plumbing q - 22 or ...
 

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[Closed] plumbing q - 22 or 15 for shower

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 DT78
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bathroom refurb.  fitting a decent shower, rainfall, handheld and six jets.  inlets are all 15mm and existing feed into bathroom is 15mm.  as I have the boards up I'm wondering about repiping in 22 to increase flow, at least to the outside of the bathroom as once it's under tiles it will be a pita to change.

should I ?  will cost a chunk more in parts and time.  but it would coat a lot more if I had to redo


 
Posted : 06/09/2018 10:28 pm
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How far back can you change the 15mm?


 
Posted : 06/09/2018 10:38 pm
 DT78
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easily just to the outside of the bathroom, say 3m, with moderate difficulty I can take up the boards in the next room which should get me most of the way back to the boiler as it is in the adjoining vorrifot.  though I'm not 100% on the pips runs.  haven't looked at the boiler yet as kids asleep but presume that's also a 15mm


 
Posted : 06/09/2018 10:56 pm
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22mm will hold more water and therefore longer for the hot to come through at first.

What type of water system? Combi boiler and therefore mains pressure? In which case usually best left as 15mm, little advantage to 22mm. If gravity fed system def go to 22.


 
Posted : 06/09/2018 11:06 pm
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<p>Match your hot water to your boiler outlet, cold water is better 22mm main with 15mm spurs to each outlet otherwise you can get flow issues. I piped mine 15mm throughout, like a fool.</p>


 
Posted : 07/09/2018 12:53 am
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I'd  hazard a guess if you're on a meter it's reduced to 15mm at that point. Have a rainfall head on my shower and it's fine. No jets though, thought they worked better on pumped systems?


 
Posted : 07/09/2018 3:10 am
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If it's a combi stick to 15


 
Posted : 07/09/2018 3:42 am
 DT78
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yep on a combi and a meter

.other shower has a rainfall (but no jets) and has good flow and pressure and from what Ive seen so farl all on 15.  I'm thinking ahead to when my two boys are older and there is the possibility of 3 showers on the go at once.

bolier is a valiant 48 I think, likely I will have replaced it in the next 10 years though.


 
Posted : 07/09/2018 6:57 am
 DT78
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quick look at boiler.   it's piped in 15mm for the first metre or so and then it's into 22mm for the hot all in copper, so at some point in the next room it's reduced to 15mm speedfit before the bathroom I'm returning.


 
Posted : 07/09/2018 8:08 am
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3 showers on the go on a standard combi at once won't work. You just wont have the required flow or pressure (whichever one is most important) , I'm not a plumber btw just a realist. What we do in our housing sites is 2 normal showers max and then go for a good quality electric shower, that way if there are any boiler issues you can still have a hot shower. Otherwise it would be a pressurised hot water cylinder.


 
Posted : 07/09/2018 9:34 am
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Keep it in 15. No value to changing.  And with Wrightyson on this you won’t run 3 showers at the same time off a combi anyway, there’s not enough flow rate.


 
Posted : 07/09/2018 10:32 am
 DT78
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hmmm I thought I might have issues with flow on 3 showers and I thought 22 might help.  Great suggestion on the electric shower.  The third bathroom is next year's project


 
Posted : 07/09/2018 2:01 pm
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Don’t get a cheapo electric shower either. 10.8kw minimum for a decent shower if you are used to mains pressure showers.

Mira Sport Max 10.8kw is a winner.


 
Posted : 07/09/2018 3:27 pm
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its depend on your bathroom size, your balance and water.


 
Posted : 06/10/2018 12:14 pm
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Three bathrooms FFS; have you got five teenagers in the house or somefink???


 
Posted : 06/10/2018 7:59 pm
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One thing I discovered was that standard isolation valves for 15mm pipe are very restrictive.  You can get high flow ones from screwfix which are not.


 
Posted : 06/10/2018 8:34 pm

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