System A could cause air to be drawn down the vent pipe during high demand. System B is the correct way.
Jeff
Jeff
squeaky";p="3276051 said:Maybe they just don't like you. You seem to know all the answers anyway
LOL..Yes I know all the answers, I just wish I knew the CORRECT answers, that's what I am trying to ascertain.
Everybody has answers...
You don't need them equations. They don't apply. You don't have perfect pipes. You DO need the experience to know what works, and maybe a few charts, once in a blue moon. It's a garden tap not a chemical pipeline.
So, sure a tad of common sense and simple science, but more importantly, whether burrs on pipes, or stopcocks, or gate valves, or bends, or the regulation check valve, actually affect whether it'll work WELL ENOUGH that the plumber gets paid!.
System A could cause air to be drawn down the vent pipe during high demand. System B is the correct way.
Jeff
This reminds me of a new home I worked on years ago. It was a very rural location with a Private water supply. The Architect for whom the house was being built, was from the 'Plumbing is easy' brigade. He'd buried about 2 Miles of 25mm MDPE pipe from the elevated 60M high water tank to his new home. He was very, very disappointed when his Water flow rate was so pizz poor it hardly would flow out the pipe!!
Never confuse pressure & flow.
System A could cause air to be drawn down the vent pipe during high demand. System B is the correct way.
Jeff
Interesting.... Would it work if the cold feed was 22mm and the vent say 8mm
Have you any thoughts of a way around it Jeff. Is it possible/acceptable to put a non return valve on the vent pipe?
This reminds me of a new home I worked on years ago. It was a very rural location with a Private water supply. The Architect for whom the house was being built, was from the 'Plumbing is easy' brigade. He'd buried about 2 Miles of 25mm MDPE pipe from the elevated 60M high water tank to his new home. He was very, very disappointed when his Water flow rate was so pizz poor it hardly would flow out the pipe!!
Never confuse pressure & flow.
This is another occasion where he should have known how to apply the Darcy-Weisbach equation.
This guy seems to know what he is talking about:-
http://www.johnhearfield.com/Water/Water_in_pipes2.htm[/QUOTE]
No, Darcy-Weisbach equation is pressure!! You're getting the two mixed up fella!!
System A could cause air to be drawn down the vent pipe during high demand. System B is the correct way.
Jeff
Interesting.... Would it work if the cold feed was 22mm and the vent say 8mm
Have you any thoughts of a way around it Jeff. Is it possible/acceptable to put a non return valve on the vent pipe?
Nope. You haven't shown a vent anyway and it should be unobstructed to the cistern. If the draw on a tap below the cylinder exceeds that which the cold feed can supply air will be drawn into the outgoing hot from a vent if it were located where it should be. You'll get spluttering at the hot tap especially if they were decent 3/4" bath taps. Minimum vent diam is 19mm according to Mr. Prescott.
No, Darcy-Weisbach equation is pressure!! You're getting the two mixed up fella!!
No, Darcy-Weisbach equation is pressure!! You're getting the two mixed up fella!!
That's why I would never make a plumber.. !
You don't want to do it like that.....
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