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

[DB-Cooper]

If I did get to the point where I need to drain the pad due to loss of power etc, should I also try to get the waterline lowered below the skimmer ?

I didn't do that when I pulled the plug in 2021, I just put pool noodle pieces in the skimmer.

 

[DB-Cooper]

On the draining note, if I drain all pumps, heaters and multi-ports, along with leaving all valves open, should I drain the filter? I'd think if I vented the top of the filter, gravity alone would dump the filter contents through the multi-port. Presumably there's a little area in the bottom that might pool some, but it'd have plenty of space to expand. Last time I drained the filter, just wondering if that was totally necessary.

 

[Newdude]

If I did get to the point where I need to drain the pad due to loss of power etc, should I also try to get the waterline lowered below the skimmer ?

I wouldn't because I'd rather have the skimmer pipe 6 to 8 inches down where it's not going to freeze.

I'd use pool noodles or half fill an empty just with dirt/rocks so it doesn't float on top to protect the skimmer from any freezing that occurs.

Gizzmos are cheap and super easy to install (seriously 5 seconds each). Order some to have for next time(s) just in case.

 

[Newdude]

should I drain the filter?

I'd drain it with the drain, not just the air relief valve. While ice expands mostly up and not out, and you'd likely be fine with so much room for expansion.......... have you SEEN what they're getting for filters these days ?????




The tank will be cold and possibly brittle and it's just not worth any risk IMO even a small one. It only takes a minute to empty it completely

And while you have the stupid extended nut thingie plug off, replace it with this one. Channel locks easily grab the outer wings or a #2 screwdriver bar fits the slot for a makeshift T handle.

 

[DB-Cooper]

I'd drain it with the drain, not just the air relief valve. While ice expands mostly up and not out, and you'd likely be fine with so much room for expansion.......... have you SEEN what they're getting for filters these days ?????

View attachment 549423


The tank will be cold and possibly brittle and it's just not worth any risk IMO even a small one. It only takes a minute to empty it completely

Yeah, not worth it, I'll just drain again. As you said, probably ok, but you just never know...

 

[ajw22]

My point was that many people use their hot-tub (in a built-in pool) in the winter with starting temperatures pretty low. Granted, it doesn't run for hours/days on end with low water temperatures and it always finishes very hot. I wish we used our hot tub more in the winter, but probably 2-3 times per year I fire that thing up and the water temperature is anywhere in the 40s-50s in the winter; 45 minutes later we're in it for maybe an hour. I feel this is a very common use case, as opposed to letting it run days on end, and/or heating it for a weekend, letting it cool and repeating again for days of usage.

Every time you run your gas heater with water below about 60F a few drips of corrosive condensation are created inside the heate. Those drips are cumulative and stay acidic as I doubt you open up and use baking soda to neutralize it in your heater. Imagine everytime you run the heater with cold water you are dripping some Muriatic Acid inside.

Do it once in a while and it does not affect the life of your heater by much. Do it too often and it can accelerate the wear on your heater by a few days, or weeks, or years. You will never really know but when people ask why their gas heater sprung a leak after a few years I ask if they have a spa they heat in the winter. The answer is usually yes. That is the cost of using the spa in the winter.

 

[DB-Cooper]

Every time you run your gas heater with water below about 60F a few drips of corrosive condensation are created inside the heate. Those drips are cumulative and stay acidic as I doubt you open up and use baking soda to neutralize it in your heater. Imagine everytime you run the heater with cold water you are dripping some Muriatic Acid inside.

Do it once in a while and it does not affect the life of your heater by much. Do it too often and it can accelerate the wear on your heater by a few days, or weeks, or years. You will never really know but when people ask why their gas heater sprung a leak after a few years I ask if they have a spa they heat in the winter. The answer is usually yes. That is the cost of using the spa in the winter.

Thanks for the detailed answer!!!

 

[dailygenesis]

I know I'm late to the party but just adding my two cents -- I "pre-heated" my pool ahead of this drop in temp. This is only my second winter with a pool but based on my experience last year when I didn't pre-heat once and then did pre-heat a different time, pre-heating the pool definitely bought me a day or two of extra time before the the water temps got to 32.

Some above have mentioned that this won't buy you much time, but I don't think that's true. If I heat my entire 17,500 gallons to 70+ degrees (which is what I did), and then run my pumps continuously from there as temps go below freezing, since the water is continuously circulating it will keep mixing the chilling water at the surface with the warmer water below and slowly bring the whole pool down in temp. It's like having this giant bucket of warm water that you can keep tapping into to buffer against the cold water at the surface. The decrease is more rapid when the water is at higher temps. It slows as the water temp gets closer to the outside air temp, which makes sense as the differential is less.

