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hot tub evaporation rate in cold

Posted by ladybugfruit (My Page) on
Tue, Dec 7, 10 at 19:37

Ok, newbie here to pool and hot tub ownership. We have a 2005 thermaspa free standing hot tub. Over a course of 3 days, the water level on our hot tub has gone down at least 3-5 inches. Initially, I thought maybe because it was cold, and I could see steam evaporating at the corners of the cover, that it was loosing water that way, but I am beginning to wonder if I could have a crack? TIA


Follow-Up Postings:

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RE: hot tub evaporation rate in cold

Not likely to be a crack in the shell but there is a leak. It may be a motor seal, gasket, or plumbing and does need to be checked out.

Cold air just makes the evaporation more visible when the top is off. It doesn't speed it up.

Scott


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RE: hot tub evaporation rate in cold

Thanks Scott!! I will get my repair guy out to look @ it! i am so relieved that it's prob not the shell... :) Whew, what a learning curve!
Erin


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RE: hot tub evaporation rate in cold

I don't have a tub, but cold air has a lower dewpoint, ie it is drier. It will suck up moisture more quickly than than warm moist air. SCIENCE!!


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RE: hot tub evaporation rate in cold

The delta is minimal at best.

Scott


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RE: hot tub evaporation rate in cold

Please pardon my ignorance, but what is delta? My repair guy can out yesterday and only found 1 small leak...he has repaired that and also caught that one of the air jets below was blowing out directly on the motor ( told ya'll I was still learning). He also fixed that. Now we will wait and see how the water level does...maybe it was a combination of the small leak and cold air. Time will tell.


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RE: hot tub evaporation rate in cold

Delta is a change.

Scott


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RE: hot tub evaporation rate in cold

Busboy,
You are right in the fact that temp does effect evaporation. But it is the air movement over the water that causes the most evaporation.
Ladybug says she uses a cover so that air movement would be minimal, even if it leaks a little.


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RE: hot tub evaporation rate in cold

Would not there be a puddle of water on your patio if that much water leaked in just 3 days?


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RE: hot tub evaporation rate in cold

It's funny you should ask that stateguy...I have looked for puddles...the hot tub sits on the deck and as far as I can tell, there is nothing pudding under the deck and there are no signs of water on the deck.
I am really getting frustrated too. My repair guy was out Friday and took the panels off and look pretty extensively from what I could tell. I went to check water levels last night and it's STILL LOSING WATER. ARGH! I've studied the shell inside and can see no visible cracks....could it be leaking through one of the jets maybe? But then we should probably see that when looking at it with the panels off?
Sigh. I am at a loss. Will be calling my repair guy to come back out today. :(


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RE: hot tub evaporation rate in cold

What is the surface that the tub is sitting on?

Scott


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RE: hot tub evaporation rate in cold

the deck


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RE: hot tub evaporation rate in cold

Evaporation rates are primarily dependent on water temperature and dew point temperature. The larger the difference between the two, the higher the evaporation rate. However, the cover should stop most of it but it depends on how many hours of the day the cover is off the spa.

I don't know where the OP lives but in Chicago with a 100 degree spa would lose about 0.025"/hour due to evaporation when uncovered. With the cover, it shouldn't lose much water at all.

Here is a link that might be useful: Evaporation Study


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RE: hot tub evaporation rate in cold

ladybugfruit,

And that is made of what? Concrete, pavers, wood...? My point is while not seeing a wet spot may seem to be a question, if the water leaked through the bottom panel, the spa may be hiding the wet spot if it can drain over a porous area.

Scott


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RE: hot tub evaporation rate in cold

mass, I am in Texas..hardly cold enough ( 25 degrees one day, 70 the next these days) for that much evaporation I would think.
Scott, ah, wood deck... I have tried to look underneath to see if it's leaking through but it's a bit awkward and hard to tell. Booger has got to be somewhere! And I haven't even bothered checking the chemistry because I can't keep up with it. As soon as we find the leak though, I am going to drain it and start over on that front ( btw, LOVE the pool forum that someone here directed me to, that uses the BBB method).


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