Thermostat Options for EWC-ST Series Control Panels

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John B.
Posts: 17
Joined: Fri Mar 13, 2009 8:57 am

Re: Thermostat Options for EWC-ST Series Control Panels

Post by John B. »

Sir,

Most zone systems "default" all dampers open during idle periods. The reason for this logic is because there may be another device tied into the duct-work. maybe a whole house humidifier, HRV or a de-humidifier, that is not interlocked into the zone system. If the zone system closed all the dampers during idle periods. These devices would not be able to function.

Some damper motors are "spring open/power close" type, so they are being powered only to close! Others are "power open/power close" type, so they are being powered continuously. However, the current ND & URD dampers (MA-ND5 motors) de-energize all by themselves when they reach full open or close position. The LED's then illuminate and draw only 26 Milli-Amp. Very low power consumption and beautiful bright LED's to indicate damper position. Why would anyone buy anything else?

So there is little concern over motor life expectancy and they are warranted for 5 years. Life expectancy is 15 - 25 years.
I have attached the Submittal sheet files for both products.

John
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John Brown :geek:

Robb
Posts: 1
Joined: Mon Dec 09, 2019 11:39 am

Re: Thermostat Options for EWC-ST Series Control Panels

Post by Robb »

I wanted to post up my experience getting my EWC-ST-2D Control board to work with Emerson ST55 WiFi Thermostats. I got the new TStats on sale ($80 a piece) and had a budget to get this all working.

My Existing Tstats were 5/2 programmable and had separate O and B wires. I realized that the newer ones had a combined O/B that would not work naively with the existing control board. I was told I needed a NCM-300 board or a MCS-DXB Selector switch. Neither of these were an option due to budget.

Looking at Page 3 figure 3 HERE https://ewccontrols.com/acrobat/090375a0115.pdf You can see that the MCS-DXB Switch is a SPDT switch and an SPST Switch. I bought a SPDT Switch form Home Depot for $5 and wired up for the Heat/Off/Cool. I decided not to wire up a SPST switch for the fan as I wired that to the Zone 1 TStat as described below

Since I had a 6 conducted wire For my original Zone 1 and 4 wire to one 2, I now had enough spares for a C wire to both. I also connected up the G wire on my Zone 1 Tstat to be able to control the Fan On/Auto through the T-Stat.

Everything works great, C wire is providing power. I have the 3-way switch mounted on the control box and it work great for the summer/winter changeover. I will mention, to have the C wire powered - the system must be on Heat or Cool from this switch, however the T-stats can be set to "off" during the shoulder seasons. I later wired my Normally Closed high level switch inline with R1 and my way switch to break the contact and shut the system down if my condensate pump fails (Used in summer for condensate and winter for Humidifier drain)

Hope this helps someone that is considering a less expensive solution.

NOTE - this would probably not be helpful in areas where heating/cooling need to change on a regular basis. I am based in New England and having to flip a switch once a season isn't an issue for me.

NOTE 2: Image was captured before wiring NC switch inline with R1 and landing G
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