EWC ST-2E 2 zone system Issues

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  #1  
Old 05-17-19, 10:40 PM
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EWC ST-2E 2 zone system Issues

I had a contractor install duct work to my new addition and during the process, we added another zone with 2 baffles (one controlling existing ducts and other controlling addition). He installed the EWC zone control system ST-2E. I also had a nest thermostat that I purchased months ago that he installed concurrently with this system using my existing thermostat wire. It seemed to work fine for a day or two after the contractor left and then no AC. My nest will say cooling, the fan kicks on in furnace but the AC unit outside does nothing. When i turn the heat on, all seems to work fine. I have not tried zone 2 yet at this time. The contractor hasn't returned any of my phone calls and I'm attempting to remedy the issue myself with the help of the community. What we wanted was 2 zones, where each thermostat could be set to heat/cool and work seperately from each other. They fried my propane furnace control board during installation and had to replace that unit as well, which worried me that things may still be messed up.

I have forced air propane and a central air conditioner unit.

Here are some pictures of the wiring job that the contractor did. Does this wiring look fine or is there something that needs changed? The 2 wire from my central air unit back to the furnace is shown connected in the top picture below to the 'C' terminal and 'Y' terminal. The remaining wires in top photo connect to the area labeled system in the EWC panel. The blue wire is just hanging loose next to system wires as shown in photo but it connected on the other end to the 'C' terminal.

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Nest Thermostat Wiring
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Last edited by PJmax; 05-18-19 at 08:53 AM. Reason: imported/resized pictures
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  #2  
Old 05-18-19, 07:46 AM
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You've got the wrong zone controller. The EWC ST-2E requires a main thermostat with separate O and B terminals to properly select cool or heat for the entire system.

https://ewccontrols.com/acrobat/090375a0115.pdf
 
  #3  
Old 05-18-19, 07:50 AM
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Am I able to set thermostat 1 to heat or cool only and thermostat 2 to the same heat or cool as thermostat 1 and have it work properly? I do not have a heat pump and do not use the 'O'
 
  #4  
Old 05-18-19, 07:57 AM
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A heat pump is usually cheaper to run than propane so surprised they didn't recommend one.

That controller doesn't care if you have a heat pump or not, it still requires a heat pump style thermostat. They also support a heat/cool switch - see figure #5 of the pdf. Recommended switch https://www.amazon.com/MCS-DXB-Contr.../dp/B01DJMS9PS is pricey but could use a 3-way switch instead.
 
  #5  
Old 05-18-19, 10:15 AM
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I'm confused as to what I need to do to make things right. Am I able to use the nest thermostat or not with this unit? The contractor knew I had the nest before he installed what he did and I need to fix any mistakes that were made along the way myself. Is this the cause of my AC not turning on now even when T-stat calls for heat?

Also, my original t-stat had separate B and O connections on it. I tried hooking that back up last night and it did the same thing as my nest is doing. Heat works but no AC, just furnace fan kicks on and circulates room temp air. The O connection on my original thermostat was never used but the B had blue wire connected which is the common if I'm not mistaken. Do I need a thermostat with separate B and O connections even though the O is not being used?
 

Last edited by Jrk5230; 05-18-19 at 10:34 AM.
  #6  
Old 05-18-19, 12:34 PM
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This has come up before and most others end up replacing theirs with a Honeywell HZ311 zone controller or similar modern one that doesn't need O or B. Your installer simply should not have used that controller unless they were supplying the matching thermostats.

With Trane systems B is "common" which can confuse things as most others use C for common. On heat pump systems B used for the heating reversing vale and O the cooling reversing valve. There is normally one or the other, not both. 20 years ago EWC made this zone controller require a heat pump style thermostat. It made sense back then as they could simplify the board design and cost by using the O and B wires of the master thermostat to set the system mode. I think this design shortcut started decades before then but others who did the same thing gave up on the design long ago.

There is a very short list of compatible thermostats and even EWC says to use a different board if you want a WiFi thermostat: https://ewccontrols.com/forum/viewtopic.php?t=405. Frankly, I'm surprised EWC is still selling that board.

Originally Posted by https://ewccontrols.com/acrobat/090377a0174.pdf
NOTE: This product utilizes “O” and “B” circuits as a means to manually control “Changeover” of the HVAC system from Heating mode to Cooling mode via the Master (Zone 1) Thermostat. This product is not a Heat Pump controller.
For now you can force cooling mode by putting a jumper wire at the board between O and R1. (B and R1 for heating mode).
 
  #7  
Old 05-18-19, 01:02 PM
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Heat has been working so should I still put that jumper in?

As for cooling, does the jumper go from R1 to O under zone 1 T-stat?

