Blocked bathroom sink
Discussion
Chaps,
Having a bit of trouble with our bathroom sink. We had our bathroom redone a couple of years ago and prior to that had no drainage problems. I seem to remember when the guys installed our new bathroom, they had a bit of trouble with the sink draining but seemed to get round it. The problem started a few months later but unfortunately the installation company had gone through from the recession so we had no comeback. The sink waste runs from trap vertically downwards to a horizontal pipe which runs over around 3-4ft into a downpipe outside.
The hot and cold sink supply pipes run right next to the vertical waste pipe.
The symptoms are:
With cold tap running, sink drains fine.
When hot tap runs (at lower pressure than cold), as soon as water gets hot, sink starts to back up. Once it is blocked, the only option is to plunge it.
After plunging, the sink will be fine for a day or two, and then back up again when the hot tap is used.
I have tried drain cleaner to no avail. I've also used a snake and pushed right through to the outside downpipe without encountering any blockage. The trap is clear. Both bath and sink drain into same downpipe and bath drains absolutely fine. There doesn't appear to be any physical blockage.
I'm now thinking perhaps the installers didn't allow sufficient fall along the horizontal pipe which goes from sink to downpipe? Would this explain why water of a lower pressure backs up? It is strange though, because I can run the cold supply at a low pressure and it doesn't back up....but as soon as hot is used, it blocks after 10 seconds or so.
Having a bit of trouble with our bathroom sink. We had our bathroom redone a couple of years ago and prior to that had no drainage problems. I seem to remember when the guys installed our new bathroom, they had a bit of trouble with the sink draining but seemed to get round it. The problem started a few months later but unfortunately the installation company had gone through from the recession so we had no comeback. The sink waste runs from trap vertically downwards to a horizontal pipe which runs over around 3-4ft into a downpipe outside.
The hot and cold sink supply pipes run right next to the vertical waste pipe.
The symptoms are:
With cold tap running, sink drains fine.
When hot tap runs (at lower pressure than cold), as soon as water gets hot, sink starts to back up. Once it is blocked, the only option is to plunge it.
After plunging, the sink will be fine for a day or two, and then back up again when the hot tap is used.
I have tried drain cleaner to no avail. I've also used a snake and pushed right through to the outside downpipe without encountering any blockage. The trap is clear. Both bath and sink drain into same downpipe and bath drains absolutely fine. There doesn't appear to be any physical blockage.
I'm now thinking perhaps the installers didn't allow sufficient fall along the horizontal pipe which goes from sink to downpipe? Would this explain why water of a lower pressure backs up? It is strange though, because I can run the cold supply at a low pressure and it doesn't back up....but as soon as hot is used, it blocks after 10 seconds or so.
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