Noisy drying cycles

I have a hopoint fdd9640 washer dryer. It washes OK no problems but when on any drying cycle it makes a start stop noise every few seconds from the powder/liquid tray. I can hear it a little upstairs pulling on the pipes as though a tap has been opened but the noise from the machine is loud. The item was only delivered yesterday so it is still brand new. Hotpoint say that the noise is normal and it is the machine sending out a jet of water to keep cleaning the machine of fluff however this is my 4th washer dryer and never have I had this kind of issue before. I don't believe it is a water pressure issue however I have turned the pressure down to test it and it makes no difference. Can you please provide any advice? The stop/start noise is really annoying and lasts as long as the drying cycle.