Condensation in bathroom after woodstove install

[BC_Josh]

Hi,

I'm not sure which forum I should post this, so I just put this in here.

Since I installed a woodstove, my basement is colder than before, when I ran the gas furnace that blew some heat into the basement through the ducting. Even during a cold snap (not too cold where I am in southeastern BC, Canada, 5F or -15C for no more than a few days to a week typically, and I notice that my basement doesn't get lower than 48F or 9C), so, no risk of freezing water pipes and no condensation issues in my basement.

But, the problem is my toilet "sweats" with condensation, quite badly and it will even pool a little water on the bathroom floor. To remedy this, we don't flush the toilet every time we use it in the winter; if it's "yellow it's mellow" rule, and only flush solid waste down there and that helps a lot. It doesn't do this during the summer or shoulder seasons, so it appears to be the cold air/water coming into the toilet from a colder basement than before that no longer has the heat coming up from the basement below (i.e. too great a temperature difference between the water pipes entering the bathroom and the bathroom room temperature). The water pipe that goes out of the wall, for the toilet, also has a condensation issue and is creating a green dripping pattern on the wall from the copper pipes, which is not good.

Obviously I wish to remedy this situation, and I want the lowest cost, easiest solution, if possible. I could hire an electrician to come and put a baseboard heater into the basement and leave it on low, but that could wind up being very costly over time since the basement walls are mostly uninsulated concrete walls with low R-value, and the rest of the basement is fine. The other solution I have is that when I turn the furnace intake fan on, it sucks some of the warm air next to the woodstove down into the basement, but the intake vent is too close to the woodstove to do this, unless I install a fresh air intake to the woodstove, which I'd like to do eventually but that's a big job and I have other commitments so I'd like to put that off for a year or two.

So, for now, if anyone here could offer any ideas I'd be grateful. I'm thinking maybe a bit of heat tape? That should be cheap to run, right? But, I don't have a ground fault interrupter outlet in the basement to plug it into either.

More insulation around the pipes in the basement?

Get a dehumidifier in the bathroom?

 

[stoveliker]

No good solution from me, but a few thoughts.

Your water coming to the toilet is too cold, leading to the condensation. You could add some (foam) insulation around the water line that also sweats. That'll avoid the green stains, but does create a bigger (uglier?) pipe.

I would be concerned a bit about the water lines that run in your walls. They might sweat too, possibly creating mold in your walls.
Moreover, how well is your air sealing; if not great, the humid air in the home might end up condensing in other places in your walls too (e.g. getting thru outlets in your external walls).

I don't think a dehumidifier in the bathroom will resolve the bathroom issue - at least not completely. If you're taking a shower, I think the humidity will be high enough for condensation on 50 F water lines and toilet (and reservoir) itself regardless of whether a dehumidifier is running.

I think a bigger dehumidifier in the home is needed.
BUT your uninsulated concrete in the basement is going to add a LOT of water to the air in the home; a decent fraction of that will move upstairs from the basement (surely if an open stairs/door connects the two).

The problem in the bathroom could be resolvable with a water line heater.
If you know the relative humidity in the bathroom (or the home as a whole) you can find the dew point, and see what temperature the water should be to avoid condensation. But yes, that'll cost kWh.
If you do that where the main water line enters the home, you avoid any condensation/mold in walls in other places too.

 

[EatenByLimestone]

I’ve seen 2 low cost remedies for this. You used to be able to buy foam kits for inside toilets. I’m not sure if they still offer them.

Next up is a mixing valve. It mixes in some warm water into the cold feed. It’ll keep the tank warm enough not to allow condensation.

 

[EbS-P]

One hotel we were at just ran a hot water line from the Sind to the toilet. After a flush or two it makes a great towel warmer.