I found an old post about closing the pool for winter in this forum and it was discussed the easier method of just adding enough RV antifreeze to the main drain without blowing it out first and when the antifreeze starts oozing out of the main drain you just close and cap the valve for the MD. I will like to know if anybody have used this method and could tell how good it works? What will be any downsides? All I can see is advantages since its seems pretty easy to do without buying or using any shop vacs or compressors. 1 gal of rv antifreeze goes for about $3 or less.
Just adding RV antifreeze vs Blowing main drain for winter.
- Thread starter puchasr
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I don't see how that would work, if you don't blow out the line the water will stay and the antifreeze will never reach the drain. You could blow it out, and instead of slamming the valve shut creating the air lock, you could try and quickly pour in a few gallons,, then blow a little more that would push it and once you see the pink come out the drain you could slam the valve shut.
I think antifreeze has no problem filling the main drain because is heavier than water.i will try to close my pool using this method I will post about it later.
I agree with dw900. If we are talking about the skimmers, I would see no problems as the skimmers can be isolated and closed off from both ends (equipment pad and with the Gizmo's). Water at the main drain (and in the piping), can mix and travel, thereby entering the pool water. There is a term, but I just can not remember. For example, I have hot water baseboard heating in my home. If I open all the valves upstairs without the heat and only run the downstairs, slowly the water will continue to mix with the hot water on the first floor and bring it to the second floor. I believe the concept will be the same with the pool. If the valves are closed, no water will mix. In my opinion, so will pouring RV Antifreeze eventually enter the pool.
An "Air Lock" traps air from the equipment pad (Jandy Valve) to the main drain so gravity does not allow water to travel up to the frost line. In order to ensure added protection, I always recommend a black rubber plug in the pump housing. The black plug should be sticking out about 1/8" and be placed on tight.
My Dad has had an IG pool for near 30 years and I have owned mine for 8 seasons. Never once in over 35 closings have we been able to blow out the main drain. Even when the water is below the returns, I estimate about 14,000 gallons of water, and though we try, 14k gallons of water is an immovable object compared to the resistible force of a 6 HP shop vac (which blows out the rest of the plumbing just fine). Our strategy is to put between a 1/2 -3/4 gallons of anti-freeze into the main drain and call it a day. All the other plumbing is blown out and capped at the pool end. Never had a problem.
Well if you think about it, even in CT, the water isn't going to freeze way down at the depth of the main drain. It's just the 3 or 4 feet on the way down that may have an issue. I would think.
This kind of makes sense. One would wonder when no Anti-Freeze is poured in the lines, if a problem could exist when it is real cold. I am guessing the Anti-Freeze in the MD will not stay there for long.
A couple of other items that I have noticed, which I will pay a little more attention to this winter. The ice that forms on the pool surface (under the cover) for some reason is not completely frozen near the liner, therefore indicating that the liner, steel wall and soil behind it somehow insulate that small area (probably 1"). The water is only frozen at most 1"-2" at the surface, meaning the remaining water in the pool is over freezing temperatures.
Additionally, the returns jets (not on the walls, but the bottom of the piping) are encased in about 6" of concrete (called the collar) which runs all the way around the pool and a few feet off the diving board. This also insulates the pipes in the ground (3' down) + a few inches. The filter is located about 2-3' higher, making gravity naturally take water downhill. Lastly, the 5' of concrete around the pool (naturally graded for water run-off), at least for me, will not allow water to sit, freeze and expand over time. Assuming soil outside concrete will put some pressure from expansion, but not enough to make a difference.
One should always assume worst case scenario, as breaking up 60,000 lbs. of concrete to fix plumbing lines may not be very cost effective.
In theory, antifreeze is sort of a redundancy. If all the lines are blown out and capped, there is nothing for the antifreeze to keep from freezing. However if there is a leaky cap, the antifreeze will, at worst, create a slush. When it comes to the main drain, if you detach the tank from the plumbing, that whole end is open. So if water does freeze, there is non-airtight room for expansion. On the other hand I think the piece of mind is well worth the $9.38 for 3 bottles of antifreeze.
