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We all have thermostats in our houses but how often are they in a horrible place? You often want to place the temperature sensor in a different location than the control and display unit. There are lots of models that have remote sensor capability but they come with a high price. If you already have a thermostat and just need the temperature sensing to be disconnected from the control unit you might be able to simply remove the sensor and mount it remote to the unit and connect it with a few wires.
That was the ideal solution to my dilemma. I recently acquired a building which has a central hot water boiler system, this means that the boiler is either firing and pumping hot water through all of the rads in the building or it’s off. There was one thermostat in a single suite to regulate the heat in the entire building. This normally works fine since most suites will have similar heating requirements as long as the radiator placement is well laid out. Big issue with this setup is that you need to provide 24 hours notice to adjust the temperature. I wanted to continue to monitor the temperature from the same location the thermostat was but I wanted the control to be in the mechanical room. I used the same thermostat wire to go from the thermostat to the temperature sensor and used a new wire from the thermostat to the boiler. The boiler control is a simple N/O (normally open) contact that closes to call for heat. So far the system is working great! I have tweaked the temperature once with no bothering of the tenants.
The model of the thermostat is a White Rodgers Model 1F178 NON_PRGM, this one is the non programmable style. As you can see from the board inside the unit and the LCD the programmable version is identical except for some magic that must happen in the factory to “make” one version programmable. I am sure the thermistor in both units will be identical so upgrading to the programmable version might be something that will happen soon.Â
The future goal for the system is to mount digital temperature sensors in each suite and other various rooms such as the laundry room and mechanical room. These sensors would come back to a microcontroller based device to make heating decisions. This would allow for a nice average of suite temperatures to be used and also monitor rooms like the laundry room for freeze danger. The stretch goal would be to push some data from the system onto the internet with no internet connection on-site.
If you are interesting in having a look at some hi-res pictures from this project, you can see them here.
