solar loop will not pump

Drew_2

0 degrees F should equate to around 35% propylene glycol. This should give you a flowable fluid to -10 degrees F and burst temp of -60 degrees F.

Bob Gagnon plumbing and heating

solar loop did not pump

yesterday morning when it was real cold, below zero. By the time I noticed it had already turned to steam from my evacuated tubes. I pumped water through and it worked good for the rest of the day. I saved a bucket of anti-freeze and left it out overnight, it was almost as cold outside, and it turned to slush but it still seemed like it would pump. I was careful to mix the anti-freeze and water before I pumped it into the system 2 years ago. I may have a little more than the recommended 50% Mixture of anti-freeze. My pump is a Grundfos 15-58 and it was on the high setting. Do you think I had a slug of water or could the anti-freeze be too thick at the higher concentration?
Thanks, Bob Gagnon

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Brad White

50% PG

should definitely be freeze protection at those temperatures, Bob. I can see if you used 30% for burst protection and wind up with a hydronic slurpee and that seems like what you had. 50% is a tad syrupy but if the line sizes are reasonable for water, the difference should not be that great. Sounds like you were getting a trickle.

Maybe you mis-calculated your system volume?

Did you take a refractometer to the mix? How well was it mixed before being injected?

Solarstar

Hi Bob .It was -10 f yesterday ,My solar pump started at about 8a.m. My evac tubes took my 120 gal tank to 175 deg by the end of the day about 4 pm. My mix is 50/50 and i think thats a bit thick so I'm contemplating adding about 10% more water (2.4 liters) to my mix for better flow/pumpability and heat transfer. Paul

Bob Gagnon plumbing and heating

The anti-freeze solution

is 60% or 70% antifreeze to about 30% to 40% water. I mixed it pretty good in the bucket before I pumped it into the system, then I pumped it through the system and ran a hose into another bucket to mix it further, to prevent freezing. Do you think the strong anti-freeze solution is too thick? Thanks Brad, Bob Gagnon

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Brad White

60-70%

is pretty rich, Bob. I would take it down a notch. There is not much more protection with that rich a mixture from what I have seen. There is a flat-line in burst protection at least and I think the freeze protection levels off. In any case it is richer than you need. A higher head pump would help but why put yourself through that?

Good luck. Your place sounds like an engineer's house!

Brad

hr

The % depends on the brand

and they are all different. Utility and several other brands are premixed and ready to install.

Some glycols ship full strength, some are somewhat diluted. You need to look at the label on the container to get the proper mix for the protection temperature you desire.

I know straight DowFrost HD gets real thick in the barrel in cold weather. Just barely pumpable with those 1/2hp Teel transfer pumps, and very slowly. I've found 35% Dow HD is plenty.

Typically the fluid, in a solar system, is real warm and pumpable by the time the differential controler turns on the pump?

hot rod

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mark schofield

from the slant fin site

http://www.slantfin.com/documents/383.pdf

This is a link to an article on using antifreeze in a closed hydronic loop.

Bob Gagnon plumbing and heating

glycol mix

I just read the bucket and it says at 60% anti-freeze I get freeze protection down to 0 degrees and burst protection to -70. It was below 0 so I guess I'll mix more anti freeze
in. They said a 70% solution was good to -17 freeze protection. I think my evacuated tubes heated up much quicker than my outside pipe runs, even though the pipes were double insulated. Bob Gagnon

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