Mains feed and hot water from combi.

[MickBrown]

I am putting in some new pipework at my daughters house, it is a new extension and a new combi boiler is going to be fitted there. The mains is about 3 bar and will run some 12m to combi then the hot will run 8m to bathroom both in 15mm. I will put as many pulled bends as possible but does anybody think these may be better in 22mm?

 

[TBServices]

I am putting in some new pipework at my daughters house, it is a new extension and a new combi boiler is going to be fitted there. The mains is about 3 bar and will run some 12m to combi then the hot will run 8m to bathroom both in 15mm. I will put as many pulled bends as possible but does anybody think these may be better in 22mm?

No, bigger pipe means more wasted water with no benefits. I hope she's prepared to wait 3 minutes to get hot water at her outlets 20m away. This is really basic stuff and I might suggest you should think about getting a professional in to suggest a better boiler location/solution. Combis aren't the best

 

[Centralheatking]

TBS has given you very sensible advice on the basis of your question - can you post a diagram but it seems you will not be thanked for what your planning in the long run -
good pun as well centralheatking

No, bigger pipe means more wasted water with no benefits. I hope she's prepared to wait 3 minutes to get hot water at her outlets 20m away. This is really basic stuff and I might suggest you should think about getting a professional in to suggest a better boiler location/solution. Combis aren't the best

 

[MickBrown]

I did not plan the combi position, it was planned by my daughter and son-in-law along with the Gas safe plumber who is fitting the boiler. I am just helping fitting the pipework to save them some money. The 22mm pipe was advised by the gas safe plumber, I was a little surprised so that is why I posed the question on this forum. The hot water would have about 8m from the boiler not 20m, 20m is the total run from where the cold enters the house. The bathroom is the new ensuite in the extension, the existing bathroom has an electric shower, the hot water taps in the existing bathroom would be about 5m from the combi. The existing cylinder (vented) is as far from the ensuite as the combi, the combi is a compromise to boost the shower pressure. They do not have any funds to upgarde the cylinder to a pressurized system.