Thanks for the encouragement!

We did OK despite a high KW/hr electricity rate, we burnt a lot of firewood and are out of our good dry wood now. For the water source for the system, I hope to explore to a 500' depth +- for a possible hot water strata, as shown by a 'hot' well five miles from us along the Castle Mt. fault.I will develop the well with my appreciation, and application of, Boyles Law. No guarantees of hotter water than 40 degree f, for sure!

We kept the GSHP system simple with only one inside zone and a Grundfos 26-64 pump with about 14'x300' loops of 1/2" hdpe; HP run times were satisfyingly long. Heat stratification was not uncomfortable, but the top floor bedrooms were a bit cooler as is logical and perhaps desirable.

I need to get the buffer tank going as we have no GSHP DHW and so we heat DHW with the woodstove.The buffer tank is purchased, 2500 gallons. I hope that my kids will be able to use it as a swimming pool as well as have it support the Domestic HW needs.

Also, we are adding heat to the house with a modest solar hot air system. Nighttime temps are still cool here this date, but we are getting solar gain and we have begun 'breakup' yesterday.The trumpeter swans have just arrived. The moose are grumpy, nothing to eat. Spring projects have begun!

What is the preferred ACID for cleaning a HX? What is a preferred PH? Upon disassembly of the HX piping, significant 'Slime' is built up. Since it is apart, I will do my first cleaning of the system.

Just as a note, this system worked well to not admit O2; it had negative atmospheric pressure, as evidenced by my two flexible couplings crushing in on themselves when the ground source water pump was not on.

What little flushing I've had to do has been with Nickel-Safe. I'm not sure what to make of your 'slime' Could it be bacteria from iron?

I'm confused by the idea of a 2500 gallon swimmable DSH buffer tank, but it sounds like fun!

It Must be iron bacteria...brown gelatinous slime...I am a bit surprised by the quantity and depth of buildup on the piping. This could be a good argument for a closed loop.

Plus a closed loop will never freeze. But to minimize iron slime, you might consider O2 barrier pipe all the way from the well to the heat pump. And set up valves and a pump so that an acid flush is very quick and easy.

.

You know, I overlooked the piping O2 permeability as the source of the oxygen. Our groundwater is naturally anaerobic and high in Fe and Mg; pumping it through the system must be allowing enough O2 for the bacteria to thrive.

My system is good enough to go for a pressurized system flush, I think. I need to locate my 1/2 hp utility pump and will proceed with caution with acid and sodium hypochlorite and will look for nickel safe.

My understanding is that acid + inhibitor is far better than acid alone (in not effecting the metal). It would be interesting to monitor COP (or even just amps) and see how fast it changes with slime buildup.

Titanium HX here...my quick search of terms titanium and acid turned up this tidbit:

Severe corrosion damage on titanium equipment has resulted from cleaning procedures utilizing pure hydrochloric acid or acid inhibited with amines. If hydrochloric or sulfuric acid is used to clean titanium surfaces, it is recommended that sufficient ferric chloride be added to effectively inhibit corrosion of the titanium.

(http://events.nace.org/library/corrosion/MatSelect/corrtitanium.asp)

So, again, inhibitor with the acid, rt? Or perhaps a brush and sodium hypochlorite? Brushing would have advantages, but would make the cleaning more time consuming by having to open the system.

In the interest of science, I should take amp readings b4 and after...my cop numbers were screwy, as I recall.

Titanium HX here...my quick search of terms titanium and acid turned up this tidbit:

Severe corrosion damage on titanium equipment has resulted from cleaning procedures utilizing pure hydrochloric acid or acid inhibited with amines. If hydrochloric or sulfuric acid is used to clean titanium surfaces, it is recommended that sufficient ferric chloride be added to effectively inhibit corrosion of the titanium.

(http://events.nace.org/library/corrosion/MatSelect/corrtitanium.asp)

So, again, inhibitor with the acid, rt? Or perhaps a brush and sodium hypochlorite? Brushing would have advantages, but would make the cleaning more time consuming by having to open the system.

In the interest of science, I should take amp readings b4 and after...my cop numbers were screwy, as I recall.

Depending on the material something like white vinegar is a good cleaning agent.

Check with some better sources than me (like the manufacturer), but it sounds like diluted nitric acid alternated with bleach is appropriate for titanium and biofilms.

Here is a pic of the slime:

The manuf (Palm) got back to me and recommended: H3PO4 or Oxalic acid(HOOC-COOH). What I have today is a 50% mix of 5% Bleach sitting in the HX. I have not seen comments that that is harmful; I am hoping it is beneficial.

....couple sketti noodles and garlic toast......
Can't really identify it the color suggests iron, but the texture, not as much.......

Keep us posted. Closed loop is expensive, and documenting the effects and manageable solutions should be useful in making an OL/CL decision (ie, might save someone a lot of money).

Posted By joe.ami on 29 Apr 2013 08:10 AM
....couple sketti noodles and garlic toast......

That reminds me of the song: snake farm; just sounds nasty, pretty much is....

Back to the system: It is a system and part of it is not working...on the piping, I included a pressure tank; i've eliminated it from the system now as It might have held an extra quantity of O2.

I need to come up with a unified system that includes my DW and GSHP water...I am thinking a big, non-pressurized contact tank for Domestic, dose that with NaClO, the tank will get filled with the GSHP outside water, control the level in the Domestic tank with solenoid switches, run that bleached water through a filter and the filter can backwash through the HX.