Sounds like my hvac contractor didn't have the proper knowledge on what to install for us. I cannot use my nest thermostat that also cannot be returned now that he installed it. Can only use the nest if I upgrade the panel I take it?

I posted a thread over at EWC also.
https://ewccontrols.com/forum/viewto...9&p=2984#p2984
 
  #8  
Old 05-18-19, 02:01 PM
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Maybe your version of the panel can do heat without the B. Don't know.
Yes, for cooling jumper the R1 to O that is under zone 1
 
  #9  
Old 05-18-19, 02:15 PM
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Ok, thanks for your help. The other thing that was weird, the AC worked for a couple days after he finished the installation and then stopped and hasn't worked since. But it wasn't working all the time. Occasionally I had to turn the cooling off and back on for the central air unit to kick on. Sometime it would cool when called for and work as normal and other times it had to be cycled off and back on to work.

On a side note, do you know what the blue jumped is for that goes from R on t-stat 2 to R1 on t-stat 1?
 
  #10  
Old 05-18-19, 09:47 PM
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This zone controller board was never meant to work without O and B connections. It not working right with how it is installed on your system is not unexpected.

R1 on this board is always hot (24vac). The R's on the thermostat connections are only supposed to be hot when there is a signal on O or B (turns thermostats off if heat/cool switch is set to off). Your installer probably saw no power on R and thought they could jury rig this board with that blue jumper to make it work.
 
  #11  
Old 05-19-19, 07:23 AM
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If I do what you said with the jumper, will the AC stay on until jumper is removed or am I able to control it from thermostat?

I know how to wire a house with 110v but dont fully understand how the low voltage works in HVAC yet. So the red wire is always the 24v hot and it runs from control board on furnace to the thermostat? Guess I get confused because I have a control board on furnace itself and a EWC control board also.

The NEST thermostat has the following terminals with the corresponding color wires connected...

Y1: YELLOW
Y2:
G: GREEN
O & B:
Rc:
Rh: RED
W1: WHITE
W2/Aux:
C: BLUE
*:

Zone 1 thermostat terminal block on the EWC zone panel. Terminals below...

C: BLUE
W: WHITE
Y: YELLOW
R:

R1: RED & jumper to R on t-stat 2
O:
B:
G: GREEN

Hoping this helps with troubleshooting..

On a side note, is there supposed to be a common wire connected to my C terminal on Furnace Board inside furnace panel? There is a white wire connected that comes from my central AC unit outside and a blue wire but the other end is not connected to anything. Could this be part of the issue?
 

Last edited by Jrk5230; 05-19-19 at 08:50 AM.
  #12  
Old 05-19-19, 10:25 AM
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If I'm understanding correctly, i would need 7 wire run to add B & O connections at EWC Panel and T-stat 1 to make thermostat change between heat and cool but cannot work with the nest unless a relay is added or the EWC Switch? I currently only have 5 wire in the wall at T-stat 1 and 7 wire in wall at T-stat 2. I found the EWC switch but wanted to see what the relay or 3 way that you mentioned looks like on Amazon as I'm not sure what I'm looking for. My old thermostat has B & O connections as showing in link from post #7 but does not have a C connection. My blue wire which I'm positive is a common wire, was connected to the B before contractor came in and added the 2nd zone and EWC panel.

Thanks for your help.
 
  #13  
Old 05-19-19, 08:09 PM
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Normally the two wires from the outside condenser go to Y and C on the furnace board. Then Y would continue on to the zone controller. Y also may go through a safety overflow switch.
With a zone controller C does not need to connect to the furnace as you see on the left there is no place for one.

Advice is to cut your losses and reduce your long term aggravation and replace the zone controller with one that doesn't have issues with standard thermostats.
 
  #14  
Old 05-19-19, 09:39 PM
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You've got the wrong zone controller. The EWC ST-2E requires a main thermostat with separate O and B terminals to properly select cool or heat for the entire system.
My original Honeywell t-stat which was what was used prior to adding the zone control & 2nd zone to addition has separate O & B connections. Looking at the NEST t-stat wiring, how should I connect the wires to my Honeywell to test its compatibility? I believe it should work since it has the separate O & B.

Advice is to cut your losses and reduce your long term aggravation and replace the zone controller with one that doesn't have issues with standard thermostats.
If my original Honeywell model isn't compatible, what zone control board do you recommend? You mentioned the Honeywell HZ311 in a previous post, are there any others recommended? Hoping my original Honeywell can get the job done and save me from buying a 2nd zone controller.

Thanks for any and all help.
 
  #15  
Old 05-20-19, 07:48 AM
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What model Honeywell thermostat did you have? The Trane version uses the B as common, not reversing valve so wouldn't work. A thermostat that also has a C should be good and the wires connect one-for-one after removing the blue R to R1 jumper (note master thermostat's R goes to board's R1). In the PDFs there were lists of compatible thermostats.

