On Tuesday, December 10, 2013 11:54:27 AM UTC-5, Danny D'Amico wrote:
It finally got cold enough at the house to turn on the heat, for the first

time since last winter - and - and - nothing happened.



The heat didn't go on all night, so this is what I saw in the morning:

http://farm8.staticflickr.com/7419/1...2b188768_o.gif



I really do not understand how home heating systems work.



I figured I'd start by taking apart the thermostat to see if I can test

if it's giving the right signal to it's Payne 394JAW propane heater:

http://farm3.staticflickr.com/2890/1...c9c93247_o.gif



The little mercury bulb appears to work, at least at the extremes:

http://farm3.staticflickr.com/2837/1...d6aa35f3_o.gif



And, there's this calibration thingy that seems to be already set:

http://farm4.staticflickr.com/3796/1...1339eb39_o.gif



But, I couldn't see what I'm supposed to *test* without removing screws:

http://farm8.staticflickr.com/7452/1...ff18c35f_o.gif



Yet, once I removed the three flathead screws, I was met with this!

http://farm4.staticflickr.com/3797/1...d18b3e08_o.gif



May I ask:

Q: How do I test this thermostat to see if it's actually working?


The photos appear to show a heating only thermostat, a very basic
one. For heating with one stage, which is all that tstat is
capable of, you would have 3 wires: power, heat, fan. While there
is no standard that must be followed, typically red is the power,
white is heat, green is fan. That leaves the blue. What it's doing
there, IDK. If you had AC, I'd say it goes to that.

But, in any case, connecting red to white should fire the furnace.
And connecting red to green should turn the blower on. Given
the simplicity of the tstat, I would suspect it's not the problem.