WC Pan empties of water on flushing and very slow to fill to normal level and glugging in doing so.

[Penelopejean]

Hello all,
Hope you can help please. I have a suspicion that our upstairs ensuite could be blocked somewhere having looked at other threads.
We had an ensuite built upstairs about 2-3yrs ago. The soil pipe has been made as complicated as it gets with about 3 bends before it gets to the vertical stack plus the basin and shower outlets coming into it. Then there are about 4 bends before the straight run to the manhole. The problem shows when the wc pan empties of water when flushed and then the water slowly glugs back into the pan to near normal level. I thought there was a rodding point at the base of the svp but on unscrewing it there is a sort blind blanking plug underneath. Any ideas how I can try to unblock it if this is the problem. I've tried chemicals (friendly and unfriendly) and buckets of water but am unsure of using a metal bendy rod from the top in case I damage something. Incidentally we still haven't had the building control inspector out for the pressure test and the final certificate yet as our builder can't seem to get it organised. I wonder why now!
Any advice gratefully received.
Penny

 

[Newboy]

The access cap you have at the base of the stack allows the plug to be removed - be careful in case the satck is full!

Better to have the drain checked from the nearest access chamber/manhole

 

[Hugh Jaleak]

If it was blocked, I'd expect the level to rise during flushing, then slowly drop back down. If the pan is emptying then slowly refilling afterwards, it's a siphonage problem, possibly indicating a partial blockage, or badly run soil pipework. I would be very careful undoing anything at a lower level, especially as you've used chemicals. I think a CCTV inspection of the pipework might be needed to see what exactly is going on.

Being nosey, but I assume this is another property as your other post is talking about a bungalow?

 

[Penelopejean]

Thanks Newboy and Yes Hugh, well spotted and thanks for replying again! The bungalow is our holiday home near the coast. The suspected blocked ensuite wc is at our main home. Is there a special easy knack or tool for removing the plug thingy at low level. There doesn't seem a way to avoid any nasty effects once it's removed. I would hope the chemicals have dispersed away by now as this is ongoing for a few months now anyway. We looked in the nearest manhole then but it was a clear run.

 

[Hugh Jaleak]

I will assume you have a circular cap on the access point, which you have removed. Inside there will be a shaped plug, (it is moulded to the internal bore of the pipe to allow free passage past and not provide a ledge for material to catch). This should prise out with gentle persuasion using a screwdriver or similar. Note which way round it fits, some have a notch to ensure replacement the right way round. I'd stand to one side when doing this as if there's any pressure behind it, you dont want to be in the firing line when it releases....

Have you had someone watch at the manhole when the problem pan is flushed? I'd expect the water to come through all at once, if it takes a while and flows through as a trickle, then this could indicate a possible blockage.