HVAC Questions? Ask an HVAC Expert for Answers ASAP
Hello my name is XXXXX XXXXX will be my pleasure to assist you. By blower do you mean the furnace blower or the blower in the gun itself?
Okay if you turned the power off to change the transformer if maybe going through a prepurge cycle where the blower will run for 90 seconds before trying to ignite the furnace. Let it go through the 90 second prepurge and see if it will try to reignite
ran the blower for 4 minutes and it kept running
Okay if you go to the thermostat is the fan switch set to auto or on?
thermostat was off
Is there a white knob sticking out of the fan limit?
I am working with my son over the phone , so there will be some delay sorry no white nob
Is this a honeywell fan limit with a silver cover over it/ If so pop the cover off and try turning the dial by hand to see if the fan shuts down when the dial is truned down.
the switch did not stop the blower, having him run it for 90 seconds and try it again
after 90 seconds blower still running
Something is wrong in the wiring do the thermostat wiores connect directly to the transformer?
the termostat wires (2 only) go to the primary control
the furnace was running with this arrangement
the original arrangement there was only 2 wires on the secondary of the transformer and they went dirrectly to the relay
I said the original arrangement , it still that way I have not changed any of the wiring
Just the two wires from the transformer to the relay
yes there were only 2 wires on secondary
They go to the relay?
Switch the wires from the secondary side of the transformer to the relay swap them put one to the other.
yes I can trace them very easily
The ones you hooked up swap them
The ones on the secondary side.
we swapped the wires last night but I'm not sure if we ran it for 90 seconds in both con figurations we are switching them now
my son switched the wires and the fan is still running after 2 min. with no burner attempt
I will have to opt out I can picture the thing or find the schemtic sorry.
I'm going to try to get some dinner but I will keep an eye on the screen as best I can might be some delay
red wire on Rh terminal , white on the W terminal on the thermostat
on the primary control red to T , white to 3/T
The transformer you replaced....are you referring to the oil primary control that has T and T and F and F?
Here is the confusion....On the furnace we have T and T which start the burner...furnace heats up...a heat switch makes contact and the blower kicks on.
On the thermostat Rh is 24v from one of the T's...and the W on the thermostat is the return back from the thermostat to the other T.
You say you have a added transformer..but it works as a fan center for blower only. But you do not have G hooked up at the thermostat.....so the question is.....does the G wire go to a summer or blower switch?The fan center is installed for when ac is added to a oil burner. Then a wire also runs from R on fan center to Rc on thermostat...and a wire to Y which turns on outdoor ac unit....and G which turns on circulation fan only.
the furnace has no AC with it, at the start nothing would come on , trouble shooting I discovered there was no 24 VAC coming from the control transformer ,(open secondary winding). orginal transf. had a blk. and wh. leads for the primary and 5 terminals on the secondary, primary wired to incoming 120VAC, secondary from terminals G and C went directly to the relay that controls the fan that blows heat thur the house. contacts on this relay NO blk. 120VAC feed to blk to the fan, NC blue from the fan and limit switch to blue to the fan. I did not find a transf. like the orginal, I used a generic transf. that is 120VAC and 24VAC out. Because the original had just 2 wires in and 2 wires out I thought this would do the job.
The thermostat has only 2 wires red from terminal Rh goes to T on primary controler white from terminal W goes to 3/T on the primary controler. The furnace was running when it stop and had run for at least 2 years. I did not add anything or change anything. All I did was replace the transformer as described above. Now when I turn on the power the fan starts and continues to run and nothing else happens. The way the wiring is I don,t understand what is not happening or what sould happen to get to function correctly.
You can attach using the small tree icon at the top of the dialog box.
Attachments are only available to registered users.
Is the schematic from the furnace or from the part? You see the only reason I am still perplexed is the control with T and T where the thermostat wires are attached has its own transformer inside. This is responsible for the furnace operation. Then the fan/ limit kicks on the blower when heat builds up.
Thus if there is no fan switch or ac...there is no need for the transformer with the G and C since the only function of that control is turn on the blower manually instead of with heat build up.That makes the new transformer redundant and doing nothing if there is not a fan switch.
If furnace only...T and T on the primary control is all that is needed.
When I pulled off the G wire the blower did not come on but the furnace didn't start. Apparently when someone wired this furnace the transformer was no good or they destroyed it some how and that allowed them to start the furnace. I attempted to start the furnace with G disconnected. Nothing happened , 120VAC on L1 , 24VAC across T and T/3, on the primary controller, I pulled the oil nozzle igniter assemble and cleaned it looked good, while investagating I discovered that as I lifted the cover,( where the cad cell and the connections for the igniter are mounted). the green light on the primary contoller would come, it just dawned on me now it was probably the cad cell picking up the flourescent light hanging in the panel, the question is what do I do (check) next to see why it won't start when there is 24 VAC coming from thermostat and 120VAC coming from the fan limit switch
Unhook the cad cell wire from F (either one)....then see if unit starts...if you have 24 v between T and T.....then you should be able to directly jump T and T which bypasses the thermostat. Also just in case.....hold the oil primary reset button down for 30 seconds in case in hard lock out. Unhooking the cad cell makes the primary think it is ok (dark) but then you only have so much time to either jump F and F together or reattach cad cell wire and hope cad cell is ok.
I was not able to see the diagram. There must be a glitch. However I am very familiar with the oil furnace wiring and operation and am confident we can make headway. Lets run the test I mentioned and then go from there.
Thanks for your patience!
That is excellent news...I am very glad you were persistent and stuck with it. Well done!