flow rate

[bomberns127]

my plumber came round last night and measured the mains flow to my outside tap, its getting approx 10 litres a min, he says this is fine for a combi, he measured the flow to the makeshift kitchen as its going through an undersink water heater which is using 8/10 mm flexi pipe to the tap he said it was getting approx 8 litre a min.

my question is, if a 24kw boiler gives 11 litres min a minute how can the mains keep up? i had a regular boiler for years until the kitchen rebuild, every plumber i have spoken to suggests a combi but last night was the first time 1 showed up with a measuring cup, it seems thats the only measuing device he has for doing this.

is a combi ok?

we have to my knowledge never had a problem with mains pressure and i have lived here since the 80's

 

[bomberns127]

i have just used a brewing fermenter with litres marked on the side, outside tap gives me 9 litres a minute, what will this tell me, combi or regular or even a system boiler? plumber said 8 litres and above ok for combi, do you think 9 litres a bit low?

 

[Dan Robinson]

A combi is fine if you are happy with that level of performance.

Personally I wouldn't be.

However, the get better may cost a lot more when you factor in tanks, pumps or accumulators.


Also, don't confuse pressure and flow.

 

[bolshy]

9 litres/min is poor flow for cold mains. However, a combi only needs 2-3 litres/min to fire up. Modern combi boilers modulate to match demand. If you don't mind waiting 10 - 15 mins to fill your bath then you should be fine. A thermostatic mixer shower will probably struggle a bit at your flow rate.

 

[bomberns127]

i have an electric shower, seems the washing machine, dishwasher is always on during the evening and everytime i want to shower one of the kids(adults) are in there! lol
what do you mean modulate? the boiler waits till it has enough water to supply? it has a mini tank inside?
i got to ask because i like to know how things work
apologies if its a dumb question......

 

[bomberns127]

i have contacted the local water company about the flow, seems that my supply is via a lead pipe which over the years has narrowed affecting my supply, i can get the pipe changed from lead to plastic from the road to the stopcock then it seems the supply problem will be solved, they will for free change it from my boundary to the valve under the pavement, i on the other hand will have to pay to replace from the boundary to my stopcock, is it worth doing to up the flow rate or just put in a regular boiler? the pipework in is 30 years plus so needs to be changed,seems im gonna have all pipework to and in my house replaced.