Rickavo
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Registered: 2nd Jul 09
Location: Manchester
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quote: Originally posted by deanmcreynolds26
quote: Originally posted by Rickavo
No mate they don't.
how does a combi not give mains pressure hot water? it is not by any means pumped at all,
heating is pumped, primary water is pumped through the secondary plate exchanger but it is mains water that comes through the taps on a combi boiler,
and also the only time when u will have mains water into the cylinder with not tank in loft is an unvented cylinder
[Edited on 22-10-2009 by deanmcreynolds26]
I am not saying that the hot water is pumped, i am sayin that at the taps the cold will have a greater pressure (Flow rate) than the hot. As the hot and cold are from fed from the mains yet the hot has to go through the boiler to be heated. Therefore at the mixer the pressures (flow rates) will not be eqaul.
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mattk
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Registered: 27th Feb 06
Location: St. Helens
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flow and pressure are 2 different things...
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mattk
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Registered: 27th Feb 06
Location: St. Helens
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you can have a 8mm pipe with 2 bar of presure in it and a 22mm pipe with 2 bar of pressure in it, the 22 will have a greater flow rate
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Rickavo
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Registered: 2nd Jul 09
Location: Manchester
User status: Offline
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but when you are talkin about a shower when its runnin 'standing' pressure is Irrelevant.
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mattk
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Registered: 27th Feb 06
Location: St. Helens
User status: Offline
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yeah standing pressure is irrelevant, the pressure when the valve is open is whats important
the hot will flow less than the cold on a combi boiler, but as long as the pressures are the same on both sides the mixing valve will regulate the flow on each side to give the water the desired temperature
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