DHW Flow Saga

[Ian123]

Last Year i had a 33KW Combi Boiler installed. This is meant to put out 13.5l/min
This year i have had my bathroom fitted to suit the combi boiler and do away with my electric shower.
My Boiler is only putting out 10l/min the guys who installed it were blaiming the cold water supply flow rate, when i called them back - i measured this to be 18l/min.
The hot water reduces significantly when the cold water is turned on.
I've had the water board check the pressure this 2.5bar, the house is fed in polly pipe and at the water meter he got a flow rate of 30l/min(so their side is ok)
I've changed the Stop Cock to make sure this isn't the problem.

What is the normal flow of supply water?
What flow losses would you expect between the meter and house(12l/min)?
Any other ideas, before i start looking ito the Polly Pipe?

 

[Meldrew's mate]

The hot water reduces significantly when the cold water is turned on.

Total flowrate = hot flowrate + cold flowrate

So if you get 18 l/min at the hot tap to, say, the bath, what do you get at the bath's cold tap with no hot running?
What do you get at each with both taps running?

Is there a flow restrictor on the boiler cold water inlet?

2.5 bar at what flowrate?

Lots more questions than answers so far.

MM

 

[Bamber gaspipe]

Last Year i had a 33KW Combi Boiler installed. This is meant to put out 13.5l/min
This year i have had my bathroom fitted to suit the combi boiler and do away with my electric shower.
My Boiler is only putting out 10l/min the guys who installed it were blaiming the cold water supply flow rate, when i called them back - i measured this to be 18l/min.
The hot water reduces significantly when the cold water is turned on.
I've had the water board check the pressure this 2.5bar, the house is fed in polly pipe and at the water meter he got a flow rate of 30l/min(so their side is ok)
I've changed the Stop Cock to make sure this isn't the problem.

What is the normal flow of supply water?
What flow losses would you expect between the meter and house(12l/min)?
Any other ideas, before i start looking ito the Polly Pipe?

It does what it says on the tin.

It won`t give you the flow rate at at every hot water tap all at once, read the small print.