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Hi.. I'm looking into remotely turning on my 441 & 2400 Monitor heaters at my weekend place in NH. I normally set the heater to 46F when I leave Sunday afternoons. Since the heaters use a funky thermostat, I thought I could work around this limitation by tricking the sensor (thermistor) into thinking it was colder indoors than it actually is. Initially I thought if I had second sensor OUTSIDE, and a way to switch between the two sensors, I could make this work. Switching will be easy, but temperature / resistance ramp details on the thermistor are no where to be found (with any certainty anyway).
Monitor replacement thermistors for these heaters are a bit pricey at ~$25 (used on eBay) and $50+ (new). Since I have no need to actually convert a temperature to a resistance value, I thought I could get away with substituting a variable - or even better & cheaper - a fixed value resistor instead. From what I've read in the service manual, the resistance of the sensor at 77F is 10k ohms. Someone else said that 70F is ~12k ohms and at 58F is ~16.5k ohms. The accuracy of that info is unknown. Since I need to drive the heater to "high fire" from an ambient of 46F, I need to know what the resistance of the thermistor is at ~46F. I also need the temperature (and the amount of resistance associated with that temperature) that would be low enough to bring the burner into "high fire" from this 46F temperature. I also wonder if there is a temperature that is so low that the Monitor will not attempt to start?
The switching will be made possible via a wifi "smart plug" (that works with either Alexa, Google Home, or a associated proprietary app) to energize a RIB "RIBU1C" relay which will switch between the thermistor (normal operation) and resistor (produces the high fire call) input to the heater for remote starting - when triggered. I have a couple wifi cameras that I can be use to provide visual confirmation if I feel the need.
Of course, if this has already been done - I don't need to reinvent the wheel. Just point me where to go and I'll be on it! (FYI: my links in the post were removed.. those remaining were provided by the system).
Thanks in advance!
Monitor replacement thermistors for these heaters are a bit pricey at ~$25 (used on eBay) and $50+ (new). Since I have no need to actually convert a temperature to a resistance value, I thought I could get away with substituting a variable - or even better & cheaper - a fixed value resistor instead. From what I've read in the service manual, the resistance of the sensor at 77F is 10k ohms. Someone else said that 70F is ~12k ohms and at 58F is ~16.5k ohms. The accuracy of that info is unknown. Since I need to drive the heater to "high fire" from an ambient of 46F, I need to know what the resistance of the thermistor is at ~46F. I also need the temperature (and the amount of resistance associated with that temperature) that would be low enough to bring the burner into "high fire" from this 46F temperature. I also wonder if there is a temperature that is so low that the Monitor will not attempt to start?
The switching will be made possible via a wifi "smart plug" (that works with either Alexa, Google Home, or a associated proprietary app) to energize a RIB "RIBU1C" relay which will switch between the thermistor (normal operation) and resistor (produces the high fire call) input to the heater for remote starting - when triggered. I have a couple wifi cameras that I can be use to provide visual confirmation if I feel the need.
Of course, if this has already been done - I don't need to reinvent the wheel. Just point me where to go and I'll be on it! (FYI: my links in the post were removed.. those remaining were provided by the system).
Thanks in advance!
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