glycol solar

BillyBob

In considering the design for solar + boiler for radiant heat and dhw, I have heard arguments for and against glycol. Since there is lots of discussion going on here for solar, I thought I'd throw this in.

If one is designing a drain-back system, would glycol even be a consideration?

Does it matter if the water that available is from a well and is very hard?(It can be softened).

glycol vs water pros & cons?

Does using flat panels or evac. tubes influence the decision?

Thanks

Carl PE

hmm..

if you're using a drain-back, you don't need the glycol. just make sure all your piping is sloped so that you don't have any "traps".

most people would tell you to fill it up w/ distilled water. depending on the size of your storage tank, this might get expensive. I'd have a sample of your water tested to see how bad it actually is before making a decision there.

evac tubes are a better choice if you need hotter water than the flat panels can deliver. hot-water-fired chiller, for example. water doesn't behave very well at 230º.

BillyBob

water vs glycol

Ok, I guess what I'm wondering now is what's a better system, closed loop glycol or drain back using H20? Why would anyone use glycol if a drainback system works great with better efficiency? (no necessity for dual walled heat exchangers, cheaper fluid...). I'm looking for a balance of the most efficient yet hassle free system. I don't mind paying more $$$ upfront for the right system. I only plan on heating the domestic water and the radiant floors with the collectors (maybe a pool in the summer) so are evac. tubes overkill or the right choice? Seems like this is up for debate here?
Thanks

Kevin_in_Denver

glycol

No one should use antifreeze if a drainback system can be installed.

If the collectors are more than 30 ft. higher than the drainback tank, pump selection is trickier. What's the best solution in this case, based on anyone's experience?