflicting reports about how to fix this.  One company wants to put in a new iron filter dedicated to the geo system.  Another company says that filtration won't really work because of the volume of water the system requires (the media tanks would have to regen multiple times each day etc).

It's hard to figure out who to believe, particularly when we were told when we built the house to not worry about the iron in the geo at all, and it wouldn't be a problem (whoops).

Any thoughts or opinions?  We have thrown a bunch of money at trying to fix it, but I can't say that we've had too much success.  Anyone have any experience with problem water with respect to geo systems?  It seems like it much be a common problem?

I don't even want to think about it right now, but I suppose the "nuclear option" would be to drill a new well (and hope for better water) or retrofix to closed loop (I don't even know if this is possible and must surely be extremely expensive).

Any help?

I have suggested before that the recent explosion in closed loop is due to the change in geo buyers.
MI has more open loop than closed systems and a lot of iron.
Fact is geo used to be for engineers and gadget guys.
Folks that can do their own flush can still enjoy cheap comfort.
How many years deep was the flush required? How big is the drain pipe if it is clogged, a clean coil doesn't matter.
joe

Fixing an open loop water quality issue may be nearly impossible or prohibitively expensive owing to the large amount of water involved. I don't think treating the water will be feasible.

What you label an (undesirable) "temporary fix" may in fact be reasonable periodic maintenance in exchange for cheap efficient comfort at low first cost.

Consider this analogy: Over time, the quality of oil in a typical car engine degrades. There are systems available to microfilter a side stream of the main oil flow through the engine, extending its life. Or one can go with a "temporary fix" consisting of changing the oil and filter periodically. Since the cost of materials for this for a typical car runs about $20, this is the best solution. For an over the road trucker for whom a fully synthetic oil change runs $200+, a microfiltration system coupled with periodic lab testing of the oil is a viable, lower cost alternative. (I have a Ford Superduty with a bypass filtration system whose oil hasn't been changed since late 2000 - periodic top-ups and lab tests confirm oil's suitability for continued use)

Treating water required for a open loop geo system is going to be cost "scarry " based on the volume of water needing to be treated. 1 ton of geo = 1.5 to 3 gpm of water while unit is running, multiplied by amount of tonnage. Cleaning or flushing of the coil is some of the periodic maintanance required for an open loop geo. If your flow restrictor orifices are plugging up, "I really hate those things" a switch to throttling valves with flow meters will be much more tollerant to the iron, and the turbulance created by the throttled valve would actually promote self cleaning.
A brief note about well driling and aquifers. There is no free lunch. I stopped counting the number of wells that tested clean of iron to start and over time the water quality changed, usually for the worse in regard to the geo. There is also many types of iron present in water. They are all different and require diffferent treatments to cure. In many states the treatment of raw water for re-introduction into the aqufer or enviroment is un-lawfull so check with your authorities.
Eric

Thanks for the responses so far.

What I am hearing is that filtration is probably not a reasonable choice.

It could be that I simply need to change my mindset from a permanent resolution to one of periodic maintenance, as engineer mentioned.  In that case I suppose the question becomes - what is the right kind of routine maintenance to be done, and how often?

It seems to be that there are a few different issues:
- Iron buildup in the piping in and out of the unit (this is all 1" PVC)
- Iron buildup in the unit itself

We had the unit flushed with acid about 6 months ago, which is about 4.5 years into the life of the unit.  I could handle having this done every few years.

The buildup in the plumbing seems like a problem but I'm not sure.  Right now we have a spin-down sediment filter that has be thoroughly cleaned on a weekly basis or else I have trouble getting enough flow.

I'm handy enough to handle routine maintenance on my own, if I know what to do.  At least I'm glad I posted here before signing up for a $4k iron filter that won't get the job done.

So I guess this makes me a very naive person, but what is the right kind and frequency of maintenance to do here?  We also had the well bleached recently, and it seemed to help for a bit, but my understanding is that this covers up the issue without really fixing anything.

Cheers, all the advice is appreciated.

(joe.ami - we are in Indiana, lots of iron down here too)

Is your heat exchanger standard material, or is it upgraded to a more robust type of material for open loop systems? If standard, I wonder if it will hold up to the environment and cleanings over time?

Iron oxide can and should be filtered - one could use larger filters or an automatic backwash to reduce the labor involved with this. Dissolved iron is different and some people aerate the well to convert dissolved iron into iron oxide. But once the water is past the filter, make sure that oxygen doesn't get to it.

There isn't a cheap way to remove hardness, so it needs to be kept dissolved. Easiest way to encourage this is to only use geo for heating (not cooling).

It should be possible to set things up so that an acid flush is a simple operation - turn a few valves, turn on a pump for a few minutes, put back.

