Can I not drain my solar pool heater for winter?

[Rocket J Squirrel]

In my mild climate, I don't close the pool for winter. But every winter, I drain my solar panels, leaving the drains open. This is to prevent freezing in the panels, which look pretty delicate with all those little tiny tubes through which water passes.

In my climate, we may get 2 or 3 nights a year when the temperature falls below freezing. But I sure don't want to damage those panels.

Now I have a new Pentair EasyTouch 8, which includes a setting for solar freeze protection (as well as main pump freeze protection) and the proper sensors for air, water, and solar temperatures. It would be more convenient to enable that than to drain the panels.

So my question is: have any of you used solar freeze protection on the EasyTouch, and did it work? Any panel damage, mold buildup, or other unintended consequence of not draining the panels?

 

[sktn77a]

Here's a free bump! I'm not sure how well the freeze protection would work for an exposed solar panel (on you roof?).

 

[Rocket J Squirrel]

The panels are on a pergola near the pool. This means both top and bottom of the panels are exposed to the air.

There's a photo in this post.

 

[sktn77a]

Well, I don't think the likely hood of a freeze is high, but you know what they say on the roads up to Tahoe- "bridge freezes before road"! I'm sure it would be OK but if you choose not to drain it, I'd probably set the pump to run normally if the "freeze protection" is just a trickle.

 

[Rocket J Squirrel]

OP here.

I spoke with my solar guy today and he said he doesn't know how well the Pentair freeze protection works for solar. He advised me to drain the panels and not trust the freeze protection.

The EasyTouch documentation on solar freeze protection is not terribly clear, so rather than take the chance, I drained the panels and disabled solar at the controller for the duration of the winter season.

 

[Rocket J Squirrel]

Re: Can I not drain my solar pool heater for winter? - SOLVED

It turns out that the Vacuum Relief valves in the thermal solar system require more pressure to close than the typical Freeze circulation speed provides. So running the Solar circuit with freeze protection would cause water to leak out of the VRs.

In a setup with a separate booster pump for solar, it would be OK to leave the panels full and run freeze protection. But not when using a VS pump at low speed via a 3-way valve.