The HZ311 is probably the best known zone controller. Others will work and EWC makes some as well.
 
  #16  
Old 05-20-19, 08:43 AM
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What model Honeywell thermostat did you have?
RTHL2410C1005.. I looked at the manual last night and it's a heat pump type thermostat where B is for heat pump. So that blue wire in my pics shouldnt have been connected before because I think that's the common in my setup which really wasnt being used if I'm not mistaken. Picture of the connects can be found further back in this thread.
 
  #17  
Old 05-20-19, 10:52 AM
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Right, that Honeywell doesn't use a common so nothing on the controller's C. The RTHL2410C1005 has the right connections so give it a try. Hopefully it still controls the O and B terminals even when configured as conventional/not a heat pump. You will need 6 wires - connect it to R1, O, B, G, W, Y.
 
  #18  
Old 05-20-19, 12:02 PM
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You will need 6 wires - connect it to R1, O, B, G, W, Y
I currently only have 5 wires in the wall. So this isnt an easy solution either. Will have to run another wire to test this out. I guess anyway you slice it, with my heating/cooling, I will need 6 wire and not 5 so it'll have to be done. Another thing the hired contractor should have done :-( I'll pickup the wire and pull it thru while removing existing wire hopefully in next couple days and post back with the results.

Do I still need that jumper that goes from R1 on t-stat 1 to R on t-stat 2 with the new wiring setup?

If this Honeywell's does work, am I able to use my nest as the 2nd t-stat since it wouldnt be the master? Doesnt appear to need O and B on the 2nd t-stat.

On the other hand, with this EWC board, I have to have t-stat set on cool or heat and 2nd matching the first to work properly, correct? If I got the HZ311, i could set either thermostat to heat and cool both where the t-stat can do everything on it's own? If that's the case, I may just change out to the HZ311 anyways and use 2 nest thermostats since they are compatible with that board. In the meantime, I'm going to try my original Honeywell for the time being and decide to upgrade later if it works.
 

Last edited by Jrk5230; 05-20-19 at 12:21 PM.
  #19  
Old 05-20-19, 12:37 PM
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Just thought of another idea. T-stat 2 location in addition has 7 wires. I could make that t-stat 1 master and not have to run new wire then.
 
  #20  
Old 05-20-19, 02:44 PM
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You need to remove the jumper from R1 to R for the board to work correctly.

Yes, you could use upstairs as the master and that thermostat would be the master. Use R1 to feed it.
 
  #21  
Old 05-20-19, 03:00 PM
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I did the switch about an hour ago. Switched t-stat 1 & 2 on the zone board and also damper 1 & 2. Plus added the O & B wire. My original Honeywell thermostat seems to be working GREAT as the master in the addition. I've had Cool on in both zones and its working as expected now. Also, removed the blue and green wire from the NEST thermostat from picture and only have the white, red, and yellow connected now. NEST seems to be working fine also. The only thing im concerned with is with the NEST thermostat at t-stat 2 location. Doesn't it need a common wire to constantly feed 24v of power otherwise it may cycle my furnace on and off to get power? Can I connect the blue wire to 'C' on NEST and then to 'C' on t-stat 2 for constant power?

Can the NEST turn the fan in furnace off and on if it doesn't have the Green wire attached to 'G' or only the master?
 
  #22  
Old 05-20-19, 10:26 PM
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If Nest doesn’t have a C then it will steal power from Y1. This normally works with a simple a/c unit but causes other things like zone controllers to cycle the a/c too often. So yes, connect blue to C at the Nest and at the zone controller.

With that controller it automatically turns the fan on for Y. The furnace controls the fan when W is activated. If you want you can connect Nest to the G terminal in addition to it connecting to the other thermostat.
 
  #23  
Old 05-22-19, 07:42 PM
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Very excited I troubleshooted and got the system running properly myself. Thanks for all your help Astuff, it was great.
 
  #24  
Old 05-22-19, 09:12 PM
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Good you got it working.

One more quirk to be aware of. If the main thermostat is turned off (neither heat or cool so neither O or B are powered) then R is turned off which feeds the zone 2 thermostat. Nest will give an error about power loss but can be ignored.
 
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  #25  
Old 05-24-19, 11:35 PM
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Thanks, and one last question.. The only way I can run a second nest at the main thermostat would be if I upgrade the zone control board to ones you mentioned previously?
 
  #26  
Old 05-25-19, 06:40 AM
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To run a standard thermostat on the main zone would need an upgraded board, hard-wiring a jumper for heat/cool mode, an external heat/cool switch, or wiring up a few relays.
 
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