[otsegony]

I don’t know whether you can get a completley silent unit, but I can say that our Mitsubishi heat pump does make a high pitched sound while running. Although I am used to it now, I found it annoying until I got used to it. It is very different than the intermittent low pitched rumble of my oil boiler.

[monssooon]

Thanks. Yeah I heard others say the same. And that the sound can increase as the system gets older...