General question about winterizing plumbing in homes that have a hot water heating system (any type of hot water boiler or geothermal system for hot water baseboard or radiant floor heat). Almost any heating system I have seen that circulates hot water for heat will have a make-up water supply line from the plumbing system. I live in an area (Western Montana) that has a lot of snowbirds, that own property here, but often leave for the winter. Most of them perform some degree of winterization where they at least shut off the main water supply (typically a well pump), and often have the plumbing blown out to prevent freezing water lines.
Question - how much water do most hot water heat systems need to draw from the make-up water supply during a 6 month period? If the plumbing water supply is completely shut down, and the hot water heating system left running (usually at a low temp), will the hot water heating system be starved for make-up water?