Tempering Valve to Stop Toilet From Sweating


Aug 7, 2020
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If you starting seeing my hand in magazines, don’t be surprised. As you can see, my hand is model quality and I hope you appreciate it.

Back when I was taking up the tile in my bathroom, I noticed that the sub-floor to the side of the toilet was a little wet. I thought this could be caused by two things…the water that shoots out of the shower because of having a lousy shower curtain setup or from the toilet tank sweating. I have recently come to the conclusion that most of the moisture is coming from the shower, so when we put the tile in, I will make sure things are nice and caulked back there.

I did notice a small ring mark around the toilet tank feed pipe as well. This leads me to believe that during the summer, that pipe (and maybe the toilet tank) sweats due to the heat and humidity. There are a few ways one can deal with this type of issue. You can insulate the inside of the toilet tank, insulate the feed pipe, run hot water into the toilet or install a tempering valve. I think the best thing to do is to purchase a pre-insulated toilet tank and wrap some pipe insulation around the feed pipe. There are mixed views on the tempering valve.


My friend was kind enough to give me a tempering valve that he was not using. I think he said he changed the size of his piping, or something like that. That’s fine with me, because I wouldn’t mind giving the tempering valve route a try.

Some people have claimed that after installing a tempering valve, they didn’t notice any difference and their tank still sweat. I hear that more often than not and I think it is because of the length of pipe from the hot water heater and the toilet tank. By the time the warm water gets to the tank, it’s already full. What’s the way around that? I would guess it would be to hook the hot water up directly to the toilet tank. That way, when the toilet is flushed, the cold water in the pipe will partially fill the tank and then the rest will be filled by the hot water. I am not sure if I have ever heard of anyone recommending that, so don’t do it. Actually, you can do it and then leave a comment here letting us know how it worked out. Just don’t yell at me if it turns out bad.

When I get a chance, I am going to install the tempering valve. I think that having it is better than not and I also want to use my new torch again.


Aug 3, 2020
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Having the toilet operate solely off the hot water line is a bad bad idea for several reasons. Yes your theory is sound at first glance but here is the problem:

1. Assuming this is the first time you flushed the toilet today, you’ll get a mixture of cold and hot water = warm water. Which is good.

Now say you flush the toilet again, only this time all you get is hot water at what ever temperature your water heater operates at.

2. If you have several people living in your home, and assuming everyone is using the toilet, the water heater will be taxed even higher which will mean a higher electricity bill.

3. If it is only the one temperature line, you have no adaptability to change according to the current environment. Meaning you still have to use hot water when its not necessary, and again wasting money.

4. If your water temperature is set too high, there is the possibility of damaging the rubber portions of the mechanics that are only meant for cold water.

5. If you get toilet water splashed on you, ouch.

6. If you have a kid playing with the toilet, which every kid does at a certain age…that’ll be a problem.

7. If your toilet floods? Sometimes you have to stop a toilet from flooding by messing with the tank while its overflowing with water. Impossible to do that while it is super hot.

So you best be installing an adjustable temp valve.
Tempering Valve to Stop Toilet From Sweating was posted on 09-24-2021 by Cameron in the Home Forum forum.

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