Oh geez. Best of luck with several plumbing failures at once!
I had good luck when my furnace's input gas valve died with Lancer Contracting in Belmont (+1 617 489 2555); I don't think they're the cheapest, but the guy who visited had good diagnostic skills--knew his way around with a multimeter and didn't replace parts just to see what was broken--and was meticulous about the annual service I asked him to do as well.
FWIW, electronic thermostats use a thermistor as a temperature sensor, which is a calibrated temperature-sensitive resistor. Several methods can be used to determine the resistance, and a table lookup turns that resistance into a temperature, which is compared against the stored temperature in the microcontroller's memory, and opens or closes the thermostat's relay appropriately.
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Date: 2008-02-18 09:29 pm (UTC)I had good luck when my furnace's input gas valve died with Lancer Contracting in Belmont (+1 617 489 2555); I don't think they're the cheapest, but the guy who visited had good diagnostic skills--knew his way around with a multimeter and didn't replace parts just to see what was broken--and was meticulous about the annual service I asked him to do as well.
FWIW, electronic thermostats use a thermistor as a temperature sensor, which is a calibrated temperature-sensitive resistor. Several methods can be used to determine the resistance, and a table lookup turns that resistance into a temperature, which is compared against the stored temperature in the microcontroller's memory, and opens or closes the thermostat's relay appropriately.