I am helping a friend install a Glow-worm 30 cxi gas boiler. He lives i
France but bought the boiler in the UK. It is intended to use the syste without a hot water cylinder and we have concerns about the possibl reduction in flow rate as more hot water taps are turned on. We woul like to run 22mm pipe from the hot water outlet on the boiler but a the inlet is only 15mm this may prove fruitless. Does anyone know ho we could provide a steady flow rate of hot water with this boiler
-- cjevans4u
It's worse than fruitless -- it will just cause you to run off more cold water before the hot comes through, and you'll end up wasting more unused heat in the hot water left to cool in the pipe afterwards.
And by the way, French pipe sizes are not 15mm (and probably not 22mm). IIRC, 14mm is the nearest, but I might have misremembered.
I don't know that boiler, but if you mean what I think you mean, then you probably didn't want a combi.
No point, the limitation is the maximum power output of the boiler - the flow rate it will give will easily be carried by 15mm pipe.
You could always run a hot water cylinder off the radiator side of the boiler, just as you would with a "heating only" boiler. Then just use the "instant" hot water output for the kitchen sink of for a shower.
What you don't want is influence from cold taps on the hot water. Run a pipe to the combi in 22mm from the stop tap. At the stop tap tee off and run to the cold supplies. Don't have one 15mm pipe snake around the house and the combi taken off as if it is another tap at a basin. That is asking for trouble. Put a filter on the return to the boiler to catch any crud.
Don't do this, as it just means there is more cold water in the pipes to clear every time you turn on the tap. The hot water rate will be limited by the boiler capacity, not by the size of the pipes, unless the house water supply pressure is very, very low.
Yes, but only enough for one good shower at a time. If you want more flow rate, you either need a bigger boiler, or some energy storage, like a hot water cylinder or heat bank.
Christian.
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