Hi, I have just plumbed all of the Cold Water for my house. I have put in a new 15mm stop cock, pressure reducing valve, drain cock and then 15mm copper pipe with soldered joints to my Kitchen and then to my bathroom. I have done it ALL in 15mm, including up to the Bath taps etc. The reason why i did it all in 15mm is because the external and internal stop cocks are both 15mm and i didn't think that increasing the bore after these bottle necks would make any difference. Was this a mistake? Would i have been better off going up to 22mm after the stop cock and then only going down to 15mm again for kitchen sink etc, but keeping 22mm right up to the Bath? The house is still fairly ripped out at the moment, so i am happy to re do a large section of the pipework in 22mm copper if if you think it will improve flow rate. But the stop cock will always be 15mm. We are currently getting a flow rate on the bath cold of approx 12 litres/min on 15mm. However i have used 300mm long 8mm bore flexi hoses on the bath, which i plan to rip out and redo all in solid copper pipe right to the tap as i think these are restricting flow. I recon the flow on the bath might increase to 15 litres / min once i change the flexi hoses to solid copper. Any thoughts? Thanks
Also, another crazy idea. Would there be any benefit in making my water main pipework into a loop, so the end feed back to the stop cock again. Almost like a ring main, everything being fed from two sides. Would this increase flow rate or help to prevent pressure drops when two water items are use at once such as Toilet and Shower?
I think its fairly standard for mains pressure (direct) pipe to be in 15mm, and loft pressure (indirect) to be in 22mm. Of course if you have two paths for water to go, twice the area and less loss of pressure. But assuming its mains pressure I doubt it will make much difference.
Your flow rate is mainly restricted by the incoming 15mm and what ever feeds that from the main supply. At 12l/min your flow is low but would 22mm improve it? Maybe not as the flexi hoses are a bottle neck. You can get flexi hoses with 13mm bore size ... http://www.screwfix.com/p/hep2o-push-fit-flexible-tap-connectors-22mm-x-mm-x-300mm-2-pack/9473f which removes any restriction and they are easier to fit that accurately getting solid copper in place. I would try that first, and then consider again whether an upgrade to 22mm will be of benefit. Do you know what you can get immediately after the stop tap?
Hi, thanks for your replies. Thanks for the link. I will look into these. However i'm not a fan of anything push fit, i'm paranoid about them failing. I don't even like compression fit (another reason why i'm ripping out the flexi hoses!) I did find some very expensive solder end stainless steel flexible pipes though which i may use: http://www.toolstation.com/shop/Plu...s/sd2807/Flexible+Stainless+Steel+Hose/p16172 Sorry i didn't understand your question. Do you mean what flow rate can i get immediately after the stop tap? I have no idea!, but good question. I will have to try and find out.
I can understand the paranoia, however if you stick with the premium brands and do it "by the book" ... There are also all copper versions of those flexi pipes too. Yes, flow rate after the stop tap.
At a previous place replace the lead mains with 32mm mdpe pipe reduced down to connect 22mm mains stopcock & used 22mm copper, teeing off from 22mm for bath, 15mm for basin, bog,etc, worked well due to good mains pressure.
Hi Let me tell you a story about flow and pressure of water! Once upon a time.. I converted an old farm yard to 8 flats, the supply pipe was only 15mm copper to the yard. I laid a 3" water main from the yard to the main road, to supply the water to the flats. The water board were contacted to connect the mains, but there was going to be a delay so I connected the 15mm copper to the 3" water main,this allowed me to test the work. Well, what append waz.. the work was finished and flats occupied, and 3 months later, I realised the water board had not connected the mains up? The flats were all ok, with no complaints! The 3" main was acting like a giant accumulator.. And every one lived happily ever after
3" over a long run certainly would ... cross section is maybe 35 times that of 15mm. Would short runs of 22mm do the same ... only for a few seconds though.
Hi guys, I have just removed the old standard Isolation Valve (narrow bore) and replaced with a Full Bore Isolation Valve and the full bore Stainless steel / Copper flexiblle pipe and it has made a MASSIVE difference to the flow rate for the bath. Before i measured it at 12 litres/min using a stop watch and a 1 litre jug. Now it's consistantly measuring between 25-30 litres/min. Cheers!
It's surprising the different a full bore lever valve & full bore isolation valve can make with flow rates.
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