Winterizing is performed when a house is prepared for vacancy. This process prepares the plumbing system and its components to not be affected by extreme temperature variations and should be performed when a house is expected to be vacant through the heating season. Once winterizing has taken place, a house can sit empty safely without heat and other utilities.
The winterizing process involves fully purging the plumbing system of water, which includes emptying the water heater, draining all piping and filling various fixtures with an anti-freeze solution. If the house is on a well system, the pressure tank should be run dry. The water heater, all toilets, toilet tanks and pipes all need drained, making sure there is no water left standing in low-lying loops of any pipes. Non-toxic propylene glycol antifreeze, such as that used in RVs and boats, in the toilets, sink p-traps, dishwashers, washing machines and drains will keep the liquid sealed between the sewer or septic system and the air in the house. Ethylene glycol antifreeze used in automobiles is toxic, is an alcohol product that evaporates quickly, and should never be brought into the house. Mix the antifreeze according to the label, in the same proportions as you would to protect a vehicle in your climate.
In order to drain your system efficiently, follow this check list:
Shut off the house water supply by closing the main shut off valve.
Turn off the gas or electricity to the boiler and the water heater.
Siphon the water out of the tub of the clothes washer. If the drain hose can be lowered to a floor drain, it will usually drain itself.
If you have hot water heat, open the drain faucet on the boiler and let the water flow into the floor drain. Next, remove an air vent from a radiator on the top floor so that air will replace the water as it drains into the boiler.
Working floor by floor, starting at the top, open all hot and cold water faucets – including all tubs, showers and outdoor faucets – and flush all toilets.
Open the drain faucets on the water heater and the water treatment equipment.
Finally, open the drain faucet on the main supply line to release any water that may remain in the pipes. You may have to disconnect a meter connection to drain completely.
At this stage, your plumbing system will be adequately drained for repair or remodeling work. If you are closing the house for the winter, take additional precautions. Walk through the house to make sure every area where water may collect is completely drained. Attach an air compressor to each faucet and give a low pressure blast of air to blow out any remaining water.