[RFI] Lennox brand HVAC RFI experience

[Jeff Blaine]

I looked into the similar family 2-stage compressor unit.  Seems the 
2-stage is done with respect to the fluid / gas compressive loading 
applied to a SINGLE speed motor.  So from my review of the manual, it 
seems this **may** be similar with respect to noise generation.  I 
suppose a control board could be located inside with some electronic 
goodies but I will have to check into that.

73/jeff/ac0c
alpha-charlie-zero-charlie
www.ac0c.com


On 7/18/22 10:12 PM, Jeff Blaine wrote:
> Thanks for that link Steve.  It looks like this Lennox heater uses 
> exactly that 5-speed constant torque motor.  In looking at how those 
> motors are constructed, and the layout of the control board, I don't 
> see any sort of thing that screams "PWM IMPLEMENTED HERE SO LET THE 
> WAVEFORM CHOPPING CONSOMME AND LETS RIP SOME RFI!!!"
>
> I had a long talk with my HVAC guy, and showed him the shack, and the 
> test gear and so he was comfortable that I would be able to implement 
> any abatement - if needed - especially since any 120/240 stuff would 
> have my electrician's seal of approval and keep them off the hook for 
> "user tampering" or whatever other things they may be worried about.  
> And from that, we did not talk about any of the variable speed this 
> and that solutions out there.  It was all single/dual speed only.  No 
> variable anything.
>
> I've got a few messages from guys saying the RFI issue was contained 
> (in those cases) by following the generic suppression stuff (common 
> mode primary, some differential if needed - and a bit of shielded runs 
> to the thermostat in one case).  I suspect that I could make a 
> variable speed system work but it looks simpler and may be a higher 
> chance of no-problem if I just stick with the dual speed options which 
> is where I am now.  In fact, I may consider a 2 speed aircon 
> compressor if those are winding-selected 2-speed implementations 
> instead of 2-setting variable speed things.  Need to check more.
>
> 73/jeff/ac0c
> alpha-charlie-zero-charlie
> www.ac0c.com
>
>
> On 7/18/22 6:57 PM, Steve London wrote:
>> This is certain to raise W0LEV's blood pressure:
>> http://library.coburns.com/HVACTechTips/Motors%20what%20is%20going%20on.pdf 
>>
>>
>> GL finding a new PSC-motor furnace and compressor. If you find one, 
>> please post it - I'm in the same position as AC0C.
>>
>> 73,
>> Steve, N2IC
>>
>> On Mon, Jul 18, 2022 at 3:55 PM Jeff Blaine <KeepWalking188 at ac0c.com> 
>> wrote:
>>
>>     We are looking at a replacement HVAC and these items are proposed 
>> for
>>     the install.  I'm paranoid about the RFI noise profile out of modern
>>     HVAC systems and would be interested in any comments.
>>
>>     The Lennox P/N recommended are:
>>
>>     Merit series - ML14XC1$-042 compressor 14 SEER
>>
>>     Elite series - EL280UH090E488 dual-speed (2-stage?) furnace 80%
>>
>>     The installer is aware of the Lennox 604552-01 kit which includes a
>>     differential filter and a snap-on toroid.  I've made it clear that
>>     the
>>     single snap-on toroid is likly and that a multi-turn type 31 
>> would be
>>     used in lieu if needed.  Which would not have a warranty issue as 
>> the
>>     HVAC guy and I share a common electrician who has vouched for the
>>     safety
>>     of this "mod."  And we have discussed that similar (multi-turn
>>     toroid)
>>     treatment may be added to the thermostat line as well.
>>
>>     Appreciate any advice on other guys who may have experience with
>>     Lennox
>>     gear in general, or these families in particular.
>>
>>     73/jeff/ac0c
>>     alpha-charlie-zero-charlie
>>     www.ac0c.com <http://www.ac0c.com>
>>
>>
>>     _______________________________________________
>>     RFI mailing list
>>     RFI at contesting.com
>>     http://lists.contesting.com/mailman/listinfo/rfi
>>
> _______________________________________________
> RFI mailing list
> RFI at contesting.com
> http://lists.contesting.com/mailman/listinfo/rfi