Millivolt, Dual Pressuretrol Boiler Question

Tim_23

Hi there. I have an old boiler with a Millivolt control system. There are two pressuretrols. One is above the low water cut off and one goes directly into the boiler. I've learned that one is the main control to be set at the minimum, and the other is the ultimate high setting (or something like that), but I don't really know which is which.

In experimenting with it, it seemed like the pressuretrol above the low water cutoff was the main control, as its pressure setting was maintained by the boiler.

Thanks for any additional information.

tim

Unknown

Two pressuretrols

one is the standard pressuretrol for operation of the boiler probably mounted on the low water cutoff. It should be set at 2lbs off .5 lbs on. It should be wired in series with the low water cutoff and the thermostat circuit to the millivolt gas valve.

The other pressuretrol is a safety which should be set at 14lbs off 9 lbs on and is wired into the wire coming from the 750 millvolt pilot generator from the pilot. Its purpose is to safely shut off the system in the event of a runaway system.

If you have any further concerns about it call me at 401-437-0557.