I actually have a 3" schedule 40 PVC with 2 end caps that I will be using as an experiment this winter (outside). The bottom cap is going to be glued together and filled up with water all the way to the top and then capped off. The whole 4' PVC will be standing upright against the corner wall (near my office) so I can watch it closely to determine if the water will expand up into the cap and/or towards the sides and break the PVC. This will be an interesting one.
I tested out a Corona bottle (filled up about 80% of the way up) and the bottle broke in the freezer. (Had it is a thick plastic bag so there would be no damage). The force was out, not up. This was glass. I know thin plastic expands drastically. So this will be interesting regarding the white PVC.
It will bust through the side. It has to do with how the ice forms within the tube.
In your opinion, (talking about the pool plumbing only), if there was 50% of the water left in all the plumbing, could it cause any issues?
Most plumbing lines are not completely free of all water, even upon closing as they are plugged off. Only if the water was drained below the returns, could you possibly remove 100% of the water, which is not what everyone does. Some PB close pools with water filled 1/2 way in the skimmer. Just curious to know what your thoughts were. Of course, we all know the MD can not be plugged.
I have always only put Antifreeze in the skimmer boxes and skimmer lines. As far as the MD goes,the remaining water in the pipe is below frost line so no antifreeze needed.
That's what I was getting at earlier. If it's in the ground below the frost line it's safe.
I just finished blowing the main drain of my agp a small 2 hp (armour all) did the job. I let it run for about 1 minute. Plenty of bubbles were coming out and then closed the valve and capped the 2 openings on the valve.I didn't use the antifreeze after all since the small shop vac was enough to blow the main drain (1 1/2" and about 15' long ) some pics here Google Photos
Frostline in northern IN is about 4' the MD of my above ground pool is about 2'deep. I wonder if the water above it acts as insulation.
I just blowed out the MD and didn't add any antifreeze, hope the air stays there until next spring.
I would assume that water does act as an insulation. This winter, I will pay closer attention to the thickness of ice that freezes on the surface. The ground surface, line, steel walls should also act as insulation, or one would see at least a foot of frozen water on the pool surface.
I believe the layer of ice on the top actually protects the water on the bottom from freezing, especially as wind is a big contributing factor to water freezing.
Since you did blow out the MD you also created air space in the pipe, if it does freeze at least it has room for expansion.
Now if it was a solid pipe full of water, maybe a different story at that depth.
The thermal conductivity of water is around 0.6 W/(m K) while for ice it's 2.22 W/(m K) at freezing and goes higher as the temperature drops. The thermal conductivity of concrete varies but is roughly on the order of 1 W/(m K). The thermal conductivity of soil varies a lot depending on soil type and water content but roughly will be in the concrete to ice range.
So while the initial layer of ice prevents evaporative cooling, after that there is probably more loss of heat per square foot through the ice than through the pool walls, at least until the ice was roughly twice as thick as those walls. Of course, the ground temperature makes a big difference here. I wonder if the ice depth level in a pool is the same level as the frost line. It's probably close though perhaps may go somewhat below that due to the greater thermal conductivity of pure ice compared to frozen soil. Anyone have any experience with that (i.e. measured ice depth in pool vs. ice depth in soil)?
So while the initial layer of ice prevents evaporative cooling, after that there is probably more loss of heat per square foot through the ice than through the pool walls, at least until the ice was roughly twice as thick as those walls. Of course, the ground temperature makes a big difference here. I wonder if the ice depth level in a pool is the same level as the frost line. It's probably close though perhaps may go somewhat below that due to the greater thermal conductivity of pure ice compared to frozen soil. Anyone have any experience with that (i.e. measured ice depth in pool vs. ice depth in soil)?