Jonr,

Just how many of these have you done?

Bergy

Couldn't think of anything substantive to say huh?

I appreciate all the posts in response to my question.

However I realized tonight that I was asking the wrong question in the first place. While most of my first post is accurate, I am pretty certain the real problem is not the iron in my water (which we do have a lot of), but that iron bacteria stuff instead. We definitely have that, and it seems likely to me that that is what is clogging up the works.

I know it's hard stuff to deal with. Any advice?

Sorry for posting misleading information in the first post - mea culpa.

It has been my experiance that once bacterialised iron is identified as the culprit it is a death blow for your system. Maintanance intervals will become shorter and shorter untill the frequency is undesireable. The time it takes to go from where you are to system failure are the only variables.
We have tried every solution put forward by the brain trusts and drunk guys at the bar and nothing works. We have redrilled to different aquifers and converted to closed loop as the only solutions.
Eric

Posted By jonr on 28 Sep 2010 09:00 PM
Couldn't think of any substantive to say huh?

Couldn't think of a way to answer the question and still sound as if you actually know of what you speak huh?

Bergy

No fix for bacterial iron. One must just stay away.
I agree it's unlikely you will be able to avoid it at this point so closed loop is the only fix if you are to stay with geo.

Good Luck,
Joe

Sounds nasty. Some questions come to my mind.

What precautions should be taken when addressing this issue? Could a new well be contaminated by any bacteria left in the piping or unit? If closed loop is chosen, could bacteria be a problem in the closed loop if it gets contaminated?

During times of little or no geothermal use, could the bacteria migrate back from a return well to the unit or to the extraction well? Does special care need to be taken not to introduce the bacteria into a closed loop when topping off the pressure with domestic water?

Posted By jonr on 28 Sep 2010 09:00 PM
Couldn't think of any substantive to say huh?

I think it is fair and substantive to ask one who offers imagined solutions, where they have employed them with satisfactory results.

As we know you have never installed a geo system, nor own one but have been barred from another forum for misleading folks, it is reasonable to ask "where is what you propose in place and working?"
 
Your sensitivity to the question doesn't make sense unless you hoped to pose as something other than a recreational researcher.

joe

I, too, had to give up on an open loop geo system due to fouling from iron bacteria. I made it 10 years before giving up. My issue was between the well and the geo unit. The 125 foot run of pipe would plug up. Well company shoved a fishtape through the line to open it up, in addition to using compressed air. Each tx lasted about 2 seasons.

I switched to closed loop vertical this summer. I made sure the loop was filled with deionized water ... Meaning not a drop of my well water will see the inside of the loop.
Hope my bad experience helps!!

Look up "ad hominem fallacy". Especially relevant when someone other than the original poster can't comment on the argument itself. But to make it even clearer, I'll add an explicit "not a geo installer" to my profile - even though in this case, other water treatment experience with in use systems is relevant.

Regarding other forums, I have a complete disdain for the moderator at geoexchange.org who couldn't tolerate discussion (as in pointers to examples of what large project geo engineers were doing) of "voodoo" (not my name calling) concepts like thermally enhanced grout performing better than normal grout (go read it). Of course this has been discussed over and over and apparently almost everyone now agrees that it does. Some geo installers have even gotten to the point where they think simulation software is worth using. I think that most of the problem comes from a large number of commercial geo installers (not engineers and not designers) who are trolling for business. Of course they can never admit that their 20 year old knowledge might need updating. Or that they know little about thermodynamics. Don't expect anything other than one sided discussions from geoexchange.

> No fix for bacterial iron.

Joe, where is your Civil Engineering degree from? What are all of the solutions you have actually tried for iron bacteria? These are relevant questions.

> Cheers, all the advice is appreciated.

You are welcome.

"> No fix for bacterial iron.

Joe, where is your Civil Engineering degree from? What are all of the solutions you have actually tried for iron bacteria? These are relevant questions."

Got me there, all I know is that bacterial iron voids the warranty on virtually every brand of geo system.
Therefore I've not tried to fix the water.
If I were on "Water Treatment Talk" and made that statement it would be really silly (kind of like someone who doesn't install geo systems arguing with geo pros about treatment of water for use by a heat pump).
j

How anyone could talk ill of Phil the moderator at geoexchange is a true mystry to me. Nothing but good things to say and feel about him.
Eric

Wikipedia definition

Moderator
thank less job, but some one has to have the last word and keep the community civil and happy.

So Joe is changing from "No fix" to 'never tried any fixes, might void the warranty that you may or may not have'. Hmm, hard to get more misleading and poser than that.

It's interesting that Joe seems to be at the heart of most non-civil discussions in the geothermal forum.