HVAC wiring help

[kenmac]

I keep recommending hooking up on the low voltage strip because that is where your board is waiting for inputs and how it "knows" what is going on. You will have to get much more complex within the furnace if you take a different path.

Yes, I agree. If he already has everything set up, then just take the easiest path to get the results you want. there are many ways it could be wired to operate.. As far as the fan being on a time delay relay instead of instant off. It's because the furnace manufactures are mandated by your government to be efficient. 1 way to get a little more efficiently out of the furnace ,is to extract a little more heat out of the combustion chamber B-4 shut down

 

[Dutch445]

here's a thought
while i'm connecting R and G, the fan is coming on, simulating heat. furnace
is in the mindset it is going to be lighting the burner and therefore the delay
for cool down is active.

when i run "fan only" from the tstat, it tricks the furnace into thinking
the a/c is on, so therefore the fan shuts instantly with the switch.....????

so if that theory is true, can i use the Y and R wires to power the fan, or will
that goof up stuff in the A/C side?

if i get time and can verify the furnace will fire the way i have it now, then i won't worry
about it and run with it. although fan speed may be an issue here, and with a high speed
fan for heat it may not heat up the system cuz it's pulling air too fast thru it.

 

[kenmac]

no . If you connect y to r you will send power to pull in the contactor for the A/C.

 

[kenmac]

here's a thought
while i'm connecting R and G, the fan is coming on, simulating heat. furnace
is in the mindset it is going to be lighting the burner and therefore the delay
for cool down is active.

when i run "fan only" from the tstat, it tricks the furnace into thinking
the a/c is on, so therefore the fan shuts instantly with the switch.....????

so if that theory is true, can i use the Y and R wires to power the fan, or will
that goof up stuff in the A/C side?

if i get time and can verify the furnace will fire the way i have it now, then i won't worry
about it and run with it. although fan speed may be an issue here, and with a high speed
fan for heat it may not heat up the system cuz it's pulling air too fast thru it.

When you connect R and G , the fan is coming on ,but it's not simulating heat. It is only bringing in high speed fan for cooling.. If you have a gas furnace. It should be wired accordingly ...Low voltage R is the wire that sends power to everything (so to speak)... W= power to Gas valve....G brings in cooling relay so, your fan will (mostly) be running on high speed when your A/C condenser is on . so when you power the green wire. the furnace blower fan should be all that comes on. This is assuming everything is wired correctly at your circuit board terminal block

 

[Dutch445]

ok thanks,,
no to using Y!

 

[Loadstar]

Here is a thought on possibly what's happening with a delay for heat when r+g is jumped. If you are powering your unit up with r, g, and w there may be a delay like on this carrier. Look at code 12