Unvented cylinder feed pipe

[tridimnaw]

Hi, Im going to be installing an unvented cylinder to a property next week. I've got the cert and hand books but I can't see any info on pipe sizing for the feed! The ones I've done in the past hve all had a 22 mm rising main, this one has a 15 mm. The pressure and flow rates are good. Will it have an effect on how the system will work? Or should I replace the cold pipe from the stop tap to the cylinder with 22mm pipe?

 

[IDCHAPPY]

So you are G3 registered? I'd be safe and take it there in 22mm mate, everyone I've fitted had a 22mm feed. Last thing you want is the customer coming back and busting your bum if there problems with flow(there probably wouldn't be but why take the chance? ).

 

[sheff paul]

Hi, Im going to be installing an unvented cylinder to a property next week. I've got the cert and hand books but I can't see any info on pipe sizing for the feed! The ones I've done in the past hve all had a 22 mm rising main, this one has a 15 mm. The pressure and flow rates are good. Will it have an effect on how the system will work? Or should I replace the cold pipe from the stop tap to the cylinder with 22mm pipe?

In an ideal world 22mm all the way,best to pipe 22mm down to the stoptap,then in the future they can upgrade the cold incoming.A couple of weeks ago fitted one with 15mm feeding the control valve,with a view to upgrading when there finances permit,worked better than a combi,but same problems when a few taps were open at the same time.If the existing 15mm had poor flow/pressure then it wouldn't be an option

 

[chris watkins]

If you only have 15mm coming in then replacing it in 22mm will only help with the friction losses. On high pressure systems these are relatively small so unless you have lots more than 3bar or a very, very long run of 15mm with lots of elbow in it or they are defiantly going to replace the incoming mains from the street stick with the 15mm into the valve set. You should pipe the outlet through to the cylinder as well as the hot all in 22mm.
What pressure & flow do you have on the existing 15mm???

 

[Destroyer2813]

I've gotta a old black water main coming in my house but ran 22mm back to it and will upgrade watermain when I do my front extension, it works fine at the minute

 

[stratplus]

15mm incoming to a/c in mine too with no issues, just not balanced.

 

[AWheating]

doh matta what size pipe you fit unless the main has a good flow rate. Pointless specin an unvented cylinder for a job unless you have atleast done some checks/tests on the incoming mains supply. Basic g3 stuff.

 

[sheff paul]

I've gotta a old black water main coming in my house but ran 22mm back to it and will upgrade watermain when I do my front extension, it works fine at the minute

got exactly the same incoming into my gaff,took 22mm from it runs fine

 

[sheff paul]

If you only have 15mm coming in then replacing it in 22mm will only help with the friction losses. On high pressure systems these are relatively small so unless you have lots more than 3bar or a very, very long run of 15mm with lots of elbow in it or they are defiantly going to replace the incoming mains from the street stick with the 15mm into the valve set. You should pipe the outlet through to the cylinder as well as the hot all in 22mm.
What pressure & flow do you have on the existing 15mm???

Chris mate I think you need more time on the tools than on the books

 

[tamz]

Unventeds will "work" with any pressure or flow no matter how low ie you will get water out the hot tap but working and working the way it should are 2 different things.