Seemingly stupid question about flow rates

NickNickleby · 29-07-2020 02:47PM #1

Attic tank is slow to fill. The whole house has been replumbed. I know the incoming pipe is that black hydrodare (I think its called), with either 3/4" or 1" O.D and I'd guess the bore is 1/2". I also know that the incoming feed has been stepped down to 1/2" qualplex where it feeds the cold tap - where the pressure isn't brilliant either. So, my question is: could this 1/2" qualplex link be sufficient to reduce the pressure of the mains to render it quite poor?

If the answer is Yes, then its time to see how to increase the bore from the end of the hydrodare to the tap, and on up to the attic. If the answer is No, then the outflow from the hydrodare will need to be examined. Not the preferred choice, as I suspect its under the new expensive floor tiles:( .

thanks

Lenar3556 · 29-07-2020 04:13PM

NickNickleby wrote: »

Attic tank is slow to fill. The whole house has been replumbed. I know the incoming pipe is that black hydrodare (I think its called), with either 3/4" or 1" O.D and I'd guess the bore is 1/2". I also know that the incoming feed has been stepped down to 1/2" qualplex where it feeds the cold tap - where the pressure isn't brilliant either. So, my question is: could this 1/2" qualplex link be sufficient to reduce the pressure of the mains to render it quite poor?

If the answer is Yes, then its time to see how to increase the bore from the end of the hydrodare to the tap, and on up to the attic. If the answer is No, then the outflow from the hydrodare will need to be examined. Not the preferred choice, as I suspect its under the new expensive floor tiles:( .

thanks

It’s a combination of length and bore size that will affect the flow rate. Too long a run at 1/2” and the flow gets poor!

Replacing a short run of 1/2” pipe is unlikely to make much difference. 1/2” heavy gauge hydrodare has an outside diameter similar to 3/4”.

There are mains booster pumps you can get like Grundfos SCALA (or lower cost alternatives) which can make a big difference.

What is the outside diameter of the hydrodare? How far from kitchen sink to water meter?

NickNickleby · 29-07-2020 07:44PM

Thanks Lenar, for taking the trouble to respond.

Standard 3 bed semi. Probably about 40' to the meter from the tap. Not my house, so I can't go rooting around or the daughter (and more importantly, her chap) will go nuts for my interfering.:D . I saw the house when it was being stripped and renovated - but didn't see the plumbing going in. I can only guess at what's been done, by referring to memory and looking under the sink at the exposed pipework.

I'm trying to come up with scenarios to explain to them why their tank emptied when guests were showering - it only refilled at a trickle. I will try to get a look at the attic tank to see what's feeding it.

Seemingly stupid question about flow rates

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