EWC Controls Forum

I thought I read somewhere the thermostat "C" terminal can be used for the "B" wire and then the "O/B" terminal can be used for the "O" wire in Zone 1. Anyone know if this is true?

This is not true.
The manufacturers GE, York and Trane use the B terminal as a common or "C".
I'm assuming that is what you are referring to.
This is not the same as the separate B terminal required for the ST panels.

_________________
Patrick Cyrana
Pcyrana@ewccontrols.com
1-800-446-3110

I guess that the Braeburn 6100 cannot be used as a zone 1 thermostat (no seperate "O" "B"), but I could still use it to program my zone 2 heating/cooling. Correct?

Yes that thermostat would work fine on zone 2.

_________________
Patrick Cyrana
Pcyrana@ewccontrols.com
1-800-446-3110

I purchased a house a few months ago and decided to upgrade the thermostats since they were pretty old. A EWC-ST-2C is installed. I installed a HoneyWell RTH8500 to Zone 1, but now only the fan is working when trying to run the A/C. I read that you do need a thermostat with separate B and O inputs. This thermostat has a shared O/B, but says to use O on O/B and B on C. W is also setup to wire to the Aux input per instructions. It also says to leave the jumper in from R to RC which I did. Do you know if this will work, or should I be looking at getting a different thermostat?

Unfortunately that thermostat will not work with the ST Panel.
If you want to use a Honeywell thermostat with that zone panel, the Pro4000 would be your best choice.
Your only other option would be to use a Summer/Winter switch to choose between Heat, Off and Cool.
The model for that part would be the model MCS-DXB.

_________________
Patrick Cyrana
Pcyrana@ewccontrols.com
1-800-446-3110

I'm in somewhat opposite position. I have the summer/winter switch in use currently, and would like to replace thermostats (zone 2 isn't flipping off as it should, resulting in freezing AC upstairs).

Does this restrict me further, or open up more options? I have an order out for 2 Pro4000's, assuming they will still work.

Changing the thermostats to Pro4000's will open up more options in your case.
You will no longer need to use that master selector switch to choose between Heat-Off-Cool.
The Zone One thermostat will now have the capability to control this.
If you would like to continue to use the master selector switch you can simply leave it as it is and replace the thermostat wire for wire.
If you would like to eliminate the master selector switch you will want to wire the "O" and "B" from the Zone One thermostat terminals on the zone panel to the "O" and "B" terminals on the new Pro4000 thermostat.
If you have any further questions on this process, please give our Tech Support Line a call at 800-446-3110.

_________________
Patrick Cyrana
Pcyrana@ewccontrols.com
1-800-446-3110

I too have a 1F35-613, but mine is the master, on the first floor. I have two other identical Ultra-Zone thermostats, one in the basement and one on the second floor.

I have a gas furnace and central air with one compressor. Damper doors in all the ducts. I can take a shot of the control panel if it would help.

Is the 1F35-613 a 24V, 4 wire system? Could I use any 4 wire, 24V thermostat to replace the master unit? What about the other zones?

Thanks in advance!

Hi - My serviceman installed a American Standard thermostat ACONT602 as the master. It seems to be working, but the slave thermostat isn't (it's a ACONT600) Are these thermostats compatable with the ewc-st-2e?
Lisa