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Help with Cross Manifold wiring installation
I am confused about how to wire the CM devices. I think I know; but I am just not positive.
I was told that I must not apply power to the control inputs because it will damage the controller. This single point is driving this post. It is a more complicated discussion than it probably needs. But I am real concerned I may screw up.
Normally, CM inputs are direct connected thermostats. In my system, the inputs to the CM controllers will be from multiple Tekmar 369 controllers. The only connection to thermostat demand is through the Tekmar controllers. The Tekmars normally operate relays to feed operating valves on the manifold. In my case it will need to feed the CM controllers. The relays in the Tekmar have terminal blocks for the connection to the "valves". The relay terminals have an output to the controlled device. They are organized as six terminals with each pair sharing a common connection for the pair. That common connection can be either power or a system ground. Thus I need to define what that common wire should provide to the CM controllers. I can provide (normal) 24 VAC power or a common (ground goes to all Tekmar devices) to the base CM controller. The common appears to be the ground plane for the controller.
Then we get to the problem.
There are three CM input wire connections for every valve. Just ignore the valve part. It is also unusual, but not involved in the issue. These contacts are for operating the controller. They receive the demand generated by the Tekmar controllers.
There are three wire connections available for each controlled device on the CM controller. They are labeled R, W, and C. I have attached an image of the control documentation.
COM - connection may or may not be involved with my connections. Not used for 2 wire connections. Might be involved.
RED - seems to be power. Which contradicts what I have been told about power input. It also appears to sit on a bus that spans all of the RED connections and is isolated from the board ground plane. Presumably, RED provides bus power to all of the inputs. Probably 24 VAC.
WHT - seems to be the active switching wire. It can be extended to adjacent input sets, without an additional RED connection.
COM may or may not be connected to the grounding system of the Tekmar controllers. Somewhere there needs to be a common system ground between CM and multiple Tekmar devices. CM provides an isolated wall wart to provide 24 VAC to the board. That needs to have a ground common to the Tekmar system. The COM on the power connection and the COM on the input connections seem to be the same. All Tekmar controls have a system ground.
WHT appears to service the trigger signal from individual external switches. Voltage (or lack of voltage) not specified. Needs to have a system common relationship.
RED seems to be the power supply for the control inputs. Voltage 24 VAC? This appears to have to be an external source. There is already an external 24 VAC supply connected to the overall power input for the board. Why are these not the same power system? RED is isolated from the board ground.
Question - what do I connect to what. I have several CM devices. Even if I damage just one; it i expensive.