Fitting a second shower pump?

[Tommy48]

I have a positive system - tank in attic, bathroom upstairs, hot water cylinder downstairs in utility room. Bathroom has separate shower with dedicated Watermill Wasp 66 dual impeller pump. Surrey flange fitted to H/W Cylinder with this supply dedicated to the bathroom. Everything has been working well for a year. The pump does change tune as the hot water comes through. It is not running 'dry' and I think this must be something to do with air in the hot water. If I run the bath tap until hot before turning on the shower, the time until hot water comes out of the shower is reduced and the change of tune is that much sooner. I wonder if fitting a check valve would have any effect. I am certain the pump is not running without any water at any stage.
I now want to fit an additional shower room at the opposite end of the house. I am told I cannot run 2 shower pumps from the same supplies because one will dominate and starve the other. It is impractical - without very major disruption to new carpets and old planks now covered with ply etc.... - to alter the supply to upstairs. I had laid pipes in anticipation of this new shower room before I was told I could not fit 2 pumps.
My plan is to have a house rule that only one shower can be used at a time! and to fit check valves onto all pipes to the pumps in an effort to ensure they don't run dry.
Does anyone have any suggestions how this could be improved on.
Have thought about fitting a single impeller pump at the H/W Cylinder and single impeller pumps to the cold supply to each shower but I would still have the pumps fighting each other. Suppose I had a single impeller for the hot supply and no pumps for the cold supplies - would that work or would I end up with two rather hopeless showers?
As usual, I should have thought things through more carefully when I installed the first bathroom!

 

[Best]

You can use one pump to do 2 or more showers.
Just need a dual pump capable of doing the job - a whole house pump, but just feed the showers. Pressure supplied from the pump doesn't need any more than about 3 bar usually.
A negative head pump sometimes is needed even if you have positive head if the pipework is raised over an attic for example, or if your second shower valve was to a too high position.
The noise your pump makes may indicate the hot water in cylinder is too high & a blending valve might be one answer.

 

[Best]

Forgot to add, - Stuart & Turner are great pumps IMO.

Also, don't use check valves on any pipework. All pipework needs full flow & only valves fitted should be lever valves on the hot & cold supply to pump. Pipes need proper size etc. If you are not a plumber, get an expert to do it & preferably in copper.

 

[Pumpman6]

Hi, lots of questions to answer here. Airated hot water excessive temp does cause more noise than un-airates or cold water. What flange have you got / how is it connected to pump (errors are made connecting them up the wrong way round somtimes) Never fit a NRV on the supply pipe to a pump as this will cure nothing and possibly cause problems.

As 'best' is suggesting 1 good quality negative head pump fitted correctly will give you what you want. The Stuart Turner Monsoon universal pump should fit the bill. Size 2.0 bar 3.0 bar etc will depend on your requirments V's shower requirments.

Hope this is of help.