[RFI] Fwd: HVAC

[Dave (NK7Z)]

Hi,

I am confused by your question, can you restate it please?

I think I indicated that the variable speed unit was noisy.  If you are 
asking why the Carrier units are quiet, I would assume they have 
filtering, as mentioned my another poster here, in this thread.

If you are asking why his changing the cycle times on the Mitsubishi  
made things better-- he had it set to cycle on every 7 minutes, no 
matter what the temp was, just to stir the air in his home.  So every 7 
minutes, I would get a 4 to 7 minute burst of RFI from the unit, then 7 
minutes of silence, then another 7 to 5 minute burst of RFI, That cycle 
would repeat, twenty four hours a day, seven days a week, three hundred 
sixty five days a year, taking out over fifty percent of my listening 
time on the mentioned bands.

Now that he has it set to on demand, (only when the temp is below the 
set point does it start), it turns on far less than it did before, thus 
giving me far more operating time on the named bands.

It still generates the same amount of RFI, but not near as often.  
Sometimes it never even comes on during the day now... I used to tune to 
any of the named bands and half the time, RFI was there, now most of the 
time the unit is off, and no RFI. Does that clear this up?

73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources


On 11/11/24 10:09, Steve London wrote:
> Why would a multi-speed device be much quieter ? It's still changing 
> the frequency to control the motor speed, isn't it ?
>
> 73,
> Steve, N2IC
>
> On Mon, Nov 11, 2024 at 10:47 AM Dave (NK7Z) <dave at nk7z.net> wrote:
>
>     Think of a variable speed fan controller as an automatically
>     controlled,
>     dirty 500 watt square wave generator, connected to a long non twisted
>     wire, running a motor...  They are quite noisy...
>
>     I have a neighbor that has one, (probably 70 feet from my
>     antenna), and
>     he used to run it 7 minutes on, 7 minutes off to clean his home
>     air.  I
>     asked him if he could change that to as needed, and I now have 17,
>     15,
>     12, and 10 back, when it is not running, which is most of the time...
>     He has two Carrier units, and they make zero noise.
>
>     His Mitsubishi unit is the culprit in the RFI generation. The model
>     number is:
>
>     SUZ-KA12NA
>
>     The installer has no idea of what RFI is...
>
>     73, and thanks,
>     Dave (NK7Z)
>     https://www.nk7z.net
>     ARRL Volunteer Examiner
>     ARRL Technical Specialist, RFI
>     ARRL Asst. Director, NW Division, Technical Resources
>
>
>     On 11/11/24 08:40, Dan K2YWE wrote:
>     > Thanks Jack.
>     > Do your units have variable speed or multi-speed fan control?
>     >
>     > 73, Dan
>     >
>     >
>     > On Mon, Nov 11, 2024 at 11:10 AM Jack Ference
>     <jackference at gmail.com> wrote:
>     >
>     >> Hi Dan,
>     >>
>     >> Both Frank W3LPL I have had good luck with Carrier. He replaced
>     one unit
>     >> as nd  replaced two a few years apart.
>     >>
>     >> I bonded the cabinet door to the sides, installed a powerline
>     choke on the
>     >> power to the blower motor and installed a coil of wire choke
>     around the
>     >> thermostat wires.
>     >>
>     >> I opted for one step down from the highest efficiency units so the
>     >> compressor had switched settings rather than variable settings 
>     controlled
>     >> by electronic circuitry.
>     >>
>     >> Carrier was aware of my concerns and supplied the documentation
>     for the
>     >> fixes. They happened to be the same fixes I did on my first
>     unit replaced.
>     >>
>     >> Jack W3KX
>     >> Sent from my iPhone
>     >>
>     >>> On Nov 11, 2024, at 10:56 AM, Dan K2YWE <dan.k2ywe at gmail.com>
>     wrote:
>     >>>
>     >>> I'm need to replace my 25 year old HVAC with a new oil
>     furnace and AC
>     >>> system.
>     >>> EMIis a great concern. It's a small house and efficiency is of
>     little
>     >>> importance.
>     >>> What are the recommended brands and/or models?
>     >>>
>     >>> 73, Dan
>     >>> _______________________________________________
>     >>> RFI mailing list
>     >>> RFI at contesting.com
>     >>> http://lists.contesting.com/mailman/listinfo/rfi
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