Very slow draining of bath, how to cure?

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I have a problem with improving the rate at which our newly installed bath drains. The old one was just as bad, the difficulty is the poor design of the original installation which I am rather stuck with.
The bath is in a flat and is positioned about two or three meters from the main service duct where the sewage downpipe is. The waste pipe from the bath runs essentially horizontally from the trap under the bath across to the downpipe. Not surprisingly, especially towards the end, it drains very slowly. It's impossible to get at the connection of the waste into the downpipe as it's inside a brick built service duct, all you can get at is a 40mm 'socket' where it pokes through a hole in the brickwork.
Can anyone suggest any clever ways to improve this? It'll be quite difficult to do anything much about the drop in the pipe although there is currently access from below (the kitchen) as the leaks from the old bath and drain have caused a bit of the kitchen ceiling to collapse. However even if we took the pipe down through the ceiling I can't see how it could then be routed to the service duct without major building work. I suppose it could join the waste pipe from the kitchen sink but how would you prevent water 'welling up' into the sink?
Is pumped waste possible? Are one-way valves for waste pipe available?
The washbasin waste pipe is even worse, it has a near horizontal run of four meters or so and the same difficulties of improving the drop apply. It could run into the bath waste and gain some drop that way but, again, how do you stop it coming up into the bath?
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Chris Green ( snipped-for-privacy@x-1.net)

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<Chris Green> wrote | The bath is in a flat and is positioned about two or three meters | from the main service duct where the sewage downpipe is. The | waste pipe from the bath runs essentially horizontally from the | trap under the bath across to the downpipe. Not surprisingly, | especially towards the end, it drains very slowly. It's impossible | to get at the connection of the waste into the downpipe as it's | inside a brick built service duct, all you can get at is a 40mm | 'socket' where it pokes through a hole in the brickwork. | Can anyone suggest any clever ways to improve this?
It's not clear if the bath outlet runs within the floor void or if it *has* to, but if you could elevate the bath by a couple of inches (say by using a couple of floor joist -like bits of wood on their sides as planks under the bath feet) that might give you enough more fall on the pipe.
Even if the pipe has to stay within the floor void, elevating the bath a bit should give an increase in flow because of the increased 'head', thus encouraging most of the water out a bit quicker and reducing the amount that sediments/stagnates in the flat bit of pipe.
Owain
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point of view though as the bath panels sort of fix the bath's height.
The existing waste pipe runs above floor level, it would be a real pig to get it into the void as it would have to go through several joists.
The real problem though is the impossibility of moving the position of the waste where it goes into the service duct. That's why I was thinking of taking the waste down to the kitchen below, that gives lots of gradient - much too much really - but that's an issue one can deal with isn't it?
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Chris, are you absolutely sure that the entry into the foul downpipe is truly clear? I had a similar problem in one of my flats that I eventually traced to 'rusticles' on the inside of the cast iron down pipe catching a hairball. Nothing was visable in the branch pipe until it was stripped out to a bare socket when with a torch the problem was obvious and easily cured.
Another possibility is something I found in my own house. Basin waste pipe joins main pipe from bath to downpipe at a 'Tee' which had been installed with the 'swept' branch flowing towards the basin rather than towards the outlet (yes >I< must have done it many years ago when I changed the bath - 1985 I think!). Turning the Tee made a vast difference.
Andrew Mawson
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down the same downpipe quite successfully.

waste goes into the downpipe isn't perfect but there's little I can do about that as it's very inaccessible.
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What size is the waste connection at the outlet for the kitchen system ? If you have a 50mm out flow from the kitchen, then you can combine both the bathroom and kitchen to the one outlet, and then cap the old bathroom waste at the service duct. But this can only be done if the kitchen out flow is 50mm at the outlet to the main stack.
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something I haven't spotted.
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The 50mm would be the minimum you'd need to take two or three appliances emptying at the same time. If the bath and hand wash basin are both being evacuated at once, and from that raised position, you'd need at least 50mm pipework to take the flow required, or you're back in the same boat with a slow running waste system.
I was always told that anyone can bring water in, but it takes a good plumber to take it all away again safely and fast enough.
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<snip> The only thing that immediately occurs is to use a larger bore of pipe for as much of the run as possible. i.e. have large bore pipe from the sink and/or bath right up to the 40mm socket in the trunking. I think that this would ease the flow of the water by reducing the resistance along most of the pipe; having said that I don't think modern baths drain well at all. ISTR that baths in old houses (and old hotels) used to drain much faster. I have guessed that this is due to larger bore lead waste pipes in old installations.
Other option is to raise the bath with a step next to it to make getting in and out easy (opposite of a sunken bath). This would give you a better head of water/drop over the length of the pipe run. You could also raise the basin by putting it on a raised base - but this might look wierd :-) Think of it as a part raised floor in the bathroom.
Combine the two - have a large bore pipe under the raised bath.
Our main bath drains slowly, and the waste just runs the length of the bath (taps away from the outside wall) so I think you will be lucky to get reasonably fast draining with anything but the shortest run.
Having a rambling day today :-)
Dave R
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I had a similar problem after changing my bath. After looking at the 'plug hole' I noticed that the old one had a sort of cast grid while the new one was just drilled holes. By the time I noticed this I had already thrown the old one out, and could not find the same type in my local suppliers. I eased it slightly by cleaning up the holes and putting a sort of 'countersink' on them but it is still not as good as the old one.
While on the subject, my new toilet does not flush a s well as the old one either. And if I turn the taps on too quickly on the hand basin the water streams out of the other side. I have decided that the older ones looked so functional because they were. The newer ones look pretty because they are not so functional.

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If the old one was as bad, you might have grease in the pipework making it worse (causetic soda and caution) or a mchanical partial block (bendy springy thing)
I didnt follow the setup entirely, but can you parallel your 2 waste pipes? If you can that would speed it up to some extent.
Finally pumped waste is simple enough, but AFAIK you'd have to either make the sensor and control circuit yourself, or else just use a manually operated switch for the pump, preferably a push switch with built in timer, as used in communal hallways etc.
Regards, NT
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so won't help the bath wast at all. There's no way to add extra waste pipes because the downpipe is inaccessible in the service duct.

I've seen are Saniflow ones which are too big for what I want, I want a 40mm only pump.
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Could you solve the gradient problem by lifting the bath onto blocks, and put skirting panels around it?
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Tony Williams.

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snipped-for-privacy@isbd.co.uk wrote in message wrote:

Probably, but it also might be the two together. Slow draining water is going to deposit grease much more. Might be worth a try anyway.

Any DIY supplier will sell you a pump. Wickes do them for somewhere round 30 IIRC. I wouldnt expect it to come with 40mm fittings though.
Regards, NT
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seems to be aimed at waste pumping except the Saniflo ones.
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snipped-for-privacy@isbd.co.uk wrote in message wrote:

Central heating pump. Designed to pump with a moderate amount of crap in the water, which will work fine, as long as you dont feed lots of little screws down the plughole. Youre pumping grey water, the saniflo is for brown not grey.
Regards, NT
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wrote:

And running dry between baths how long will it last? Or how do you sense to turn it on?
Andrew Mawson
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How about an automatic bilge pump intended for a boat. They come on when water hits the sensor and continue until free of water. They're low powered and quiet and often deal with less than pristine water.
Try a few of the online chandlers.
Tony
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wrote in message

Just read the thread and see what was suggested. It would last much longer than in a CH system since it is running much less. Youre right to half make the point that its run time shouldnt be too OTT.
Regards, NT
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