Advice on running pool heater for a day ahead of polar vortex

[DB-Cooper]

I have been long advocating draining the pad equipment since pretty much the beginning of this forum. But generally, only when air temperatures drop below freezing for more than 12 hours per day.

Under those conditions, I just don't see any advantage in running a pump to prevent freeze damage. When air temperatures are that low for that long, the water temps are not far behind so algae is pretty much non existent so I see no benefit in keeping the pump running. I only see more risk.

I generally agree, and if I was leaving town, I'd do it, but as I said in my last post, there is a bit of hassle, repriming, etc. Also, last time I drained, I still had pipe damage (which was fortunately easily accessible).

 

[DB-Cooper]

This is another aspect of the week long calculated risk. If the weather forecast changes and heavy falling snow shows up, it may turn the top of the pool into a slurpee/slushie. It won't take much for the returns to fill the skimmers or pump basket with it where it may brick up and cause a blockage. With no flow it's game over in minutes.

Yeah, that's what broke my previous fountains which were huge soup bowls of snow, and basically it blocked the pump from pumping water. I've since replaced those with side facing sheers which are performing real well!

Fortunately, for this storm, there's no snow in the forecast at all.

 

[mas985]

Yeah, I think my point is in line with yours, the difference being I see the point of trade off as being much further down the road than just 12 hours sub-freezing. Maybe it's just the difference in our climates, but I would consider it very low-risk to keep pumps running through sub-freezing periods of 1-2 days as I have done this several times now even in my short bout of pool ownership. This current spell we are in is going to keep us below freezing for at least 4.5 days and I think I'll make out fine on this one too -- but that is with me pre-heating the pool. Somewhere around this 3-5 day mark, though, is for me where I'm starting to feel the cut off might be. I just haven't gotten up the nerve to try draining the equipment and hoping for the best. It is still appealing to me to prevent the ice as long as possible.

The other thing to think about is do you really want to be scrambling to drain pad equipment in the middle of the night should the power go out.

I prefer to be proactive rather than reactive.

 

[DB-Cooper]

Pumps do not change the density characteristics of water.

And even in a pool there is typically thermal stratification.

Pools turnover the water just like lakes.

Let's back up just a bit to talk about what happens before the lake freezes. During the summer, most lakes are thermally stratified. Warm lower density water sits on top of colder higher density water. As summer transitions to fall, the upper layers cool, breaking down that density difference. Eventually, the surface of the lake cools to 4 degrees Celsius (39.2 degrees Fahrenheit), the temperature at which water is most dense. This causes the water at the surface to settle to the bottom, pushing the now relatively warmer water at the bottom back to the surface. This process continues until the surface water cools below 4-degrees Celsius, at which point it becomes less dense, and eventually freezes. Remember, water is most dense at 4 degrees Celsius. It becomes less dense above and below this temperature. If water were most dense as a solid, lakes would freeze from the bottom up, eventually freezing solid. In that case, little or nothing would survive in the lake. Most lakes and ponds don't completely freeze because the ice (and eventually snow) on the surface acts to insulate the water below. Our winters aren't long or cold enough to completely freeze most local water bodies. This process of lakes turning over is crtically important to the life in the lake. It is these turnover periods that infuse and distribute oxygen throughout the entire water column.

Since it's obvious you are 1000x more educated on this, going back to my earlier questions:

Let's say the actual water temperature goes below 32F as reported by the thermometer. Since water is fed from main drains and skimmers, that water would be representing the basic temperature of pretty much the whole pool. If the water is, let's say 30F but moving, there is a 15 minute period of freeze protection cycling where that 30F water is sitting still in a pipe waiting it's turn for the valves to open. That water doesn't just instantly freeze in a 2" pipe right?

Not that this will remotely happen, but is there a theoretical temperature that basically the water will start instantly freezing? Using an impossible example (for this storm), could water read 20F and still survive this?

 

[mas985]

Under supercooled conditions, still water can remain a liquid at sub freezing temperatures and doesn't freeze until it starts to move (opposite of what you would expect). It is all about nucleation points.

Supercooling - Wikipedia

en.wikipedia.org

It is a very complex system that has a lot of dependencies where generalizations are not very useful.

 

[ajw22]

This all makes sense, but I feel like it is sort of in line with my point.

The point I was making is only that in some cases we as pool owners might be better off to just drain the pad and let things sit during bouts of sub-freezing weather. Whether or not this is true is dependent on how long the sub-freezing temps last and probably a lot of other factors, and it's usually not something we can definitively know in advance, so we just make a bet. We bet that running our pumps 24/7 will be better in the long run because it will delay the surface freezing (by disrupting the natural phenomenon you describe above) and we bet that the air temps will return to above freezing before any issues arise out of this. The trade of is that if temps don't return to above freezing in time and our pool water lowers all the way to it's most dense point and below, then we might be in a situation that is worse than what we would have been in had we just drained the pad and let it go.

