New Furnace Electrical Noise Problem

[Goedjn]

Is the harness shield or anything else actually grounded?

[MLD]

The end of the harness connected to the control board has the shield going to the same pin as the green ground wire. (Both connect together at the back of the connector). At the end of the harness going to the motor the shielding ends about 6 inches from the motor connector and is floating--that is, connected to nothing!.I guess the next step should be-----make a positive connection from the floating shield to a ground. What do you think? MLD

[Mark]

noticed the

e-noise. The

operating), so

background.

interference in

I'm gonna GUESS that this motor is also brushless but that it is variable speed and is controlled by some electronic device that uses Triacs like in a lamp dimmer and it is this "dimming circuit" that is actually casing the problem. Can you see any brushes sparking going on inside the motor? If it is indeed a brushless motor and the problem is the electronics, I'm gonna also GUESS it's a design problem and you may have to go to Trane to engineer a solution. Got any ham radio operators near you. They would be very happy to help you as your furnace is probably causing them grief.

Mark

[MLD]

Because there has been a number of comments/speculation about the inducer motor I dug out the Installer's guide. Listed under Service facts is the specs for all of the major components. In the wiring schematic the motor is identified as a "Vent Motor" and it does not indicate whether or not it is an AC or DC motor. The schematic does not indicate that the wiring harness between the motor and the control board is a shielded harness. Could just be a sloppy representation of the truth or a recent fix that Trane has been using in response to the RF noise problem. In the Specs the motor is called a "Combustor Fan", not to be confused with the Blower Motor. Specs are as follows: Type--- --------------Centrifugal Drive-No. Speeds---- Direct - Variable Motor HP-RPM-------1/50 - 5000 Volts/Ph/Hz------------33 - 110/3/60 - 180 FLA-------------------1.0 Just some more info. MLD

[KHE]

I have a similar problem with my Ham Radio. When the ignitor kicks on it creates a great deal of radio frequency interference on all bands of my radio. KHE

[Micky]

Thanks for sharing.

[hrhofmann]

If the furnace cannot be fixed satisfactorily, I would threaten to contact the FCC. There are many FCC rules about not causing interference to licens ed radio services, and this sounds like a flagrant violation of those rule s. The whole general subject is called "electromagnetic compatibility", an d there are professional organizations like the Institute of Electrical and Electronic Engineers that have worldwide members who specialize in electro magnetic compatibility.

[gregz]

Wonder if FCC really cares. I did a little with my noisy variable speed switched pulse fan system. I attached ferrites on all wires comming out of furnace, including thermostat. It helped some.

Greg

[Gator]

Outdoor antenna and some quad-shield coax? Make sure teh furnace and the tv are not on same circuit.

[hrhofmann]

Using the battery operated portable am radio is the best that you can do wi thout sophisticated equipment. See if the noise appears to be radiated int o the house, or is it being conducted onto the power lines at the furnace a nd then carried by the power lines throughout the house.

[Tony Hwang]

I think there is kit available from the manufacturer to deal with the noise problem. DC VS motor servo circuit board is source of noise most likely.

[gregz]

Use increasing frequency to better pinpoint. AM. CB vs AM broadcast. Aircraft vs CB, etc.

I first noticed FM broadcast interference while taking car out. Turn out to be my LED outside lights running switched curren limiting. Ferrites helped.

Greg

[Micky]

Are you saying the LEDs in your car's tail lights, parking lights, interfered with FM radio in the car? In your house? That's terrible!

[gregz]

The house LEDs I have out in the yard, with many feet of interconnection wire antenna.

Greg

[Micky]

Wow. Just when I thought i had all the world's problems solved, a new one.

[Tony Hwang]

Many different Ferrite cores. Have to pick and choose for right one.

[billyinseattle]

Here is an RF (RFI) Kit:

[makolber]

the fact that details like this were not resolved before the design was put into production has to make one wonder about what other details are lacking.

M

[trader_4]

+1

And what a kit. It's not just one simple 5 min thing.

Glad I bought a Rheem instead of the more expensive Trane, Carrier, etc. stuff. No EMI here.

[Slowpoke]

replying to MLD, Slowpoke wrote: i am having the same problem with my ham radio station.....the vent blower runs

4 minutes then the furnance blower starts while the vent blower still runs for another 4 minutes then it shuts off and my noise disappears from my radio but the furnance motor still runs with no noise on my radio..... please help me get rid of this noise......furnance only 1.4 years old......hhheeelllpppp.....