What happened to 1 3/4" PVC wastes?

[Eric]

I am trying to connect a new shower tray to the existing waste pipe.

The existing waste is an 1 =BE=94 PVC pipe. I think that this standard has now been abandoned =96 all the wastes in B&Q are now 40mm (1 =BD=94). Is it likely that a plumbers merchant will stock 1 =BE=94 fittings =96 I need a new P trap?

What are the prospects for connecting a 40mm P trap to a 1 =BE=94 waste pipe? Do I just stuff a bit of 40mm pipe inside the 1 =BE=94, whack some silicone sealant round it and hope for the best or is it possible to find an adaptor from 40mm to 1 =BE=94?

Indeed will 40mm PVC pipe fit inside 1 =BE=94?

[John]

I am trying to connect a new shower tray to the existing waste pipe.

The existing waste is an 1 ¾? PVC pipe. I think that this standard has now been abandoned ? all the wastes in B&Q are now 40mm (1 ½?). Is it likely that a plumbers merchant will stock 1 ¾? fittings ? I need a new P trap?

What are the prospects for connecting a 40mm P trap to a 1 ¾? waste pipe? Do I just stuff a bit of 40mm pipe inside the 1 ¾?, whack some silicone sealant round it and hope for the best or is it possible to find an adaptor from 40mm to 1 ¾??

Indeed will 40mm PVC pipe fit inside 1 ¾??

Bear in mind that you don't just need watertight connections - you also need the inside to be as smooth as possible - otherwise it will clog with all manner of horrid stuff.

[boltmail]

50mm waste is still very much in use, and a plumbers merchant will stock a trap or an adaptor if you prefer. The leap from B&Q not stocking something to the conclusion that it is no longer available isn't really sustainable. All wood other than banana wood would have been abolished for a start.

[Rick Hughes]

I am trying to connect a new shower tray to the existing waste pipe.

The existing waste is an 1 ¾? PVC pipe. I think that this standard has now been abandoned ? all the wastes in B&Q are now 40mm (1 ½?). Is it likely that a plumbers merchant will stock 1 ¾? fittings ? I need a new P trap?

What are the prospects for connecting a 40mm P trap to a 1 ¾? waste pipe? Do I just stuff a bit of 40mm pipe inside the 1 ¾?, whack some silicone sealant round it and hope for the best or is it possible to find an adaptor from 40mm to 1 ¾??

Indeed will 40mm PVC pipe fit inside 1 ¾??

1 1/4" and 1 1/2" are very much still available ... in metric guise of 32 and 40mm

Some places will also stock 50mm

You can get reducers to connect between the sizes

[jim]

How old is the installation? What is the make?

If it is a true imperial size then it must be at least 30 years old, more likely older. If a true metric size it could be either a 'special' or perhaps a size peculiar to one (?minor) manufacturer.

If you can discern the manufacturer's name it might be worth ringing up their technical help service (look on web for tel no) for suggestions.

Otherwise (& especially if imperial) IMHO it would almost certainly be best to strip out & renew using standard metric sizes. Domestic plastic waste fittings aren't that expensive & biting the renewal bullet now might suave you lots of aggro in the future.

If it is a true 1.75inch bore the changing to 50mm might be the best option.

It is possible you might find a good plumbers merchant would recognize your problem and be able to fish out an adapter from under the counter. OTOH he might not :-(

no not if both are internal bore diameters. using mastic/sealant might work for a time but in thene IMHO will fail.

HTH

[Ed Sirett]

There are two standard of plastic waste pipe.

1) BS 5454 is the push fit type, this is compatible with the copper sizes. The ODs are 35 and 42mm. 2) BS 5455 is the solvent weld size. The ODs are about 36 and 44mm. The next size up has an OD of about 56mm.

Compression fittings fit both standards. Just to make matters more confusing the basin/bidet size is called 32mm or 1¼" (based on its approx ID). The Shower/Sink/Bath stuff is called 40mm or 1½" likewise.