I posted on this awhile back with no joy so in desperation I'm posting again. I replaced my front AC with an Atwood and used the accompanying Atwood thermostat. I moved the original Duotherm thermostat to the bedroom to control the back AC. Now I want to install a simple 2-wire heat only Atwood thermostat to control this single Atwood 8900 III furnace. Can't figure it out. I have the schematic from the Atwood manual but it doesn't reflect what I am seeing at the furnace.
Does anyone know how to direct wire the thermostat to this furnace? Thanks.
jor
Not sure what unit you have but it looks like if you connect the two blue wires together the furnace will come on and run until you separate the two blue wires. Of course these blue wires are at the furnace and could be changed to another wire color.
What are you seeing? Pictures?
Looking at another diagram for a heater it is showing the two wires going to the thermostat are red and white. Need to know exactly what you have to get it right before letting the smoke out.
The original thermostat had only a data cable. This little heat only guy is set up for a red and white wire (marked R & W).
At the furnace:
From Behind the Furnace: 2 blue wires: one to the ckt brd power terminal and the other to the motor.
Into the Furnace Compartment from the Left Side: 4 Wires
* Blue to ckt brkr
* Blue to motor & time delay relay (I think that's what it is)
* Yellow to time delay relay
* Red to ckt brkr
Regarding "before letting the smoke out" too late. I smoked one already. Fortunately, they are only 20 bucks or so so I can still make the rent. However, I think two should be enough for this job.
jor
There should be a pigtail that plugs into the side of the furnace which should have a red a black and 2 blue wires. The red is for 12 volts + and the black 12 volts- and the blue to the thermostat. One of the blue will have 12 volts positive and the other carries the 12 volts back to the furnace to activate the furnace. There is a time delay before the fan comes on and then the circuit board has a delay before ignition.
That hing in the upper right hand corner of your photograph? It's the time delay relay so that the bower runs for a while after the thermostat is satisfied and turns off the fuel. Two terminals are for the fan motor. Two are for the heating element in the relay.
Run the power through the thermostat and into the TDR.
Jor don't know about the furnace but I used Atwood simple thermostats for my aqua hot heater. The TStat interrupts the 12 volts needed to turn on the aqua hot. Not sure that it's the same with the furnace but you wire diagram will show it.
One of the blue wires is coming off the circuit breaker. Other blue wire is coming off the circuit board. I think you will find them exiting the furnace on the right side when facing the unit.
Finally got the dedicated heat thermostat installed. Just as suggested, wire to circuit breaker and other to time delay switch. Heat! As usual, I was over complicating a simple project (character flaw). Thanks to all.
jor
One-half century ago I was taught this mnemonic for the three thermostat wires, red, white and blue. Will Begin and Will Run.
Of course one of the standards Foretravel used was Blue for power.