This is an odd question but: I like taking hot baths every once in a while, but our current tank isn't big enough to fill our tub. I don't really want to replace the tank because it's plenty big for all other uses; I can take a shower, wash dishes, run laundry, etc. with no problem but I just can't get a good hot bath. I'd hate to spend money to replace a perfectly good heater, and I'd really hate wasting energy heating more water than I generally will use.
Has any one heard of something that could just temporarily heat a larger volume of water and can be turned off when not needed? (Other than a kettle, smart-arses. )