Do you agree with this?

I don’t bet when I can have a sure thing.

Properly draining and winterizing the pool is a sure way to prevent damage. It does not take that long to do once you have the proper tools and know what you are doing.

I watch these TX/OK freeze wrecks every year and can only conclude you folks prefer worrying to doing.

 

[dailygenesis]

I don’t bet when I can have a sure thing.

Properly draining and winterizing the pool is a sure way to prevent damage. It does not take that long to do once you have the proper tools and know what you are doing.

I watch these TX/OK freeze wrecks every year and can only conclude you folks prefer worrying to doing.

Are you and @mas985 advocating the same thing? You seem to be advocating a full shut down / winterization (I assume with blowing out the lines, etc.), while I believe @mas985 is just advocating a temporary drain at the pad in advance of a weather system like this.

For me, the full winterization / shut down isn't a preferred option because we want to use our spa during the winter. Of course, we could give that up and shut it down, but that's a factor in our consideration.

My deliberation here is really between the "keep the pumps running" approach and what @mas985 advocates as far as a temporary pad drain.

 

[ajw22]

Are you and @mas985 advocating the same thing? You seem to be advocating a full shut down / winterization (I assume with blowing out the lines, etc.), while I believe @mas985 is just advocating a temporary drain at the pad in advance of a weather system like this.

Depends on the details of your pool and equipment what is required to protect the vulnerabities.

For me, the full winterization / shut down isn't a preferred option because we want to use our spa during the winter. Of course, we could give that up and shut it down, but that's a factor in our consideration.

I can winterize my pool in an hour and open it in 30 minutes.

You going to use your spa during the freeze?

You see a freeze coming then take an hour or two and safe you pool.

I don’t get the big deal and resistance other then laziness to pull together the tools and learn how to do it. And my apologies to those that have physical limitations that may prevent them from doing it. In which case phone a friend.

My deliberation here is really between the "keep the pumps running" approach and what @mas985 advocates as far as a temporary pad drain.

Figure out what is a sure thing for your pool and not a bet and do it.

 

[DB-Cooper]

Under supercooled conditions, still water can remain a liquid at sub freezing temperatures and doesn't freeze until it starts to move (opposite of what you would expect). It is all about nucleation points.

Supercooling - Wikipedia

en.wikipedia.org

It is a very complex system that has a lot of dependencies where generalizations are not very useful.

So this still supercooled water sits in a 2” pipe still for 15 min, then the valve opens and it gets movement, does it harden immediately?

 

[mas985]

To me it is mostly all about water temperature.

If the water temp dips below 50F and stays that way for months, then a full winterization is warranted. If however, there are cycles of 2-3 weeks of below 50F and then above 50F, the a partial close might be more beneficial to avoid a green pool at opening. It just depends on local conditions and your own preferences.

 

[mas985]

So this still supercooled water sits in a 2” pipe still for 15 min, then the valve opens and it gets movement, does it harden immediately?

I ran an experiment one winter by putting a small bottle of pool water out on the pad where the temps got well below freezing ~20F. Did the bottle bounce like in the video and it froze immediately. So it potentially could happen in the plumbing.

However, I did not run freeze protection during that test and my equipment did not freeze. The bottle froze first because of exposure and size. The equipment will take much longer to freeze.

 

[dailygenesis]

I can winterize my pool in an hour and open it in 30 minutes.

You going to use your spa during the freeze?

You see a freeze coming then take an hour or two and safe you pool.

I don’t get the big deal and resistance other then laziness to pull together the tools and learn how to do it. And my apologies to those that have physical limitations that may prevent them from doing it. In which case phone a friend.

Understood. I have thought about this before. For me, it's not about laziness but uncertainty in being able to figure out how to do this -- and also the uncertainty of what will happen to the pool and spa if the surface freezes hard (which will happen every time if I don't keep the water moving).

Can you point me to any threads or documentation about your method for winterizing temporarily in situations like this?

Do you have any thoughts on the issue of the surface freezing? Is this a non-issue?

 

[DB-Cooper]

I ran an experiment one winter by putting a small bottle of pool water out on the pad where the temps got well below freezing ~20F. Did the bottle bounce like in the video and it froze immediately. So it potentially could happen in the plumbing.

However, I did not run freeze protection during that test and my equipment did not freeze. The bottle froze first because of exposure and size. The equipment will take much longer to freeze.

