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Tekno9000 01-26-2010 12:03 PM

Sweating toilet tank
I have a toilet tank which sweats profusely. This is on the second floor. The first floor tank does not sweat. Placed aluminum trays beneath the tank but water still gets on the floor. Can some one please suggest a good method to stop sweating.

Please help.


I searched the forum but didnot find anything on this.

Thurman 01-26-2010 12:36 PM

My first thought is that you don't really have a problem with your toilet- -it's with humidity within the bathroom. Water coming into the tank is much cooler than the ambient (surrounding air) temperature of the bathroom, and especially the air against the toilet tank. When the tank fills with the cooler water it lowers the temperature of the air immediately against the tank causing the water within the air to condense onto the outside of the tank. This is known as "lowering the dew point" of the ambient air. The air gets cooled enough to make the moisture (water) within the air condense and want to drop out and it is coolest at the tank. Do you have an exhaust fan within the bathroom? If so, you are not allowing it to run long enough to remove enough moisture after a shower/bath, or maybe there is a blockage within the fan exhaust line. IF you do not have an exhaust fan, this is a sure sign that you need one. So, why does the second floor unit do this and not the first floor? Maybe the water is cooler coming into the second floor toilet, or maybe you are running an exhaust fan longer on the first floor. Something is causing a difference in "relative humidity" within the two bath areas. Good Luck, David

Tekno9000 01-26-2010 02:19 PM

I dont have exhaust fan on both floors. Will leaving the bathroom door open after taking a shower help? I also noticed that the ceiling has condensation too.

Ishmael 01-26-2010 03:23 PM

Watts anti-sweat mixing valve.

Since the problem toilet is on the 2nd floor, it poses more of a problem. To install an anti-sweat mixing valve, you have to have access to a hot water line, and a way to pipe the outlet of the mixing valve to the toilet supply. If the toilet is next to a vanity, you can install the mixing valve under the sink and run a new toilet supply out the side of the cabinet. The old toilet supply can just be shut-off and left where it is, or capped in the wall (in which case you'll have to patch the wall).

Another option is to get a toilet with an insulated tank - usually a styrofoam liner inside the tank. They sell retrofit liner kits, but they don't seem to work very well.

Finally, your flapper may be allowing water to leak into the bowl which means there's a constant/steady flow of cold water to the toilet. You may need to replace the flapper. This could explain why the first floor toilet doesn't sweat, but the 2nd floor one does. (Either that or the 1st floor toilet has a mixing valve, and the 2nd floor toilet does not).

plummen 01-27-2010 12:47 AM

put one of those tank sweaters around it like they sell at kmart

plumbdoc 01-27-2010 01:12 AM

its your fill valve or ballcock
its your fill valve/ballcock possibly flapper if its leaking to much water. I say its your fill valve, sweating tank is tall tale sign of fill valve/ballcock

Tekno9000 01-30-2010 01:22 PM

I saw that there was a small leak, changed the flapper. Now the condensation has reduced considerably. Will observe couple of days.

Thanks to everyone for helping.

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