[matthewdgreen]

Since we're dreaming about appliances: could someone please design a simple computer-controlled valve that shuts off the water and drains the pipes when the house temperature drops below a certain point? We very nearly had a $100,000+ home repair when a burst pipe shorted out our furnace this winter. This cannot be a very hard device to build?

[quickthrowman]

It’s easy to control a valve actuator based on a space temperature sensor reading, monitor the space temp and when it hits setpoint, send a signal to the valve actuator to open up. Add in a flowmeter on your drain pipe and you can even close the valve when the water is done draining. Probably there is a fitting with a valve and flowmeter in one.

The difficult part is opening up all of the plumbing fixtures and taps automatically, I haven’t tried draining water out of a home’s plumbing system without opening all of the taps and am unsure if it works.

If you have a well, you’ll need to drain the expansion tank and turn off the water pump, the latter can be achieved with a relay that breaks power to the pump but I’m unsure of how to handle the former.

You’ll also need to automate filling the traps with antifreeze, unless you’re cool with replacing sink traps and toilets after a freeze event.

[jyoung8607]

The controllable shutoff valves are already a thing, on the market. They even measure flow rates and look for slow leaks and notify you in an app.

Draining the pipes isn't that simple, and even if you did, you still have things like a water heater, toilets, softeners, filters, and expansion tanks. You also wouldn't get the water sitting in drain traps; winterizing a house or RV involves pouring a little RV antifreeze down each drain.