Poor flow from new shower install

[Glenn73]

I have just installed a new shower stand in place of a bidet and utilised the 15mm hot and cold pipes that were already there. I had to extend the pipes and run them up the wall. In total now there are quite a few 15mm in line valves and 90 degree turns. I think as a result the water flow is very poor.

Do you think this can be resolved by replacing these with less restrictive piping? What kind of flow eg volume per minute etc should I expect to see to know whether I am on the right tracks?

Are there any other alternatives?

 

[leakydave]

A lot of bidets use tank feeds from CWSC. What have you got: tank or mians fed hot & cold?

 

[Glenn73]

I traced the feed back and there are 22mm pipes running back to a hot water cylinder in one of the bedrooms and the cold runs to a cold water tank in the loft. Does this make sense?

 

[leakydave]

So the pressure you get at the shower is dictated by the height from shower head up to water level in the water storage cistern. This could only be a few feet, so consequently the flow will not be very good. Every metre is 0.1 bar pressure.
It might make a small differene if you remove some elbows on this run, but the better option IMHO would be to fit a shower pump.

 

[TicklyT]

Many inline valves have a small bore, and can restrict the flow, particularly when you have low water pressure. Full bore valves may help a little.

Check the shower manufacturer's spec. for the recommended minimum water pressures. some recommend 0.5 or 1 Bar minimum.

If you measure from the base of the cold tank instead of the water level, the answer will be more pessimistic than Leakydave's measurement, but allows for the water level dropping as it is used, and a bit for
losses in the pipework. this may avoid disappointment later.

Measuring that way, the water pressure you have available at the shower head may then be less than 0.1 Bar.

Some shower manufacturers supply alternative parts (shower head etc.) for low pressure gravity fed installations.

Sometimes it is possible to raise the height of the cold water storage in the loft to gain a little bit.

Even after all that, as Leakydave has already said, a pump may be a better and easier option.