Winter closing - antifreeze?

[sande005]

So - Minnesota. For the last 25 years I've closed the pool using my trusty air compressor into the pump pot to blow out all the lines. It has pressure, but not a lot of volume. Usually run it pretty high (80 psi) at the compressor, figuring as it expands when hitting the pipes the pressure drops significantly. I usually have to redo each skimmer/outlet two to four times before it stops burping any water. Since there is doubt, I've always used a screw in elbow and length of pipe to funnel in a couple gallons of -70 antifreeze into each line, except the main drain.
Because of filter/plumbing changes, using the compressor gets a more complicated this year. So the Cyclone blower is coming. Yea! Volume of air, without high pressure.

Don't know what the pool companies do, and the lawn sprinkler guys definitely don't do antifreeze

Yes, we can have periods of a week at -20 or -30F at night, and from about Xmas to March are pretty much always below, or well below, 32. Frost line can be from 3 to 4 feet. So if something can break from trapped freezing water, it will.

So - keep on adding the antifreeze, or will using the Cyclone do a better job of getting out the water, and I can skip that step?

 

[Bperry]

So - Minnesota. For the last 25 years I've closed the pool using my trusty air compressor into the pump pot to blow out all the lines. It has pressure, but not a lot of volume. Usually run it pretty high (80 psi) at the compressor, figuring as it expands when hitting the pipes the pressure drops significantly. I usually have to redo each skimmer/outlet two to four times before it stops burping any water. Since there is doubt, I've always used a screw in elbow and length of pipe to funnel in a couple gallons of -70 antifreeze into each line, except the main drain.
Because of filter/plumbing changes, using the compressor gets a more complicated this year. So the Cyclone blower is coming. Yea! Volume of air, without high pressure.

Don't know what the pool companies do, and the lawn sprinkler guys definitely don't do antifreeze

Yes, we can have periods of a week at -20 or -30F at night, and from about Xmas to March are pretty much always below, or well below, 32. Frost line can be from 3 to 4 feet. So if something can break from trapped freezing water, it will.

So - keep on adding the antifreeze, or will using the Cyclone do a better job of getting out the water, and I can skip that step?

The cyclone will do a great job but keeping the water out depends on how good your shutoff valves are.

 

[sande005]

The cyclone will do a great job but keeping the water out depends on how good your shutoff valves are.

It all gets pumped down below the returns first. After the antifreeze add, returns are capped and gizmos in the skimmers. So the only airlock is the main drain.
Except for that one, I leave all the valves (and drain ports on heater, pump, etc.) open to give any potentially compressed air (from ice) a place to go.

So - will the Cyclone blow out enough that I can skip the antifreeze step this year? Or should I continue with the belt-and-suspenders addition?

 

[sande005]

FYI - not very hard or expensive to do, except for hauling 12 jugs of antifreeze around, but would be nice to not have to...
And in the spring, I have a pipe to screw into the skimmers/returns, so on start up I can pump the antifreeze out of the lines onto the lawn, rather than have it get added to the pool water. It's non-toxic, and has never bothered the grass. Would be one less thing to do if I don't have to add it to begin with.

 

[Bperry]

It all gets pumped down below the returns first. After the antifreeze add, returns are capped and gizmos in the skimmers. So the only airlock is the main drain.
Except for that one, I leave all the valves (and drain ports on heater, pump, etc.) open to give any potentially compressed air (from ice) a place to go.

So - will the Cyclone blow out enough that I can skip the antifreeze step this year? Or should I continue with the belt-and-suspenders addition?

If the air is really out of all the lines, the filter, heater, etc then there’s no reason for anti-freeze. Anti-freeze prevents -water- from freezing so if there’s no water to freeze then there’s nothing for the antifreeze to do. If the water is below the returns and stays that way all winter I see no reason to add antifreeze. But if the water level rises and leaks into your returns, then there’s potentially an issue if your frost line is that low.

I’ve just put a gallon in each skimmer once the gizmo is in just in case rainwater runs down into the skimmer body (which is always does). No antifreeze anywhere else and it just gets mixed in with pool water when I open. Though last year froze pretty good so I may reevaluate.

