Bath hot water pipe size All aspects of plumbing questions and answers, help, tips and information

[barkby123]

I'm changing my bathroom round and want to put the bath where the sink was. The hot water supply to the sink is a 15mm spur from the 22mm supply that enters the bathroom. Do I need to replace all the 15mm pipework to where the bath will be with 22mm, or is it only necessary to add a small section of 22mm to connect to the bath tap?

[Rico]

barkby,

It depends on what water system your on combi boiler or cylinder.

If combi you can use the existing pipe work and get some 3/4 inch - 15mm flexi hoses.

If water comes from cylinder then you will need to replace 15mm with 22mm to get a decent flow rate to the bath.

Hope this helps
Rico

[Skids]

Hi Barkby123

its all about flow and pressure.

if you have a combi boiler, you should be ok, as you should have 1.5 bar + of pressure.

if you are running from a HWC, it may be slower as there is less head of pressure from the CWSC and with a smaller pipe (15) the flow will be down.

if you can change to 22mm for the bath all the better (faster), however it's not going to harm just be slower to fill.

Regards

Skids

[htg engineer]

All depends on where your hot water is fed from, if from a tank or cylinder it should be 22mm from tank or cylinder to bath.

If it's a combi, it can be 15mm from boiler to bath

[barkby123]

Thanks for all your replies. 22mm it is then.

[htg engineer]

Don't use flexi hoses -they're rubbish, have seen/known of many splitting. This happened in my house, I installed the upstairs bathroom, 2 years later the flexi hose split - luckily we had just went to bed after using this bathroom and I heard the water running - if we'd been asleep the ceilings downstairs would have come down and who knows what other damage would have been caused.