Line Voltage Thermostat - wrong forum?

I'd started a post about my circulating pump but it turned out my pump works it's just not getting power.
Now I'm trying to troubleshoot that and I need some help but wonder if I should post this in the electrical forum instead?
I have power to a switch near the pump but nothing upstairs where my thermostat is and I'm really not to sure how the whole system works. I used to have Honeywell CT60A (I think) non-programmable thermostats and I replaced them with AUBE TH140-28 line voltage ones (last winter) and they both worked. I've swapped the thermostats and they both work on the one working zone. If I check for power at the working thermostats location I get 120VAC. If I check at the other thermostats location I don't get anything but I'm not sure where the power should be coming from. I've flipped breakers etc. but just need a little guidance I think on how to properly test this if possible via this forum (or another).

TIA, MD

 

It is very unusual these days to see line voltage thermostats. You need to determine from where the power comes for the thermostat. A thermostat is nothing more than a switch. You just have to keep following wires backward from the thermostat until you find 120 volts. The problem could be a switch, bad connection at a wire nut, or nearly anything. It might be worth your time to install a switching relay such as a Honeywell RA89A, pull low voltage thermostat wire & use a low voltage thermostat. Is it at all possible the switch for the circulator is bad? If power comes from a source, thru the switch, to the thermostat, then to the circulator, the switch could be the trouble. All depends on where the switch is within the circuit.

 

I'll start with the switch then as there is power there.
I like your idea of replacing these line voltage thermostats but the wiring is a real challenge in my house since it's a 4 level split. The one that is not working might be doable though since it is in my living room almost directly above the furnace room.

Thanks for you advice.

 

Let me know how things go.

 

Hey Grady,
Just wanted to 'sort of' update this post.
No success so far other than I did try to figure out my wiring and although I think I know what goes where (see url) I still don't get any power to my one thermostat location. This is by having the switch on and using a volt meter at the thermostat location on the actual wires. So for now I've just got the 2nd pump lugged into a timer that runs a few different times during the day.
http://i97.photobucket.com/albums/l214/mdjbhouse/linevoltagethermostats.jpg

Let me know if my logic is correct on this wiring and short of pulling some new low voltage cable not sure what else I can do.

 

Just to be sure you are checking voltage properly: You should be measuring from the terminal to ground. If you get voltage there, measure across the two terminals. A voltage reading there, indicates an open switch. Also if you measure "hot" to ground & get voltage but not from "hot" to "neutral", you have a bad neutral. The bad neutral can drive you crazy if you are only checking to ground.