How best to prevent freeze damage in NC?

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old_monk

Well-known member
Mar 28, 2024
115
Raleigh
Hi All,
It's been a while since I last posted in summer (I've kept my poolmath up-to-date so pls take a look and advise if anything not right), this being my first winter with pool and NC in freeze most of this week, looking for some guidance if I'm doing the right things or can optimize them.

This week (like most of the country under freeze), night temps here in Raleigh are below freezing for 6-8 hours. To avoid any freeze damage, I'm running my pump on two timers. Timer 1 runs 5pm-9:45am at high enough rpm to trigger my pool heater at 65deg. Timer 2 is 9:45am-5pm at lower rpm to keep heater off. My heater can't go below 65deg for water temp.
It's working fine, but I'm seeing high water evap rate which isn't really a surprise for this situation.

Is there anything I can optimize to reduce the water evap or in general for this situation? Please advise.

Thanks!
 
You don't need to run the heater. Moving water alone will prevent freezing. You somehow need to switch between spa and pool modes regularly to keep water moving through all pipes. Do you have automation with freeze protection? That would do it automatically. Otherwise doing it manually all night sounds like a big pain. Most automation switches between modes every 15 or 30 minutes I believe.
 
old_monk said:
Thanks ajw22. Any specific cover you would recommend keeping in mind we don't winterize the pool like in northern states?

Is something like this from Amazon good enough?

Amazon.com

www.amazon.com
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Yup, any solar cover over the water will prevent evaporation and heat loss.

I'd be surprised if you are willing to pay the gas bill to keep your pool at 65 degrees all winter. Is there any reason you want to keep the water so warm?
 
Parac said:
You don't need to run the heater. Moving water alone will prevent freezing. You somehow need to switch between spa and pool modes regularly to keep water moving through all pipes. Do you have automation with freeze protection? That would do it automatically. Otherwise doing it manually all night sounds like a big pain. Most automation switches between modes every 15 or 30 minutes I believe.
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That's the part I'm not sure, more experienced folks can give me feedback... is circulating water enough to avoid freeze when night time temp is below freezing for 6-8 hours? I wasn't sure so forced the heater on.

I can control thru the valves that water is pulled in from both pool bottom and skimmer and pumped back to both pool and spa. Wouldn't that keep water flowing thru all the pipes?
thanks!
 
old_monk said:
That's the part I'm not sure, more experienced folks can give me feedback... is circulating water enough to avoid freeze when night time temp is below freezing for 6-8 hours? I wasn't sure so forced the heater on.
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You're still in the 20's. Circulating water alone can work indefinitely and at even lower temps.

old_monk said:
I can control thru the valves that water is pulled in from both pool bottom and skimmer and pumped back to both pool and spa. Wouldn't that keep water flowing thru all the pipes?
thanks!
Click to expand...
That sounds like it should work.
 
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 www.troublefreepool.com

Circulating water will handle freezing nightime temperatures with daytimes above freezing.

Even circulating water can begin freezing around the edges with a hard, sustained freeze caused by multiple days of temperatures in the 20s and below. Your gas heater will not keep up if you get hit with that. There comes a point when shutting down the pool and draining the equipment is your only safe option.
 
ajw22 said:
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 www.troublefreepool.com

Circulating water will handle freezing nightime temperatures with daytimes above freezing.

Even circulating water can begin freezing around the edges with a hard, sustained freeze caused by multiple days of temperatures in the 20s and below. Your gas heater will not keep up if you get hit with that. There comes a point when shutting down the pool and draining the equipment is your only safe option.
Click to expand...
Thanks, very good read. Based on the table in that first post, since my plumbing is all 2" pvc, it should all be safe. Temps here do dip to 20s in night but daytime is in 40s or 50s. Just circulating the water (which I have done all year anyway since I like the look and sound of spa spillover) should prevent any freeze.
 

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old_monk said:
Just circulating the water (which I have done all year anyway since I like the look and sound of spa spillover) should prevent any freeze.
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Keep an eye on the water flowing over your spillover in freezing conditions. That is one of the first places water will freeze around the edges, and it can damage your grout, tile, or stone.

Water flowing in pipes underground are more insulated from the cold then exposed water flowing on the spillover.
 
ajw22 said:
Keep an eye on the water flowing over your spillover in freezing conditions. That is one of the first places water will freeze around the edges, and it can damage your grout, tile, or stone.
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Can that freeze happen with 6-8 hours of nightly temp drop and day temps in 40s/50s? I gathered from that thread it needs to be sustained hard continuous freeze extending days.
 
old_monk said:
Can that freeze happen with 6-8 hours of nightly temp drop and day temps in 40s/50s? I gathered from that thread it needs to be sustained hard continuous freeze extending days.
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Your spillover is the most exposed area. It depends on the spillover design and environment. There may not be much water movement around the edges which can let it freeze. It does not take much freezing water to crumble grout.
 
Don't become complacent about freeze damage because you have the pump running and water flowing.
 
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ajw22 said:
Don't become complacent about freeze damage because you have the pump running and water flowing.
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+1 ^^

There have been many on the forum that have been caught by power failures. This is why I am a very strong advocate for draining the pad equipment of water when the time below 20F increases to the point where there is a high probability of plumbing freezing solid should there be a power failure. The risk to me is much too high to rely on power operated freeze protection.
 
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Further reading the TFP tutorials, looks like I was doing exactly what is not to be done, running heater in this situation (corrosive condensate). Leaving it here as reminder to myself what not to do in future.
 
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