Getting closer to restoring full Geothermal Cooling, but need help cleaning heat exchanger.

Factual Questions
1

Ok, my Geothermal cooling/heating system has no more coolant leaks. Both stages are up to proper pressure. The Tstat is functioning, and I’ve powered off the electric backup heat at the panel so that the electric heat can not be thrown on accidentally by the Tstat (this happens sometimes on some models).

Now, I am not getting quite the cooling I should after a few initial minutes of artict blast air (lasts 5-10 mins), and I have eliminated all but a few major variables: One big one is a clogged, poor performing heat exchanger. Based on the air temps, the temps go from artict to mildy cold air. I don’t think the exchanger is flowing well enough to take the heat away.

I know that it (the exchanger) used to be serviced regularly via flushing. Not sure if chemicals were used. Near the unit, I pieced together the assorted hoses, bucket and pump and have determined that I need to back flush the heat exchanger. A mere test revealed the most vile, red, iron/rust riddled water I’ve seen in a long time. This is an open loop setup, and there are no surprises that iron is gooping up the works.

So, the exchanger has not been flushed since 2005 or 2006! Yes… and with the well water it uses, I would think every 3-6 months is a must. My wife’s first husband passed away, and he was the one who maintained the unit. I’ve pieced together the unit’s history, design and quirks. I’ve pieced together the backflush components, and know which valves to shut down to flush 'er out.

I am concerned about the effectiveness and whether there are chemicals to use. I am having a hard time finding legit help (so far, I’ve been 1-2 steps ahead of two local Geothermal experts). The web is riddled with ads, etc. I’m not sure what chemicals can be used to descale, etc. I’m not sure how I would know when to stop, etc.

Compliments to the SDMB, because we’ve been able to get farther along with help here than we have with help from anyone in the industry. I am pretty sure, given the current symptoms and know history of unit and water, that this will get the Geothermal unit back to being efficient again.

2

I would look for radiator cleaner in the auto supplies. I haven’t for a while, but there used to be 2 types, sort of a detergent to remove oil, and oxalic acid based ones. I would go with the oxalic acid based ones. It should be strong enough to cut the rust with minimum damage to the copper. Same if you find citric acid based ones. Follow directions. If it calls for warming the engine to speed things, you may need to extend the time instead.

3

I’ve seen mention of phosphoric acid, too. I think it is generally coming down to one of those.

4

I recall using a product to flush out radiators. Called CLR. IIRC CLR stood for calcium, lime, and rust. Which is pretty much most likely what, if anything that built up in there. What the active ingredient is I don’t remember.

5

I’ve been using Iron Out on both the Geothermal units I’ve owned. The first unit was a Climate Master with a Copper heat Exchanger. I tried CLR but it wasn’t powerful enough. My local service company started using Iron Out too (for their other customers) when they found that CLR wasn’t strong enough. That first unit lasted for fifteen years before severe electrical problems caused by a storm killed the compressor. My second unit is a rebranded Climate Master again with copper coils and I’m again using Iron Out. I first back flush using plain water. You would be surprised what you get out. Then I run a solution of 1/2 a cup of Iron Out in a five gallon bucket of water. I run this for a half an hour. I then back flush again with just plain water. Do lots of back flushing with the plain water. It is very possible that you will loosen large deposits and these deposits can foul your solenoid valves. Which will then require you to dismantle the valves to clean them. I’ve probably been doing this wrong for years, but so far it hasn’t bitten me on the ass. While I can get no one to officially bless what I do, I can’t get anyone to tell me I’m doing wrong either. Oh, I use a cheap clear water pump from Harbor Freight for the back flushing. It runs between $24 and $40 dollars, depending if there is a sale or not. It kicks out 600 gph which is just about perfect for my geothermal. My first one lasted for 10 years, before it froze up. Before that I was using those cheap pumps that hook up to an electric drill. Those don’t have enough power and can take all day to do the job. Hope this helps.