Washing machine drain

[timegoesby]

In order to save kitchen space, I was looking at fitting a washing machine in an upstairs hall cupboard. The drain would have to run under the hall and across the bathroom in the suspended floor space. The joists run with the drain route, so no problem getting the drain under the floor. The water is pumped by the washing machine and using a clamp on non-return valve connector on the drain pipe I don't see any problems. Does the drain need a strong fall to it?

Another point is that can the drain pipe be in a 'U' shape? The pipe drops from the washing machine, under the floor and then rises up and connects onto the 110mm WC pipe. Water will be trapped in this pipe. As the washing machine pumps water via a non-return valve I can't see this being an issue. This would make matters much easier.

Any comments welcome.

[Shrek-the-Ogre]

----- Original Message ----- From: Newsgroups: uk.d-i-y Sent: Thursday, June 01, 2006 1:19 AM Subject: Washing machine drain

You don't need a 'strong fall' at all, although this would help if you are emptying out over a long distance, what you do need is a minimum height above the floor level of the machine to stop the water syphoning out mid-cycle. Usually the machine will have a red line or some sort of indicator at the back of the machine to show the minimum height required for the pipe. As long as it goes above this height for some part of the journey, preferably close to the machine, I don't see any problems.

Ian Tilley

[dom]

AIUI the drainage pipe should have a u-bend trap and a 1 in 40 fall over it's whole length. The underfloor bit sounds fine, the rises up and enters the soil pipe bit doesn't. The rises up bit sounds like there would be quite bit of water pooling there, where debris will collect and eventually block the pipe. The connection to the soil pipe may have the potential to allow sewage back into the washing machine drainage pipe. Check the building regs, they have things to say about distances and directions for drainage pipes connecting to soil pipes.

[David Hansen]

On 31 May 2006 17:19:59 -0700 someone who may be [e-mail] wrote this:-

How long would this run be? What size of pipe?

Presumably you are thinking of a pipe that ends in a blank, with the connector clamped to this? Far better to have an open ended standpipe into which the pipe from the machine is put.

Not unless you want the trap of the standpipe to be siphoned out. Assuming that the run is long, you will certainly need some form of air admittance.

You appear to be saying that the pipe already exists. The answer is that such an arrangement is foolish, as well as breaking a number of regulations. The pipe should fall gently all the way to the stack. When it gets to the stack it will need to connect some way below the toilet connection. Depending on the layout this may mean a few bends to get to a suitable place to make the connection.

It would make it easier for the pipe to block, which is one of the reasons they should fall constantly. It would also mean that the pipework is under pressure when the machine is pumping. Waste pipes are not designed to operate under pressure so you would probably have a spectacular leak before the pipe blocked.

[Christian McArdle]

The pump of the washing machine isn't intended for long tortuous runs like this. It should empty into a trap near the machine.

However, all is not lost. You can buy pumps which are intended for this purpose. The Saniflo range would not be suitable as they do not allow a vertical run at the end, only at the beginning. However, a Sanisplit K2 (different company) should do the trick. They're not cheap, though. The other alternative is to run by gravity to the base of the vertical run and then install a Sanivite at that point, rather than near to the washing machine. However, it won't be any cheaper and probably a whole lot less convenient.

Christian.

[David Hansen]

On Thu, 1 Jun 2006 10:05:32 +0100 someone who may be "Christian McArdle" wrote this:-

One can go from the 22mm Saniflo outlet pipe to a larger size near the vertical drop though. This will allow air in and thus not siphon the whole of the 22mm pipe.

Using such a device may also allow other locations to be considered.

While any added complication is best avoided if possible these pumps are useful in some situations and work happily for a long time if not abused.

[Christian McArdle]

My understanding is that the pipe rises vertically at the end, rather than dropping. If it dropped, then it would probably be possible to design a gravity system.

Christian.

[Guy King]

The message from "Christian McArdle" contains these words:

I've run several washing machines discharging via lengths of long pipe and never had any problems. The longest was about six meters of 32mm pipe just lying on the floor along behind some units, round a bend, behind more units and into a spigot on the sink outlet. Ran for years without trouble. The pumps are very simple, and worst comes to the worst, they're under a fiver off eBay.

