Bath Pipes


Postby rinkydinkydooodaa » Wed May 07, 2008 9:33 pm

When I lifted floorboards to work on pipes for my bath I noticed that the hot water pipe had run from 15mm to 22mm and back to 15mm again and the cold was 15mm. Does anyone know why it might have been messed with and should I change them ?
Cheers
Bill
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Postby plumbbob » Wed May 07, 2008 10:13 pm

The hot water supply from your cylinder to the bath tap should always be in 22mm unless the feed is at mains pressure ( eg, a combi boiler is installed) whereby 15mm is then sufficient.

Are you sure the 15mm is not a branch off to the basin? In which case this would be normal.

Maybe the plumbing was changed when a new suite was installed?

Cold water supplies will always be 15mm in standard installations.
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Postby rosebery » Wed May 07, 2008 10:23 pm

Probably not a case of being "messed with" more likely that's the way it was left the last time it was worked on.

With either a gravity HW or fully pumped system the feeds to a bath are normally done in 22mm. This is to give max flow rate at the sort of pressure you'll get from the static head between the water level in the CWST in the roof and the bath taps.

If you have a combi boiler the HW cylinder will have been taken away as will the CW storage tank in the roof. Most times the combi boiler installer just "reverses the flow" in the pipe that previous fed HW to the kitchen (normally in 15mm or 1/2" if it's getting on a bit!) so that hot from the combi now goes up that pipe to the bathroom.

Hope that explains possibilities. Which type of system do you have?

What are you trying to accomplish on the pipes for your bath?

Cheers
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Postby rosebery » Wed May 07, 2008 10:27 pm

I see that the answer to my last question is actually answered in another thread you started where you have stated you are replacing the bath.

It makes sense to keep it all in a single thread, if you don't mind me saying so, and thus avoid wasting peoples time when trying to answer you.

Cheers

Edited for spelling
Last edited by rosebery on Thu May 08, 2008 6:53 am, edited 1 time in total.
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Postby rinkydinkydooodaa » Wed May 07, 2008 11:39 pm

I'm tiling my bathroom and wanted to make sure the bath would fit ok. It's a free standing bath so I had to reroute some of the pipes. The bath came with a mixer tape and the fittings supplied were for 22mm pipes. As i'm still repairing a few old floor boards I had noticed the pipe layout. So I wondered weather I should change what I had done or get different fittings.
I do have a combi boiler & thanks for youur help.
Bill
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Postby rinkydinkydooodaa » Wed May 07, 2008 11:44 pm

I'm tiling my bathroom and wanted to make sure the bath would fit ok. It's a free standing bath so I had to reroute some of the pipes. The bath came with a mixer tape and the fittings supplied were for 22mm pipes. As i'm still repairing a few old floor boards I had noticed the pipe layout. So I wondered weather I should change what I had done or get different fittings.
I do have a combi boiler & thanks for youur help.
Bill
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Postby plumbbob » Thu May 08, 2008 12:03 pm

If you have a combi boiler then the feed can happily be 15mm so there is no need to change the pipework.
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Postby rosebery » Thu May 08, 2008 9:36 pm

Bath taps always expect 3/4 inch (22mm near as dammit) tap connectors but they WILL be 3/4" and not 22mm. If your feeds are now basically in 15mm you just need a 15mm > 3/4" tap connector to make the connections at the taps.

Cheers
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