dedicated water supply to combi in loft?

[Thegift]

So there is a 30kw combi in loft kitchen is been refitted so all pipework will be exposed.

currently has 25mm mdpe in kitchen under sink with 15mm stopcock. Goes up about 6 inches in 15mm then tees off feeding cold tap, outside tap and washing machine. Goes up into the bathroom then tees off again to feed cold tap on bath, basin, toilet and shower, goes up again into loft then feeds combi.

Now is this arrangement fine or another way I was thinking was replace stopcock for 22mm, just after stopcock 22mm tee feeding 22mm pipe all the way into loft reduced into 15mm just before combi for its own dedicated supply.

Then another tee just after the first tee from stopcock in 15mm feeding all the cold taps, toilet and shower in house can reduce the flow to all these outlets with the aim if giving the combi as much supply as possible with the aim of getting the best possible pressure from hot outlets with in mind things like pressure/flow and work rate of the combi.

 

[Ermintrude]

Set up a "balanced cold" basically run 22mm to loft, fit a pressure reducing valve in kitchen and then after the valve drop in a tee tee to all other stuff and the 22 onto combi feed. Simples. Prv is there to regulate pressure .

 

[Chalked]

You could do that, but it won't make your combi produce any more hot water.

 

[plumben]

have you tested flow rates at all appliances and referred to MI for what your boiler should/will give out?

 

[Ermintrude]

But will make hot cold fluctuations less

 

[AWheating]

22mm stop tap, 15mm cold first tee straight to loft space or 22mm to upstairs and 15 teed off 22 to loft. The boiler will only need a 15mm supply, its where this 15mm is connected that really matters.