Kitchen sink waste pipe run

[triggersbroom]

Hi all,

I've just bought a new house and it's in a real state - so having seen so much helpful advice on this site I'm hoping you might be able to help me with some questions regarding the Kitchen!

We are looking at a few options and one of them involves knocking through to make a kitchen/diner. We feel this would actually work better if we install the new kitchen in what is currently the dining room.

Please bare with me - I'll get to the plumbing in a moment...

So the dining room currently has a large chimney breast in the middle of the longest wall, which we are considering opening up and putting a range cooker into. This would leave us enough space to the left of the chimney to fit a washer and dishwasher. The waste for these would go out of the left side (as you look at that longest wall) into the drain in the back garden.

Still with me? Good.

To the right of the chimney is about 1400mm before the living room wall. I'm thinking this would be worktop as it's not really enough to comfortably get a sink in I don't think. So I was wondering about putting the sink on that adjacent lounge wall. And finally to my question(s):

1. The sink waste will need to go out the same way as the washer/dishwasher - i.e. the other side of the room. Is it possible to take the pipe round there, which would involve a run of say 1 metre towards the left, followed by a 90 degree turn and a run of approx. 4 metres?

2. You may have realised that this would take the waste behind that chimney breast! Probably a silly question but is that a problem.? What's to stop putting in 2 strategically drilled holes to allow the pipe to pass at the correct fall angle? ...apart from the possible heat output from the back of the oven I suppose...

Anyway, sorry if these are newbie questions - I'm not the most experienced! Thanks for any advice. If this is never going to work, taking the chimney breast out is an option - but an expensive one.

 

[muggles]

Maximum run on 1 1/2" standard sink waste pipe is 3m, and 2" is 4m, if you want to go further than that you'll have to increase to 4" (6m max run) which is plainly not suitable. You do have options however. You could get a new drain dug in and installed in the area where your sink is proposed to be (assuming it's on an outside wall) or, if you're really desperate, you could find somewhere to put a Sanivite. The Sanivite should be an absolute last resort though, to be considered after considering redesigning the kitchen

Some plans of what you're intending to do sketched on the PC and posted as a picture would help us to advise you better

 

[triggersbroom]

Thanks muggles. Hmm we might just get away with 2" then - distances I have mentioned are very much off the top of my head, I need to go back and measure properly.

The proposed sink location is nowhere near an outside wall unfortunately, and yeah I did consider a Sanivite. For about 30 seconds!

But in theory then, I'm OK to go behind a cooker with a sink waste?

I'll do some measuring and knock up a plan tomorrow if It's not going to work how I hoped.

 

[muggles]

You should check how much heat is lost to the rear of the cooker before you put a waste there. If it's a new cooker it shouldn't be much in theory but always good to check. I'd put high-temperature waste in there as a precaution in any case (Hunter solvent-weld waste is HT as standard, so use this if you can find it)

 

[triggersbroom]

Great stuff - thanks again

 

[Richard C]

Maximum run on 1 1/2" standard sink waste pipe is 3m, and 2" is 4m, if you want to go further than that you'll have to increase to 4" (6m max run) which is plainly not suitable.

Those maximum lengths only apply to unvented branch lines; fit an AAAV to the branch or vent through a Hepvo trap/valve & you can make them as long as you want. As long as you have the required fall & access points it will work & comply with BR’s.

You could get a new drain dug in and installed in the area where your sink is proposed to be (assuming it's on an outside wall) or, if you're really desperate, you could find somewhere to put a Sanivite

Completely unnecessary considering the above.

 

[triggersbroom]

Those maximum lengths only apply to unvented branch lines; fit an AAAV to the branch or vent through a Hepvo trap/valve & you can make them as long as you want. As long as you have the required fall & access points it will work & comply with BR’s.

Wow - that's great news. I just did a quick Google to find out what a Hepvo or AAAV is and I see what you're getting at.

So, assuming I go down that route, would I be able to use 32mm pipe and could you just clarify the 'fall and access points' please? As far as I can tell, it will be about a 5m run in total, which would require 20mm per 1m fall, right? So coming off a sink I should be fine, being that total fall required is 100mm. Or am I mistaken?

 

[Richard C]

You can’t use 32mm (bidets & wash hand basins only); minimum size for kitchen sink waste is minimum 40mm but with a 5m total run & if you have other appliances discharging (dishwasher, washing machine), I would consider using 50mm at least from any point where other appliances discharge; this may also affect how you vent it. Fall required is 18-90mm/metre but in your case 20mm is a little shallow & I would advise a minimum of 25mm/metre fall, possibly 30mm which will increase the total fall. For access you basically you need to be able to clear a blockage from any section of pipe from one end or the other; of course if you use push fittings rather than solvent weld then you can just pull it all apart.

Have you downloaded a copy of Building Regs Part H:
http://www.planningportal.gov.uk/uploads/br/BR_PDF_ADH_2002.pdf

 

[triggersbroom]

Thanks again Richard, I'll be sure to take a good look at the regs.