It is generally not recommended to depressurize the water supply pipes and leave them full of water while leaving the electric water heater turned on when the house is vacant in winter. Here's why:
Freezing Risk: When water is left in the pipes without any pressure, there is a higher risk of the water freezing if the temperature drops significantly. Frozen water expands, which can cause pipes to burst and result in extensive water damage when the water thaws. To minimize the risk of freezing, it's typically advised to drain the water supply system or take appropriate measures to prevent freezing, such as insulating exposed pipes.
Energy Waste: Leaving the electric water heater turned on when the house is vacant for an extended period is unnecessary and can result in wasted energy and increased utility costs. If there is no need for hot water during this time, it's more efficient to turn off the water heater or put it on a vacation mode if available.
When leaving a house vacant in winter, it's generally recommended to take the following precautions:
Drain the water supply system: Shut off the main water supply and open all faucets to drain the water from the pipes. This significantly reduces the risk of frozen pipes.
Turn off the water heater: If the house will be vacant for an extended period, it's advisable to turn off the electric water heater or put it on a vacation mode if available. This will save energy and reduce the risk of malfunctions or damage to the water heater.
Insulate exposed pipes: Insulate any exposed pipes in unheated areas, such as the basement, attic, or crawl spaces, to provide additional protection against freezing.
Consider other winterization measures: Depending on the climate and specific circumstances, additional winterization measures may be necessary, such as setting the thermostat to a low temperature to prevent freezing inside the house or having a trusted person periodically check the property.
It's always a good idea to consult a professional plumber or follow local guidelines and recommendations to ensure the proper winterization of your home's plumbing system when leaving it vacant in winter.