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Thread: Sweaty toilet bowl - how to prevent?

  1. #1

    Default Sweaty toilet bowl - how to prevent?

    Hi,

    My bathroom has a skylight. My current toilet is unlined. Particularly during the hot humid summer months, the light and heat beat down on the tank, which then sweats and drips onto the floor (which is wood).

    How can I prevent this?

    I am thinking of purchasing a new toilet. (I don't like my current toilet, so if I can solve the sweating problem and get a better toilet, I'm all for that). Possibly one with a lined tank. I am also considering something like the Toto Ultramax, or one of their other one piece models. I'm a bit worried though, that the tank, being unlined, may still sweat.

    So, can anybody fill me in on how the one piece Totos are with sweating?

    I'm also open to any other ideas you might have to fix my problem.

    thanks,
    Geoff Ruby

  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
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    One way to solve this is to put a tempering valve on the supply to the toilet. This is basically a valve that mixes the cold water with some predetermined hot to put the mixed water temperature above the dew point. You need access to hot water to the supply valve, though. If your supply water is cold enough, insulation won't help. Are you on a deep well?
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  3. #3

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    Water supply is municipal water (from Lake Ontario). I don't know how well a tempering valve would work for us - the water heater is a long way from the toilet in question - so the water has to run for a long time before it gets any heat if we haven't used hot water in a while. And, it would involve plumbing, tearing up the floor etc (am I correct there?), and I'd like a better toilet.

    We've looked at replacing the skylight and/or getting a custom blind installed, but a new toilet would be considerably less expensive.

    In all seriousness, I'm hoping a new toilet is a viable solution, as I think it would be the cheapest, easiest way to go, if it will solve my problem. And, did I mention yet that I'd like to get a new toilet?

    Thanks,
    Geoff Ruby

  4. #4
    Retired Defense Industry Engineer jadnashua's Avatar
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    This comes up occassionally. INsulation only helps a little bit. If the toilet is flushed several times, the insulation only slows the transfer of heat - it will be overcome and get cold enough to sweat. An air conditioner or dehumidifier helps. Maybe someone else will have some better ideas.

    Most of the new low-flow toilets don't dump all of the water out like the old ones did, so that means that the incoming water is mixed with room-temperature water which would help a little bit. They rely on the height of the water in the tank to help provide some of the needed pressure, but stop the flow before the whole thing empties.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  5. #5
    Plumber plumber1's Avatar
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    Take a good look at the toilet again, It may need to be repaired..........

  6. #6

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    I think the existing toilet is ok, it is not leaking, the problem pretty much goes away in the winter - the problem is it's hot in the summer at least (high 90s tomorrow, well over 100 with the humidity factored in), the water here comes from a very large, deep source, so stays quite cold, the existing tank is 13 L (3? gallons), so there's a fair bit of water and surface area, and this is made worse by the skylight - probably a poor quality one. On a hot summer day it's like an oven in our washroom.

    I was also shown a toilet which held the water in a container that did not contact the tank's walls except during the flush. That might be the way to go? Can't remember the brand - I'll try and do a return visit tomorrow and find that out.

    Cheers,
    Geoff Ruby

  7. #7

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    Quote Originally Posted by Geoff Ruby
    I was also shown a toilet which held the water in a container that did not contact the tank's walls except during the flush. That might be the way to go? Can't remember the brand - I'll try and do a return visit tomorrow and find that out.

    I just installed that type of toilet for some friends of mine. Took some getting used to, but I think they like it now. We live in New Mexico, where it's dry, so I can't say if it'll help with the condensation problem. But it seems like it would, since the water only contacts the tank when you flush. Have you tried one of those furry tank covers? They also make a booster fan that fits in your AC vent to help cool down areas that need extra cooling (or heat them up in the winter). You would think that without a liner, the water in the tank would assume room temp. pretty quickly.

    I vote for a dehumidifier coupled with a furry tank cover.

    Eric

  8. #8
    DIY Junior Member biffnh's Avatar
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    I doubt that the skylight has anything to do with it - other than the sun beating down on it will warm it up and help evaporate the condensation. It is the humidity in the air that is the culpret. I have not found that insulation works. Tempering valves do work and I have had success with them - even thought the water heater is a long distance away the water in the hot water line was warm at one time and is now likely to be as warm or warmer than the air temperature and this will stop condensation. If plumbing one in is difficult consider going to a toilet that uses no water in a tank. I have two compressed air toilets in my house (20 years now) and they are terrific. 0.5 gallons per flush, no sweating and no double flushing!
    I highly recommend them.

  9. #9
    Plumber jimbo's Avatar
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    I agree with Biff's post....the skylight has nothing to do with it. Condensation happens when warm moist air hits cold porcelain. If the sun could heat the tank or bowl enough, there would be no condensation. The issue is warm moist air. A ceiling fan or any fan to circulate air would help. An insulated tank would help. A dehumidifier would help.

  10. #10

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    It was indeed the Niagara flapperless that I was looking at.

    I pretty much agree that it is the humidity in the air that is causing the problem. I think the skylight does make this worse, due to the fact that it heats up the room, and the warmer air is, the more moisture it holds. It's also probably true that when the sun does directly beat down on the toilet bowl, some of the condensation is burned off.

    Given the comments to my question, I'm now leaning to the Niagara toilet to see if it eliminates the problem or limits it enough that I don't have puddles on my floor.

    Any other toilets (ie the compressed air ones, for example) that you'd recommend I have a look at?

    Thanks again,
    Geoff Ruby

  11. #11
    Retired Defense Industry Engineer jadnashua's Avatar
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    Hotter air is capable of holding more moisture, but unless some is added, the relative humidity actually goes down as the temperature goes up.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    DIY Senior Member Pewterpower's Avatar
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    I'm guessing that you don't have AC.
    And if the skylight is not well insulated, or not tinted, then I can see how it would get damn hot in there in the summer. You said you don't have the problem in the winter, right?
    Try covering the skylight with cardboard (or something that won't permit alot of the heat/light to come in) for a couple days, and see if the tank still sweats.

  13. #13
    Retired Defense Industry Engineer jadnashua's Avatar
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    Watch the relative humidity during the day...as the temp rises, the humidity goes down, as the sun goes down, the temperature often falls to the dew point. The warmer room is less likely to sweat than a cooler room unless there is standing water in the room that is evaporating to raise the absolute humidity level.

    If you use a tempering valve, even though the hot water may not actually make it to the valve, it will be at least at room temperature rather than much below as the cold water could be since it came out of the hot water tank. That is the best solution as if the toilet gets flushed several times in sucession, the insulation only slows the heat flow, not stops it...it will still sweat.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  14. #14
    Plumber plumber1's Avatar
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    Tank cover is not a good way to go.

    If it was my problem I would try putting a small $10.00 fan on a shelf in the bath room and move the air.

    How many flushes does that toilet get? Seems to me if it's not flushed more than once every 2 or 3 hrs that there wouldn't be excessive condensation. If there is do you know how to prove that the toilet isn't leaking through?

  15. #15

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    Quote Originally Posted by dc_homeplumber
    A tank cover on a sweaty toilet tank absorbs the moisture and then mildews and stinks because it never dries. No offense, but not a great idea.
    My thinking was to put it over the tank when it's dry (or dry the tank yourself and then put it on.) The cover would then act as an insulator between the cold porcelain and the moist air.

    But if your experience shows that this doesn't work, I won't disagree.

    Eric

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