Shower pump versus unvented pressurised hot water tank?!

[greg r]

apparently my new bath mixer tap requires 3-5 bar to work. i fitted it and the cold flows ok(ish), as soon as i even slightly turn to open the hot value the flow is reduced to a dribble, i assume the cold it being sucked back up and the hot pressure is poor?
I therefore added a 2 bar shower pump which had little if no effect so removed and returned it...

Is my only option to now have a unvented pressurised hot water tank fitted? Im happy to invest by only if it is guaranteed to work!

 

[Corgigrouch]

I would say that the mixer valve is duff and needs stripping down or the imbalance in the pressure between hot and cold is causing the cold to flow up the hot pipework.. Are you trying to pump the cold water directly off the mains and hot out of the cylinder?

If you go unvented, then the best that you could hope for would be 3 bar, assuming your mains gives you even that...

 

[greg r]

i added the pump to the hot water feed only.
my current setup is a gravity fed hot water and cold straight off the mains

 

[Corgigrouch]

What's the pressure of the incoming main?

 

[greg r]

i need to get a guage to measure it, but based on the fact that when the mixer is 100% on cold the the flow rate is OK on the new tap

 

[Corgigrouch]

But if you have a pressure imbalance, then the cold will force its way out wherever it can, some will come out of the outlet, some of it will force its way up the hot pipe when you are trying to mix hot with cold.... Was this an ebay jobbie?

 

[greg r]

So referring back to the original question will a unvented tank do the job?

 

[Corgigrouch]

Maybe, assuming that the mixer tap is working as it should.

 

[Madrab]

Usually, people fit a tap to suit the system, much cheaper than installing a new system to fit the tap... Easier to buy a new tap methinks...