It shouldn't be, if the installer has commissioned the appliance properly then it's gas rated under actual use, at max rate. That and the gas rate isn't marked to 3 decimal points so that figure would suggest he has done it properly but never say never.
Are you talking about the gas pipe or the water pipe? I presume the water pipe? Always a possibility but 28mm water pipe is rarely used in a domestic setting and only if the loading units/pipe sizing exercise calls for it. It would be a very big house with a fair number of outlets to call for anything larger than a 22mm distribution pipe. Sometimes 28mm would sometimes be used from the CWSC to the HW cylinder, again if the demand called for it but that would usually be to multiple gravity fed bathrooms.
Are you talking about the gas pipe or the water pipe? I presume the water pipe? Always a possibility but 28mm water pipe is rarely used in a domestic setting and only if the loading units/pipe sizing exercise calls for it. It would be a very big house with a fair number of outlets to call for anything larger than a 22mm distribution pipe. Sometimes 28mm would sometimes be used from the CWSC to the HW cylinder, again if the demand called for it but that would usually be to multiple gravity fed bathrooms.
Agreed but it's possible. I have a shower room maybe 7m from my combi. I run the hot in 10mm buteline. The pressure is good and surprisingly hot water is very quick. I need to do the same with my kitchen sink.
It all comes down to demand and water velocity. Water pipe sizing and standards dictate that to minimise noise and wear on pipe and fittings (friction), reduce the possibility of water hammer and minimise pipe movement then ideally water velocity should be kept between 1>2m/s in normal 22/15mm service pipework. The larger the pipe used then slower the velocity to deliver the required amount of volume. This is an often ignored or unknown principle which is learnt during level 3 advanced hot and cold water work.
Of course 10mm supply pipework can be used if the design principles can be met and yes it minimises HW delivery times and HW use (lower volume pipe) and if the outlet can be satisfied by 10mm pipework then no reason not to use it. Wouldn't be any use on a shower that delivers 15>20L/Min or a bath outlet that is full flow though I wouldn't think.
Certainly agree there is much more focus on water saving and low output outlets these days and the standards may change to suit but the fluid principles won't.
Unfortunately though none of this addresses the OP's issues I don't think.
It shouldn't be, if the installer has commissioned the appliance properly then it's gas rated under actual use, at max rate. That and the gas rate isn't marked to 3 decimal points so that figure would suggest he has done it properly but never say never.
He made excuses for fitting plastic pipework, promised the plastic elbow was 15mm (I'm sure it's a 15mm fitment, I'm more concerned about the internal diameter) and turned up the water pressure on the whole house.
I have insane pressure from the cold tap but a little higher than it was on the hot... I think... Still that pressure is being restricted somewhere.
I spoke to Viessmann who said there is a static limiting valve inside the boiler, eg: not variable/responsive.
That's all I know for now. Still don't have anywhere near mains pressure hot water.
When I read all this thread it makes me think that the boiler has been selected without having made any measurements of the dynamic flow rate available from the water supply mains.
Simply, to operate a shower head you need to have a residual pressure in the supply pipe of say 0.5 bar to ensure the water exits the shower head small holes at a high velocity to give that tingly feeling on the body.
If the supply cannot deliver say 15 litres per minute dynamic flow rate the performance will fail to deliver the full capabilities available from the boiler.
When I read all this thread it makes me think that the boiler has been selected without having made any measurements of the dynamic flow rate available from the water supply mains.
Simply, to operate a shower head you need to have a residual pressure in the supply pipe of say 0.5 bar to ensure the water exits the shower head small holes at a high velocity to give that tingly feeling on the body.
If the supply cannot deliver say 15 litres per minute dynamic flow rate the performance will fail to deliver the full capabilities available from the boiler.
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