Why shower flow rate lower than bath?
Discussion
Just moved into a new house, and it has a Grants V90 combi boiler. The mains water flow rate aint fantastic but its workable. In the downstairs bathroom, I have a separate walkin shower and bath. In the bath, the cold water tap takes 10 seconds to fill a 3litre jug, hence 18 litre/min flow rate, and for the hot water, the flow rate reduces such that it takes 15secs to fill the jug (12 litre/min). It is expected for hot water to flow slower than cold, as presumably its the ability of the boiler to pass the heat quick enough.
However, in the shower, which is right next to the bath, it takes 23secs to fill the 3L jug, hence only 8 litre/min flow rate. Why is the rate so much slower via the shower? I'd have thought they' be feeding off the same pipework as the bath?
However, in the shower, which is right next to the bath, it takes 23secs to fill the 3L jug, hence only 8 litre/min flow rate. Why is the rate so much slower via the shower? I'd have thought they' be feeding off the same pipework as the bath?
Busterbulldog said:
remove the flow restrictors
Ah. Is that something that people install to save water? Where are they installed, and why would they be put only on the shower and not the bath?ETA - a quick 60sec google on flow restrictors suggests that they are in the shower head, but I removed the shower head to perform the test.
Edited by kryten22uk on Friday 17th January 22:30
barryrs said:
It's a building regs requirement these days.
The developer has to provide water usage calcs demonstrating a max 125 litres per person per day IIRC.
A bath will use the same amount of water regardless of the flow rate whereas showers are restricted to around 7 litres a minute.
So how do they achieve the restricted flow, and how do I undo it? The developer has to provide water usage calcs demonstrating a max 125 litres per person per day IIRC.
A bath will use the same amount of water regardless of the flow rate whereas showers are restricted to around 7 litres a minute.
BTW this isnt a new house, but I presume that the plumber who did the bathroom (relatively recently) just applied new regs anyway.
Do you not just unscrew the shower head and remove it?
http://www.showerstore.com/support/water-pressure....
http://www.showerstore.com/support/water-pressure....
It's a combination of losses from the valve, bends, pipe diameters, shower heads, restrictions etc
I recently did some research into a grove digital shower mixer for a customer, and they have advised that a 2 bar pressure to the valve will result in approx 12.2litres p/m from a 310mm ceiling rose, but approx 20lktres per minute at the valve.
Also the diameter of the pipe is important, 22mm pipes allow something like 4 times more flow than a 15mm pipe!
In my experience the BEST shower on the market to give you the best possible shower is a Mira excel, it's amazing how much variation you get from exactly the same supply with an array of different showers!
I recently did some research into a grove digital shower mixer for a customer, and they have advised that a 2 bar pressure to the valve will result in approx 12.2litres p/m from a 310mm ceiling rose, but approx 20lktres per minute at the valve.
Also the diameter of the pipe is important, 22mm pipes allow something like 4 times more flow than a 15mm pipe!
In my experience the BEST shower on the market to give you the best possible shower is a Mira excel, it's amazing how much variation you get from exactly the same supply with an array of different showers!
check for any isolating valves leading to shower, I think these reduce the flow somewhat, and fit a compression socket instead.
worth a try, I have same problem and there is an isolating valve for the shower feed sowill be removing that to see if any difference. both taps and shower for me are fed in 15mm
worth a try, I have same problem and there is an isolating valve for the shower feed sowill be removing that to see if any difference. both taps and shower for me are fed in 15mm
Bath piped in 22mm pipe, shower 15mm typically.
Bath taps are quite free flowing.
Shower valves, thermostatic, will be quite restrictive.
What is the max hot water flow rate of the combi??
Restrictions on the shower feed pipes? Non full bore isolators inline.
Flow restrictors supplied with the shower valve. Typically located either where the shower feeds enter the unit, or where the hose attaches to the shower valve. Often fitted by standard. So maybe not removed.
Bath taps are quite free flowing.
Shower valves, thermostatic, will be quite restrictive.
What is the max hot water flow rate of the combi??
Restrictions on the shower feed pipes? Non full bore isolators inline.
Flow restrictors supplied with the shower valve. Typically located either where the shower feeds enter the unit, or where the hose attaches to the shower valve. Often fitted by standard. So maybe not removed.
The shower mixer is an exposed unit but all the pipe worke is in the wall and then probably under the tiled floor, so cant access it to see what size pipe or whether any restrictors/valves. The mixer unit feeds the shower rose by a fixed/rigid pipe rather than a hose, so cant really undo that to look if there is anything immediately in the mixer outlet.
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