unequal flow from thermostatic showers (pressurised system)

[dmm27]

Can anyone offer some advice as to whether this is supposed to happen? Or why it is happening?

We have just had 3 new showers fitted, along with a new heating/hot water system.

We have an Oso water cylinder at 2 bar. Mains pressure is 5 bar with 30l/min flow (tested by waterboard). Also a new mains supply pipe and stoptap.

Some of the showers arent as good as we expected them to be. I have measured the flow rates at the shower head (time to fill the bucket etc) and have found the following:

First shower gives 15 l/min flow with cold turned on, and 15 l/min with hold and hot turned on (this shower give a nice shower)

The second (same make as first) has 15 l/min with just cold water, but 9 with cold and hot water. Surely the flow should be the same as its a balanced system?

The other gives 10 l/min with cold only, or hot and cold. This is supposedly a better make, and according to the manufacturer, we should get 18l/min at the shower head with the pressure/flow on our system.

Kitchen sink gives 10l/min via 15mm pipe

As far as I know, all pipes are 22mm for most of the runs.

Does the system need flushing or something, or do we have faulty shower mixers, or balancign valve or something like that?

Thanks

 

[Dan Robinson]

Possibly:

stuck non return valve.

Clogged filter on shower inlets.

Service valve not fully open.

Defective shower.

 

[gas4you]

Could also depend on the distance from each shower to the balancing valve/Oso and what size pipes your installer has used.