[David Hansen]

On Thu, 1 Jun 2006 11:13:23 +0100 someone who may be "Christian McArdle" wrote this:-

It isn't clear whether the plan is to install a pipe that rises at the end, or it already does. If it is just a plan then a vertical rise at the end certainly does not comply with the Saniflo instructions and thus would undoubtedly invalidate the warranty.

However, I was thinking of changing the pipe design so that at the end it dropped onto the stack far enough away from the toilet connection.

Of course with a Saniflo it might well be easier and better to go up from the first floor cupboard and through the loft (assuming a two storey house) to the stack. This would avoid a lot of difficult work under the floor and could all be done in 22mm pipe, assuming the length is suitable. It would probably be a matter of pulling a few bends in copper pipe and clipping it to suitable places. The stack connection would also be much easier. I would bond the pipe and it certainly should be insulated in the loft. Costing labour and disruption against the cost of the unit this might even be cheaper considered in the round. From memory only the Saniflo itself cannot pump vertically, the others in the range can pump up to something like 3m. I can't be bothered to look at the web site to check.

Indeed.

[Christian McArdle]

Indeed. The Sanisplit, on the other hand doesn't have this restriction, which is why I would recommend it if this pipe routing was chosen.

Yes, that would probably be a preferable routing if feasible.

Christian.

[timegoesby]

Thanks to all.

The length of the drain pipe from washing machine under the floor is about 15 foot, 5 metres. At a 1 in 40 fall (that is falling 1 cm for every 40 cm in length) that is a pipe fall of about 10cm. That will just be enough space in the floor. I can take the pipe out of the outside wall which opens up into the roof space of the brick lean-to kitchen. From this space I can then take the pipe outside via the side of the lean-to and down into a gully below.

I can take the drain pipe across the floor, rise and connect onto the toilet 110mm elbow. It could rise 3 foot so no soil from the toilet can run into the washing machine drain. The Sanisplit pump should be capable of doing this. Can I tee into the soil stack just behind the toilet? I see no reason why not as long as the pipe rises above the WC pan preventing backflow.

If this is not feasible because of obstructions, the Sanilav, which uses 22mm pipe can rise up and across the loft and connect onto the stack outside. It may be tricky getting the 22mm pipe out of the eves. Does it have to be copper pipe? Sanilav have a model that is about =A3210 for basins and showers. Would this do a washing machine and condensing dryer? I can't see why not. I "think" it has a 22mm discharge pipe.

[Guy King]

The message from [e-mail] contains these words:

Washing machine pipes are always full of water.

I really think you're making this more complicated than it needs to be. If you're in any doubt about whether the washing machine pump will cope, make a mock-up with a length of 32mm waste pipe laid on the floor and you'll see it'll cope no trouble.

[Pete C]

That's far too pragmatic...

[Guy King]

The message from Pete C contains these words:

Ah, sorry, I forgot this is uk.mountains-from-molehills!

[Doctor Drivel]

Most washing machine drain pipes I find that don't have a good fall, or are straight, end up being fully or partially blocked with gunge.

The best is gravity of course, using slow bends where used. Using a Sanilav or Sanisplit pump is the last resort but should work well. Even the gravity fall pipe I would have accessible rodding points at every opportunity. One could be at the washing machine end under the floor of the cupboard the washing machine is to go. Have an easily removable trap. I would use solvent weld pipe and fittings. I would also occasionally use Mr Muscle drain unblocker down the drain pipe to burn away any gunge.

If using 22mm pipe and a Sanilav pump I would also put rodding points in, or have compression joints in the loft to easily break the pipe and get a rod in.

[Guy King]

The message from "Doctor Drivel" contains these words:

All I can say is it's never happend to me on several long washing machine drains and two dishwasher drains - though they weren't so long, only about two meters.

[David Hansen]

On 1 Jun 2006 09:46:13 -0700 someone who may be [e-mail] wrote this:-

Unless the connection uses one of the patent fittings then the new connection must be more than IIRC 100mm from the toilet connection.

They have a web site with lots of details. From memory pushfit joints (obviously) and flexible pipe are frowned upon.

They do a few models designed specifically for the hot waste from washing equipment.