Opened spa drain for freeze protection - now spa draining when pump off.

[Trek631]

Hello. New pool owner & forum member here and apologies in advance if this is a silly question. We are expecting freezing temperatures and freezing rain here tonight in Atlanta so I was trying to get out ahead of it by doing some research. I read that for proper freeze protection the spa drains should be slightly open to allow complete water circulation, and my spa drains were closed.

I tested opening the spa drains today -- and everything seemed fine... I was still getting adequate water flow over my spa spill into the pool... but when I shut off my pump I noticed 20 minutes later that the water level in my spa was lowering... and 45 minutes later that the water kept lowering - 6" below normal. I turned the pump back on and the spa filled back up. Any ideas what could be happening? I have an overflow drain in my pool which may be worth noting here if the water is draining to the pool. Thanks in advance.

 

[mknauss]

Welcome to the forum.
The spa and pool levels will balance if the lines are open between them with the pump off and no check valve exists on the line. So you will need to reset the valves when you turn the pump off once the freeze is past.

 

[Trek631]

Thanks. so you're saying that the spa will always drain out if the spa drains are open and the pool pump is off? I thought my spa drain was open when I bought the house and my pool guy closed it... So I'm wondering if there could be something else at play. I appreciate your help.

 

[mknauss]

If the spa suction is open and the return is open to both the spa and pool, and there is no check valve in line, the spa will drain to the pool level with the pump off.

 

[ajw22]

Post pics of your equipment pad and show us the way your valves are set and which one you opened. Let’s make sure we are all using the same terminology.

 

[Trek631]

I appreciate it. Here are a couple of images. I've marked the spa drain return in question. I opened this very slightly yesterday to allow for water movement and to prevent freezing in that pipe, but when I shut off the main pump water levels in my spa decreased by several inches in less than an hour. My heater is not operational so my main concern is preventing frozen and damaged pipes during freezing temps.

 

[colinn]

I appreciate it. Here are a couple of images. I've marked the spa drain return in question. I opened this very slightly yesterday to allow for water movement and to prevent freezing in that pipe, but when I shut off the main pump water levels in my spa decreased by several inches in less than an hour. My heater is not operational so my main concern is preventing frozen and damaged pipes during freezing temps.



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I had the same thing happen to my spa when the pool was first built. If the pump was stopped, it would drain. The problem was that the check valve has debris in it that kept it from closing. Once i cleaned it, the problem stopped.

 

[ajw22]

Your spa is siphoning through that open suction valve to the pool. The return side valve has a check valve on the spa side to prevent siphoning since it can be open to the spa and pool for the spillover. It is not normal for the spa suction to be open at the same time as the pool so no check valve is on that side.

You should run your pump whenever you have the spa suction open with the pool suction open. Close the spa suction when freeze protection is not needed. That is the best you can do with your setup.

You can install a check valve in your spa suction to prevent the back flow siphoning when yiu have the valve cracked open for freeze protection and the pump is off.