15mm water mains feed too small

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Hi guys. Never done this before. Have an unvented hot water cylinder to go up in a loft conversion and think I'll have to dig from the mains stopcock as the existing is old lead (7 1/2LB) 15mm and needs to be 22mm and feed back into the downstairs kitchen and up into the loft, connecting to cylinder for balanced hot and cold to all other outlet. The thing is I need to know if it's a thames water job. As far as I know if I'm downstream of the cock it's a plumber task, also once the adjustment is made this has to be notified to undertakers.
The pressure is brilliant out of the existing mains. 3bar standing and with kitchen tap and outside tap blasting giving 1.5bar on which I thought is really good. What I need to realise it might change as it's about a good 10m up which mechanical means it's a 1bar loss.. just wished I weren't doing and was always thinking the mains was 22mm as there's always been two bathrooms and 3 toilets in the dwelling and the small mains has good pressure.. but boy. I'd it goner be a days work or two to do the dig.

 

[ShaunCorbs]

if the water mains/pipe is lead maybe ask the water board to come and test they might renew for free, and then you can run a 22mm upto the loft for you unv cylinder

 

[Ch4 plumbing]

What's the flow rate? And I wouldn't really consider 1.5bar to be great on an unvented cylinder tbh.

Have you thought of where you will terminate the TPRV/PRV?

 

[PlumbBobBob]

are you G3 registered?

 

[spanner]

are you G3 registered?

Yep G3 registered since 2013.
Standing pressures 3bar and from downstairs outside tap and kitchen tap on full blast get 1.5bar flow rate. With kitchen tap off get a 2bar. Mechanically the pipe has to go up another vertical 9m do fingers and toes crossed tomorrow ( as the I've dug out the trench) and tomorrow going to do the MDPE connection from the cock straight through to the kitchen and up to the loft in plastic PF.. Today the weather's so brilliant here, I must have lost a LB in sweat.

 

[mutley racers]

Yep G3 registered since 2013.
Standing pressures 3bar and from downstairs outside tap and kitchen tap on full blast get 1.5bar flow rate. With kitchen tap off get a 2bar. Mechanically the pipe has to go up another vertical 9m do fingers and toes crossed tomorrow ( as the I've dug out the trench) and tomorrow going to do the UPVC connection from the cock. Today the weather's so brilliant here, I must have lost a LB in sweat.

You need to measure the flow rate feller. No good having 3 bar and 8 litres a minute. You need at least 20 litres a minute, that means with 2 outlets on you will get 10 litres a minute at each shower which at 1.5bar is ok

 

[mutley racers]

full blast get 1.5bar flow rate.

You're mixing up pressure and flow rate. Get a weir cup and measure that to see how many litres a minute you're getting. If you don't have one use a bucket and a stop watch and then get one. Handy bits of kit and great for commissioning combi's

 

[spanner]

if the water mains/pipe is lead maybe ask the water board to come and test they might renew for free, and then you can run a 22mm upto the loft for you unv cylinder

Yep possible.. the hot cylinder has an enclosure and knocked out the old cast stack and replace with plastic
The run is short about 2m and terminals into manifold.. still not got to this stage. Should be all finished by Thursday.
I'll do the flow test tomorrow.

Need to dry out the water after today. It was not a day for turning off the water supply ... the dust jheez. Had to go out and buy the buckets and ration..
Time for a nice cold carling darling.. buurrrp..

 

[spanner]

The jobs in Wembley. The pressure at all times has been good won't surprise me tomorrow if I'm going to get 25Ltr/min+
Was getting 16Ltr/min before with 15mm outside tap.

 

[spanner]

full blast get 1.5bar flow rate.

You're mixing up pressure and flow rate. Get a weir cup and measure that to see how many litres a minute you're getting. If you don't have one use a bucket and a stop watch and then get one. Handy bits of kit and great for commissioning combi's

How do you do it with a bucket lolz..!! If I had to fill the buckets it'd filled one in 10 seconds 0.5ltr/sec
Not only that but there's no water way till the morra...
AND now can't it lolz So going to have to buy yet another weir tomorrow flipping £20 a pop..