Weak shower pressure

[AP77]

I recently replaced my Mum's very basic shower but have noticed the water pressure from the new shower seems quite low.

She lives in a bungalow, the cold is supplied from a tank in the loft, the hot is supplied from a hot water cylinder in the airing cupboard which goes into the loft and back down into the bathroom.

The original pipework was 22mm and I had to reduce this to 15mm for the new shower. The reduction from 22mm to 15mm is only for about the last 2 or 3 feet before the pipework enters the shower.

Would changing from 22mm to 15mm make much difference to the pressure?

The new showerhead has a very fine spray so am wondering if a different head with larger holes may help?

Appreciate that fitting a pump or electric shower would help but don't really want to do that as my Mum thinks the old similar style shower was more powerful.

Many thanks.

 

[terryplumb]

Firstly ,is the new shower suitable for a low pressure gravity plumbing system .in a bungalow you are unikely to have more than 0.2 bar pressure at the shower head and possibly less ?

 

[AP77]

Thanks for replying.

It's a very basic single lever mixer shower. I think it is a Triton Kaho from Screwfix which says min operating pressure is 0.1 bar

 

[pete50]

I live in a bungalow and had a similar setup. Reducing that couple of feet pipe diameter will, almost certainly, be the reason why the pressure has dropped. Even as it was previously the pressure would have been pretty dismal and if you have fitted a ceramic temperature controlled shower there will not be enough pressure to push the water through the cartridge. That was the problem I had and I found the only solution was to fit a pump. Now my shower nearly takes my skin off which is just the way I like it.

Ah thats an electric shower. They are pretty much rubbish at the best of times but I would think the larger pipe is the culprit.

 

[terryplumb]

.not electric Pete. Think you have a triton Kaho. Which is supposed to deliver 4.9 litres per minute at 0.1 bar. I assume the old shower had 22mm straight into the mixer and the new one has 15 . if so the old one would have given a better performance.

 

[AP77]

Thank you.

The new shower is definitely not electric. It's described as 'Manual single lever mixer shower'.

I don't think the previous shower had much pressure so it's hard to say how much less powerful (if at all) the new one is. Water does come through but it seems quite gentle.

 

[AP77]

Yes, sorry for they typo it's Triton Kaho

I still have 22mm feeds from the loft (about 20 feet distance) it's just the last couple of feet that go into the back of the mixer that I have changed to 15mm. Would that make that much difference to the pressure?

Thanks.

 

[terryplumb]

You could run it for one minute into a bucket ,then measure how many litres are there. If its 5 litres ,or there abouts , ,that's what it says it will do. If its considerably less ,you could check the filters are not blocked .you have used copper pipe haven't you ,as plastic has a much smaller inner bore ,and would further hinder the flow rate.

 

[AP77]

Thanks terryplumb, really appreciate the suggestions. I will do the bucket test next week when I visit my Mum again.

I did use copper pipe so that should be fine. I did run the water supply through the pipes before connecting to the mixer so should be no blockages. I don't recall any filters so will check the instructions again.

I am thinking now that as the pressure from the old shower was already weak, changing from 22mm to 15mm is likely to have the pressure about 25% less. So to improve it a small pump may be needed.

 

[terryplumb]

Not likely to be that high ,was old valve ,22 mm straight into the valve ??

 

[AP77]

Thanks, just to clarify, are you suggesting loss of pressure by changing last couple of feet from 22 to 15 is likely to be less than 25%?

Yes, the old old valve required 22mm feed. When looking for a new shower I struggled to find any valves that took 22mm pipe so went for a cheap 15mm valve.

 

[terryplumb]

Pressure and flow rate are two different things. You have the same pressure in your 22 mm as you do in the 15 mm ,but 22 will give you a better flow as will the old valve that was designed to take it . you are not comparing like with like. Old valve ( internally ) would most probably be offering less resistance to flow than the new one ,hence their designer specs it to take in 22 mm pipe. By introducing a new valve ,which by design takes 15 mm feeds ,straight away puts you at a disadvantage as you have to reduce from 22 to 15. Even if you only had a short length of 15 to each side of the valve the performance would be little difference . a shower pump would give you a dramatic improvement. The filters I refer to are in the shower valve inlets by the way.

 

[AP77]

Excellent, many thanks for explaining. I will check the filters. I guess going back to a 22mm valve is one option (assuming I can find one) for a small improvement but a better bet would be to fit a pump for a significant improvement.