Pool & spa switching during freeze mode thoughts

[pcm2a]

I have a spa with a waterfall spillover into the pool. During freeze protection both pumps run in pool mode for 30 minutes then it turns off, valves shift to spa mode, then both pumps run for 30 more minutes. If it's below freezing for 7 days straight the pumps turn off, valves shift, every 30 minutes for 7 days. That doesn't seem like the best design to me, so I have some thoughts on having it run without turning off.

I can set the suction side valve in between modes (the one circled in red below), turn it off and then the pool pump will suck from all of the lines at the same time. If the spa pump is off then the pool pulls too much from the spa and it will slowly drain out (neat trick when you need to drain the spa for work). With the spa pump on this doesn't happen. Last night I did a trial run and I ran both pumps all night long, everything seemed ok.

So here is what I think could work:
1. Position valve half way, turn both valves off so make sure they aren't adjusted automatically
2. In the aqualogic controller change the system from Pool & Spa - Single to Pool only. My thought here is this will keep it from turning off every 30 minutes.
3. In the controller have freeze protection on for the pool pump & spa pump
With this both pumps should turn on and off during freeze mode.

Downsides:
One downside is that anytime it is above freezing, if I want to run the pool pump I will need to run both pumps or walk around and adjust the valve.

Anyone have any thoughts on this or if there is some problem I'm not seeing if I try this out?

 

[ajw22]

I don’t have a complete picture of your equipment and plumbing to say if anything is unprotected but sounds like you have thought it through.

 

[pcm2a]

Here is the whole setup. In this photo the valves are in spa mode. In my picture above they are in pool mode (both modes pull from the spa). I have an annotated version of this that I made a couple days ago that I can't find!

 

[proavia]

I thought the system was supposed to switch from pool to spa and back repeatedly during freeze protection to keep water flowing on a regular short time interval.

Maybe @Jimrahbe can shed some light on this.

 

[mas985]

It is unnecessary for water to continuously run in plumbing to prevent freezing. Even at 0F, it would take several hours for still water to freeze. Running periodically resets the time to freeze.

 

[pcm2a]

Yes absolutely, it switches back and forth from pool to spa, to keep water flowing in each of those modes on a 30 minute interval. That is controlled by the aqualogic controller, since in the controller it is set on "pool and spa". My idea is to manually set the valve so water flows through everything, all at the same time, eliminating the need to turn off or to change valve positions every 30 minutes.
Which is harder on the lifespan of the system:
1. Two pumps running for 24 hours straight
2. Two pumps running for 24 hours straight, turning off for 30 seconds every 30 minutes, and valves shifting position, for 24 hours

It is unnecessary for water to continuously run in plumbing to prevent freezing. Even at 0F, it would take several hours for still water to freeze. Running periodically resets the time to freeze.

The aqualogic controller does not have the ability to run for an hour and then turn off for an hour. Once the temperature you set as "freeze" hits they come on forever until it is above that temperature.

 

[mas985]

I wasn't suggesting that you turn the pump on and off. My point is that the valves switching back and forth provides sufficient protection against freezing. You don't need to have water traveling through all parts of the plumbing at the same time.

 

[ajw22]

Which is harder on the lifespan of the system:
1. Two pumps running for 24 hours straight
2. Two pumps running for 24 hours straight, turning off for 30 seconds every 30 minutes, and valves shifting position, for 24 hours

I think you will find no practical effect on the life of the pump or valves due to the switching.