Toilet leaking at base when water heater is on

Dutch,

That's good to know, thanks!

Brettmm92 wrote:
Well, I'm happily embarrassed to say that it seems the problem was just the external water line connections needing tightening... Is taking it out as easy as undoing the waterline and the two bolts on the floor?

Good on you for finding it without major surgery! Let me mention, this isn't the first time this has happened.

Please install a shutoff valve in that supply line while your mind's in the toilet. Here's one that just pushes in place, a "Sharkbite" design. I think it'll have instructions how much of the tubing to cut out. So long as you have enough straight run, it's very easy.
In Amazon, "plastic pex valve"
A house, of course, has a shutoff at every toilet, every faucet, most appliances (dishwasher, clothes washer, icemaker). Impractical to do that in an RV, BUT... The Toilet is probably going to be the one that would otherwise force you to turn the whole water system off. Shower or faucet may drip, but that water goes down a drain.

You made a very good find. I ended up repairing our floor around the toilet. I think prev owners had a leak where you did, and tightened those two flange bolts thinking that was the problem. So my repair included a new flange.

Brettmm92 wrote:

Someday I want to give my toilet a real good cleaning where I can't reach while it's connected. Is taking it out as easy as undoing the waterline and the two bolts on the floor?

Yes, but I suggest having a new floor gasket on hand for reinstalling it. Get the correct gasket from an RV parts source, do not use a wax seal from the local hardware store that's intended for residential toilets.

Well, I'm happily embarrassed to say that it seems the problem was just the external water line connections needing tightening. I can't believe I didn't even think of looking behind the toilet! Very easy fix, thanks for the proper directioning!
Someday I want to give my toilet a real good cleaning where I can't reach while it's connected. Is taking it out as easy as undoing the waterline and the two bolts on the floor?

gbopp wrote:
You may want to check the water lines and make sure hot water isn't going to the toilet.

Easiest way would be to turn the water heater on, let it get up to temperature, then flush the toilet long enough to see if the water flushing it is hot.

But hot or cold, toilet flush valve still shouldn't leak...

dougrainer wrote:
As Newman stated, there is no relation between the Toilet water and the Water Heater water. EVEN if you had hot water to the toilet input, the hot water increase pressure(VERY SMALL) would not leak out at the Toilet base. You have a HOT water leak that is caused by the small increase in water pressure, probably at the EXIT HOT fitting of the water heater. The HOT water is causing the line bevel washer to leak from the HOT of the fitting. Can you get access to the back of the water heater? Doug

Or when it gets hot the weld at the anoide rod threads expands it leaks when it cools off leak stops

As Newman stated, there is no relation between the Toilet water and the Water Heater water. EVEN if you had hot water to the toilet input, the hot water increase pressure(VERY SMALL) would not leak out at the Toilet base. You have a HOT water leak that is caused by the small increase in water pressure, probably at the EXIT HOT fitting of the water heater. The HOT water is causing the line bevel washer to leak from the HOT of the fitting. Can you get access to the back of the water heater? Doug

Sounds like water heater is a suburban tank failed at the top water is going under the flooring coming out at the toilet

Heating the water up from cold will cause the system (cold and hot, if there's no check valve on the cold water inlet to the water heater) to pressurize more. My guess is that the toilet valve is leaking under the added pressure, which means the connection is barely adequate under normal pressure. It likely just needs to be tightened.

This would be the flush valve, not the seal between the toilet base and the sewer. The two nuts holding it to the floor have to deal with the latter connection; check that there isn't some other water connection accessible somewhere (or possibly inaccessible somewhere). I guess it's possible that the fresh water connection may be routed within the pedestal, but I don't think that's at all typical.

You may want to check the water lines and make sure hot water isn't going to the toilet.
Someone could have hooked it up wrong, even if it's a new RV.