Thermostat Options for EWC-ST Series Control Panels

[Erik W.]

It seems to me that you have a wiring issue, which would be better handled over the phone rather than the forum. You can contact me at the number and extension below and I will gladly help resolve this issue for you.

Erik Wnoroski
EWC Controls, Inc.
385 State Route 33
Englishtown, NJ 07726
800-446-3110 ext 483

[hancox]

Thanks Erik. I'll likely have to call tomorrow, as I want to confirm my panel wiring first. In theory, it should match diagram 3 on http://ewccontrols.com/acrobat/090375a0115.pdf , but my thermostat wiring never matched that (as you can see from my earlier posts)

[hancox]

So - looking at my old post, and looking at the diagram in that PDF, I'm fairly sure my upstairs Robert Shaw was mis-labeled.

From my old post:

My upstairs Robert Shaw thermo has:
White --> W
Red --> R
Black --> B

So, my Y terminal on the panel is wired to "B" on the TH4110D1007. I'm guessing this merely needs a switch to "Y"

Assuming I'm right - better question is - how did this work with heat all of this time?

[Erik W.]

what wire was in the b terminal on the panel?

[cheaproomd]

Same thermostat for both zones?

[Erik W.]

Use the same thermostat for both zones, you will need 6 wires in zone 1(y,w,r,o,b and g) and only 3 wires (r,y and w) in zone 2.

Erik Wnoroski
EWC Controls, Inc.
385 State Route 33
Englishtown, NJ 07726
800-446-3110 ext 483

[gregwink]

Hello Erik,
I have an EWC ST 2E ultra zone control panel.
It provides master/slave control to two separate (very old, mercury controlled) Honeywell thermostats (zone 1 and zone 2).
I want to replace the old thermostats with new ones - nest 2.0 learning thermostats.
I replaced the master (including a C (common) wire, so the thermostat can draw 24v power from the control panel, and it works fine.
I tried to replace the old slave thermostat, but I can't get it to work - the nest will not recognize any wires I installed (R, Y, and W). I do not know how to install a common wire on the slave.

My question: Can I use a second nest for the slave - is this possible? If not, can I just use the old Honeywell thermostat that is there now as the slave, with the nest as master?

I would like to install nest for both, if possible? Do I need to install a "switch" (i.e. MCS-DXB) to run the second nest thermostat as a slave? Or should I just return the second nest and leave the first nest as master, and keep the old Honeywell thermostat as the slave?

Many thanks in advance.

-Greg

It seems to me that you have a wiring issue, which would be better handled over the phone rather than the forum. You can contact me at the number and extension below and I will gladly help resolve this issue for you.

Erik Wnoroski
EWC Controls, Inc.
385 State Route 33
Englishtown, NJ 07726
800-446-3110 ext 483

[Erik W.]

You need to use the MCX-DXB switch if you are using nest thermostats. The problem is not your zone 2 thermostat but actually the zone 1 stat. The zone one or master thermostat needs to have separate o and b terminals which the nest does not have. Installing the switch will allow you to use nest thermostats in all zones.

Erik Wnoroski
EWC Controls, Inc.
385 State Route 33
Englishtown, NJ 07726
800-446-3110 ext 483

[gregwink]

Erik,
Thanks for the swift reply.
I heard about this switch from a previous post.
Is this the switch to which you refer? - http://www.ewccontrols.com/acrobat/090375a0222.pdf
If so, is there somewhere I can go/see the instructions or guide to learn how it is wired to the EWC ST 2E?
Or can I reach out to you to guide me on how to install such a switch?

Many thanks...
-Greg

[gregwink]

Erik,
I have done some reading, and I found out how to install that MCX-DXB switch to work with my EWC ST 2E panel.

One more question: Since this switch is taking over the master "function", that is to say that the MCX-DXB will now control the [cool/off/heat] and the [on/auto] functions, the two nest thermostats I will be installing - both of them - will now act as "slaves". The question is this: Is there a way to power both of these two nest thermostats with 24v current from the panel? Do I run a wire from the "c" block from each of the tstat blocks (both of the zone 1 and zone 2 blocks on the EWC ST 2E have them) to the "c" receptacle on each of the nest thermostats? Will this method provide power to both of the nest thermostats?

If that is the case, once I do that wiring - I should be done.
Many thanks...
-Greg

Erik,
Thanks for the swift reply.
I heard about this switch from a previous post.
Is this the switch to which you refer? - http://www.ewccontrols.com/acrobat/090375a0222.pdf
If so, is there somewhere I can go/see the instructions or guide to learn how it is wired to the EWC ST 2E?
Or can I reach out to you to guide me on how to install such a switch?

Many thanks...
-Greg

You need to use the MCX-DXB switch if you are using nest thermostats. The problem is not your zone 2 thermostat but actually the zone 1 stat. The zone one or master thermostat needs to have separate o and b terminals which the nest does not have. Installing the switch will allow you to use nest thermostats in all zones.

Erik Wnoroski
EWC Controls, Inc.
385 State Route 33
Englishtown, NJ 07726
800-446-3110 ext 483