Need help in wireing the Thermostat

[scottp73]

I am going to be installing the Z-wave thermostat and see that it needs a common. My present system is just the 4 wire hookup. I do have the blue wire already run just not used at this moment. On the HVAC Control board where the thermostat wires connect is a "C" and in the manule it shows it running to the AC unit. I also see right behind that there is a post connector with "COM" and under that is one listed as "24V" and thoes are running to a transformer. Where should I connect the Blue wire too on the Board? The "C" on the board or to the 24v befor the transformer? the Board is a Nordyne 624631-a if that helps.

Thanks in avance for all your help.

I just rather ask befor hooking up an brakeing it due to hooking it up wrong.

[rmasonjr]

Which Z-Wave thermostat are you installing? I have the WDTC-20 on one of my A/C units. One thing I highly recommend is to use the included labels and label each wire as you disconnect from the original thermostat.

[scottp73]

tz43

I am thinking about tZ43 I beleve

[scottp73]

????

So do I hook up the Blue WIRE to the "C" on the Control board of the HVAC? or do I hook it up somewhere Elce on the HVAC? for the 24v COMON

[scottp73]

Or

Or can someone point me in the right direction where I could find out the INFO

[rmasonjr]

On my particular HVAC unit, the blue wire is indeed set to common.

Disclaimer - you will not always have a blue wire and it may not always be common. I have seen other installations with different colors of thermostat wires used.

[scottp73]

The Blue wire

at the moment The blue wire is not connected to anything on eather end. What I want to know is on the Control board of the HVAC there is a "C" next to all the screew post for the that are wired to the thermostat. I know on the thermostat that I need to connect C. Do I conect the Blue wire that is free at the moment to the C or to somewhere elce on the Control board of the HVAC? I also see a post in a diffent spot that said COMM and another one that said 24v both of thoes are running to a transformer.

My question is just at this moment about the HVAC connections. As in wireing the thermostat I know what to connect too.

[rmasonjr]

That, I have no idea about. I dont know much about HVAC when it gets to the outside unit. Maybe someone else will chime in about that connection.

[Stuart]

This might help you out a bit.

Stuart


http://www.hometech.com/learn/hvac.html#wiring