Installation manual

10.3. Noise

Noise is not normally an issue. Our turbines are normally quieter than others as they turn

slower and are fully enclosed. Hence if noise is an issue at your site you should check the

following:

 The runner is not hitting the jets, it has been packed out correctly and packer

washers have not been missed out

 The magnetic rotor turns freely, you have not picked up magnetic debris on the

magnets when putting it together

 The bearings have been greased correctly as per the manual

 The bearings are in good condition (likely the cause if noise has increased gradually

over time)

 The unit is running at the correct speed. Incorrect speed can be caused by clients

installing jets that are too large for the generator power rating resulting in excessive

RPM. If you have MPPT regulation with no diversion load fitted then the turbine will

speed up and the noise will increase when the batteries are full.

 The noise is not related to how the turbine has been mounted. A heavy timber or

concrete base will be quieter than steel/aluminium framed base.

 The line is free from air. Compressed air expansions at the jet are very noisy

See Section 19 for some noise data. We have not taken extensive noise level readings, as

all hydro sites are different and it does not seem to be an issue. That said, some clients have

installed turbines too close to their homes.

Generally the higher the head the more noise from the unit. At our test site at 160m head

and 1.6 kW you can talk normally standing by the turbine, but you are very aware it is there.

You can just hear it at 30-40m away. It sounds like a washing machine in spin. If allowed to

free spin unloaded the noise can travel 200-300m.

On low head sites less than 10m (30ft) the river is likely to make more noise than the turbine.

A turbine can be closer to a dwelling in such cases.

Vegetation around the turbine will dramatically reduce the distance that noise carries.