Originally Posted by mdshunk
I can't dig up a schematic on the Armstrong EG6E. I know it's a condensing gas furnace made about 1991. It has a Robertshaw ignition module, but that has nothing to do with the blower, as it is not one of the newer integrated ignition modules that also control the blower. One simple check you could go is see if you have 24VAC on the G terminal at the furnace (sould be a green wire). Check for 24 volts between G and the metal of the furnace, and see what you get. If you have 24 VAC here, then the stat is causing it to run. Thinking as I'm typing.... you said it only runs the blower on call for heat and not all the time.... better try to post a schematic.
Yes, A schematic on the Armstrong EG6E would help.
Let me try to clear it up a little.
The blower fan runs at start up, or apon call for heat, IOW it does not let the burner come up to the fan limit control of ~120-130,and then come on. It (the blower) continues to run with the burner,then, when the t-Stat is "happy" with the room temp. the burner will shut ,the blower fan will continue to run till the fan limit reaches the 90 degree "fan off" temp, The fan limit control is set to as per the manual.
Here is a longer explation, Hope this makes sense. It is the best I can explaine it.
IOW is designed to operate the blower motor on low as soon as the t-stat calls for heat, instead of allowing the burner to burn for a few minuets before starting the blower.
All the looking at the schematic that I have done, and testing voltage at the relays and testing the relays for proper operation, according to the schematic, as far as NO/ NC/ and the opposite continuity/or lack of when the coil is energized. being confirmed, and again studying the schematic, leads me to believe this system is working as designed. I'll try to explain this the best I can.
It appears to me, + power comes in, (goes through the interlock)
to a 3 way connection; 1st to the power in side of the fan limit, 2nd to the 1st pole of the NO combustion blower relay,
a STDP relay (power is then bridged to the 2nd pole of the NO combustion blower relay, but that side is for the combustion blower) and then to the fan relay, (NO terminal (R2,S2 of the relay goes to the High of the blower motor, but thatís only used for the A/C, the fan relay is not energized in the heat mode.)
Now out of the Combustion blower relay, comes a red wire, and (when the t-stat calls for heat this NO relay is energized, and in now closed) sends power to the Red wire, that runs all the way up to the fan side of the limit control, and also taps off before limit control, to the NC side of the fan relay (R2, through the NC side, (witch is closed because the relay is not energized), out of there and to the low connection on the blower motor.
So IOW the power is fed out of the combustion relay, into the NC side of the fan relay, out of the NC side of the fan relay to the motor(low speed). After the burner shuts off the combustion blower relay drops the voltage to the NC side of the fan relay and the NC fan relay now gets its power from the Limit control.
See if I remove the red wire from the combustion relay, the blower does not run at the start of the cycle, but only comes on when the NC (side) of the fan relay gets power from the limit control.
The way I am reading the schematic, and have tested the relays , It seems to me the blower has no choice but to run at initial start-up.
Well I'm sure I made this "clear as mud" I wish I had a scanner to post the schematic, so You could see what the hell I'm talking about, If I am correct, or if I am missing something.
I may try to get someone to scan it and put it on a floppy so that I can post it.
I tried to find a schematic on line but had no luck.
Maybe the public libary in town has a scanner they will let me use.
Hope this makes sense.
Thanks, Tony D.