Pulling some water from spa drain in pool mode during freeze protection

[dailygenesis]

Hello everyone -- this is my second post to the forum -- and both in the same day. After this, I promise to stop as I have been needy enough for one day

This is our first winter with a pool (new pool/spa combo constructed summer of 2022 - details in my signature) and we have decided to leave the pool open and running through the winter.

The controller has freeze protection, which has been running the last few nights as we've dipped into the low 30s / high 20s. Everything's been going fine.

But, since we have the spa, the controller alternates between Pool and Spa every 30 minutes. This seems kind of strange to me, and potentially more risky due to constantly moving the valve actuators and also leaving certain pipes without running water for 30 minutes at a time.

I wanted to figure out if there were a way to adjust the configuration of the system such that I could just use one mode -- Pool Only -- during the winter months so that when freeze protection comes on it doesn't have to alternate and so it can just keep water moving through all pipes all the time.

Our spa has a spillover and so when the system is running in "Pool Mode" -- it's sending half the returns to the spa, half to the pool, but only draining from the pool main drain and skimmer. In this mode, everything has water running through it EXCEPT for the spa drain.

So, my question is this -- could I adjust the suction valve to allow a bit of suction from the spa drain but keep the majority coming from the pool. The returns would continue to go half to the spa and half to the pool. This would still retain a spillover, it would just be a bit less flow as some of the spa water would be pulled from the spa drain. I would then change the configuration of the controller to just run "Pool" mode so it doesn't try to alternate during freeze protection.

I asked my installer about it but they said they don't recommend making any changes from the initial setup. This tends to be their response to everything for liability reasons (which I understand), but I figured it was worth checking with some other knowledgeable people to see if my idea has merit.

To me, it would be advantageous to only run one mode (Pool Mode) during the winter while we're mostly just trying to keep water balance and avoid freezing. I thought this solution seemed reasonable, but I don't trust myself yet on these types of things. Is there anything I'm missing that makes this a bad idea? Anyone else ever tried this?

 

[HermanTX]

But, since we have the spa, the controller alternates between Pool and Spa every 30 minutes. This seems kind of strange to me, and potentially more risky due to constantly moving the valve actuators and also leaving certain pipes without running water for 30 minutes at a time.

This is perfectly normal and many controllers have this logic to move between Pool and Spa mode every 30 minutes.
The 30 minute interval should not allow any pipe to freeze unless you are at very low temperatures.
Refer to this article

The Physics of Freezing and Freeze Protection

Recently, there have been a lot of questions from those living in moderate climates about using automatic freeze protection or running pumps to prevent freezing and what a pool owner should do when temperatures drop so I thought it might be useful to have a thread which dealt with the issue from...

www.troublefreepool.com

So, my question is this -- could I adjust the suction valve to allow a bit of suction from the spa drain but keep the majority coming from the pool. The returns would continue to go half to the spa and half to the pool. This would still retain a spillover, it would just be a bit less flow as some of the spa water would be pulled from the spa drain. I would then change the configuration of the controller to just run "Pool" mode so it doesn't try to alternate during freeze protection.

You would have to test this because the spa could drain quicker than you can fill it and that would be more of an issue.
I would not recommend it but you can test your theory.

 

[Toxophilite]

There may be more to it, depending on your plumbing set up. Some set ups, the preferable kind, use a bypass line and valve off the pool return to circulate to the spa and overflow during pool mode going to dedicated returns in the spa - not to the spa jets. Some, shortcut method, share pool return to spa return at the main actuator valve by partial close to spa. Partial return simply goes to spa jets. If you have the former set up, you will have 2 returns to spa to contend with, a change to a stop in both actuators for pool/spa suction and return, and then what happens when it goes back to normal mode after temps rise.

 

[dailygenesis]

You would have to test this because the spa could drain quicker than you can fill it and that would be more of an issue.
I would not recommend it but you can test your theory.

Thanks! I forgot to mention that I did test this once. I put it in pool mode and then manually overrode the actuators to open up the spa suction just a bit. I'm able to keep the spillover going (which indicates there's still more water coming into the spa then going out through the drain), but to do so, I have to really only open the spa drain just a small amount. I'd say it was about 80% pool and 20% spa suction at that point.

From your reply, I gather you feel the better path is just to leave it as is and let it rotate between spa and pool. I appreciate that. It might be more trouble than it's worth to do what I was thinking.

 

[dailygenesis]

There may be more to it, depending on your plumbing set up. Some set ups, the preferable kind, use a bypass line and valve off the pool return to circulate to the spa and overflow during pool mode going to dedicated returns in the spa - not to the spa jets. Some, shortcut method, share pool return to spa return at the main actuator valve by partial close to spa. Partial return simply goes to spa jets. If you have the former set up, you will have 2 returns to spa to contend with, a change to a stop in both actuators for pool/spa suction and return...

I'm pretty sure we have the second (shortcut) method. In pool mode, it's just sending half the return to spa and half to the pool. There is only one return to spa and it sends water through all the spa jets. This is why I thought my solution might work because the only thing not getting water flow during pool mode is the spa drain.

...and then what happens when it goes back to normal mode after temps rise.

In the scenario I'm proposing I would change the control configuration for the pool to function in pool only mode all the time. I would stop using automated actuators altogether -- just setting them in one position and leaving them for the duration of the winter. Then reconfigure when it's time to heat the spa again.

 

[Toxophilite]

Then, just think of your pool and spa as a pool with 2 drains, split. The only constraint being there's an overflow wall regulating spa level, so not pulling more from spa than returning is issue as said above. Since you can't gauge how much, or if any, suction is actually happening with the spa, that might be something to be mindful of. I know on my return bypass, just a nudge one way or the other on the hand valve is the difference between a slow trickle over spillway, to nothing to, a whole lot. You won't have the ability to fine tune your suctions or returns, so the options may be a dry spa v. returning a big bulk of return to spa.

 

[Rocket J Squirrel]

I believe the main purpose of freeze mode is to protect the pump and secondarily the above ground plumbing exposed to air at below-freezing temperatures. Your spa drain line, being mostly underground, is unlikely to freeze.

Automation designers probably figured they might as well circulate water through both pool & spa lines to protect both sets of exposed pipes. My Pentair EasyTouch switches every 15 minutes.

I would let your system operate as designed and not over-think the situation.

 

[dailygenesis]

I would let your system operate as designed and not over-think the situation.

But overthinking things unnecessarily is my specialty

Sounds like pretty much everyone believes it's best to just use the freeze protect as is. I appreciate all of the feedback and advice!