Need to descale my Open Loop Geothermal Coax. Any advice?

[Skooterj]

It is stupid hot here and my Geo unit is struggling to keep up. But it has been stupid hot before and it has worked great until now. So I did some research and found out I should have been descaling my unit every 2-3 years. It is on year 8 and have never had an issue. So I think this is the problem. And all the local companies are swamped fixing people who have no AC. So I'm thinking about trying this myself. Anyone have an experiences or suggestions? Where can a regular guy get 5 gallons of descaler?

My plan is a small submersible pump, a 5 gallon buck, some washing machine hoses and 3-4 hours of pumping. Luckily my unit already has hose bibs set up on the in and out lines. Turn off unit, close the valves supplying and draining the water and flush, running the solution through the coax backwards.

 

[larry4406]

I recall folks using undiluted white vinegar to descale Rinnai tankless water heaters...

 

[PCustoms]

I recall folks using undiluted white vinegar to descale Rinnai tankless water heaters...

Yep, just did my Rheem this spring with cleaning vinegar.

Bought a cheap submersible pump of Amazon, dropped it in a bucket and dumped ~3 gallons in. Hooked the hoses up and walked away for a while.

FYI, it will leach the color out of washing machine hoses.

 

[Mark_17]

It is stupid hot here and my Geo unit is struggling to keep up. But it has been stupid hot before and it has worked great until now. So I did some research and found out I should have been descaling my unit every 2-3 years. It is on year 8 and have never had an issue. So I think this is the problem. And all the local companies are swamped fixing people who have no AC. So I'm thinking about trying this myself. Anyone have an experiences or suggestions? Where can a regular guy get 5 gallons of descaler?

My plan is a small submersible pump, a 5 gallon buck, some washing machine hoses and 3-4 hours of pumping. Luckily my unit already has hose bibs set up on the in and out lines. Turn off unit, close the valves supplying and draining the water and flush, running the solution through the coax backwards.

I do this with mine. I don't use a submersible pump, just a cheap regular pump I got off amazon. I just used use white vinegar.

 

[PCustoms]

I do this with mine. I don't use a submersible pump, just a cheap regular pump I got off amazon.

I looked around and this was simple to drop in a bucket. Was $36 when it was in stock

https://www.amazon.com/dp/B0BZYS3QLC?tag=atomicindus08-20

 

[niget2002]

related/unrelated ???

I use distilled white vinegar to descale coffee makers.

 

[pcmeiners]

Citric acid is a mild acid, especially for copper, work slower than stronger acids but is much safer on metals or use the available lime scale removers at the big box stores, be care of any which use strong acids such as hydrochloride acid. I would heat up any solution you use,. warm but not above 150° F. Call the coax manufacturer see what they say

 

[bwringer]

I don't suppose there's a user manual moldering in a kitchen drawer somewhere? Maybe hanging in a bag on the side of the air handler?

I know, Reading The Fine Manual is counter to the home brew DIY aesthetic around here, but it might be a good place to start.

Or check the manufacturer's website. Or ask the company that installed it, perhaps. Maybe they'll refuse to tell you anything, maybe they'll point you in the right direction.

I dunno, dumping random acids into my massively expensive system of inaccessible underground pipes based on the word of a bunch of Internet randos seems... other than wise. Also, we don't know anything about your local water chemistry, etc

Then again, some of the folks here actually are experienced HVAC pros...

 

[PCustoms]

I don't suppose there's a user manual moldering in a kitchen drawer somewhere? Maybe hanging in a bag on the side of the air handler?

I know, Reading The Fine Manual is counter to the home brew DIY aesthetic around here, but it might be a good place to start.

Or check the manufacturer's website. Or ask the company that installed it, perhaps. Maybe they'll refuse to tell you anything, maybe they'll point you in the right direction.

I dunno, dumping random acids into my massively expensive system of inaccessible underground pipes based on the word of a bunch of Internet randos seems... other than wise. Also, we don't know anything about your local water chemistry, etc

Then again, some of the folks here actually are experienced HVAC pros...

Drama much?

It's a heat exchanger, already setup with isolation valves. Running commercial descaler or vinegar thru it isn't exactly rocket science

 

[gregs]

I did mine a few years ago with a commercial product designed for the job. If I recall it starts out dark purple and turns yellow when its loaded with scale or vice versa. I dont know if I really noticed much difference in the performance. Hard to say how much buildup there was and it was the first time in 15 years....

 

[rlitman]

Drama much?

It's a heat exchanger, already setup with isolation valves. Running commercial descaler or vinegar thru it isn't exactly rocket science

That depends on what level of corrosion is tolerable. We don't know what that heat exchanger is made of. Is it stainless, copper, monel, aluminum, titanium?

 

[PoorUB]

If you have a farm store nearby they often have phosphoric acid. Phosphoric works great on hard water scale and is fairly safe with most materials you will find in a hydronic system.

Why not fill the system with distilled water and glycol or some other inhibitor to prevent scale build up??

 

[gleman]

I do water heaters with this kit.



with vinegar.

Nice, compact and the kit fits in the bucket for storage.

You could probably build the same kit for sixty or seventy bucks.

 

[rlitman]

...Why not fill the system with distilled water and glycol or some other inhibitor to prevent scale build up??

Because he said it is open loop. It's circulating ground water. But we also don't know what his ground water chemistry is like.

 

[Skooterj]

I don't suppose there's a user manual moldering in a kitchen drawer somewhere? Maybe hanging in a bag on the side of the air handler?

I know, Reading The Fine Manual is counter to the home brew DIY aesthetic around here, but it might be a good place to start.

Or check the manufacturer's website. Or ask the company that installed it, perhaps. Maybe they'll refuse to tell you anything, maybe they'll point you in the right direction.

I dunno, dumping random acids into my massively expensive system of inaccessible underground pipes based on the word of a bunch of Internet randos seems... other than wise. Also, we don't know anything about your local water chemistry, etc

Then again, some of the folks here actually are experienced HVAC pros...

It is an open loop system, so nothing will go into the underground pipes. The descaler will just run through about 5 feet of normal cold water filled pipe that acts like the air handler of a normal AC unit. I tried to get ahold of my installer, but he hasn't called or texted me back. It has been 8 years.

 

[toplessHO]

I used some color changing chemical for a unit I bought used.
I used one of those $10 drill pumps.
When the unit finally got pinholes in the condenser(25 yrs later)
I retired it,cut the condenser in half to see what was inside.
No scale,just a brown film that would wipe off with a finger.

 

[toplessHO]

If you are brave and have some gauges,you can freeze the condenser
and when the warm water hits,all the scale will be washed away.
This is what I do in lieu of chemicals,BUT you must know what youre doing.
I was demonstrated this method at the factory where TempMaster units were made.

 

[larry4406]

It is an open loop system, so nothing will go into the underground pipes. The descaler will just run through about 5 feet of normal cold water filled pipe that acts like the air handler of a normal AC unit. I tried to get ahold of my installer, but he hasn't called or texted me back. It has been 8 years.

Find the model and serial tag on the unit, look it up, get the manual, and proceed from there?

 

[PoorUB]

Because he said it is open loop. It's circulating ground water. But we also don't know what his ground water chemistry is like.

Ahh, I was thinking pressurized versus an "open" non-pressurized system.