Plumbing question

[Penners]

Discharge into a gulley shouldn't make any difference. And yes, Durgo valves are available for smaller pipe runs - 32mm and 40mm - as well as the soil stack (110mm).

Lime has a point about the sheer volume of water running through a (I presume) 40mm pipe, but it depends how many wastes the pipe will serve and how many of them are ever likely to flow out at the same time.

I've never experienced any really significant noise from a Durgo valve, and our last house had three.

One other point about your jointing - as has been mentioned above, the neoprene sealing ring in pushfit fittings can become dislodged if the push-in pipe is badly cut. But you can minimise this risk by (a) slightly tapering the pipe end, and (b) using a tiny smear of silicone lubricant.

 

[Flyfisher]

Here's what I'm trying to do. The waste pipes are shown in grey. I can't really connect into the existing sink pipework because this exits the wall above the shower level and is too far from the washing machine and new sink to provide adequate fall.

(Apologies for the scrappy quality but the PC I'm currently using only has MS-Word to create a drawing and I had to photograph the screen to get a jpeg!).

 

[Andrew Bodenham]

I would run all three appliances (sink, shower, w-m/c) into one pipe run, but use 50mm pipe after the washing machine (maybe even after the first branch) to reduce the chances of trap seal loss. In this way you have one less hole through the wall and one less pipe outside to look unsightly / freeze up. I've done this in a couple of similar installations and have not had any problems. The extra capacity of 50mm ensures that the pipe never runs full bore, and gives some leeway for hair / soap scunge build-up from the shower. Good idea to include a 'T' blanked off with a screwed access plug somwhere in the run to allow rodding of any obstructions. If you've a very long run then include an expansion joint, otherwise you'll be plagued with creaks and ticks as the pipe grows with heat.
Most decent builders' merchants carry 50mm solvent-weld parts, or try bes.co.uk for great prices and service on any plumbing stuff. No connection, just a happy customer.

 

[MdB]

(Apologies for the scrappy quality but the PC I'm currently using only has MS-Word to create a drawing and I had to photograph the screen to get a jpeg!).

Hit the Print Screen button (or Alt - Print Screen for just the window you are currently using) to copy the current window. Open up Microsoft Paint and hit paste. Save as jpg.

 

[Penners]

I entirely agree with Andrew's suggestion - there's no need to run two wastes if you increase to 50mm pipe just before the washing machine.

But, if it were my system, I would also extend the pipe back to a point just before the new sink, turn it up vertically to a height above the highest possible water level in the sink, and pop a Durgo valve on top.

 

[MdB]

Approved Doc H Table 2.

If I read this correctly up to 4 devices can be connected to one 50mm branch pipe as long as it is less than 4m in length and has a drop of between 18 and 44mm per m. If this is exceeded then then end of the pipe has to be vented externally or internally using an air admittance valve (section 1.20).

 

[Flyfisher]

Thanks for taking the time to look throught the sketch (and for MdB's jpeg tip - I thought there'd be an easier method but couldn't think of one in a rush and only had my camera to hand).

50mm pipework sounds like the answer - single waste pipe and neater external appearance. Distance shouldn't be a problem as the room width is only 2m. Good tip about a rodding point; that will be easy to include at the 90 degree bend just after the new sink. I'll work on the following revised plan. Thanks again.

 

[Jon Maine]

The fact that it is vented outside where it enters the gulley is very helpful at allowing a free flow, It is unlikely that a sink and a shower on a 38mm pipe would be an issue, add a washing machine then it gets iffy. So I would recommend 50mm up to the washing machine branch at least and then 38mm beyond, or put two pipes in.

We actually used copper, chrome plated in a couple of exposed places in our bathrooms which looks posh and loverly but is bloody expensive although left overs come up on fleabay reasonably time to time. ( went back to solvent weld plastic out of sight quickly though).