I am in OKC so we have a bit colder weather than you. I started at about 70 degrees when we went below freezing friday night. We haven't been back above freezing since and won't be until Wednesday. A day and a half later I'm at about 48 degrees and that's coming off a night where the outside temp was zero. Today's high will be 10. Tomorrow's high will be 15. Tuesday's high will be 25. I still expect to get close to 32 by the time our temps get above freezing on Wednesday, but I believe if I hadn't pre-heated, I would be at 32 much sooner, which just adds risk.

That said, last year my water did get to 32 degrees one time and we still survived with no damage. We had a sheet of ice 80% across the surface but the water kept flowing and we survived.

This year we have a whole-home generator in place so if we do lose power we're still covered.

The pre-heating is expensive and might not absolutely be necessary but for lengthy bouts of sub-freezing temps I think it's worth it.

Regarding the issue of heater condensation and running at low temps, I have gleaned a lot from this article - Heater Condensation - Further Reading

That article suggests that if you are going to run with lower water temps, just keep it running until you reach 60 or 70 degrees. With my Hayward heater, the manufacture actually uses 50 degrees as the cutoff. We have a spa that we use throughout the winter and so we are regularly kicking it off when water temps are in the high 40s but it quickly gets up above 50 and then we run it all the way up to spa temps. I'd imagine this will have some effect of shortening the life of the heater, but I'm hoping it is minor and it is the cost of using the spa year round as @Newdude mentions.

My main concern is I just need to get a heater bypass installed so if the heater does spring a leak I can keep things running. But that's for another day.

 

[JJ_Tex]

Some above have mentioned that this won't buy you much time, but I don't think that's true. If I heat my entire 17,500 gallons to 70+ degrees (which is what I did), and then run my pumps continuously from there as temps go below freezing, since the water is continuously circulating it will keep mixing the chilling water at the surface with the warmer water below and slowly bring the whole pool down in temp. It's like having this giant bucket of warm water that you can keep tapping into to buffer against the cold water at the surface. The decrease is more rapid when the water is at higher temps. It slows as the water temp gets closer to the outside air temp, which makes sense as the differential is less.

The big misconception is that you are focusing on keeping the water in the pool above 32 thinking that will protect you. The real enemy is water not moving and becoming still in a pipe or equipment (likely due to power outage or equipment failure).

If you have a power failure, the water stuck in your pipes, heater, pumps, etc. is only going to equate to a few cups of water in each. Those few cups will quickly freeze, regardless of the starting temp. That is why I'm saying "pre-heating" your pool is a waste of time, energy, wear & tear on your heater and is giving you a false sense of security.

Please focus on keeping your water moving through the system and have a solid plan to quickly drain the water from your equipment if needed.

Note, my water is 48 and well above freezing but if we lose power the water stuck in my pipes would freeze and start to cause damage within an hour since it is in the teens. The same would hold true if my water was currently 70 degrees.

 

[dailygenesis]

The big misconception is that you are focusing on keeping the water in the pool above 32 thinking that will protect you. The real enemy is water not moving and becoming still in a pipe or equipment (likely due to power outage or equipment failure).

If you have a power failure, the water stuck in your pipes, heater, pumps, etc. is only going to equate to a few cups of water in each. Those few cups will quickly freeze, regardless of the starting temp. That is why I'm saying "pre-heating" your pool is a waste of time, energy, wear & tear on your heater and is giving you a false sense of security.

Please focus on keeping your water moving through the system and have a solid plan to quickly drain the water from your equipment if needed.

Yes, agreed that if the water stops moving the difference in heated vs. non-heated water is minimal. But would you agree that if the water is moving that having higher temperature water is preferable to lower temperature water? Isn't it true that 32 degree water is still dangerous, even if it is moving? To me, the extra cost is worth it to put off 32 degree water for as long as possible, assuming water keeps flowing.

Agreed there must always be a backup plan for power failure or pump failure. I installed a generator this year so we are covered for power failure, but pump failure could still happen at which point I agree the higher temps won't make a difference.

 

[JJ_Tex]

Water moving at 32 is not going to freeze, and I do not expect our pool water will approach 32 (but I can’t remember if ours got close to 32 before I shut it down for snowmageddon).

Regardless, as long as you are aware of the expense and wear and tear on your heater, limited benefit, and most importantly do not get a false sense of security by looking solely on your water temp.

I’m just worried about people pre-heating their pool and not reacting quickly enough if they do lose power or have equipment failure.

