Water pressure and showers

[woodynut]

Hi all

I would like to have a shower fitted in my upstairs bathroom and I am just starting the process of seeking a plumber and getting quotes etc, but before I do................

At the moment there is a bath/shower mixer, it is only a couple of months old but it never has been very good - when I first had it fitted we could just about have a shower (not much pressure) that has dwindled to just a trickle now and having a shower is not an option.

Silly question No 1........Are all showers dependent on water pressure - even those with pumps?

Silly question No 2........What type of shower would be best for my situation

Because my knowledge of plumbing is little to non existent I am worried about being sold a system I don't need or one that is totally inadequate (as in the mixer taps)

Any pointers in the right direction would be much appreciated, thanks.

 

[echoes]

All showers work best when the water pressure is matched to the pressure they were designed for. i.e. you will get poor flow from a shower suplied by low pressure which was intended for a high pressure system.

A reduction in flow from the norm could be due to a scaled-up head, a kinked hose or some other blockage.

Before anyone can suggest an approriate shower, we need to know how the hot and cold water to your bathroom is supplied. e.g. cold mains, combi boiler, vented cylinder from a loft tank, unvented high-pressure cylinder etc etc.

A pumped shower, or a power shower with an integral pump, will boost pressure from a gravity-fed (tank) supply (0.1 - 0.5 bar typically) to between 1.5 - 3 bar, enabling you to use a shower rated at these higher pressures. Extra plumbing may be required to supply the pump with feeds direct from the cold tank and hot water cylinder, and the loft tank and cylinder will need to be adequate capacity. A pump must not be fitted to the mains water supply.

You could also choose a shower designed for low pressure - these are designed to give a good flow rate at low pressures - they won't wash you down the plug hole but will still get you wet quickly.

 

[woodynut]

Thanks for the reply.

Have no experience with plumbing at all so I don't know the techie terms!

There is a large storage tank in the loft on a raised platform with a small tank next to it.

There is a cylinder with immersion heater in the airing cupboard.

How would i tell if the bath cold tap was mains fed or tank fed?
There seems to be quite good pressure at bathroom sink and en-suite sink but it appears that the pressure is less at the bath taps (could be just an illusion as its a mixer)

 

[echoes]

From what you say, it sounds like standard low-pressure gravity fed hot and cold water to your bathroom.
And I would guess that the bath/shower mixer is not suitable for low pressure, hence the poor flow.

(Don't confuse flow with pressure - you might get loads of flow from your taps, but if you can shut the flow off with your thumb over the spout it's low pressure - you wouldn't be able to do that with mains pressure!).

If you close your mains water stop-cock (so that the kitchen cold tap stops), any taps that still work will be tank fed.

That being the case, then without major and expensive works upgrading your hot water system, and epending on whether you want a gentle drenching or a pressurised blast:

a) low pressure shower mixer & head.
b) pump would give you a very decent shower - you might even be able to keep the existing mixer. Or opt for a separate shower mixer - decent theromstatic ones are very good at keeping the temperature stable, (though that is not normally an issue with pumped H & C feeds done correctly).

There are also venturi showers which run off cold mains and low-pressure hot that give a decent pressure shower, with the advantage that there are no noisy and possibly troublesome pumps.

When considering showers, I consider 10 litres/minutes flow rate as a 'decent' minimum. But remember: the higher the flow, the quicker you will use up your hot water. (20 L/min shower will use up a 120L cyl of hot water in about 6 mins.)

 

[woodynut]

Thanks so much for your help, at least I will know vaguely what someone might be talking about when i start getting some quotes!

Final couple of questions if I may.

Out of interest, with a shower pump, does it pump the cold or hot water or both?

Is it likely to cost an arm, leg or both?

 

[echoes]

A shower pump can pump both hot and cold water, and this is the preferred type. They require a dedicated cold feed from the tank, and a dedicated hot feed from the cylinder, preferably via an Essex flange (a cylinder connection which delivers air-free water to the pump).

The pumps themselves cost from about £150+. Best to avoid the cheaper (£100) end. Stuart Turner are a respected make.

As for mixer valves, riser rails - anything from £60 - £300 depending on quality and I-saw-you-coming factor.

I can't help with labour costs, since it would depend on what plumbing was required, how easy the pipe runs are etc. and perhaps an electric supply for the pump. And I'm not a plumber...

 

[woodynut]

Thanks for your help, all the best!

 

[echoes]

No problem - happy showering!