My pressure gauge is reading zero, but I think it's a malfunction. The loop pipes are vibrating and the motors running smoothly. Also, the brass fittings have frosted over as they tend to do when circulating in winter and there is condensation on the pipes. 6 inches below the gauge location on a vertical pipe (closer to the working loop) is another fitting and unused connection. This fitting is cold but the gauge fitting is room temp. Also, all the pipes have slight condensation but it stops at the same level as the unused connection. I'm thinking that somehow the flow is not getting up to the gauge to register. Any thoughts? I don't want to burn out a motor but I think the system is pressurized so I'm reluctant to turn it off.