Hi Temperature Alarm

I’ve always had concern that my boiler would overheat at night and I wouldn’t know about it. I have a power fail alarm but that doesn’t cover some problem with the boiler system. Some years ago, I had the spring coupling break and jam/stall the circulator. Fortunately, it was during the day and I was there when it happened.

For over temp, I have a Honeywell L400B aquastat that provides a closed contact (I set the temp at 220 degrees). My boiler is in the basement and I wanted an alarm upstairs when I was sleeping. My simple solution, that someone has probably all ready done, was to use a doorbell alarm. The one I purchased was a Fimei wireless (to 1000 Ft.) doorbell kit. I modified the pushbutton by removing the circuit board and soldering two wires to the button switch contacts. The two wires connect to the Honeywell L400B over temp aquastat. I also clipped out the LED, that illuminated the pushbutton, since I didn’t need it and I didn’t want any unnecessary current draw from the 12V battery in the pushbutton circuit.

The wireless transmission works great from the basement up to my 2nd floor bedroom. The alarm has 4 volume settings and is plenty loud when on maximum.

John M.

I don't know what I would shutdown with the over temp controller. I have a Tarm MB55 natural draft boiler. It is an older style boiler and only has a Samson mechanical draft regulator and circulator. There isn't any blower, for forced air induction, to shutoff. The Samson is very reliable and would shutoff the primary air. My condition of concern is when I put a full load of wood in for the night and I have some sort of circulator failure. I do open my main heat zone (water coil in heat pump air handler) on over temp, so I get some thermo-siphon action. There is a secondary air inlet, in the wood loading door, which I usually have half open. Air will come in through this opening.

My boiler has a tankless coil which I don’t use to heat my domestic water. I have a 40 Gallon Amtrol Boiler Mate for that. The domestic water supply is connected to the tankless coil. At the outlet of the tankless coil (which goes to my storm water drain) I have a trim valve set at a water flow that cools down the boiler in a reasonable amount of time. If I get an alarm, for an overheat condition, I would open the supply to the tankless coil for boiler cool down.

As you can see, my boil operation is mostly manual.

John M.