I purchased a vacation home in a resort community in December. Home inspection clean. First clue, I noted that water coming out of cold tap was not really COLD, throughout home. Water bill arrives and it is a whopper. Utility company confirms this a usual bill for home. Prior to our purchase, home used heavily as short term rental, but we are there few days a month at best.

Handyman hired comes out rules out leak between home and water line by turning off water to home and monitoring meter throughout day. We then check toilets for leak and in turning them off I notice several of them handles on shut off warm to touch and water in bowls is also. Handyman decides several toilets leak and replaces fill valves in them. Also installs check valve in hot water heater (there are two tanks.) He mentions it could be bigger problem but this might work.

The water bill after toilet repairs is normal again ($35 for a month instead of initial $200) but warm water at cold taps persists. I have also noticed by now when I am there that the hot water heaters seem to run a LOT and make a loud fan noise when doing so. The running does not seem to coincide with use of hot water, either. By then our first gas bill arrives and it too is a doozy. We locate breaker for water heaters and turn it off when we leave and back on when we arrive. This continues and has helped gas bill but not the constant fan noise when on or warm water from cold taps.

I am told it could be as simple as a failed mixing valve anywhere (shower, kitchen sink, anywhere there is not a Hot and Cold tap) to (worst case) hot water and cold water plumbed wrong somewhere in the infrastructure. It is a large home, three stories and hot water heaters are side by side on first floor. There are four showers. Dishwasher, washing machine. Where would you start?

I intend to have a real plumber out to address issue but had hoped to isolate further and provide more specific info by being here more. I have visions of multiple visits without progress. All I know by being here couple days a week is it is a real problem. Everyone reports showers start hot then turn cold and by end of shower you have to practically have all the way to HOT for warm water. I suspect this why there are two hot water heaters, I imagine renters would have complained about not enough hot water. When we are here, we often come without kids and use the master shower only, it still runs colder quickly regardless.

Thanks for any insight and direction you can provide.