Question about plumbing/shower

Mrsmoneypenny

My daughter has moved into a house, the guest bathroom has a shower unit over the bath.
It really is not very good.
She doesnt want the expense of a new unit.
So I did a little experiment, I got a jug and time how long it took to fill it from the shower (on the cold setting and again on the hottest setting) it took four times longer to fill than when I did the same thing using the bath taps.
So my question is, if she were to get mixer tap with a shower head to replace the existing bathtaps would the shower be any stronger?
Thanks

ormus

the pipes to the bath taps will/should be 22mm, and the ones to the shower head 15mm.
add the shower head rose restriction and theres the main difference.

MX5huggy

What type of water system does she have? ie does she have a cold water tank in the loft and a hot water tank? or just a combi, (there is a thrid option of a hot water tank but no cold water in loft but that seems unlikely).

Mrsmoneypenny

Hi
She has a hot water tank in the airing cupboard (upstairs) and a cold water tank in the loft.

Moss5

Try removing the shower rose to see if it is blocked. You could borrow the rose from the other shower for a test.
The shower mixer tap must be fed with equal pressure from hot & cold supplies. This is achieved by taking cold water from the tank, not the cold main.
The mixer must be suitable for a low-pressure supply.
If the cold tank is one metre above the shower rose, the pressure is 0.1bar. If the cold tank is 10 meters high, the pressure is 1bar. My mains pressure is 5bar.
The driving force for hot water flow is the height of the cold tank. If you have roof space, the cold tank can be mounted on a platform to increase the pressure driving the hot and cold water.
A twin-impeller pump can be introduced to increase pressure/flow rate.
If you fit a bath/shower mixer tap, the cold supply must come from the cold tank, not the mains.

property.advert

Moss5 wrote: »

..If you fit a bath/shower mixer tap, the cold supply must come from the cold tank, not the mains.[/FONT]

Not in every case. If your hot water came as mains pressure then there would be automatic / near automatic equalisation.

If out of equilibrium, one could use a pressure equalisation valve to constantly balance the pressure of the higher down to that of the lower. This would also assist if there was no thermostatic protection.

In the OP's case, equilibrium is provided as both hot and cold are fed from the same header tank QED the same pressure.

What you can find on cheaper mixing taps is that the internal machining is not accurate which has the effect of skewing the available pressure at the point of delivery.

Moss5

"In the OP's case, equilibrium is provided as both hot and cold are fed from the same header tank QED the same pressure"
Forgive me. I have not visited the property.
You have expanded the discussion to include unvented or combi-boiler systems.
The OP described a vented system.
My own house had a bath mixer fitted by a plumber(?) who had connected mains cold verses hot tank pressure. The shower had poor flow on hot only and high flow on cold only, but blending was not possible. The use a pressure equalisation valve (in my case) would have reduced the cold pressure to that of the inadequate hot pressure.
The solution (in my case) was to raise the cold tank and bring a new cold supply to the tap from the cold tank.

The previous owner had an electric shower fitted to solve the problem.