Limitations were.
Must drain into the sink trap located on an external wall
4 stories up, external plumbing mods impossible
The single kitchen drain outlet is 55cm above the floor. The sink drain is vented and functions perfectly.
Island location not negotiable.
The distance is within the pump spec ie < 3m
On the recommendation of the plumber we had installed a sealed drain connection to the sink trap via the original corrugated washing machine hose, looped to under bench height, then down into 25mm pressure pipe via a sealed connection which runs in a 50mm cavity between the slab and timber floor to behind the sink cupboard and up to the large size washing machine spigot immediately under the sink bowl and above the sink trap.
It works but the pump cycles abnormally during final spins and is clearly not happy.
Research says the double lift is a problem and the original advice was flawed.
Could an aav at the machine or a one way valve solve the issue, or alternatively removing the pipe loop at the machine and just relying on the one lift at the sink to avoid siphoning be the solution?
