Water pressure loss

[Ssan diy]

Hi can anyone help i fitted my new bathroom few weeks ago the bathroom was all done in 22 mm pipe i took it all back to the feed coming into the room and redone the room in 15mm but since this my hot water pressure in my kitchen which was fine before is now low
The feed to the bathroom comes straight from boiler and then from bathroom to kitchen

 

[Madrab]

If you drop the pipe size feeding the kitchen then it's entirely possible that the flow would be reduced. The pressure would probably be the same though

Any reason why you didn't keep it at 22mm?

 

[Bodd]

It depends on what system you have.
Gravity: 22mm + is always best
Unvented: 15mm should be fine
Combi boiler: then 15mm is better than 22mm

 

[Ssan diy]

Yeah this my thought small pipe more pressure Ive got combi boiler

 

[Ssan diy]

Pipes were in the wrong place so moved them
N then just used 15mm

 

[Bodd]

Future combi boiler Installations ( Where possible) I will run 10mm pipe hot from a manifold to the sink and basins. Showers (10/10)??? not sure
Bath 15mm.

 

[terryplumb]

Yeah this my thought small pipe more pressure Ive got combi boiler

Doesn't work like that . Pressure is the same ,but flow rate is reduced by using smaller bore pipework.

 

[terryplumb]

If your hot water is under mains pressure from a combi boiler ,and your kitchen hot water tap is giving less flow it's possibly restricted. The hot distribution pipe from the boiler is 15 mm copper ,have you used 15mm plastic when re plumbing ?
If so that has smaller bore diameter and further restrictions with the pipe stiffeners.

 

[Madrab]

Doesn't work like that . Pressure is the same ,but flow rate is reduced by using smaller bore pipework.

Exactly ...... spot on That and friction will be higher at every turn.

Do you know what your dynamic pressure is, it may be quite low, therefore there isn't enough dynamic pressure to sustain the same flow through 15mm pipe as there was in the 22mm pipe.

If dynamic pressure is quite good then system tend to get noisier as the velocity through 15mm is higher that design spec.