New boiler condensate pipe plumbing - advice please

[jim2000]

I plan to plumb the condensate pipe from my new boiler into the waste pipe that currently serves the kitchen sink, the washer and the dishwasher.

Having looked at old topics on this group, it seems I may need a trap - no problem.

What I am worried about is drain water travelling under pressure up the condensate pipe to the boiler when the washer and dishwasher are pumping dirty water out at the same time. Goodness knows what this would do to the boiler. I guess negative pressures could be a problem as well.

Does anyone know if this is this a realistic concern, and is there anything that can be done? Maybe some sort of mini air admitance valve like the ones you get for soil pipes?

The boiler is only about 2 foot higher than the top of the washer and the appliences are sealed to the waste with clips. The waste joins a ventilated soil stack outside.

Thanks.

[andyv]

I had a minor concern about this situation too, but reasoned that if it was going to be a problem then the washing machine waste would first of all pump up though the sink trap.

As it doesn't, no probs.

[David Hansen]

On 18 May 2006 04:56:04 -0700 someone who may be "jim2000" wrote this:-

Read the boiler instructions. Many have a trap built in.

Unless the level of the boiler outlet is close to that of the existing waste pipe then that will almost certainly not be a problem. If it was a problem water would come back up your sink plug hole in this situation.

[dg]

I used one of those clamp on waste connectors designed for washing machine waste hose. It has a one-way valve.

dg