Today's install.

[TBServices]

Best thing about UV is the can size pipes properly. 22 for bath, 15 for showers and 10 for basins. Can save a lot in wasted heat and water.

 

[DirksPlumbing]

22mm feeds straight to the bath taps to give optimum flow rate.

At 37l/min HW you are still below 2m/s. That gives you around 56l/min mixed water. At an appliance that is designed not to give off more than 36l/min HW at 1bar. So you can loose 2+ bar in your pipes. Which gives you an equivalent pipe length of over 100m. If you would use that pipe length then a quarter of you 120l cylinder gets used just to fill the pipes.
From a 15mm pipe you still get 20l/min at an equivalent of 40m.
(Hot water, not mixed water)

 

[SafeGasInstall]

At 37l/min HW you are still below 2m/s. That gives you around 56l/min mixed water. At an appliance that is designed not to give off more than 36l/min HW at 1bar. So you can loose 2+ bar in your pipes. Which gives you an equivalent pipe length of over 100m. If you would use that pipe length then a quarter of you 120l cylinder gets used just to fill the pipes.
From a 15mm pipe you still get 20l/min at an equivalent of 40m.
(Hot water, not mixed water)

Interesting point

 

[Howsie]

How many hot draw offs?

 

[DirksPlumbing]

If you avoid stopcocks in the HW pipe you could even go to 5m/s which provides you with 40l/min. draw offs apparently share what is there. At 20l/min you can have 3 showers going at the same time or 1 shower and one filling the bath at the same speed as with an 35kW combi on its own. You just need to watch your hydraulics a bit for not preferring the bath to much as it could rob the other appliances.

 

[SafeGasInstall]

If you avoid stopcocks in the HW pipe you could even go to 5m/s which provides you with 40l/min. draw offs apparently share what is there. At 20l/min you can have 3 showers going at the same time or 1 shower and one filling the bath at the same speed as with an 35kW combi on its own. You just need to watch your hydraulics a bit for not preferring the bath to much as it could rob the other appliances.

what do you mean "watch your hydraulics" , like your posts

 

[DirksPlumbing]

With hydraulics I meant the way the pipe runs. Like having a long run to the bath and the shower mixer (hot) close to the bath of the branch could lead to an unpleasant pressure drop if someone starts filling the bath whilst an other one uses the shower.

Or the less likely event that your mains only supplies a low pressure and/ or low flow rate.

 

[Whn1]

Dirk, please bear with me whilst my brain processes your comments....

 

[SafeGasInstall]

Last post does not make sense to me ....... sorry but not sure how to understand it

 

[SafeGasInstall]

Do you suggest 15mm independent supply to bath and shower ?