tank overflow

[tf21]

Hello, I'm new here. I'm a homeowner who had geo installed four years ago and I've been very happy with the system, although I had a strange problem last week. The flowcenter tank located in the basement started to overflow from the top. At one point I had lost so much fluid, the flow center was pumping air. I filled the tank with water and waited. After three days, the tank had emptied again, although I don't know if that was just air in the system collecting in the tank or if it was more overflow.

It's been about week now, and I haven't lost any more fluid. What do you think caused the overflow? Is two tankfuls of fluid replaced with water a problem? Am I going to need more antifreeze? I have a 1500' total line.

[stickman42]

1500' of 3/4" ID pipe would be 34.5 gallons of loop fluid. Add in the distance from the header to the flow center and let's round it to 40 gallons. If your flow center reservoir emptied twice, I figure that may be 3-4 gallons maybe? So you've replaced 10 percent of your antifreeze mix with straight water. Doesn't sound too dangerous, but you probably should find out the antifreeze concentration if you could. You could also put a sample in the freezer to see when at what temp it starts to solidify.

No idea on what would cause the overflow. Only thought I have is that it "burped because of air in the loop"?

[tomfox21]

Thanks for the response. The overflow hasn't returned, so I have no idea what caused it initially. How does air get in the loop? Would an expansion tank help prevent this from happening again?

[stickman42]

I'm assuming you have a closed loop and a non-pressurized flow center like a B&D brand. This is what I have. My reservoir has a screw-on lid which seems to tighten enough to keep loop fluid from escaping. If your loop was properly filled in the beginning, I would think that air could only enter the loop by replacing lost fluid. The only logical place I could see that happening is in the reservoir. From what I've read, the loop pipes do expand and contract, which would cause the level in the reservoir to fall and rise.

[tomfox21]

I'm assuming you have a closed loop and a non-pressurized flow center like a B&D brand. This is what I have. My reservoir has a screw-on lid which seems to tighten enough to keep loop fluid from escaping. If your loop was properly filled in the beginning, I would think that air could only enter the loop by replacing lost fluid. The only logical place I could see that happening is in the reservoir. From what I've read, the loop pipes do expand and contract, which would cause the level in the reservoir to fall and rise.

Yes, that's exactly what I have. Do you have an expansion tank?

[stickman42]

No expansion tank on my loop. Fluid level goes up and down only an inch or two from summer to winter.

[tomfox21]

I figured I would update this thread. After topping the tank off twice with water back in October, the overflowing completely stopped. Maybe it was a result of switching from AC to heat, although I would think switching to heat would cause a decrease in pressure since the coolant is dropping in temperature.