Hot Tub +Addendum

Here’s the background.

When I went on my cruise vacation I turned the hot tub temperature down to 50 degrees to save on electricity.

While I was away, the weather turned unseasonably cold – with nighttime temperatures in the mid to low teens (I think it got down to 14 degrees a couple nights).

When I got back – I went to turn up the hot tub temperature and was dismayed by what I found.

The hot tub had drained down to the filter level (about a foot below the normal fill level). When the water gets that low – the pump sucks in air and you get an air lock in the system (air from the filter since water level drops and the intake can on take in air at that point). The pump runs – but it is running dry – i.e. it is not pumping water – just running.

How long the pump was running (but not pumping water) is anybody’s guess. Days perhaps? Those pumps are not designed to run ‘dry’. That’s a sure fire way to burn out a pump.

So – I threw the main breaker to turn the system off. Then I drained all the remaining water from the hot tub (so it wouldn't freeze and burst the pipes or crack the tub).

Also – I noticed long icicles below the deck under the hot tub. Obviously where water had come from the hot tub and frozen.

Since it was still in the 20’s when I got back – the plan was to wait till warm weather and try and diagnose the problem.

Which was today (Sunday).

I’ve filled up the tub to the proper level, removed the side panels and insulation panels, checked the filters and valves (one valve was partially closed) – and then threw the breaker switch to turn the system back on – and waited to see what happens.

The pump and heater came back on. I ran the system self check code – turned the air pumps on and off. Cycled the water pump from low to high a couple times.

Everything is working properly.

I can’t see any leaks inside the housing.

In short – as far as I can tell – everything is running perfectly.

Which is great. Except that something caused the water level to drop while I was gone – and I can’t figure out what happened.

One idea is a line froze up since I had it set on 50 degrees instead of the usual 100 degrees and maybe a frozen blockage cause the water to pump into the tub and over the side instead of circulating through the system.

Or maybe it’s a super slow leak that I can’t see.

Anyway – I’ve still got the sides off and am going to watch it though out the day.

If nothing unusual shows up – I’ll put the insulation and side panels back on and see what happens over the next week.

It’s supposed to turn cold again with temperatures back into the low 20’s. If it’s a line freezing problem – maybe it will show up.

On the other hand – I’m not going to turn the temperature down just to test my theory. I now think it’s best to leave the temperature at the normal operating setting of 100 degrees. Even if I’m away for a week or two. It’s not worth risking a freezing line and damaging the hot tub just to save a few cents in electricity.

Penny wise and pound foolish.

Addendum 1/10/11

Well, it's been over a week now and the water level has stayed the same and the hot tub has been operating perfectly.

Obviously I'm glad everything is working fine, but the great hot tub mystery remains.