A diagram of the whole system would be helpful. But in general, chlorination and filtration is a good solution to iron in drinking water.

I'm on a well for my domestic water and I use an aeration type sand filter for removal of iron and sulfur from the water. I works pretty good and is relatively low maintenance - I just replace a few hundred pounds of sand every year or so and add some crushed oyster shells to help control acidity. It does take two pumps for this system though; a 1/2HP submersible pump in the 100' well and a 1/2HP shallow well pump and pressure tank on top of the sand filter. However, my system isn't large enough to provide sufficient contact time for the volume of water needed for an open loop GSHP. When the time comes to install my GSHP, I will be going closed loop vertical wells to avoid the maintenance needed for an open loop system with my water quality.

Discovery of the iron bacteria is a whack on the side of my head. I see HX and pipe clogging issues, a possible failing septic system, w/o a remedy.

I imagine health issues, but am told iron bacteria is not harmful, per se, but allergies come to mind and using it as Marinara sauce with spaghetti noodles shows intuitively it being good is an uh-uh. I like my water potable:} Whoever would use that slime as a dipping sauce؟

Diagramming a solution is where I need to be. Struggling with variables...How to treat the water?

In a Hydrology class, I was told how great a sand filter is at removing 'stuff'. A aerated sand filter has merit, but what kind of system?; pressurised/non-pressurized.

I saw this: http://www.epha.eg.net/pdf/0013-2446%20v85%20n3-4%202010/1.4.pdf


Arkie6, have you posted details somewheres re the system? I guess that it is non-pressurised with a collection tank and solenoid valves to control the flow to the system. Some sort of out of water or low water switch must be there too.
It would be a great help if you could post some details about your sand filter.
With a search ""arkie6 "water filter" site:www.greenbuildingtalk.com/""
you wrote you have a "10' x 14' building I use for a waterpump / water filter system"

A sand filter, I could see, would only be practical for domestic water usage, due to the quantity of water flow. If there was a bleach system for domestic, with water held for some time for contact time, backflushing a filter of some kind containing bleach into the HX, that would keep bacteria growths down?

Dosing the well with bleach is said to not be a good idea. Perhaps dosing just the HX, off peak, when system is off, with bleach is an option. Just trying to be creative with the Open System that is installed here...practical alternatives for iron removal seem to be converting to ferric iron with bleach, ozone, aeration, hydrogen peroxide and then filtering.

I have two 'shallow' water systems, both relatively low head, one high flow, at the rate of about 18gpm @ less than 5psi, one low flow at the rate of 2gpm @20 psi; increasing the shower water pressure is one goal. Having a booster pump dor domestic as has been mentioned earlier is valid. How to incorporate it? The GPM for the HX is good to go, supposedly. Just thinking out loud...Diagramming is in the future for this puzzle, if I know what the pieces are.

My sand filter water treatment system is non-pressurized. It is a rectangular fiberglass tank ~ 5' long x ~3' wide x ~3' deep. It is divided into three sections with the middle section only being ~2-3" wide and the two sections on either side ~2.5' wide. The first section also contains a spray tower that stands ~2' high above the tank below. The first section contains a 3/4" water supply line from the well connected to a simple float valve (similar to a toilet float valve or stock tank float and valve assembly). When the water in this section drops, the float drops, opening the water valve. The outlet of this valve has a flexible 3/4" pipe up into the spray tower. Here the piping divides into 4 spray nozzles which are nothing more than adjustable brass garden hose spray nozzles that point downward and spray a fine mist to expose the water to the air and release any sulfur gas. The top of the spray tower is vented and covered with screen. The water in this section has to flow down under the middle section partition wall, then flow up the middle section before flowing over the top of the partition wall into the last section of the tank that contains the sand. The bottom of the sand section of the tank contains a series of parallel 2" PVC pipes in the bottom with tiny slits in them to admit water but not sand. They are all connected to a common header that then has a 1" PVC pipe going up to the top of the tank that connects to the suction of my 1/2HP shallow well pump that is pressure controlled at 50-60 psig. These pipes below the sand are covered with ~6" of pea gravel, then ~2' of sand.

This type of sand filter was manufactured by a local water well pump supply service for many years before they eventually went out of business due to more and more homes in the area connecting to "city water". I actually bought my sand filter and pump assembly used from someone that connected to the rural water supply. This same company also manufactured a larger version approximately 7' long x 4' wide. A friend at work built his own sand filter using a 750-1000 gallon rectangular open top concrete septic tank. He built the center partition wall using regular cement blocks (CMU) with holes knocked out of the block cores low on one side and high on the opposite side to allow the water to flow up and over into his sand bed. A large concrete tank like this could actually be set in the ground with a small shed built over the top. This would keep the water temperature closer to ground temperature.

I have seen some sand filters that use a small chemical pump and tank to supplement the sand filter by injecting chlorine into the tower section and accelerating the oxidation of the iron. If the chem tank filled with regular chlorine bleach was mounted high above the sand filter, all you would need is a small solenoid to gravity feed the chlorine solution to the spray tower and a small float switch to control the solenoid.  Another thought I had at one time was to get the large chlorine tablets used for pools and put them in a nylon mesh sack similar to that used for oranges, and hang this in the spray tower section of the sand filter. The water spraying on these tablets would then gradually dissolve the chlorine and add it to the water. I'm not sure how safe this is for drinking water, so I never really pursued it. Plus I've never really been a big fan of having chlorine in my drinking water. But it should work fine to oxidize iron and kill bacteria for a GSHP water supply.