 

[dailygenesis]

Water moving at 32 is not going to freeze, and I do not expect our pool water will approach 32 (but I can’t remember if ours got close to 32 before I shut it down for snowmageddon).

Regardless, as long as you are aware of the expense and wear and tear on your heater, limited benefit, and most importantly do not get a false sense of security by looking solely on your water temp.

I’m just worried about people pre-heating their pool and not reacting quickly enough if they do lose power or have equipment failure.

Fair enough. I never feel secure about anything so I guess I wasn't thinking of it from a perspective of getting a false sense of security. Last year was my first year of pool ownership and my take after last winter is that keeping a pool open through freezing temps is an unsettling activity where you just do your best to mitigate as much as you can but never rest easy about it. There is no magic way to ensure everything is fine. I think the only way to rest a bit easier is to close the pool down. That's not an option for us because we want to use our spa throughout the year so we deal with the burden of keeping it open all winter, but it's not fun in times like this.

I'd like to know more about how dangerous moving water at 32 degrees is. All I know is last year in our first freeze we hit 32 degree water about a day or so before the temps got above freezing and it was pretty nerve wracking. Ice was forming across the top of the pool and into the skimmer and the pump was starting to feel sluggish, though it never shut down. I think we got a little ice in one of our spa jets because one of the jet nozzles was damaged but that was all the damage I am aware of. From that point my takeaway was just anything I could do to keep the water temp higher for longer would be helpful.

That said, I have talked to many people around this area who do pretty much nothing to their pools through these types of weather events and claim they come out fine.

 

[mas985]

That said, I have talked to many people around this area who do pretty much nothing to their pools through these types of weather events and claim they come out fine.

What they say could be true. Most damage in pool plumbing due to ice is caused near closed valves. It isn't so much the ice itself that causes the damage, it is the pressure it creates due to expansion. As long there is nothing that blocks that expansion and the pressure is released, the plumbing will be fine even though it might be frozen solid. The risk depends on how the plumbing is setup and how the valves/check valves are configured. Pumps and filters will actually freeze after the pipe since they generally have more water so it takes longer for those to freeze. Latent heat of fusion delays freezing so both temperature and time at that temperature are important.

I live in an area where we get sub freezing temperatures occasionally and have never used any form of freeze protection. I discuss how I can get away with it in this post:

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 seems like many on this forum over state the actual risks which I completely understand as there is nothing wrong with being overly cautious.

 

[dailygenesis]

What they say could be true. Most damage in pool plumbing due to ice is caused near closed valves. It isn't so much the ice itself that causes the damage, it is the pressure it creates due to expansion. As long there is nothing that blocks that expansion and the pressure is released, the plumbing will be fine even though it might be frozen solid. The risk depends on how the plumbing is setup and how the valves/check valves are configured. Pumps and filters will actually freeze after the pipe since they generally have more water so it takes longer for those to freeze. Latent heat of fusion delays freezing so both temperature and time at that temperature are important.

I live in an area where we get sub freezing temperatures occasionally and have never used any form of freeze protection. I discuss how I can get away with it in this post:

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 seems like many on this forum over state the actual risks which I completely understand as there is nothing wrong with being overly cautious.

I have read that linked article several times and many posts from you. While I find them very informative, I have still not quite determined how or if that approach translates to our climate. We will get 1-3 events per winter where temps will be sub-freezing for multiple days in a row (like right now). From what I've read from you, it seems you would recommend shutting down and draining in these situations rather than to try and keep water moving. I'm just not sure how that would work for us generally, and also because we have a raised spa so the water level of the spa is a little higher than the equipment and higher than the pool water level. Which means, there is a check valve on the spa return line that will constantly have water pressing against it, and if I open the spa suction valve while draining the pump, it will have to drain until the spa water level reaches the level of the equipment. This is going to be an issue for me at some point if we ever lose power (less likely now that we have a whole-home generator) or lose the pump or spring a leak or whatever else could take the equipment out. So, it is something that I need to figure out how to handle.

In such a situation like mine, would you say I should just drain the spa down low enough to where it is below the equipment level? Is there any issue then that the water level would be on the plaster rather than the tile in the pool?

