Not feeling the heat

Shortly after coming home from a trip our heat stopped working again. Naturally this happened on a Saturday morning. A Saturday with a high of 25 F. My first hope was that I could just hit the reset button on the motor. But the motor would not fire. I could hear the pumps pushing (cold) water around, but nothing else. I tried turning the boiler power on and off. It was like no power was getting to the motor.

Fortunately our furnace guy picked up his phone that and came over within a couple of hours. After about 10 minutes he had the diagnosis: dead aquastat.

The aquastat is the gray box with the power lines coming out in the above photo. What it does is route power around to the water boiling motor (black box at the bottom) and/or the pumps that push water through the house when asked. While it was sending power to the pumps it was unable to power the motor.

Back of aquastat. See the problem? Probably not.

One little spot was burned out. I asked whether I could just re-add some solder to it, but our technician said that it would probably quickly die again.

Closer in. See the burned out spot in the center?

So for about $250 we got a new one installed. Which was a fair price, since the aquastat alone costs around $150. Especially for a Saturday emergency repair. If you read the reviews in the Amazon link you will notice that most of the complaints are about the solder failing. If it dies again, I may just try slapping some on with my $15 RadioShack soldering kit and seeing what happens.