I think the boiler hates me

I’ve got a good story today, but first you need a little bit of boring background information. This is an aquastat relay, which controls the boiler, the circulating pump (which moves water through my radiators), and the chimney damper. It also powers and receives a signal from the thermostat. There are 4 screw terminals for the thermostats near the top, but 2 of them have a metal strip factory installed to jump them because most systems only need the other 2. You can see that strip covering up the word thermostat right above the little plastic sheet, and the TV terminal is one of the ones for the thermostats.


The heat wasn’t working after I finally got all the thermostats hooked up right, and first I assumed that the complicated thing I have with 3 thermostats and 3 zone valves (instead of 2 wires on 1 thermostat) was the problem. So I took down the thermostat in the living room and connected it right to the relay with some extra wire. Now with simple wires it should turn on.

But it didn’t.

My dad had been worried that we blew one of the transformers by wiring it wrong, so I thought either it was that or the thermostat was bad. But I waited for my dad to come down with a multimeter so we could test for bad wires and what not. And so he came in and put the multimeter across the thermostat terminals and immediately, click! The relay flipped and the boiler fired up.

I gasped. The thermostat is bad and current is running through the volt meter and turning the boiler on. How is this possible? So I tried just running a wire across. That should be the same as when a thermostat saying “turn on” to the boiler. But it did nothing. Did I have a whole lot of faulty wire? He switched the meter to measure resistance and found that the wire was good.

And then he stuck wires across the terminals and click! Whoosh! On it came. And I did it again, and nothing. We did this a few times and then I asked him to sit there until the house warmed up. He said no. But finally, he pushed the wire against one terminal only and on it went. So we realized that he was flexing the circuit panel and something was connecting that wasn’t connected before.

There must be a bad solder on the back side of the circuit panel. So we disconnected every wire going into that relay, took it off the boiler, and dismantled it. Nothing looked bad. I figured I needed a new relay, which I guessed I could afford at $160, even though I had just said I could not afford $130 for an automatic ice maker in my freezer.

But then, remember those 2 thermostat terminals with the jumper running across them? The ones I don’t actually need? One of them was loose. So we put it all back together and what could have been a 2 second job was accomplished instead in 3 hours.

I went and reinstalled that last thermostat in the living room and we connected it back to the relay. And nothing happened. So remember the wire we used to bypass the thermostat before? I put that back on. Now my heat is on all the time until I get hot and go downstairs and power off the aquastat.


5 thoughts on “I think the boiler hates me

    1. Chad's Crooked House Post author

      This was all pretty simple (once we figured out the incredibly stupid problem of the loose screw) – and the problem that remains is all 24 volt thermostat circuits, nothing that will hurt us or burn the house down.


  1. Scraps

    This reminds me of our wonky water heater that my husband spent multiple weekends trying to get it to a) turn on a b) stay on, including replacing the thermostat and then the whole panel assembly only to find out there was a little, hidden, unlabeled reset button. Not that the other stuff probably didn’t need replacing, but still.



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