attached pool spa closed properly?

[masspoolside]

I have an older pool that has an attached spa (originally built in early 1980s...new plumbing in 2013).

I had the pool company close the pool that did the re-plumb and renovation.

When they closed the spa, they simply blew air through the line and closed the valve to create an airlock (like one closes the main drain in the pool).

My question is, since the spa is very easy to completely drain and simply close in the floor drain itself with a plug, why take this risk? It would seem to me the spa (hardly being below ground level) could freeze entirely and if the air lock/seal breaks theres a serious problem.

Apparently the pool company warrants the lines if they break in winter, put the risk is huge: breaking up a brand new poured concrete deck for one.

Would appreciate thoughts on this.

Many thanks.

 

[Matt Ush]

We usually fully drain the spa and blow out the drains/returns if we can. I know of people who do not and have never had issues, but that is just the way we like to do it to be safe.

 

[JasonLion]

In Massachusetts I would definitely expect them to drain the pool low enough that the spa, and associated plumbing, was completely drained (and blown out).

The pool main drain is commonly air locked, but that only works because it is well below the frost line. Air locking a spa drain is not likely to be sufficient that far North.

The further North you are, and I consider Massachusetts fairly far North for pool purposes, the more important it is to defend against freeze damage in several different ways. That way if any one method fails you still have an entire other reason, or two or three, why there won't be any damage.