I know this post is seasonally inapporpriate, but if I don't ask it now I'll forget and it will be winter already...
We have a vacation home near Lake Tahoe, CA, and would like to turn the water off during long periods of our absence over the winter to save on heating. We have a Rinnai R85 tankless water heater. We also have a water system that automatically drains when the water main is shut off and a faucet valve opened. My questions are as follows:
1. When the water main is turned off for an extended period, should the gas and electric to the water heater also be shut off?
1a. If the gas and electric should be shut off under the above circumstances, what if the water is just being shut off for a short time (a few hours)?
2. To prevent any damage to the water heater from water freezing, do we need to drain the water heater in any way other than opening a hot-water faucet upstairs?
3. Is it foolish to turn the heat completely off over the winter even with the water shut off?
4. Is there any other information that I should consider in determining whether to turn the water off (and heat down or off) in the winter when we will not be there for weeks at a time?