Branching off cold feed to combi boiler

[noodle26]

Hi all

I am a bit stuck as to the optimal arrangement of pipework of the incoming mains feed prior to arriving at a combi boiler. I have an 25mm MDPE supply pipe with a 25->22mm brass stoptap fitted as it enters the kitchen(not below the sink, sink on adjacent wall 4m away). The boiler will be sited in a utility room which is off the kitchen from the wall furthest from the stoptap, (this utility room will also have a sink,washing machine, little bathroom with toilet and sink in). In the bathroom above the kitchen is a bath (directly above stoptap) basin, toilet (above kitchen sink) and electric shower (above kitchen sink).

There are numerous ways of feeding cold water to these appliances but I am sure there is a 'right' and 'wrong' way to go about it.

option 1. 22mm all way to boiler with a tee to 15mm at ceiling height above stoptap to feed bathroom above (bath, electric shower, toilet and basin) with a second tee in utility before boiler to feed sink, washing machine and little bathroom?

option 2. 22mm all way to boiler with a tee to 15mm (at wall where utility meet kitchen) to feed everything else (bathroom, utility and little bathroom).

option 3. 22mm all way to boiler with a tee to 15mm (at wall where utility meet kitchen) to feed shower only and another tee off the 22mm to feed everything else.

option 4. 22mm all way to boiler with a tee to 15mm at ceiling height above stoptap to feed just bath above. A tee to 15mm (at wall where utility meet kitchen) to feed shower only and then another tee off the 22mm (at wall where utility meet kitchen) to feed basin, toilet, utility room and little bathroom.

option 5. None of the above, there is a better way!

Im thinking the shower should be on a dedicated branch off the 22mm but does this matter with electric showers as opposed to mixers? Im thinking option 3 or 4 seems the way to go with maybe pressure reducing valves off the tees but would you use one of these if the bath cold was being fed from that branch aswell? Maybe a full bore lever valve as stoptap instead?

I would be really happy for any help regarding this as I want to do the job properly.

Thanks in advance

 

[downthesouth]

Bit complex to take that all in. Do you have any pictures?

 

[on31ll]

draw a diagram ? whats your pressure and flow like ? run 22mm for as much as you can but if pressure and flow if ok you will be fine with 15mm at sink and utility rooms ! the shower will be fine with its own branch to feed shower !

 

[kay-jay]

Just run your pipes where it is most convenient/less obtrusive to hide them.

 

[noodle26]

Hi

Thanks for taking the time to reply, ive drawn a picture to make it clearer. flow rate is 18.l/min and pressure 4 bar. Obviously I could route the pipework the easiest way, branching off the 22mm wherever I needed to, but is this the'correct'way, is it best practice to only branch off the 22mm once and use that to feed everything else? Or maybe twice, one for everything else and a dedicated 15mm to shower? Ie is there an optimal arrangement that would ensure the flow to boiler and shower was not affected by taps being opened, toilets being flushed etc. I am sure it is better to understand the situation now so the pipes can be routed correctly than find out later that the shower is poor when a tap is on or something that could have been avoided by doing the job right is the first place.

Thanks in advance

 

[Howsie]

Four.

 

[kay-jay]

Hi

Thanks for taking the time to reply, ive drawn a picture to make it clearer. flow rate is 18.l/min and pressure 4 bar. Obviously I could route the pipework the easiest way, branching off the 22mm wherever I needed to, but is this the'correct'way, is it best practice to only branch off the 22mm once and use that to feed everything else? Or maybe twice, one for everything else and a dedicated 15mm to shower? Ie is there an optimal arrangement that would ensure the flow to boiler and shower was not affected by taps being opened, toilets being flushed etc. I am sure it is better to understand the situation now so the pipes can be routed correctly than find out later that the shower is poor when a tap is on or something that could have been avoided by doing the job right is the first place.

Thanks in advance
View attachment 12814

You're fitting a combi mate, the shower will always be crappy when someone opens a tap no matter how its piped

 

[AWheating]

your combi does not need a 22mm supply, i would run a seperate 15mm supply to the combi from the first tee on 22mm cold pipework. where ever that maybe. 15mm supplies to all other fixtures. then fit flow restrictors to reach fixture to help ensure an even supply.