How about a fan to take the steam away?
If tank condensation is in a particular situation caused by steam from the shower condensing on the tank, because of the cold water in it. how about redirecting some of the shower drain (hot) water thru the tank. You can use a heat exchanger coil of 3/4 inch copper , a small radiator,or even a direct line of 1/4 inch plastic icemaker line, of course the overflow will go down the standpipe but it will keep the tank nice and warm and cozy.
I suspended a 100W aquarium heater in the tank with galvaized wire. It is already waterproof and you can the temp from 70 to about 90 degrees. I set mine to around 72 degrees and that works most of the time. The only time condensation showed up is when the toilet was flushed several times in a row but it didn't last long.
Buy a see-through tank, a fluorescent light and you could keep fish in it!
Aquarium cleaning made easy.
Sounds like a leaking flapper. Imagine the water you have been wasting.
If someone wants an insulated tank, I sell them the ST743SD tank by Toto for the Drake.
I keep them in stock for those special cases.
It seems like with a properly working tank this would only be a problem in certain climates in winter. The supply water temp would have to be rather cold for condensation to occur--I've not seen this even in the subtropical southwest Georgia region. Modern toilets use small flush volumes and usually retain considerable residual water in the tank at the end of the flush (to produce a higher head stack for the flush.) This greatly reduces the temperature drop of the external tank wall compared to the older pre-1994 high volume toilets. Therefore, the tank wall is not likely to be considerably cooler than the ambient of the room. Now if someone takes high flow half hour showers with rather hot water...the tank, bowl, water line, etc. could stillsweat considerably.
Terry's point about flapper leak (or possibly porosity or hidden crack or a leaky fill valve) resulting in lower than normal tank temperatures is also a possibility worth checking.
But getting to the proposal at hand, it has big problems.
1. You have to collect the drain water--likely a vessel...one that will get dirty with hair and soap scum.
2. You have to pump (lift) the water to an elevation which it can flow through the tank.
3. There will be a lag before the tank warms. This might not matter with 50% or more of the drainwater going through the tank heat transfer tubing, but I suspect you were thinking of a lower fraction.
I like the heater idea, I also might add to my first idea ,that u can pump the shower drainwater to the tank with a fishtank pump with a thermostat to turn it on when it sees drain water of 72 f. it looks like the fish have all the ideas, nothing fishy about that!
the pump would be a fishtank pump with a thermostat,turns on about 70 or any temp warmer that cold input. and connection would be somthing like a tailpeice with a 1/4 inch nipple ,and if it siphons, thats ok too...
sounds pretty fishy to me,but u could try it just for the halibut, but u might be left floundering around.
I would rather waste a little electricty than send a perfectly good working toilet to the landfill. We are on a well so the water coming out of it is a lot colder than a municipal water supply and that is what causes the condensation. It only happens in the summer when it is hot and humid.