Why no freeze mode on spa blowers?

[pcm2a]

I've lived in this hour for just over 3 years. The blower hasn't worked well ever, but what I can say for sure is water is at that check valve. If I turn the water on it will blow the water down and out of that check valve. If the spa is drained it will blow all that water out into the tub. In the aqualogic controller freeze mode is disabled for it. When there is a big ice storm why doesn't this freeze and bust? During freeze mode the spa and the pool pumps run.

The spa sits above ground level and water does circulate through the spa when the pool pump (and spa pump) is running. If that makes a difference.

 

[ajw22]

Read...

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

It takes more then an ice storm to freeze water in a 2” PVC pipe.

You may also find some information in here helpful...

Preparing Pool for Cooler Months - Further Reading

www.troublefreepool.com

 

[pcm2a]

That was a great read, thanks for posting it. It doesn't answer things totally for me but it gives me some guesses. According to that article if temperatures were < 32 for 10 hours the pipe should freeze. However, that pipe goes down under the ground. Could it be that as the liquid in the pipe freezes it expands into not frozen water and then doesn't freeze?

 

[homegameroom]

I don't think that style of check valve is meant for spa blowers. See this one Blower Check Valve 1/4# 1.5"/2"

The proper valve will insure water does not get up that far.

 

[ajw22]

That was a great read, thanks for posting it. It doesn't answer things totally for me but it gives me some guesses. According to that article if temperatures were < 32 for 10 hours the pipe should freeze. However, that pipe goes down under the ground. Could it be that as the liquid in the pipe freezes it expands into not frozen water and then doesn't freeze?

The frost line in TN is 3 inches. So the risk of freezing is the top 3 inches of the water column.

Water is not very comrpessible, air is. You have an air column over the water that the ice can expand into. Ice expands about 10%. That little bit of ice expanding into the air column in the pipe is why this is not a problem for you in your environment.

 

[pcm2a]

In my picture is a check valve that keeps the water front going higher than a few inches. I don't believe the water can expand past the check valve. When the blower is on it blows the check valve down and pushes the water out.

 

[ajw22]

In my picture is a check valve that keeps the water front going higher than a few inches. I don't believe the water can expand past the check valve. When the blower is on it blows the check valve down and pushes the water out.

The check valve flapper probably has enough play in it to absorb the ice expansion.