Hello,

I would very much appreaciate any help on hunting down a description of what each wire on a GE WeatherTron BAY41X213 (model # 3AAT83D1D5) thermostat does.

The reason I'm looking for this info is that I'm trying to replace it with a Honeywell RTH7400D (which should support both single and multi-stage heat pumps). However, I can't get all the wires to match up. When I called the Honeywell folk, they didn't have my thermostat on record and can't help unless I can tell them the function of each of the old wires.

The old WeatherTron:
O
R
T
M
G
Y
X2
B
U (and W hardwired together)
F (exists on the thermostat, but not connected to any wires)


The one that seemed to stump the Honeywell guy was the M.

I tried checking out the GE website, but couldn't find anything useful. If anyone knows of another way I can find this information, I would appreciate it.

Thanks,

Andrew
P.S. I've just noticed that the new Thermostat is rated for 24 V systems, while the old WeatherTron seemed to support 30 V. Will this force me to find another thermostat?

 

this may help Almost all T-stat today will work on 24v systems.
Weathertron is a Heat pump and will require a heat pump multistage T-stat.
Honeywell makes a 8011 and vision pro that will work with it.
Ritetemp makes a 8010, 8085C, 8082C.

 

Thanks for the info. The new one I have (Honeywell TRH7400D) claims to work for both single stage and multi-stage. In addition, it works with auxiliary heat. Considering the temperature generally goes down to -40 at least once a winter, auxiliary heat is a good thing!

Andrew

 

The easiest way to figure out what "M" does is to see where it lands on the airhandler or outdoor unit.

 

That makes sense. After some fumbling around, I've managed to do that, but am still unsure what it was actually connected to.

Of the six wires (X2, Y, O, M, B, R) that went to the heat pump (I am assuming that the other three: G, W, T go to the electric furnace, but wasn't able to verify) four wires (X2, O, B, R) went one way, M went another and Y couldn't make up its mind, so split in two and went both ways. ;-)

The group of five seemed to go to some controls on top and then also down into the heart of the pump.

The M (and Y) went straight down into the depths of the pump, and connected to a cylinder (this is the best term I can use as it was hard to see, and the "cylinder" was also covered by what looked like some sort of black substance). Out of one end of this cylinder, a copper pipe (3/8" ?) came up to a "box" that had many such pipes connected to it (one of which looks like it connects to the pipe hauling coolant into the house. The other end of the "cylinder" connects by another similar copper pipe to the bottom of the compressor tank.

Is it possible from this to determine the function of the M wire?

Miscellaenous info (in case of use):

Heat Pump: - GE "Executive High Efficiency Heat Pump" 1983
- model # BWD724A100A0

From T'stat: - M, Y to cylinder connected to bottom of compressor tank
- Y, X2, O, B, R connected to other parts of heat pump
- G, W, T presumably connected to electric furnace

Oh, I almost had a good bit of luck. Inside the heat pump, I found what was once a full schematic. That would have been VERY useful. Unfortunately, the paper was so weatherworn (looks it has been soaked and dried endlessly) that I couldn't make anything out. Oh well.

Any thoughts?

Andrew

 

Has anyone identified the misterious M terminal. It is the missing link to resolve my problem in replacing the thermostat.

Thanx in advance for any advice...

 

On a print out of the RTH7400D that I have . shows Y1 or M or Y can go to Y
On the T8624D It show M can be Y1 or M can be Y2. Like Matt said find out where M goes to

 

Thank you Ed, My manual says the same thing regarding Y and M, however, I have both Y and M wires and Honeywell is not recommending I join these connections into Y.

I did open the Heat Pump to find a fairly readable wiring diagram and the corresponding room thermostat lettering codes were traceable but no M connection on the diagram at all. Does this mean that this M wire is not related to the Heat Pump?
I will try to follow the wire by it's color to see where it leads unless someone can tell me a better way to get to the root of this problem.

Mauro

 

You got it . See where M goes to?

 

Great, I have traced M to the heat pump. Specificaly, this wire is conented to some sort of valve or sensor at the bottom pipe comming from the compressor and before the muffler.

On the old Tstat, the M terminal is simply connected to a red light labeled "Compressor..." so I am guessing that it simply identifies when the compresor is operating.

My neighbor has the same HP and Tstat but his wire is capped off at the HP?

After talking with Honewell they advise to set it to Conventianal Heat although I have a multi stage HP which I only use for AC and so I have turned off the HP at the fuse breaker. Honewell advised that I connect the old M terminal to L.

Now the burner and fan do not work in unisen and the burner is comming on too frequently in short bursts, turning off, and then the fan alone comes on again within a minute or so. Since the system was working fine previous to the new Tstat, I assume that a setting is wrong, can you advise?

Thank you...