Saniflo back pressure

[nathf1980]

Hi all

I'm after some advice on a saniflo system that has been installed several years ago in a residential house I look after .

when the toilet is flushed it back pressures and blows water out of the shower tray . you get a lovely fountain of grey water 12" high .

The floor in the bathroom is tilled and all pipework runs away under floors so can't really see what is going on .

Was wondering if any one has come across this before as I and the owner had no part in fitting I dont really know whats gone on with out taking the bathroom to pieces and pulling up tiles and floor boards . lots of huge pieces of furniture and old ladies wondering around to contend with if i go down this route .

there are about 10 of these systems within the house and this is the only one that does this .

Don't really want to rip up floors unless i have to (its a 16th century house so will end up finding more problems ) hopping there is a nice simple fix as i can't think of a worse job tbh .

thanks in advance

 

[Newboy]

1) Is the fountain happening when the WC is flushed and before the pump kicks in or does it happen when the pump kicks in?

2) How is the shower waste connected to the Saniflo?

 

[Hugh Jaleak]

Need those 2 questions answered before we can give an answer really, but I'd think either, the shower is connected to the Saniflo correctly, but the non return valve on the shower inlet has failed, or the numpty installer has connected the shower waste to the outlet pipework from the Saniflo.....

May be a clue in the shower, for it to be connected correctly to the Saniflo then the tray has to be above the inlet level of the Saniflo, and unit should start if shower is used.

 

[nathf1980]

Hi thanks for replies .

Will look tomorrow as I can't remember at the moment how the shower is connected (32 rooms in the place all with there set of problems lol ) .

sat here thinking about it I think hugh could of hit the nail on the head (shower connected to sani outlet ) as i can't remember seeing a 2nd pipe into the saniflo !

will report back tomorrow !

 

[Hugh Jaleak]

I'm afraid to say a connection into the outlet (pressure) side of a Saniflo is not unheard of..... Maybe that the pipework is on a fall from the unit to the stack, (4" wasn't used due to space constraints), so shower itself will drain under gravity, but the Sani will pump out quicker than the pipework can remove the effluent, so it takes path of least resistance......

 

[nathf1980]

Right had a good look today . waste comes out when saniflo pump kicks in .

Found the outlet in a store room buried under a load of boxes !

the shower waste goes into a 42mm polypipe and then runs under the tray for 900mm turns 90 degrees into the store room runs for another 1.5m and then disappears into the floor on a 90 . The saniflo waste runs along side this until it meets the 90 in the floor and then taps into it on the 90 bend.

The only thing i can think to do is a non return valve in the polypipe but open to suggestions .

Cheers

 

[Hugh Jaleak]

Ideally Saniflo needs a dedicated discharge from unit to stack. Cap one and run new waste for other to seperate them. If this is really not practical then non return valve on the shower may help, but i'd then be concerned the pressurised output from the Saniflo may cause that to malfunction, then the gravity flow from shower may not be enough to open it. I'd try and seperate the two if at all possible for a long term fix.

 

[Agile]

Non return valve on shower waste sounds fine until you try to find one!

I needed one to put in a Saniflo outlet where it was pumping up through loft. The weight of 3m of water in the pipe was causing the Saniflo valve to leak and made the unit cycle every 10 min.

When you find a source let me know in case I ever need one again!

Tony

 

[Newboy]

Less than ideal but this might be worth a try

http://141.0.166.36/index.php/waste.../1-189-multifit-in-line-non-return-valve.html

 

[Agile]

The problem is that the good NRVs have a spring which ensures a good seal.

BUT this needs a significant water pressure to overcome the resistance of the spring.

I would say that they are only really suitable for use in vertical pipework.

Tony

 

[Newboy]

This one doesn't have a spring and offers minimal resistance to flow in the right direction. It also allows for the non-return flap to removed and cleaned if necessary.


http://www.screwfix.com/p/mcalpine-t28m-nrv-40mm-non-return-valve-white/61561?


Still don't like the idea of having to fit one but other than re-piping the arrangement there aren't many alternatives

 

[Agile]

So how does it work?

Does it really seal securely?

Tony

 

[Newboy]

The flap is top-hinged (under the access port) and rests back against a seal. I've only used one once in a horizontal waste run and it seemed to do the job OK. Still my least preferred option but when needs must .....