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Re: [RFI] Rheem AC RFI

To: "rfi@contesting.com" <rfi@contesting.com>, Karin Johnson <karinann@tampabay.rr.com>
Subject: Re: [RFI] Rheem AC RFI
From: Thomas Mills <tsmills@bellsouth.net>
Date: Sat, 5 Sep 2020 21:56:10 +0000 (UTC)
List-post: <mailto:rfi@contesting.com>
 See if the noise is there with the unit running in fan mode only.  I had this 
problem with a new install and had to add common mode chokes on the fan wires.  
The blower uses a variable speed fan motor.  You may need to do the same on the 
compressor leads if the fan is not your problem.

Tom WB4JWM
    On Saturday, September 5, 2020, 1:32:54 PM EDT, Karin Johnson 
<karinann@tampabay.rr.com> wrote:  
 
 Hello fellow RFI'ers:

I just had a new AC system installed.  Rheem model RP1748AJVCA.

The noise floor on 40 meters just went up about 20 dB when the

Unit is running in cooling mode.  Turning it off via the thermostat

Setting confirms this, as the noise floor drops back to ambient.

Rheem calls this their Classic Plus Series RP17.  It is 18 SEER rating.

 

I have downloaded most of the available installation and data sheets that

Are available on the internet.

 

I suspect this is going to be a long involved project to get this unit
quieted.

 

My local installer and distributor isn't going to be of much help.

 

I am pretty sure the major source of the RFI is the high power three phase

Inverter board that drives the compressor motor in the outside unit.  I
haven't

Actually verified this, but it makes sense as the only thing possibly
causing these

Levels of RFI would be a high power switching supply as in the inverter.

 

My question for the group.  Has anyone else had experience with this model??

I have sent an email to Rheem but was unable to contact the appropriate
department.

Most of the access to the real technical folks is going to be hidden.  I did
manage to 

Get a phone number from one of the Rheem help lines regarding some issues I
resolved

With the thermostat (ECONET) programming.  That might provide some more
info, but

For now being the weekend I will have to wait to call them.

The Rheem outside unit with the compressor does have an impressive low pass
filter board

With toroids and other filter components applied to the main 240 volt input
power feeding

The inverter board.  This indicates they at least thought about RFI.  I
have a Tektronix

Spectrum analyzer and using the connected to a 40 meter vertical about 40
feet away from

The outside AC unit, you can see the spectrum of the noise generator
(inverter).  

The Rheem documentation claims the switching frequency of the inverter is
around 6500 Hz.

Since I can't upload picture to the list, if you want to see the
installation instructions from 

Rheem, which has pictures of the inverter board and the filters.  Try
searching for

 

      rheem_rp171748ajvca-InstallationInstructions.pdf

 

It might be on the Rheem website, I forgot where I downloaded it.

 

Anyway what I asked Rheem in an email was if there was any additional
filtering kit available

For this unit.  My reply indicated that whomever answered my question was
not technical 

Enough to know the answer.  Probable because I am not talking to the right
department.

 

I have a lot of experience, being retired power electronics engineer in
designing and debugging

These types of system.  Right now I am trying my best not to do anything
that would void

The warranty.

 

Regards,

Karin Anne Johnson  P.E.  K3UU

Palm Harbor, FL

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