Mine uses a sensor on the water pipe. When the water flows, it runs until the
temperature rises, reducing the cold water before it's hot. It has an option
for a touch panel to touch to activate it before you turn on the faucet.
I think it's these sensors.
On December 22, 2025 12:43:17 AM EST, "Dave (NK7Z)" <dave@nk7z.net> wrote:
>Hi,
>
>Thanks to all that replied... I am creating a check sheet for this... I do
>not want to miss a suggestion.
>
>
>73, and thanks,
>Dave (NK7Z)
>https://www.nk7z.net
>ARRL Volunteer Examiner
>ARRL Technical Specialist, RFI
>ARRL Asst. Director, NW Division, Technical Resources
>
>Random Quote of the day:
>Government is not reason; it is not eloquent; it is force. Like fire, it is a
>dangerous servant and a fearful master.
>George Washington
>
>On 12/21/25 17:55, Michael Carter via RFI wrote:
>>
>> Did reply directly to Dave NK7Z by mistake, omitting the reflector.
>>
>> Sorry, and 73,
>> Mike, K8CN
>> ________________________________
>> From: Michael Carter <Mike.Carter@unh.edu>
>> Sent: Sunday, December 21, 2025 8:23 PM
>> To: Dave (NK7Z) <dave@nk7z.net>
>> Subject: Re: [RFI] Odd RFI case I'm working on...
>>
>> Hi Dave,
>>
>> Put large clamp-on ferrites on the flex tubing hoses at the hot water inlet
>> and cold water outlet ports of the pump. Even if those pipes are
>> 'grounded', the impedance presented to any RF currents on the pipe exterior
>> surface may be inductive and high, which negates the value of the
>> 'grounding'.
>>
>> Does the pump RFI occur on all HF bands or just a few? That is another clue.
>>
>> Does the house have PVC plumbing, copper plumbing, or a mix of the two?
>>
>> You've done all the obvious electrical fixes, albeit temporary in some
>> aspects, and the fact that RFI persists even at reduced power levels
>> suggests to me the RF ingress is via the water lines. If adding choking
>> impedance on the AC supply cord (i.e. , multiple turns of the cord on a
>> large toroid) doesn't fix the RF ingress, I would look at the cold and hot
>> water feeds.
>>
>> Before doing that work, I would set the clock timer (if this older unit has
>> one) so that the pump controller is disabled. Test for RFI in that state -
>> if the pump is not kicked on by external RF, then I'll be more convinced the
>> RF ingress is via the water lines themselves, specifically RF currents on
>> the exterior surfaces of conductive pipes (or the metal braid sheathing on
>> flex plastic hoses).
>>
>> 73,
>> Mike, K8CN
>> ________________________________
>> From: RFI <rfi-bounces+mike.carter=unh.edu@contesting.com> on behalf of Dave
>> (NK7Z) <dave@nk7z.net>
>> Sent: Sunday, December 21, 2025 7:09 PM
>> To: RFI Mail list at contesting.com <rfi@contesting.com>
>> Subject: [RFI] Odd RFI case I'm working on...
>>
>> CAUTION: This email originated from outside of the University System. Do not
>> click links or open attachments unless you recognize the sender and know the
>> content is safe.
>>
>>
>> Hello RFI group,
>>
>> I have an RFI case I am working on right now, that has stumped me
>> completely...
>>
>> A fellow Amateur has an Laing under sink recirculation pump model
>> ACT-303-BTW. Every time he transmits, the pump kicks in. The following
>> steps have been tried.
>>
>> 1. A Pile of clamp on ferrites have been added to the short power cord,
>> maybe 5 of them. No room yet to wind on an FT250-31, but that may be next.
>>
>> 2. The water piles have been connected to ground, using a car jumper
>> cable. The person who put this on tells me he used the ground on a
>> outlet... Yes, we will test differently with a real ground at some
>> point soon.
>>
>> 3. He has reduced power to 50 watts and the pump still kicks in.
>>
>> 4. He has wrapped the pump in foil, and grounded the foil. Again, I am
>> sure via the outlet ground.
>>
>> 5. His dipole, which is close to the home, has a quality Balun Design
>> choke on it at the feedpoint.
>>
>> 6. The coax has been rerouted to as far as possible from the device as
>> possible, running on the ground as a test.
>>
>> The device is an older one, and sits under the sink. The ham is not
>> sure if his cold water pipes are at actual ground.
>>
>> I intend to do the following:
>>
>> 1. Use a real ground, if needed to ground the cold water pipes to the
>> service ground then bond to the pipes at the pump.
>>
>> 2. Replace the power cord with a longer version, and wrap 12 turns of
>> AC line cord in an FT240-31, and/or add an external RF filter to the AC
>> line.
>>
>> 3. Reduce power further to try and pin down where the RF is getting in,
>> pipes, or power line by isolation.
>>
>> Purchase a good RF filter for the AC line. Can someone suggest an OTS
>> one I can recommend? He operates 80-10 Meters...
>>
>> Any other ideas?????
>>
>> 73, and thanks,
>> Dave (NK7Z)
>> https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.nk7z.net%2F&data=05%7C02%7Cmike.carter%40unh.edu%7C36fb5e00cd924dbf49c408de40ee6485%7Cd6241893512d46dc8d2bbe47e25f5666%7C0%7C0%7C639019589934679414%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=YHQggWl%2BwFAgA3cVnroHr4EklzVEn08KL3ASOtlKBEo%3D&reserved=0<https://www.nk7z.net/>
>> ARRL Volunteer Examiner
>> ARRL Technical Specialist, RFI
>> ARRL Asst. Director, NW Division, Technical Resources
>>
>> Random Quote of the day:
>> We are dominated by the relatively small number of persons who
>> understand the mental processes and social patterns of the masses. It is
>> they who pull the wires which control the public mind.
>> Edward Bernays
>>
>>
>>
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