@PlumbGate...Yes I know how they work and it wasn't made for this application. @Mikey...Yes the closer to the point of concern for freezing, the better, but of course could not be within that space. But why rely on a sensor located in a warm space to ensure that the water piping exposed to freezing, in another area, will always remain warm enough not to freeze. e.g.- temperature differential in warmer space(sensor location) requires more time for temperature drop than a cold space. Yeah that may not cause freezing of piping in the garage but it's a poor design approach. What was proposed was a simple circulator, no built in 24 hour timer and that Watts system cost at least twice as much as a simple circulator. A sensor would be nice but should be a type that could be located in the area of freezing concerns, which I believe the OP proposes.