New boiler flow rate not improved

[Richard Lindsay]

Nowhere! because a shower head has to have some restriction to give "jets of water" so you will have to settle for a compromise, maybe say 9/10 LPM. You should try and source a gravity type shower head that will give you the biggest flow with the least resistance, something like 6 LPM @ 0.2 bar which will give you 9 LPM @ 0.5 bar which is the ~ differential pressure available after flowing through the boiler and shower.

I just did a test there with shower head (off my Mira Sport 9 kw electric shower) on gravity flow and I got 7 LPM @ 0.25 bar which is almost 10 LPM @ 0.5 bar so I would think that you should realistically be able to achieve that with the proper head.

Great. Should I also look at a wider bore shower hose?

 

[John.g]

Yes, a good idea, everything helps.

 

[John.g]

Actually a very good idea...
If you can get a 12mm ID hose it will almost compensate for the head loss through the shower head even if a 10mm is already fitted, should give at least 2/3 LPM more than on the 10mm hose.
https://www.amazon.co.uk/d/Showers-Shower-Parts/12mm-luxury-large-shower-1-5M/B006WLNXQ4

 

[Rob Foster]

A shower power booster from Flowflex might be good they dont tale up much space
Rob Foster aka centralheatking

 

[Richard Lindsay]

Actually a very good idea...
If you can get a 12mm ID hose it will almost compensate for the head loss through the shower head even if a 10mm is already fitted, should give at least 2/3 LPM more than on the 10mm hose.
https://www.amazon.co.uk/d/Showers-Shower-Parts/12mm-luxury-large-shower-1-5M/B006WLNXQ4

A shower power booster from Flowflex might be good they dont tale up much space
Rob Foster aka centralheatking

Thanks a lot for the suggestions.

So, I removed the little restrictor from inside the shower hose and what a difference. I had an old Mira Excel and the shower hose has an internal diameter of 11mm. Would it still be worth it going up to the 12mm?

I also noticed that one of the washers is missing and water is running down the outside of the hose. For some reason I cant find a replacement. The washer at the other end has an external diameter of 18.5mm and an internal diameter of 11mm. Every shower washer I find is smaller internally.

Cheers

 

[John.g]

What flow rate are you achieving now?

Increasing the hose from 11 mm (which seems a unusual size, my mira sport is 10 mm ID) to 12 mm should give 1 to 1.5 LPM increase, as long as the hose length is the same, normally 1.5 M.
Changing the shower head could give another 1 to 1.5 LPM or more, it depends on what you are happy with, I think any flow rate = or > 10 LPM is classed as a power shower.

You should be able to cut your own washer to fit the missing one or a plumbers providers should fix you up with something.

 

[Richard Lindsay]

What flow rate are you achieving now?

Increasing the hose from 11 mm (which seems a unusual size, my mira sport is 10 mm ID) to 12 mm should give 1 to 1.5 LPM increase, as long as the hose length is the same, normally 1.5 M.
Changing the shower head could give another 1 to 1.5 LPM or more, it depends on what you are happy with, I think any flow rate = or > 10 LPM is classed as a power shower.

You should be able to cut your own washer to fit the missing one or a plumbers providers should fix you up with something.

Cant remember the exact figure. I will check again tonight. Should I be measuring the rate at the hottest or lowest temp? or somewhere in between?

I'm probably wrong about the 11mm, its probably 10mm. I'll check again tonight.

Do you recommend a shower head?

Cheers again

 

[Rob Foster]

just get a few they are cheap enough and see which is best for you, home and bargain or
b&m are a good start chking

 

[John.g]

Cant remember the exact figure. I will check again tonight. Should I be measuring the rate at the hottest or lowest temp? or somewhere in between?

I'm probably wrong about the 11mm, its probably 10mm. I'll check again tonight.

Do you recommend a shower head?

Cheers again

Be interesting to see that flow rate now.

I would take it in fully cold/fully hot and mixer at mid point which is where it will be ~ most of the time and should give the biggest flow, for example if you had hot water at 70C mixing with cold water at 10C to give a mixed flow of 40C then theoretically at least the mixer should be at mid position to mix equal volumes of hot&cold.
It doesnt' really matter whether 10 or 11 mm as you will still get a LPM more or so if you decide to invest in a 12 mm hose.
Shower head...as per suggestion above.

Edit: Apoligies, I have a 2 meter 10 mm ID hose (ladies hair washing I believe) on the Mira Sport and I still have the original, it has a ID of 11 mm, if not 11.5 mm.

 

[Richard Lindsay]

Be interesting to see that flow rate now.

I would take it in fully cold/fully hot and mixer at mid point which is where it will be ~ most of the time and should give the biggest flow, for example if you had hot water at 70C mixing with cold water at 10C to give a mixed flow of 40C then theoretically at least the mixer should be at mid position to mix equal volumes of hot&cold.
It doesnt' really matter whether 10 or 11 mm as you will still get a LPM more or so if you decide to invest in a 12 mm hose.
Shower head...as per suggestion above.

Edit: Apoligies, I have a 2 meter 10 mm ID hose (ladies hair washing I believe) on the Mira Sport and I still have the original, it has a ID of 11 mm, if not 11.5 mm.

Ok, so fully cold I'm getting 14.4 LPM, fully hot 9 LPM and at a nice showerable temp I'm getting 11.4 LPM

Pretty happy with that but I'm going to buy a new cheap shower head and see how that goes. I'll replace the washers too.

Forgot to measure the ID of the hose last night but I'll check tonight and look to invest in a wider bore one.

What would the ideal shower hose length be?

Thanks again to everyone for all the help. I have learnt a lot.

I still have a flow issue with my bathroom sink tap (its been an issue even when I had the old boiler) but I'll start a new thread with those details.

 

[John.g]

You are getting there, the hot water side is more restrictive hence the reduced mixed flow. The shorter the hose is, the less restriction, I actually measured my original Mira hose just there and it is 1.2M, so that would seem to be a reasonable choice.