Kirk,
Any idea what kind of glycol was in the system? I’ve seen systems stagnate for several years where the propylene glycol was still fine if it was good quality. I’ve seen people use the automotive grade propylene glycol such as Sierra brand antifreeze with poor results. I think Glenn’s suggestion of flushing with a TSP solution is a good way to go. Good luck, sounds like a messy situation! Best, August *From:* RE-wrenches [mailto:[email protected]] *On Behalf Of *Kirk Herander *Sent:* Friday, April 17, 2015 10:21 AM *To:* RE-wrenches *Subject:* [RE-wrenches] flushing DHW collectors Hello, I have an older 10 collector system in which the glycol has stagnated due to a defective collector sensor, apparently for some time. I was able to drain the collectors, the cooked glycol is black with a good bit of sediment. I tried to flush the system with water but my ½ hp utility pump could not pump the water entirely through the collectors. Suction slowed down and stopped after just a few gallons, as if the pump couldn’t overcome the effective head of the system. I had no problem using this pump to charge the loop when it was commissioned. I suspect the collectors may be gummed up with cooked glycol. I guess compressed air is next to try. Are there any safe chemicals to use to purge / un-gum the collectors? Thanks. *Kirk Herander* *VT Solar, LLC * *Proven PV provider since 1991* *www.vermontsolarnow.com <www.vermontsolarnow.com>* dba Vermont Solar Engineering NABCEPTM Inaugural Certificant VT RE Incentive Program Partner 802.863.1202
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