 

[Newdude]

Every year I blow the antifreeze out of my lines in the spring and it's darn near pure. If it was diluted even 2 gallons to one, it wouldn't be nuclear flourescent when it came out.

There will always be some amount of water which won't blow out the vertical pipes up to the returns as it's easier for the air to push past it than it is to push/ lift it out. Path of least resistance and whatnot. But that half gallon (?) will find its way to the low spot and be well below the frost line. It will also likely not fill the low spot completely and ice only expands 10% or so, so even if it did freeze, it would have plenty of pipe to expand into. Antifreeze while not necessary with well blown pipes, also won't break the bank for insurance. Problems (God forbid) might break the bank. Lol.

Here's a pic for the idea, although most have more complicated plumbing than me. The mostly horizontal green pipe will blow clear, but the short red extension at the end won't, nor will the vertical pipes to the returns. That little bit will collect and fill 10% (?) of the main pipe, leaving tons of expansion room, and being below the frost line anyway. That water is the spitting that I see at the end of blowing.



For anyone buying this year, Lowes and Walmart always stock $4 jugs of RV/Marine antifreeze this time of year and it's half the price of most places.

 

[sande005]

OK, probably looking to go too far in the other direction, so cheap insurance it will be. ~$50 for the antifreeze is cheap in comparison to the alternative.

While freezing water can break things on it's own, I've seen a number of studies that in many cases the problem can come from compressed air. Air is trapped, and as the ice expands it compresses (since water doesn't compress) leading to extremely high air pressures, which rupture the pipe. Hence why I leave most things open over the winter to give air a chance to escape at least part of the system. Since snow/rain can refill the pool, capping the pool ends seems prudent. to stop water from getting in as the level rises.

 

[Bperry]

OK, probably looking to go too far in the other direction, so cheap insurance it will be. ~$50 for the antifreeze is cheap in comparison to the alternative.

While freezing water can break things on it's own, I've seen a number of studies that in many cases the problem can come from compressed air. Air is trapped, and as the ice expands it compresses (since water doesn't compress) leading to extremely high air pressures, which rupture the pipe. Hence why I leave most things open over the winter to give air a chance to escape at least part of the system. Since snow/rain can refill the pool, capping the pool ends seems prudent. to stop water from getting in as the level rises.

Pipes can withstand something like 80psi so I don’t think you have to worry about that. If there’s enough water in the pipe to freeze the opening, it’ll crack the pipe before there’s enough air pressure to damage anything. Leaving them open allows condensation in though probably not that much. I’d focus on the return plugs more than anything.

 

[Newdude]

I've seen a number of studies that in many cases the problem can come from compressed air. Air is trapped, and as the ice expands it compresses (since water doesn't compress) leading to extremely high air pressures, which rupture the pipe

In my robust sample size of exactly *2* pools, both had negative pressure upon opening the plugs in spring. By dumb luck I removed the threaded fittings first the first several years but on year 5 or 6 I opened the rubber winterizing plug first and it sucked into the pipe and past the first 90 before my brain caught up to what happened.

Many, MANY adult words were said in the 20 minutes it took to shop vac it out, and twice as many prayers. Always remove the gizzmos or other threaded fittings first when using rubber plugs anywhere.

$50 for the antifreeze is cheap in comparison to the alternative

With 12x (?) the plumbing on the complicated builds there's 12x the chances for one leg to fail. $50 is well spent, just in case.

 

[sande005]

I may have been wrong - it is not the compressed air, but the remaining liquid water that causes the burst.
Here's one reference: https://www.jlconline.com/how-to/pl...ce can exert pressures,your way to 43,000 psi.
"This Old House" has an example of it in action on their site.

Think I'll still use antifreeze....

 

[Newdude]

I may have been wrong - it is not the compressed air, but the remaining liquid water that causes the burst.

Indoor plumbing, particularly in the exterior walls and/or once the heat is shut off, and mostly empty pool plumbing almost entirely below the frost line are two different animals. In some ways, science is science, but it's also apples to oranges.