EWC-ST-2E

[miao_yi@hotmail.com]

Hi,

I purchased EWC-ST-2E in June 2018 to replace failure one which is installed in 1998. This control system is to provide control of two zones in the house. After we installed the control panel, we found it is unable to make damper move. Since then, we are unable to have two zones in the house. Today I stump upon this forum. So I'd like to try and see anyone can shred a light.

First of all, we tested that the two dampers are working.

However, we found damper is unable to open when it is close or the damper is unable to close when it is open.

So we checked the voltage of the control panel, below is our findings (please refer to attached diagram)
When damper is in close position,
voltage between 1&4 = 24V
voltage between 1&6 = 6V <-- We found the voltage of neighbor's EWC-ST-2E is 0

When damper is in open position,
voltage between 1&4 =6V <-- We found the voltage of neighbor EWC-ST-2E is 0
voltage between 1&6 =24V

Since our neighbor has exact same heating/cooling system, they have the same control panel and damper like us. So we checked the our neighbor's ETC-ST-2E installed in 1998 (This is original one). We found the voltage of their control panel is 0 when control panel operates damper.

So I'd like to ask following questions:
1. To make the damper moves to oppose position, the voltage between 1&6 should be 0, correct?
2. So why the 1&6 of my EWC-ST-2E is always 6V?
3. If this suppose be 0, anything else I should check?

Thank you in advance!

[Steven W.]

You should be reading 24 - 30 volts
M1 is Common
M4 is Powered Open
M6 is Powered Closed


In the open position you should read 24 volts at M1 and M4 the whole time the damper is open

In the closed position you should read 24 volts at M1 and M6 the whole time the damper is closed

You could have a bad transformer or a bad zone board

[miao_yi@hotmail.com]

Thank you so much for the response Steven.
Last night, we tested the two damper actuators, found one is working, the other failed. We installed the good working one. Now zone 2 works fine. We'll get a new damper actuator and try zone 1 when we get new part.