my circulator pump isn't working properly with my boiler system, trying to narrow down problem. I've read you can test the aquastat with a multimeter (which I have but have never used). The reason I am making this post is because all the things I have read refer to a TT or a #1 and #2 to test, but I don't see any of those labels on mine. On the aquastat itself I have labels R,B,W (and W is unused), where the wires lead to I have Y,G,C,R. Can anyone help walk me through this? Thanks


B is the normally closed contact, W is a normally open contact, and R is common. So in the initial state, you'll measure continuity (or a low resistance) between R and B, and no continuity (or infinite resistance) between R and W.

When the temperature rises above the set temperature (+ the threshold), the contacts will switch. So you'll measure open (or infinite resistance) between R and B, and closed (or low resistance) between R and W.

To test it with a multimeter, you'll want to use the continuity, or a low resistance setting on the meter.

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