Durgo Valve

[jsouthwood]

We thought we had a blocked soil pipe, can't find a way to rod from the bottom of the pipe and as the pipe is internal with a Durgo at the top I removed the Durgo and rodded down. I could not detect any blockage but noticed that with the Durgo off the water ran away in the bathroom room with no problem. Replaced the Durgo and the water would not fluch away. I assume it is due to a partial vacume in the pipe, but I thought a Durgo let in air to avoid this. Have a faulty Durgo? Can't see how it can be faulty, simple device that seems to have jammed etc. Or is there another explannation? What should I do?

Thanks

 

[Penners]

If the system works without the Durgo valve, I think I would replace it if I were you. They're not terribly expensive - less than £15 usually.

 

[Lime]

No that doesn't make sense.
The valve should prevent air escaping and only let air in when a partial vacuum exists within the pipe.

If the valve is jammed open taking it off should make no difference.
If the valve is jammed shut then water should still be able to enter the pipe unless there is a blockage at the other end.

With the valve in situ and a blockage at the other end pressure is building up as more water fills the pipe and air in the pipe has nowhere to go and therefore prevents further water entering the pipe.
When the valve is removed the air can escape and water flows into the pipe. As the soil pipe is large it can take and hold a lot of water until the water level reaches the branch from the sink/bath/loo then it will stop.

 

[Penners]

Lime has a very good point.

One way in which you could test his theory would be to take off the Durgo valve and run a hose into the top of the stack. If it is blocked somewhere way down, it should eventually fill with water.

Mind you, you'd then be stuffed for using your loo until the blockage is cleared!

 

[Lime]

I forgot to say to your question

Or is there another explannation? What should I do?

It seems you do have a blockage further down the system below the bottom of the stack.
Raising a manhole or cleaning eye is the next step to take.

Another check to test if there is a blockage in the pipe is to feel if a draught of air is present coming from the pipe when the valve is removed.
If the bottom of the system is blocked or just flooded with surcharge from the sewer then there will be no draught.
(That test assumes there is no open vent in the pipe.)

 

[jsouthwood]

Hi

Thanks for your thoughts and advice. I have run water down the stack with no problems, no build up of water etc

I have jammed open the durgo as a short experiment to see what will happen and my next door neighbour has now said that their toilets are not flushing fully!

Any ideas? We have a shared drain of four houses. Our house is at the end of the chain, my neighbours is next etc

Would opening the Durgo do this?

 

[jsouthwood]

There is draught going down the pipe when the toilet is flushed.

 

[Lime]

From what you say about the draught and your neighbours the likely cause of your problem is either a "slow" blockage causing a back-up of water in the pipe (but draining away slowly) or that your street sewer is flooded or very full and covering or filling (surcharging into) your sewer pipe.

 

[jsouthwood]

This sounds sensible, if the main sewer was backing up into our shared drain then shouldn't the first house in the shared drain of four also have the problem? But now it appears that without a Durgo I have no problem but my neighbour has :?

I am totally confused and not sure what to do next. Is it possible that there is an inbalance in air pressue in the drain causing this?

What would you do next?

Thanks for all your thoughts an replies.

 

[Lime]

If your drains have a "slow" blockage it may be that the first house is "below" the blockage and not effected by it at all.

It is quite possible that "your" blockage has now moved down the pipe passed your nextdoor neighbour's pipes and is now blocking them too.

If the sewer is backing up or surcharging the pipes and the first house has an open vented system then they will not notice the problem until the water level gets higher and floods out.
(Very similar to yourself now that you have taken off the valve.)
If the drains are flooded then all your neighbours' systems will be isolated from each other. The only thing that will effect you all is the actual water level.

If you have a blockage and you run the tap for a while the water level will rise.
If you have a surcharge from the street the level will remain relatively unaltered because the system is so widespread.

What would you do next?

I'd open a manhole near the street very carefully to have a look!

If it is full of water then you either have a surcharge or blocked pipe to the sewer.
If it is empty apart from a small amount of running water flowing freely you definitely have a blockage further up the pipe.