Booster fan auto activation issue with RIB 24v

[ingues]

Hi everyone,

I have a setup identical to the end result of this post:

https://terrylove.com/forums/index.php?threads/wiring-in-line-booster-fan.81104/

I'm having an issue where the RIB (RIB2401B) will not activate when connected to the C 24v line. I've tested the RIB by connecting it to the R 24v line and can confirm that it does activate that way so I do not believe that the fault is with the RIB.

To troubleshoot I've tested the R and C connectors inside of the furnace with a multimeter. I registered around 27v. This was done with the cables disconnected. I also replaced the 3A fuse with no change in results. I reconnected the cables and then went up to the thermostat. I removed the thermostat and tested the R and C connectors behind it with the cables connected and I again registered around 27v. So I believe that this confirms that there's no break in the line but please correct me if I'm wrong.

My theory is that there may be an issue with the way that the thermostat is handling the C line but I'm a little out of my element with this and I'm not sure if that's the issue or not.

What else can I try to troubleshoot this?

For reference here's the exact relay that I purchased:

https://www.supplyhouse.com/sh/control/product/~product_id=RIB2401B

 

[Fitter30]

R-C at thermostat is the same as being at the furnace termial strip. The coil only pulls 83 ma@24 vac. Are you using white /yellow and white/ blue for the coil?

 

[Sponsor]

 

[ingues]

R-C at thermostat is the same as being at the furnace termial strip. The coil only pulls 83 ma@24 vac. Are you using white /yellow and white/ blue for the coil?

Yes, I have the white/yellow connected to the C cable and the white/blue connected to the G fan activator cable. Should this be connected in a different way?

 

[ingues]

Ok I did a quick test by turning on the fan only on the thermostat and the RIB relay clicked on as it should. I then put the fan back to 'Auto' on the thermostat and tried just turning on the heat and the relay did not turn on when the heater started running. It didn't even turn on when the fan activated with the heat.

Shouldn't the thermostat still be sending a signal to the G wire even when it's on Auto Fan mode?

 

[ingues]

Today has been a learning experience. I learned that with my gas furnace my thermostat does not send a G fan activator signal when set to heat, it lets the furnace system handle that on its own. When in cold it does send the fan activator signal on G. So unless there's a better way to do this, I think in the winter I will have to attach the white/blue RIB relay cable to the W-heat cable, and in the summer I will connect the white/blue RIB relay cable to the normal G-fan activator cable.

Is there anything I can do to not have to manually swap between the G and W cables or is this the best way?

 

[Fitter30]

Since your looking to increase air flow could find the heating speed wire and tie it to the high speed of the motor and wire the relay to the 120 volts to operate the relay. Take a pic of the furnaces diagram if your confused o f what im writing.