Electrical noise from Salus RT520TX

21 Jul 2010
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United Kingdom
Just had a new combi boiler fitted for heating & HW. Plumber supplied a wireless (battery-powered) Salus RT520TX thermostat / controller.

The wireless stat is emitting a very high-pitched electrical-type whining noise (a bit like you hear from a plugged-in phone charger when no phone is connected) every time the LCD display is lit.

I also accidentally entered the "test" menu and had it run through that cycle (whatever that does!), and the noise was even more apparent.

Has anyone else experienced this noise with a Salus or other wireless stat? Should I be worried?
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Get your installer back, and if he doesn't know what it is, he should contact Salus.
This is common, I'm pretty sure that they all do it, but as you say only when any of the buttons are pressed that causes the display to illuminate.
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It's the driver that drives the back light - there's nothing the installer can realistically do about it, 'cept put in a different brand

(Edit - I have a Time Guard unit, which also whistles. Have beside clock which also does it when the back light is energised too)

Last edited:
Great, thanks for the replies. I won't worry too much about it in that case.

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