Reduced pressure in replacement mixer bath taps - why??

[witney1]

Replacement bath now fitted and Twyfords QB mixer tap fitted but flow is so slow it will take ages to fill - hot will be cold before full!

Previous mixer tap unknown quality make but have lasted at least 18 years produced good flow.

Cold is gravity fed from loft space with 2 m head hot is gravity from hot tank with 1m head

Have used pushfit connectors to minimise any loss of flow through flexiconnectors.

Why does the outflow pipe appear to be considerably less than the 22mm inflow - is that correct?

Should i ditch the mixer and replace with single taps?

Any ideas please -

Many thanks

Roger

 

[jono44]

You've probably used a valve which requires a higher pressure- ie: min 1 bar. You'll need to use taps that are suited to lo pressure.

 

[witney1]

Yes after much trawling round found taps from Roper Rhodes specifically for low pressure - taps now changed to min 0.1bar. However there is little improvement in the flow rate. Is the only option to install a pump on th ehot and feed cold from the main?

 

[johnmcginty]

Is there any chance you can increase the height from your cwsc to your cylinder?

 

[Avatar]

You must have changed something - if the orininal pipework was 22mm copper then replace as like. Also only full bore iso valves.

If you make it like this then there is no chance the pipework is to blame.

Push fit inner dimensions are reduced, just not as much as flexi . . .

 

[Puddle]

maybe you have partial air locked pipework after re-enstating water supply to taps
had this a few times over the years