Which pipe size?

[Jabo]

I am extending supplies into an extension. Currently hot water is on dia22 and cold on dia15 from rising main. Should I continue to use the same dia pipes all round the extension or use 22 or 15 for both hot and cold, or does it make no difference? I also want to add a rad. I want to use polplumb because installation will be much easier so I could buy a coil of dia15 and a couple of lengths of dia22 to keep supply costs down. Any suggestions / recommendations

 

[Softus]

Can you imagine being asked that question by someone who doesn't reveal how the services are going to be used in the extension?

 

[Jabo]

Ok, fair comment, I'm new to this. Basically I want to supply a bathroom and, eventually, a kitchen. I want to put an electric shower in the bathroom so need only a cold supply for that from the mains (or so I understand). Other than that it's the usual bathroom and kitchen appliances.

 

[BigBurner]

What do you have right now? Mains pressure? tank and cylinder? how many baths? showers? etc? What are you adding?

Then a valued assessment can be made. Many have just extended the hot and cold and found the system works appallingly. You made need a re-think, such as maybe a high flow combi as the extension is in the loft, etc, etc.

 

[Jabo]

The new bathroom will replace the old bathroom, which is ground floor at the back of the house, small and cold. The new kitchen will eventually replace the existing kitchen, which is also small and tired. There will be no additional baths or showers, just replacements for what we have now. The existing plumbing is no more than 15 years old. There is a (quite small) CWS tank in the loft feeding a cylinder on the first floor. The new bathroom will be on the first floor. The cylinder and mains supply to the CWS tank are on the opposite side of a wall to the new bathroom. Low ceilings so not much head for gravity fed shower system. Too expensive to install larger/second CWS tank + pump.