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Monday, October 28, 2019

Filling the solar collectors for my workshop solar heating system


Every fall as the temperatures start dropping down to freezing I fill the collectors for my solar heating system with antifreeze solution, and in the spring I drain them.  I don't need the heat in the spring and summer.  If the antifreeze fluid gets too hot it will cause an over pressure in the collectors and also the fluid will turn acidic and begin to corrode the copper plumbing.

I mix a 50% solution of antifreeze and water and pump it from a 5 gallon bucket into the collectors and then run the pump long enough to purge air from the system.  Air bubbles can stall the pump and that is a big problem that can cause over heating.

Each year I note when I fill and drain the system on the wall of my 80 gallon storage tank (which is a regular water heater used just as a holding tank for solar heated water).  And yes we have a 7 to 8 month heating season in Maine!


Today it is cloudy and I don't expect any sun.  My system controller (that I manufacture - click here to learn more) shows 83F at the collectors and 121F at the top of the tank.  The tank temperature is high due to the propane backup that maintains the tank at 110 to 120F.  The collectors can heat the tank up to well over 180F on a good day and that is the free solar heat that I use to warm my workshop and office.

You can see a detailed blog about the design and construction of my solar heating system here

Here's a system diagram - click here or on the image to see live performance data.