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Trees are Cool
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Discussion Starter · #1 ·
I have a solar hot water system. A loop of antifreeze goes from my collectors to the storage tank. There is an air lock on the roof that makes it hard to fill, but once it is full it works fine.To fill it with water from my home supply is easy. Just hook up the water and it pushes right through. My problem comes when I try to put the antifreeze in. I have a 1/2 hp centrifugal pump. It makes the antifreeze froth with fine bubbles as it pumps. It is a hassle to change the fluid. I got a speed control for it and that does not help much. Would a different type of pump work better? Impeller? Diaphragm?

Unfortunately the solar controller I have has a flaw. If the collector temperature gets to 212 it shuts off the pump. Bad idea. This causes the antifreeze to boil and blow out the pressure valve. There is a cooling loop to prevent an overheat, but with this string of clear days the tank must have gotten hot, a over heat happened and thus the problem of needing the refill. I have done it in the past but it is a pain.

I know I need a bigger expansion tank and a better controller but that is another discussion.
 

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General Contractor
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8,083 Posts
I have a solar hot water system. A loop of antifreeze goes from my collectors to the storage tank. There is an air lock on the roof that makes it hard to fill, but once it is full it works fine.To fill it with water from my home supply is easy. Just hook up the water and it pushes right through. My problem comes when I try to put the antifreeze in. I have a 1/2 hp centrifugal pump. It makes the antifreeze froth with fine bubbles as it pumps. It is a hassle to change the fluid. I got a speed control for it and that does not help much. Would a different type of pump work better? Impeller? Diaphragm?

Unfortunately the solar controller I have has a flaw. If the collector temperature gets to 212 it shuts off the pump. Bad idea. This causes the antifreeze to boil and blow out the pressure valve. There is a cooling loop to prevent an overheat, but with this string of clear days the tank must have gotten hot, a over heat happened and thus the problem of needing the refill. I have done it in the past but it is a pain.

I know I need a bigger expansion tank and a better controller but that is another discussion.
Why don't you call the people who designed or installed the system and ask them how to properly do that or ask them to do that.
 
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