EWC-ST-3D --> NCM-300

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JrVarsity
Posts: 2
Joined: Tue Dec 07, 2021 7:40 am

EWC-ST-3D --> NCM-300

Post by JrVarsity »

Hello EWC.
Great forum and great product instructions -- nice work!

Homeowner from Connecticut. I upgraded from ST-3D to NCM-300 as I just replaced my 2 tstats with Ecobees. After the swap out, I noticed 2 unexpected changes in my system: 1) I have the 2nd floor tstat set at 62F but the temp never drops below ~68F, and, 2) the overall house air pressure is much stronger now, almost whistling through the registers. I know this isn't good for the system.

About my system: oil forced air, installed in 1998 when home was built, annual tune-ups performed by my oil supplier. 3 dampers: 1) first floor, 2) one labeled 2nd floor, 3) one labeled "R.O.G." and I **believe** it also runs to the 2nd floor and serves the master BR. Of note, this "R.O.G." damper wiring was NOT connected to the ST-3D so I similarly did not connect it to the NCM-300. No air comes out of the MBR registers and, as you would expect, the "R.O.G." damper motor is in the closed position.

The tstats are located on the first floor and in the MBR.

I did have to jumper #2 - #5 on the damper motors for the 2 connected dampers to get them to work with the NCM-300. I also had to run new tstat wire from basement to the 2nd floor MBR to get full functionality on the Ecobee in that room.

I feel like I am 'guessing' at system fixes now, and I wanted to ask for EWC's opinion on why my system has changed so much after the board swap out. (FWIW, my next system adjustment would be to power the "R.O.G." damper motor to better distribute air and lower overall system air pressure. But I have no idea why this damper wasn't connected previously. Then again, the MBR is reading 68F without getting air other than from the MBa attached to it.)

Thanks for your thoughts.
Chris
Steven W.
Posts: 57
Joined: Tue Jun 25, 2019 9:13 am

Re: EWC-ST-3D --> NCM-300

Post by Steven W. »

When you get a minute give me a call today
732-446-3110 X461

Thank you
Steven R. Weisneck
Steven R. Weisneck
Technical Engineer
Tel: (732) 446-3110 Ext. #461
www.ewccontrols.com
sweisneck@ewccontrols.com
JrVarsity
Posts: 2
Joined: Tue Dec 07, 2021 7:40 am

Re: EWC-ST-3D --> NCM-300

Post by JrVarsity »

Steve,
Thanks for the call yesterday.

I got a new EWC NAM motor actuator this morning and swapped it out on the "R.O.G." duct as that's the motor that was just cycling, cycling when I powered it. I had to take the damper out to do it given the motor proximity to my basement wall. While I had duct access, I then used my cell phone to look inside this mystery "R.O.G." supply duct. It appears to be a duct to nowhere, capped off as it runs up my interior garage wall (behind drywall so I can't see this being capped off when I'm in my garage). One of the options from the original homebuilder in my neighborhood was to have a finished/bonus room over the 2-car garage. My house does not have that option, but it does have an enormously high garage height, suggesting it was built for an easier future upgrade. So I suspect the homebuilder did the initial duct plumbing for a 3 zone system (thus why I have 3 dampers on 3 return ducts) and then simply did not connect what would be the Zone 3 motor wires on my old EWC-ST-3D, which is how the wiring was when this whole project of mine started.

Now both the "R.O.G" motor and the "2nd Floor" Zone 2 motor are just cycling continuously. Both motors are wired directly to the NCM-300 zone board with the wires for both motors tightened together underneath the Zone 2 Motor connector on the zone board. Not what I was expecting. (The 1st Floor Zone 1 damper does not do this.)

With the "R.O.G." duct/damper now understood to be for an add-on 3rd zone, I disconnected the wiring to it at the zone board. The 2nd Floor Zone 2 motor is no longer cycling. I can't explain why both motors would cycle continuously like that or if that is a concern.

This is my first question to you: what explains this?

Second, I set my upstairs tstat to 62F (Zone 2) and my downstairs to 68F (Zone 1). Even though I can confirm the Zone 2 damper is closed and only slight air can be felt at the upstairs registers, upstairs (Zone 2) doesn't get anywhere near 62F, it stays much warmer, in the 67-70F range. In effect, the zones aren't working for me. At this point, I think it is likely an Ecobee settings issue as it looks like the zone board and the dampers are working correctly. This is my second question: is there anything else you can think of that explains why I can't get Zone 2 anywhere close to 62F?

Note: the fan speed / CFM still seems way high, higher than when I had the EWC-ST-3D. With the dampers now known to be working correctly, I can't explain this either...

Thanks.
Chris / JrVarsity
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