Solar HW Panel Cleaning

[whalechris]

Hi All

I have aquired for free, a whole bunch of 26 solar hot water panels, that were in a commercial system heating a hospital water supply. The engineer said the system heated 3000L from 20C to 70C each day in summer. When a storm trashed 2 or 3 of the panels, they fitted a gas boiler instead.

My question for all is how best to clean them internally. They have been in service for about 12 years and stored since removal for about 2 years. I will test each to 40psi before putting a 3 panel system together for the small guesthouse I run.

I'm looking for a method of cleaning, preferably without using lots of nasty chemicals. Any ideas appreciated. It would be nice use them for direct heating but perhaps running the panel heated water through a coil inside the main tank would be better, as they are old?

I'm also working on the idea that 3 panels will heat 300 lit, based on the above figures?

Cheers

Chris in Horta, Azores, Portugal

[Old F]

Chris

I  would try a vinegar  and water mix heavy on the vinegar.    This would help clean out some mineral deposits  Then  flush with water.

Old F

[RP]

How about radiator flush stuff from the autoparts store?

[Volvo farmer]

TWENTY-SIX commercial panels?

That's one heck of a score! Copper prices are through the roof right now, I bet you got yourself at least $500 in scrap value alone! I just bought ONE 3/4" piece of copper pipe at HD, five foot long, the thin stuff... Thirteen bucks. But please don't scrap the good ones.

Do you see a mineral build up in there? If you stick your finger in the outlet a few inches and rub it around and can see copper, I wouldn't think they need any cleaning at all. If there's calcium and magnesium (hard water) deposits in there, you're going to need some sort of acid to get it out. Vinegar is the least nasty, but also the least effective. Acids move up the scale from there to stuff like LimeAway and CLR, to stuff that will eat the minerals and then the copper real quick, H2SO4 would be at the top of the list of nasty stuff but it sure does eat hard water deposits.

I've got a few of these laying around for eventual projects. I always thought closed loop glycol was thew way to go, but I talked to a HVAC guy I know recently and he almost convinced me that drain-back is better. He said the glycol wears out after a few years, turns brown and sludgy, and has to be replaced.

Tweny six panels? Man I'm jealous. Are they 4x10's? You could completely eliminate your home heating bill, and your domestic HW bill with these if you did it right.

[whalechris]

Yes I was pretty happy to get these!!! It took 3 days work to cut them out of their racks and sort the pipework and ship it to my place and then tidy the site. Worth it though. Hoping to use some for house heating as you say but space is very limited where we live at the moment so I'll be happy if we can get 3 up to do our water needs. No mineral build up I can see. We have very soft water here so that sounds promising. We get no frosts here either and winter temps don'tdrop below 8C so I was just going to use them with water circulating. Might be worth adding a corrosion inhibitor? I'd like to avoid glycol or other stuff? Cheers for your enthuisam. Thanks to all for posts.

Chris