 

[Bperry]

I have read that linked article several times and many posts from you. While I find them very informative, I have still not quite determined how or if that approach translates to our climate. We will get 1-3 events per winter where temps will be sub-freezing for multiple days in a row (like right now). From what I've read from you, it seems you would recommend shutting down and draining in these situations rather than to try and keep water moving. I'm just not sure how that would work for us generally, and also because we have a raised spa so the water level of the spa is a little higher than the equipment and higher than the pool water level. Which means, there is a check valve on the spa return line that will constantly have water pressing against it, and if I open the spa suction valve while draining the pump, it will have to drain until the spa water level reaches the level of the equipment. This is going to be an issue for me at some point if we ever lose power (less likely now that we have a whole-home generator) or lose the pump or spring a leak or whatever else could take the equipment out. So, it is something that I need to figure out how to handle.

In such a situation like mine, would you say I should just drain the spa down low enough to where it is below the equipment level? Is there any issue then that the water level would be on the plaster rather than the tile in the pool?

For climates where there more than 3 days of below zero temps we blow out the plumbing with air to remove all the water and then plug the returns and skimmers so water can’t get in there over winter.

The reason to lower water levels is to help facilitate the removal of water from the plumbing lines and to allow for some room to take on additional water over the winter from rain and snow.

 

[mas985]

In such a situation like mine, would you say I should just drain the spa down low enough to where it is below the equipment level? Is there any issue then that the water level would be on the plaster rather than the tile in the pool?

In order for a pad drain to be effective, yes the water level needs to be below the pad plumbing. Exposing the plaster is an issue in the summer but not so much for the winter and certainly not for just a couple of days. Note too that pools owners with plaster pools in the North that close for several months do this every year.

 

[dailygenesis]

In order for a pad drain to be effective, yes the water level needs to be below the pad plumbing. Exposing the plaster is an issue in the summer but not so much for the winter and certainly not for just a couple of days. Note too that pools owners with plaster pools in the North that close for several months do this every year.

Yeah that makes sense and that will be my plan in the event of anything that causes me to lose water movement. My understanding of your writings, though, is that you would recommend just draining the pad from the beginning during periods like this rather than even trying to keep the water moving. Is that right? If so, I'm not sure if I'm brave enough to make that attempt. Do you think this is the better path even without blowing out all of the lines and fully closing things down? I'm talking about during periods where temps may not get above freezing for 3-5 days.

 

[JJ_Tex]

Yeah that makes sense and that will be my plan in the event of anything that causes me to lose water movement. My understanding of your writings, though, is that you would recommend just draining the pad from the beginning during periods like this rather than even trying to keep the water moving. Is that right? If so, I'm not sure if I'm brave enough to make that attempt. Do you think this is the better path even without blowing out all of the lines and fully closing things down? I'm talking about during periods where temps may not get above freezing for 3-5 days.

My 2 cents are that there is no right answer for your area and it depends on many factors.

If you were further north I would say for sure shut things down, but obviously you lose the ability to use the spa in the winter which is a huge negative. If you traveled a bunch and would not be able to implement an emergency drain plan, I would say shut it down. If you are home and able to implement your emergency plan if needed, I would say you made the right call by keeping your pool open.

 

[mas985]

Yeah that makes sense and that will be my plan in the event of anything that causes me to lose water movement. My understanding of your writings, though, is that you would recommend just draining the pad from the beginning during periods like this rather than even trying to keep the water moving. Is that right? If so, I'm not sure if I'm brave enough to make that attempt. Do you think this is the better path even without blowing out all of the lines and fully closing things down? I'm talking about during periods where temps may not get above freezing for 3-5 days.

There is nothing wrong with trying to keep the water moving with the pump as long as you can closely monitor the pump and make sure it is running when it needs to. Draining the pad equipment is mainly for those that don't want to worry about that. It is choice.

Blowing out the lines is for long winters where the frost depth can reach the plumbing at a significant depth. I don't think you are there yet. It takes some time for the temperature of the soil to reach freezing levels. This is unlikely to happen over a week. Also, the fact that the pipes are buried delays freezing by many weeks and even for pipe that goes to the pad and is above frost depth since heat conducts through the water keeping the higher pipe water temperatures closer to that of the deep pipe. Also, the vertical pipes coming out of the ground will have room to expand should they freeze since the pad has drained and there is now air in that part of the plumbing. Just make sure all valves are open even though there is no water in the pad equipment.

If you decide to go the pump route, I would have a backup plan just in case the pump shuts off in the middle of the night or sometime when you are not around. Keeping the pad equipment warm with tarp and heaters is not a bad addition as it can give you some extra time should power go out as that heat will need to be removed before freezing can occur so it will delay the plumbing freezing.

 

[6XSBChamps]

Do we have a Cliffs Notes guideline on how fast 20,000 gallons can go from 48 to sub 32 with air temps ranging from low teens to upper 20’s over 3 days?