Trane gas furnace is not turning on automatically

DIYJoe

I set my thermostat 70 degree and furnace will work and make my home 70 and turn off but once temperature drops it won’t on again the. I have to manually turn off the thermostat and on again to make furnace on. I changed the thermostat to see if thats the problem but same problem still.
Also I noticed when temperature drops from 70 the valve turn into open position but furnace doesn’t work. So I guess my thermostat valve is working?
One more thing helped me to turn on the furnace is simply tap few times the wiring to/from? thermostat valve. I guess is there any loose contact? Please let me your experience and suggestions.

Jamie Hall

What kind of thermostat? And since you say something about thermostat valve, I presume this is hot water heat? So what kind of valve.

If things work when you tap on the wiring, the odds are very much on a loose contact or bad wires. Check and clean all contacts and connections for tightness (do this with the power off!) and check all the wiring, for starters.

JUGHNE

Thermostat batteries??

More than once it had to be explained that your multi thousand dollar system will not work without batteries. (all for lack of a common wire to tstat)

DIYJoe

Thanks Jamie and Jughne for your time and reply to my question.
@Jamie Hall
Trane XL 80 forced air gas furnace
Its a Zone air control valve not the thermostat valve (sorry)
@JUGHNE and @Jamie Hall
I had Honeywell type 69 programmable thermostat and switched to Google nest thinking if i had bad thermostat but still same problem.

Now I just got home from work heat was not on even After temperature went down.
Thank god for nest thermostat so I check home temp from work and if it is low I will just turn of the heat and on after few minutes, it will work just for that time or may be few more times. If I am home I will just tap the wiring to zone valve and furnace will initiate.
Since I have duct work infront of the zone valve wiring it’s difficult to access it. I will try tomorrow (Friday) and will update.
In the mean time if you guys can think of anything please post.
Also I am not sure about a faulty transformer, do you guys know anything about how a faulty transformer acts?
I feel like thermostat is talking to zone valve and it opens the valve and some miss communication is between zone valve and furnace. May be I am wrong.

Jamie Hall

No, I think you are right -- but with a caution: be sure that Nest has the third wire. They claim to work properly without it. They don't. That said, it is most likely that if the zone damper opens and closes properly on the thermostat command, it is a problem either with the switch on the zone damper which tells the furnace that it's open, or with the wiring from there to the burner controls. Don't assume that anything is correct or working properly -- check everything.

DIYJoe

Yes you are right They said no jumper for nest so I throw it out!
Thanks for your close attention to my problem.
I appreciate your time.
I will see what I can do Friday and Saturday.

DIYJoe

I did some fixing and cleaning today. It worked two times, waiting to see consistent performance.
I will update soon.