Groups > sci.electronics.design > #748217

Re: Ferrite ID

From	Bill Sloman <bill.sloman@ieee.org>
Newsgroups	sci.electronics.design
Subject	Re: Ferrite ID
Date	2026-09-26 16:39 +1000
Organization	A noiseless patient Spider
Message-ID	<1197pbd$8hpc$1@dont-email.me> (permalink)
References	<11965md$1i$1@reader1.panix.com> <ld3ebld0uqu18tuepnibpbns9ug7fmfgq9@4ax.com>

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On 26/09/2026 10:13 am, john larkin wrote:
> On Fri, 25 Sep 2026 15:58:05 -0000 (UTC), David Lesher
> <wb8foz@panix.com> wrote:
> 
>> Rheem tankless water heaters, fed with dual 40A 240V circuits,
>> are driving all the Leviton and other brand dimmers berserk.
>> The lighting all dims and flickers beserkly. The Rheem has a
>> sharp spike at the peaks of the positive and negative cycles;
>> that is the cause.
> 
> Probably diode reverse recovery, although I don't see why they would
> care to rectify.
> 
> Is this a resistive water heater? That's very inefficient.

Tankless implies instant heating, which uses a lot of power. It is 
remarkably efficient, in that you don't waste any of the energy keeping 
the environment around storage tank warm. You'd get more heat per watt 
if you used a heat-pump, but you have to collect most of that heat from 
the environment, which is slow and call for bulky heat-exchangers.

Sharp spikes at the peaks of the positive and negative cycles doesn't 
necessarily imply diode rectifiers - if they just connected to the main 
only at the peaks of the cycles you'd get the same kind of brief current 
spike.

It's totally incompetent design - everybody should know how to do power 
factor correction - but the extra components cost money, and tankless 
water heaters are strictly from hunger.
-- 
Bill Sloman, Sydney

Thread

Ferrite ID David Lesher <wb8foz@panix.com> - 2026-09-25 15:58 +0000
  Re: Ferrite ID John R Walliker <jrwalliker@gmail.com> - 2026-09-25 17:02 +0100
  Re: Ferrite ID Bill Sloman <bill.sloman@ieee.org> - 2026-09-26 02:55 +1000
  Re: Ferrite ID john larkin <jl@htigct.com> - 2026-09-25 17:13 -0700
    Re: Ferrite ID Bill Sloman <bill.sloman@ieee.org> - 2026-09-26 16:39 +1000
      Re: Ferrite ID john larkin <jl@glen--canyon.com> - 2026-09-26 09:10 -0700
        Re: Ferrite ID Bill Sloman <bill.sloman@ieee.org> - 2026-09-27 16:32 +1000
          Re: Ferrite ID Brian Gregory <void-invalid-dead-dontuse@email.invalid> - 2026-09-28 23:30 +0100
            Re: Ferrite ID someone <2a59d59e3809f827ce709d3815e3950eef4a6a93af5557a93a7fdfba71460843@example.com> - 2026-09-29 19:15 +0000
              Re: Ferrite ID Bill Sloman <bill.sloman@ieee.org> - 2026-09-30 17:24 +1000
                Re: Ferrite ID john larkin <jl@glen--canyon.com> - 2026-09-30 07:50 -0700
                Re: Ferrite ID someone <2a59d59e3809f827ce709d3815e3950eef4a6a93af5557a93a7fdfba71460843@example.com> - 2026-09-30 20:00 +0000
        Re: Ferrite ID Bill Sloman <bill.sloman@ieee.org> - 2026-09-27 16:34 +1000
        Re: Ferrite ID someone <2a59d59e3809f827ce709d3815e3950eef4a6a93af5557a93a7fdfba71460843@example.com> - 2026-09-28 16:30 +0000
      Re: Ferrite ID someone <2a59d59e3809f827ce709d3815e3950eef4a6a93af5557a93a7fdfba71460843@example.com> - 2026-09-28 16:30 +0000
    Re: Ferrite ID someone <2a59d59e3809f827ce709d3815e3950eef4a6a93af5557a93a7fdfba71460843@example.com> - 2026-09-28 16:30 +0000
  Re: Ferrite ID Ian <devnul@blackhole.com> - 2026-09-26 11:57 +0100
    Re: Ferrite ID Bill Sloman <bill.sloman@ieee.org> - 2026-09-29 00:42 +1000
      Re: Ferrite ID Martin Rid <martin_riddle@verison.net> - 2026-09-28 11:04 -0400
        Re: Ferrite ID someone <2a59d59e3809f827ce709d3815e3950eef4a6a93af5557a93a7fdfba71460843@example.com> - 2026-10-01 04:15 +0000
      Re: Ferrite ID Ian <devnul@blackhole.com> - 2026-09-30 17:47 +0100

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