I wonder what the water temperature was. For example, if the pool water is 30F, it sits in that pipe for 30 minutes. It also doesn't get a bang, instead the valve introduces more water at the same temperature. If you watch the bottle YouTube videos, it seems the water has no issue sloshing around inside, it requires a bang or significant shake. Also, that water is probably much cooler than 30F as it's coming out of a 0F freezer (clearly it's 0F either).

In my case, at least my pad is tarped/closed off so I don't think the water will get crazy colder sitting for that 15 minutes.

 

[mas985]

If the pool water was 30F, you would definitely see freezing on the surface because as dust drops on the surface it creates nucleation points and the surface will start to freeze and that will be your first clue that something needs to be done.

Supercooling generally only occurs in sealed system such as the pool plumbing or bottles.

As for temporary winterization, I would follow this procedure (only for pools where water level is below pad level):

First, open the filter purge valve and allow as much water as possible to drain back into the pool.

Open the pump lid

Then open all drain plugs on the pump and filter and some heaters may have drain plugs as well.

If the pool surface starts to freeze, you need to take care of the skimmers. But full winterization is probably warranted at that point.

 

[Newdude]

Can you point me to any threads or documentation about your method for winterizing temporarily in situations like this?

Closing with shop vac.

Today was the day for closing and it went great with a 6HP shop vac. I hooked my blower up for fun after, and there really wasn't much left but some spray. Anywho I wanted to do a write up for all the folks wondering if they could save a chunk of change and tackle their own closing...

www.troublefreepool.com

For complex plumbing, I'd want a cyclone blower.

For part time winter folks, I'd get blow through gizmos and blow through bungee return plugs. It would take 5 mins to plug everywhere and then the cyclone could blow the whole system from the skimmer(s) in 5 more minutes.

The blow through gizzmo(s) would allow the pool level to remain normal and also help protect from any freezing inside the skimmer.

By your 3rd attempt it would take you 20 mins including putting the extension cord and cyclone back.

 

[DB-Cooper]

If the pool water was 30F, you would definitely see freezing on the surface because as dust drops on the surface it creates nucleation points and the surface will start to freeze and that will be your first clue that something needs to be done.

Supercooling generally only occurs in sealed system such as the pool plumbing or bottles.

As for temporary winterization, I would follow this procedure (only for pools where water level is below pad level):

First, open the filter purge valve and allow as much water as possible to drain back into the pool.

Open the pump lid

Then open all drain plugs on the pump and filter and some heaters may have drain plugs as well.

If the pool surface starts to freeze, you need to take care of the skimmers. But full winterization is probably warranted at that point.

You didn't mention opening the filter drain plug and multi-port drain plug. I do agree though, try to get as much of the filter water back into the pool.

 

[ajw22]

Understood. I have thought about this before. For me, it's not about laziness but uncertainty in being able to figure out how to do this --

Everyone in the North figures this out and I am sure you Southerners are capable of it also.

and also the uncertainty of what will happen to the pool and spa if the surface freezes hard (which will happen every time if I don't keep the water moving).

Which surface?

Best to drain down below any tile line to prevent ice from loosening tiles.

Plaster walls are not damaged from freezing. You do want the water level to it right on steps as ice and spall plaster.

Can you point me to any threads or documentation about your method for winterizing temporarily in situations like this?

Others have replied above on this.

Do you have any thoughts on the issue of the surface freezing? Is this a non-issue?

Surface freezing is not a problem as long as the ice is not touching anything that can get damaged.

I suggest you read this and choose what applies to your situation…

Closing Pool for Winter - Further Reading

www.troublefreepool.com

 

[Newdude]

****** open invite to anyone following *****

Next year get a thread going in Sept when all the northern newbs are learning for the first time. Post pics of your setup and list anything relevant. We'll walk you though the supplies you'll need and also a trial run or two.

Not having to cover will save you half the battle and ALL of the heavy lifting.

 

[mas985]

Blowing out the lines, I would classify as a full winterization rather than a temporary one. I am only suggesting the surface pipes because pipes deep in the ground will only freeze after the frost depth reaches them which will take longer than a few weeks. Published frost depths are worst case and fluctuate with air temperature. Most areas of OK/TX don't get much below 12" so I don't think blowing out the lines is really necessary in those areas.

 

[ajw22]

The problem with not doing a blowout of pipes is many old pools do not have pipes or equipment properly pitched. If you know the draining gets water out from all equipment, surface pipes, and valves then blowout may not be necessary.

Watch out if the equipment pad is below the water level. And check that all valves and elbows are free of water.

People are looking for absolutes when the answer is it depends on your pool setup. If you are not sure then blowing out pipes and equipment with a shopvac, compressor, or cyclone may be good insurance.