Power for RCS TR60 Thermostats

[DotNetDog]

I have 5 TR60 thermostats to install in my house. Since the control units are connected (via the 485 bus) I figured that I would locate all 5 control units in the wiring room. I already have CAT6 homerun from the thermostat locations to the wiring room as well as homerun from the HVAC units to the wiring room.

So....if I locate all 5 RCS control units in one spot, how do I power them? I saw this thread:
http://cocoontech.com/forums/topic/6891-24v-power-source-for-rcs-thermostat/page__hl__rcs+power__fromsearch__1

Apparently, I can run down to HomeDepot and pick up a 24v transformer that is commonly used for irrigation. Cool! But would I need 5?

The specs for the RCS control unit says it needs: 24VAC 40VA

HomeDepot has a RainBird transformer that is 24v:
http://www.homedepot.com/h_d1/N-5yc1v/R-100201044/h_d2/ProductDisplay?selectedCatgry=SEARCH+ALL&jspStoreDir=hdus&catalogId=10053&navFlow=3&keyword=irrigation+transformer&Ntpc=1&langId=-1&Nu=P_PARENT_ID&storeId=10051&Ntpr=1&ddkey=Search

So can 1 transformer power all 5 TR60 thermostats and control units?

 

[fcwilt]

Normally the power for the control unit will come from the HVAC equipment that the control unit is connected to.

 

[DotNetDog]

Yeah, but if I centrally locate the control units (in the wiring room) then wouldn't it be easier to run power locally (in the room)?
I'll take a look today to see if I can locate the control units by each of the HVAC systems. I think the only challenge there will be chaining the 485 bus to each control unit. I'll need to check my wiring again.

 

[DotNetDog]

OK, now I'm trying to figure out if I can mount the RCS control units at each HVAC system (rather than centrally locate them). Since they connect via the 485 bus, I am concerned about the distance.

Is it OK to run the wires (CAT6) in a star pattern? Each control unit would connect directly to the Elk M1XSP's 485 connector. It would look like this:

 

[JayH]

You made me go look since I now have a TR60 that replaced a TR36. I am running mine off the furnace transformer though you will have to choose connections carefully to get both sides of the transformer unswitched.

Also, you could power them all from from probably a 40VA or smaller 24VAC transformer. Down side here is if there is a problem then you lose all thermostats.

For the number of devices, considering this is regular RS-485, you need to consider proper terminating resistors which doesn't work well with a star configuration. What you can do is run Cat 5 to each controller, wire in the blue _and_ orange pairs on all but the last with the resistor, and then you can wire them in bus form.

Blue -> C1 -> Orange X Blue -> C2 -> Orange X Blue -> C3 -> Orange -X Blue -> C4 -> Orange X Blue -> C5 (resistor)

Jay

 

[DotNetDog]

I decided that to keep things simple I would just install the Control Units at each of the HVAC units. I have 5 HVAC system: 2 units are in the basement mechanical room, 1 unit in a garage mechanical room, and 2 in the attic. The RS485 runs will look like the multi-drop configuration in the manual. I'll put the terminating resistor on one of the attic units.

I already installed the first TR60. I should get the others in this weekend. I'm finally enjoying playing with this stuff from the M1G. Last night I used the XEP Web Interface while laying in bed. I showed my wife how I can turn lights on or off and how I can change the thermostat in the basement. She said "Cool" then rolled over and continued reading... Gadgets...they're a guy thing!

 

[fcwilt]

You might want to invest in the RS-485 hub - it makes trouble shooting easier and would allow for the "star" setup you envisioned - I use them in my installs.

 

[tmbrown97]

I'm finally enjoying playing with this stuff from the M1G. Last night I used the XEP Web Interface while laying in bed. I showed my wife how I can turn lights on or off and how I can change the thermostat in the basement.

Now it's time for a smartphone app - either ElkDroid or eKeypad, depending on your phone!

I knew I won the battle when my wife would walk to the touchscreen in the livingroom rather than the thermostat in the hallway to change the temperature!

 

[wuench]

Are you sure you are supposed to run 5 controllers? Do you have 5 HVAC units? I think normally in a multiple zone setup you would have 1 RCS multizone controller, with all the thermostats connected (not 5 single zone units). That is complicated enough you may want to consult an HVAC company.

Something like this...
http://www.smarthome.../Item/ZC6R-232/


If you connected 5 thermostats to one unit I suspect they will compete with each other, calling for heat/cool, etc.

 

[DotNetDog]

Are you sure you are supposed to run 5 controllers? Do you have 5 HVAC units? I think normally in a multiple zone setup you would have 1 RCS multizone controller, with all the thermostats connected (not 5 single zone units). That is complicated enough you may want to consult an HVAC company.

Something like this...
http://www.smarthome.../Item/ZC6R-232/


If you connected 5 thermostats to one unit I suspect they will compete with each other, calling for heat/cool, etc.

I do have 5 separate HVAC systems. Each TR60 comes with a "Control Unit". The CU connects directly to the HVAC system; the thermostat connects to the CU and the CU connects to the RS485 bus.

I connected them all this past weekend and got the Elk talking to them. Works Great! Now I have a "Bedtime" task in the M1G that fires my lighting scene for bedtime then sets all 5 thermostats to the night time settings.