We had a new bathroom fitted a couple of years ago. The bath and toilet are fine, however the basin drained very very slowly.
I cured this by adding an antivac trap, however the sink is draining slowly again. It takes about 5 minutes to drain 2" of water. I've replaced the anti-vac valve, but it hasn't helped.
Since then I've worked out that if I push the anti-vac valve up a little, air comes rushing out of the system, sometimes with a little water and the basin drains at a normal speed.
Any idea what this means? The bath drains normally still.
I cured this by adding an antivac trap, however the sink is draining slowly again. It takes about 5 minutes to drain 2" of water. I've replaced the anti-vac valve, but it hasn't helped.
Since then I've worked out that if I push the anti-vac valve up a little, air comes rushing out of the system, sometimes with a little water and the basin drains at a normal speed.
Any idea what this means? The bath drains normally still.