Wiring between a Taco Expandable and Taco non-Expandable Switching Relay

[Srath]

I have a SR506-EXP Switching Relay connected to Triangle Tube Boiler with Zone 1 to 5 connected to hot water heating zones and Zone 6 is connected to Triangle Tube Indirect Water Heater with Priority on Zone 6. To extend another heating zone, I bought a SR-503 (not the expandable one). Do any of you know what wiring between these two will extend the Zone 7 to SR503, without changing any existing set up on SR 506-EXP?

 

[Stuff]

You have an expandable unit so was there a reason that you didn't just buy another expandable as that is its purpose?
Take a look at page 6 as might be enough for what you are trying to do: https://www.emersonswan.com/ckfinder/userfiles/files/pop112.pdf

 

[Sponsor]

 

[Srath]

You have an expandable unit so was there a reason that you didn't just buy another expandable as that is its purpose?
Take a look at page 6 as might be enough for what you are trying to do: https://www.emersonswan.com/ckfinder/userfiles/files/pop112.pdf

Thanks. I did refer to this manual and the connection you are referring to is between two non-expandable ones. In two non-expandable set up, Wire from boiler TT goes to both the switching relays. In case of one expandable relay, shouldn't the boiler wire just go to the expandable one, and another wire connects from Expandable to non-expandable?

 

[Stuff]

Since the new one is non-expandable it does not have the functionality to signal the expandable master to trigger the boiler TT controls. You need to treat them both as non-expandable. In this case you need to connect to TT on both so either can turn the boiler on. Also should extend indirect water heater trigger connection to priority zone on new one and otherwise not use zone 3 of the non-expandable unit.

Page 12 - Shows that expandable to expandable uses A,B,C terminals to communicate so boiler and heater only goes to master. The terminals are not on the non-expandable so you can't do it this way.

Also should verify that you are indeed using the TT connections and not the ZR ZC ones to fire the boiler.

 

[Srath]

Hello Stuff - I wired per your recommendations by referring on Page-6. i.e. I took R and W (Zone 6) of SR506-EXP and connected with R and W (Zone 1) of SR503. On SR506-EXP, priority is on for Zone 6. On SR503, priority is on for Zone 1 (by removing the jumper between P and Zc). Boiler Wire drops on SR506-EXP and then continues (by swapping as per Page-6) to SR503. Swapping means Left side of X (of SR506-EXP) connects to X2 (of SR503) and Right side X (of SR506-EXP) connects to X1 (of SR503).

Everything seems to be working without any noise. However, when Priority Zone is on (i.e. when Indirect heater is on), SR506-EXP switches off all other zones (Zone 1 to 5), but Sr503 does not switch off its own Zones. (i.e. Zone 2 of SR503 does not switch off).

Any expert advice to why SR503 does not switch off its zone? I have connected only one thermostat on Zone 2.

Manual of SR503 is: https://www.taco-hvac.com/uploads/FileLibrary/102-167.pdf
Manual of SR506-EXP is: http://www.taco-hvac.com/uploads/FileLibrary/SR506-EXP(102-088).pdf

 

[Srath]

Update: I spoke to Taco today. It seems there is a design flaw in SR503 LED indicators. When the Priority Zone 1 in SR503 kicks in, even though the power to Zone 2 and Zone 3 pump turns off, the LED indicators do not turn off. So for me, these LED indicators are false indicators.
Thanks Stuff. My problem is now solved.

 

[Stuff]

Glad to hear that you are up and running. Taco has different revisions of these. The newer 503-4 has zone 3 as priority with a simple switch and I believe the leds work properly.