Low pressure taps

[masona]

I have been looking at the Grohe Eurosmart bath taps and stated recommended pressure 0.2-5.0 bar

My head of water is approximately 2.1m and I understand 1m = 0.1 bar therefore my hot water pressure is 0.2 bar, so the Grohe taps is right on the bare minimum, so in theory I shouldn't have any problem with the flow?

 

[Armo74]

The flowrate will be determined by the pipe diametre and the amount of other resistance in the pipework like elbows, tee's, isolator's etc.

The pressure will remain the same unless you increase the height of the head of water.

Ideally you need full bore isolator's on gravity hot water.

 

[masona]

That make sense, so the pressure always the same but to increase flow rate is a bigger dia pipe such as 22mm instead of 15mm pipe on the hot water supply gravity system?

 

[Burnerman]

The larger pipe diameter will compensate to some degree for the lack of water head and the amount of bends that the pipe has.....and its best to reduce to 15mm for the minimum of pipe run, if you see what I mean.
The length of the pipe run is also a factor - but you should get away with it (he says, snug behind a lap top )
John

 

[masona]

have a 25 Gall (114 litres) cold water storage tank, at present I'm getting 1.8m head of water = 0.18 bar. I can raise the tank approximately 250mm which will give me 2m head of water = 0.2 bar, can also raise it in a difference position to the right side, more work but not impossible another .800mm which will give me 2.6m head of water = 0.26 bar.

I'm guessing a bigger storage tank will always be the same pressure?

Is there a big difference between 0.18 bar and 0.2 bar or 0.18 to 0.26 bar?

Untitled

• masona
• 11 Feb 2013
• 1

I have also noticed there is a 15mm Straight Isolating Valve (see photo) if I change that to straight compression coupling, would that also help to increase type hot side flow as I'm thinking the 15mm Straight Isolating Valve is restricting the flow being a smaller dia or is it more to do with water pressure rather than restricted dia?

Untitled

• masona
• 11 Feb 2013
• 1

 

[Armo74]

Your taps require a minimum pressure of 0.2 bar so you need 2m head minimum any more is obviously a bonus.

The isolation valve is obviously there for a reason replacing it with a straight compression fitting could cause some inconvenience due to no longer being able to isolate the supply to whatever pipework/drawoff the isolation valve is attached.

You can get full bore isolation valves from screwfix.

15mm, product no 46860 £4.49

22mm, product no 43961 £6.99

That will reduce resistance and aid flowrate.

 

[masona]

Thanks!

At the moment I've approx 1.8 m head of water according to convert bar to pound per square inch it's 2.61 psi


If I put the cold water storage tank highest I can go, the head of water will 2.6m which is .26 bar with 3.77 psi

I have no idea about water pressure in psi but looking at the difference between 2.61 psi and 3.77 psi, a difference of 1.16 psi more pressure, I'm wondering if this would be a noticeable difference?

Wouldn't be a problem for me to move the tank higher so might be worth doing?

Convert bar to pound per square inch
0.18 bar = 2.61 pounds per square inch
0.2 bar = 2.9 pounds per square inch
0.26 bar = 3.77 pounds per square inch

 

[Charnwood]

1 bar or a 10 metre head equals roughly 14.5 psi.