Radio Frequency Interference from Controller

[Tom M]

Hello forum, first post. I am a homeowner, engineer and ham radio operator. My new home has what looks like a BMPLUS 3000. There is a source of godawful RFI in my house that I have traced to this controller. I first turned off the 240 breaker for this air conditioner unit and the noise went away. Later with the 240 AC power on but the unit not running, I lifted one side of the 24VAC power for the controller and again the noise quit.

The controller is emitting a broadband RFI, with the worst at frequencies below 50 Mhz. The wires are acting as transmitting antennas for the RFI. My radios are unusable.

I'd like some assistance as to a fix for stopping this interference.

Can this device compliant with FCC rules for spurious emissions?

Thank you.

Tom M

[Eric K.]

Tom,

We have experienced some minor interference with systems using 4 or more zones. If you use a common mode filter/choke on the 24vac input to the zone panel, that should help clear things up.

Eric

[Tom M]

Thanks Eric. Is the source the power supply or the processor?

I have two zones. I'd like to attack the source and minimize the radiation from all of the secondary wires from the box.

Tom

[John B.]

Tom,
This zone product is quiet and we normally don't see this unless there is 1 or 2 expansion modules connected to it. Even then, it is minor. The main panel does not have a noisy switching power supply. Everything is pretty well contained on the processor.

What kind of dampers do you have and how many are there? Our dampers are quiet but our competitors may not be. Try disconnecting the dampers and leave the zone panel energized to see if the damper motors are the source.

In any case, a common mode filter choke at the 24volt input to the zone panel should clamp it down, including the low voltage wires leaving the panel.

Sorry for the inconvenience,
John