Wiring CAS-4JR Combustion Air System with multiple zone valves

shredmaster

this is my existing setup, with tt that go to the weil mclain CGA5 boiler. everything is wired like the diagram (pic #1)below and I need to add a CAS-4JT combustion air system (pic #2).

CAS-4JR Combustion Air System


Base on my understanding, the sequence should be as below.

Thermostat -> CAS-4JR -> zone valve -> TT

If there is one zone valve/thermostat, I can wire T1 to common, when the thermostat calls for heat, the W/Y (thermostat) send to T2, then send T3 to the W/C (zone valve).

but how would you wire this with a 3 zone valve and thermostats? there is no way for T3 to know which zone valve should get the return (TH) wire.

thanks in advance!

Solid_Fuel_Man

Wire the end switches (all in parallel as shown) the the combustion air, then the combustion air to the tt on the boiler. 

Sequence would be:
Any thermostat => respective zone valve end switch => CAS => boiler TT. 

Does that make sense? 

Ironman

Here’s a simplified drawing. T2 must connect to the common side of the boiler’s Transformer.

shredmaster

Solid_Fuel_Man said:

Wire the end switches (all in parallel as shown) the the combustion air, then the combustion air to the tt on the boiler. 

Sequence would be:
Any thermostat => respective zone valve end switch => CAS => boiler TT. 

Does that make sense? 

thanks for reply, that's what i end up doing. here is how everything are wire together in case anyone might be interested.

C (transformer common) -> CAS T2
Transformer R -> Zone Valve Endswitch T1
Zone Valve Endswitch T2 -> CAS T1

when Endswitch is closed, the CAS will close the relay and turn on the fan, then send Transformer R to CAS T3

I bought a 24v relay switch from amazon, wire the green to C, black to CAS T3, then hook up with NO to boiler TT.


this relay is unnecessary per @Ironman drawing.

shredmaster

Ironman said:

Here’s a simplified drawing. T2 must connect to the common side of the boiler’s Transformer.

simpler than what i end up doing and I can return the relay. thanks for the drawing, I didn't know the T T is just the R side of the transformer.

EdTheHeaterMan

Just think of the end switch as the thermostat on a single zone system. On a call for heat the end switch contacts close moments after the thermostat contacts close. Since all the end switch contacts are wired parallel to the TT on the boiler, then any of the zone end switches will act as a thermostat would act.  

You just need to know which of the Boiler TT is the “Red” or T1 or R or Power terminal and which is the C or Common or Return path to the Power Source (or in some cases Chassis Ground.)

Yours truly,
Mr. Ed

shredmaster

EdTheHeaterMan said:

Just think of the end switch as the thermostat on a single zone system. On a call for heat the end switch contacts close moments after the thermostat contacts close. Since all the end switch contacts are wired parallel to the TT on the boiler, then any of the zone end switches will act as a thermostat would act.  

You just need to know which of the Boiler TT is the “Red” or T1 or R or Power terminal and which is the C or Common or Return path to the Power Source (or in some cases Chassis Ground.)

Yours truly,
Mr. Ed

I have CGA5, how do you tell which boiler TT is the power terminal which is the C?

shredmaster

Ironman said:

Here’s a simplified drawing. T2 must connect to the common side of the boiler’s Transformer.

I just follow your diagram and was able to wired the CAS without the relay switch i got from amazon. I notice a small issue, when ES closed and boiler closed the gas valve after reached the temperature setting, the fan still kept going. would be ideal if fan only runs when ES is closed and boiler is also firing. here is the schematic wiring diagram for my CGA 5, can that be done?