New Combi boiler being installed and new bathroom

[Redhotferrari]

Hi Guys,

As title, new combi boiler being installed in a renovation project, (property never had a combi before) The bathroom is also being replaced in the process, with all the very old plastic pipe feeding the hot and cold being replaced with copper.

My question is, from a combi, will 15mm copper into the bathroom be sufficient to feed the hot and cold on bath and basins?

Am I right in thinking the hot and cold supplies from the boiler itself would be in 15mm anyway? if so I assume changing to 22mm in the bathroom to feed the bath would not give any advantage?

Look forward to hearing from you.

Many thanks

 

[JPC]

assuming its not a large house hot and cold in 15mm is fine . flow and return (heating) in 22mm through to last room (t off in 15mm)

 

[Redhotferrari]

Thanks for the quick reply JPC, just a standard 3 bed terraced, one bathroom upstairs and sink to kitchen.

Flow and return is planned to start in 22mm from bedroom at front of house, across to bathroom, out to hall and into back bedroom and terminating, so teeing of in 15mm to 3 bed radiators and bathroom, dropping down in a couple of points in 15mm to feed 4 radiators on ground floor.

Understand if this is a bit difficult to understand or visualise from the words, but do you think this will be OK?

 

[tonybhoy]

Depends on the size of the four rads but you should really ensure that part of the system is also done in 22MM.

 

[Redhotferrari]

Thanks for the advice, to clarify the landing is quite long and narrow where the main 22mm would run, the intention in apart from feeding the bedroom radiators with 22mm, except the tails, would be drop down at one point in 15mm to feed two radiators, tee of again halfway down the landing to feed one radiator, then tee of again near the end of the run to feed the last downstairs radiator.

So if my thoughts are correct from the main 22mm no more than two radiators would be fed off a 15mm tee.

 

[tonybhoy]

Personally I would always go to the last rad in 22MM but if it were a major problem (can't really see it to be honest) I would go to 15MM but only if the rads were not that big.I.E. small hall,small bedroom,kitchen or bathroom sizes(approx 6KW in total)

Having said that I have seen an entire house (about 18KW)done off 15MM and it worked. God only knows what like that system was in the dead of winter though

 

[Agile]

Normal rule of thumb is no more than three rads up to a total of 5 kW to be fed by 15 mm.

Its not to the correct standard but some cowboys feed in 22 mm which then branches in 15 mm to upstairs and another 15 mm to the downstairs. In a very small house this is within the rules but not in the average larger three bed 30's semi.

Tony

 

[Redhotferrari]

Thanks for all the advice and replys on this guys, have uploded a very crude paint drawing of the proposed layout, can you let me know what you think?

Apologies for the drawing, art was never a strong point

 

[tonybhoy]

Judging by your drawing I wouldn't be too bothered with your pipe sizing.

Still depends on rad size,re Tony's advice,but still looks ok,IMO.

Best of luck.

Cheers,

Tony.

 

[Agile]

Where can I see that drawing?

Tony

 

[Redhotferrari]

Agile hopefully you can see this now?

Many thanks View media item 1503