EWC Controls Forum

Hi.

I have an ST-2C master/slave control system with an oil-fired forced air furnace and A/C system.

I wanted to upgrade the zone 1 thermostat to a seven-day programmable thermostat that also had a programmable fan.

After talking to EWC (who are great, BTW), I settled on a White Rogers 1F95-1277 to replace a six-wire Honeywell.

This unit appears perfect: it has all the terminals, it's battery operated and it had the features I wanted.

But when it's installed, zone 2 operates even when the White Rogers is set to off.

The ST-2C bulletin explicitly says that when zone 1 is set to off, the entire system is disabled. And that's the way it works with the old Honeywell six-wire thermostat when it's on zone 1.

I thought I might have a short, so I insulated the wires with electrical tape before putting them into the subbase on the White Rogers. It still allows zone 2 to operate independently.

I've called White Rogers, who tells me they "aren't familiar with EWC and can't help." Plus, they think the system is a heat pump system because it requires O and B terminals.

EWC (again, they were great on the phone) suggested the short idea and had me confirm all the wires are correct on the control panel (they are) but also wanted me to get a voltmeter on the thermostat. (I wouldn't know what to look for.)

I am posting here hoping someone has gotten a White Rogers thermostat to work and might give me another clue to getting it to work on zone 1, which means in this case, being able to shut the whole system down when it's off no matter what zone 2 is calling for.

Thanks.

With the zone 1 thermostat in the off position, zone 2 should be disabled.

Take a look at the right hand side of your zone panel.
Are there any jumpers between any of the terminals?

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

Thank you very much for your suggestion!

By the "right" of the panel, I wasn't sure if you meant the thermostat side or the zone damper side. In any event, I have attached photos of both sides of the panel showing how it's currently wired.

My system has two zones and one damper per zone.

On the thermostat side, everything looks correct. In fact, all the wire colors match exactly on the thermostat side except for the zone 2 thermostat in which a green wire is connected to the Y terminal. I checked the zone 2 thermostat itself and the green wire is attached to the Y terminal on the thermostat. Here's a link to the image.

On the zone damper side there is one thing that didn't match. Zone 1 damper's M4 wire is connected to the 2 terminal of the transformer. I don't know why this is, but it's the original wiring from 1993. Could this have any impact on why a different thermostat fails to shut off whole system? Here's a link to the zone damper wiring image.

The damper wiring would not cause the issue you are seeing.
In order to eliminate the wiring and the thermostat from the equation, disconnect the "O" and "B" wires from the Zone One Thermostat terminal block.
If the zone 2 thermostat continues to run at this point it is a problem with the board and it should be replaced.
If the zone thermostat stops running at that point, the problem is more than likely going to be in the wiring or the thermostat.
Call me once you get to this point and we'll see if we can solve your problem.

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

At a second glance, the zone 2 damper appears that it would be forced closed at all times.
If that blue wire coming from the zone 2 damper is wired to the M6 terminal on the damper itself you will need to change the location of that blue wire on the zone panel.
You would want to move it from the Transformer terminal block to the M6 terminal on the zone 2 motor terminal block.

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

Thanks. I'll give that a try. I even tried the WR model that was listed in the most recent spec sheet for this panel and it didn't work either.

So, I put the thermostat on zone 2 where it does work, but where there's no ability to use its programmable fan functions.

Thanks again for the help.