Quote:
Originally Posted by Casey r
I was thinking about a power drop-out as well but have ruled that out only because if I turn off my batteries the thermostat looses power. When the batteries are turned back on and I cycle the mode back to heat is is still set at 73. I do plan on checking the electrical connections at the fuse box and heater power supply as well as checking the tension on the terminals in the fuse box for the heater circuit.
Thanks for your suggestion and if you should think of any thing else drop me a note.
Thanks again
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What you have said makes me believe more than ever that you have a power issue. The fact that the thermostat works correctly - and even remembers the setting - after you reset the battery is very telling.
Key question - does the thermostat misbehave if connected to shore power? If the problem only happens when you are running off batteries, that would point me to your batteries being in poor shape, and unable to hold much of a charge, or were pretty low before the night began.
The heater fan sucks the batteries to an even lower voltage. Then the battery is too low to operate the fan. The fan sends a fault signal to the thermostat, which errors out. Or the low battery voltage by itself causes the erratic operation of the thermostat.
Resetting things by unloading the battery will give a very temporary recovery of battery voltage. This is similar to starting a car with a weak battery. After several failed starts, you let the battery sit for 5 or 10 minutes and it may recover just enough to give you a start.
A loose or intermittent connection can also give low voltages.
When I was running a bank of computers on Windows 98, I found that repeated Blue Screens of Death (BSOD) were invariably caused by power supply malfunctions. I lost track of how many components (memory sticks, CPUs, and hard drives) I changed in a fruitless effort before I realized that the power supply was the faulty component.
While the thermostat is in failure mode, measuring voltage at the thermostat input and at the battery might give you an idea of whether my theory is correct.
Of course, if the problem happens while connected to shore power, and you are reading 13.7V at the batteries, then I will believe both thermostats are faulty.
Fred W