Electrical Assistance with a furnace please
Hi all, I just installed a new Suburban NT20 furnace and I need some help with the wiring. There's only four wires, red (hot) yellow(grnd) and two blue which are for the t-stat. My issue is that the ...
Forum Discussion
Many T-Stats are nothing more than a switch (or a relay) and do not care which way they are hooked up.. So it matters not which wire is "HOT" and which is "NOT" when the T-Stat is off.
Some electronic ones do care.
So, how to tell 'em apart?
IF the T-stat manual clearly indicates the POSITIVE wire is to be hooked to THIS screw.. Use your volt meter... Ground (Known good ground) and measure for voltage. the "HOT" lead will be hot.
Do not have a voltmeter.. A test lamp will light when hooked to the HOT lead, but not the other one.
Method two (If the install manual for the T-Stat does not specify)
Hook it up, try it, if it works good, if not try reversing the leads.
Odds are it will work both ways, but if it does not.. mark the leads with stick on labels or heat shrink tubing.
Some electronic ones do care.
So, how to tell 'em apart?
IF the T-stat manual clearly indicates the POSITIVE wire is to be hooked to THIS screw.. Use your volt meter... Ground (Known good ground) and measure for voltage. the "HOT" lead will be hot.
Do not have a voltmeter.. A test lamp will light when hooked to the HOT lead, but not the other one.
Method two (If the install manual for the T-Stat does not specify)
Hook it up, try it, if it works good, if not try reversing the leads.
Odds are it will work both ways, but if it does not.. mark the leads with stick on labels or heat shrink tubing.
