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- 17 Feb 2006
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Here's the setup:
Combi boiler, Vaillant EcoTec plus. 837 I think. Supplying all CH and DHW.
No header tanks, no DHW storage tanks.
Shower and bath both supplied by Bristan thermostatic deck mounted bath and shower mixer (combined, shower hose comes of underside of mixer).
I recently fitted a new bath, and as part of it tidied up the plumbing. I was really pleased as I managed to get rid of some complicated spagetti-like plumbing, and kept 15mm copper all the way up to the taps, no flexis to go wrong/reduce the bore.
Thing is, it's difficult to get the shower hot enough. Partly maybe this weather or maybe this:
The mains comes in under the house, in blue plastic. Mains pressure is good on all the cold taps.
The cold goes straight up the corner of the kitchen, into the bathroom, and the bath is in that corner. I reckon from where the blue plastic mains ends to the cold bath tap is only about 12 feet. And all copper 15mm, no flexis, and most bends are made bends, not elbows. I.e. not much to reduce pressure.
Under the kitchen floor there's a T to take cold to the boiler. Travels about 18 feet to the boiler, at least 5 elbows, a fair bit of H20 pipe work (smaller bore?) and then the same coming back bringing the hot, and then the same 12 feet up to the bath hot tap.
So I reckon the hot travels at least 36 feet more than the cold, plus 10 elbows (they reduce pressure, don't they?).
And presumably there is a pressure loss through the boiler itself.
So having felt pleased with myself for increasing the cold pressure at the bath (which definitely did improve when I got rid of the flexi) it's looking like that is actually working against me.
So as well as having better pressure to start of with, when the cold is on it'll be robbing the cold supply from the boiler, resulting in even worse hot pressure/flow.
Just did a completely unscientific test at the bathroom basin. Filled a large beaker from the hot tap. Took about 3 secs. Then turned the cold tap on and left it running while I filled the beaker from the hot tap again. Took about 5 seconds. Lever taps, so can do a quick on/off.
I can't really do too much about where the boiler is. And although the pipework to and from the boiler is a mess it'll get tidied up when the kitchen is redone.
I'm guessing that the best thing to do right now is to install a pressure reducing valve to the bath(room?) cold supply.
Any advice gratefully received.
Combi boiler, Vaillant EcoTec plus. 837 I think. Supplying all CH and DHW.
No header tanks, no DHW storage tanks.
Shower and bath both supplied by Bristan thermostatic deck mounted bath and shower mixer (combined, shower hose comes of underside of mixer).
I recently fitted a new bath, and as part of it tidied up the plumbing. I was really pleased as I managed to get rid of some complicated spagetti-like plumbing, and kept 15mm copper all the way up to the taps, no flexis to go wrong/reduce the bore.
Thing is, it's difficult to get the shower hot enough. Partly maybe this weather or maybe this:
The mains comes in under the house, in blue plastic. Mains pressure is good on all the cold taps.
The cold goes straight up the corner of the kitchen, into the bathroom, and the bath is in that corner. I reckon from where the blue plastic mains ends to the cold bath tap is only about 12 feet. And all copper 15mm, no flexis, and most bends are made bends, not elbows. I.e. not much to reduce pressure.
Under the kitchen floor there's a T to take cold to the boiler. Travels about 18 feet to the boiler, at least 5 elbows, a fair bit of H20 pipe work (smaller bore?) and then the same coming back bringing the hot, and then the same 12 feet up to the bath hot tap.
So I reckon the hot travels at least 36 feet more than the cold, plus 10 elbows (they reduce pressure, don't they?).
And presumably there is a pressure loss through the boiler itself.
So having felt pleased with myself for increasing the cold pressure at the bath (which definitely did improve when I got rid of the flexi) it's looking like that is actually working against me.
So as well as having better pressure to start of with, when the cold is on it'll be robbing the cold supply from the boiler, resulting in even worse hot pressure/flow.
Just did a completely unscientific test at the bathroom basin. Filled a large beaker from the hot tap. Took about 3 secs. Then turned the cold tap on and left it running while I filled the beaker from the hot tap again. Took about 5 seconds. Lever taps, so can do a quick on/off.
I can't really do too much about where the boiler is. And although the pipework to and from the boiler is a mess it'll get tidied up when the kitchen is redone.
I'm guessing that the best thing to do right now is to install a pressure reducing valve to the bath(room?) cold supply.
Any advice gratefully received.
