[Elecraft] Furnace RF Noise

[Chuck Catledge]

John, beware of any furnaces (or ACs) with variable speed motors.  Some are RF quiet; some are not.  There are three potential sources of RF leakage I have personally experienced:
1) Variable speed inducer motor - this is a small motor used on higher efficiency furnaces to provide draft air to the combustion changer.  Some manufacturers have a kit that MAY reduce or eliminate the noise from this motor.
2) Variable speed blower motor - this is the large motor used to move air through the heat exchanger and into the duct system.  I have a 3/4 HP variable speed motor in one system that is dead quiet; I also have a 1 HP version of the same motor from the same motor manufacturer in another system that is very noisy.  The engineer that designed the motor confirmed that in the 1HP version it was difficult to manage RFI emissions.
3) Variable speed condenser fan motor - this is the motor on the outside compressor/condenser unit.  Some manufacturers use a variable speed motor running at a fixed speed for this application.  The one I have is very noisy.

---
Chuck, AE4CW

-----Original Message-----
From: John K7JLT [mailto:k7jltextra at gmail.com] 
Sent: Saturday, February 27, 2016 18:03
To: Mailman <elecraft at mailman.qth.net>
Subject: [Elecraft] Furnace RF Noise

I am blessed with a low noise level that matches my K3 and need to replace my gas furnace without degrading my low noise level.  Has anyone out there had any experience with a Ruud model U96V? Please excuse the off topic subject.

John K7JLT

John K7JLT