[RFI] Request for Comment (Rheem RP1748 A/C System)

Karin Johnson karinann at tampabay.rr.com
Thu Nov 5 17:18:40 EST 2020

Hello Group:
Just a quick update on the RFI created by my new Rheem central A/C system.
The installer was out earlier this week to replace the UNSHIELDED thermostat
wiring with SHIELDED wiring.  They did accomplish this successfully.  While
they were at it I had them put two FairRite type 43 toroids with 4 turns of
The new wiring in the toroids.  One toroid was placed at the Air Handler
inside the attic of my home, the other toroid at the Compressor outside
unit.  I know, some folks will probably say use type 31.  The type 43 is
what I had on hand and four turns provides about 20 dB suppression with this
wiring construction, as measured on my network analyzer. 
>From some quick preliminary testing, it appears all of the RFI is GONE.
No more RFI from the unit while it is running at normal load.  I will have
To do some more documentation regarding this new wiring installation.  There
are some details that I will forward once I get some time document them.

So for now it looks like the problem is solved.  Fingers and toes crossed.

Karin Anne Johnson  P.E.  K3UU
Palm Harbor, Florida

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