Plumbing instructions self contradictory?

[tabbypurr]

Vaillant condensate circuit information:

It is not necessary to provide air breaks or extra traps in the discharge pipe as there is already a 75mm high trap inside the boiler. Fitting an extra trap may cause the boiler siphon to work incorrectly.

(b) Connecting into the internal discharge branch (e.g. sink waste or washing machine) with an external termination, the condensate drain pipe should have a minimum diameter of 22mm with no length restriction and should incorporate a trap with a 75mm (3) seal. The connection should preferably made down stream of the sink waste trap, if the connection is only possible up stream, then an air break is needed between the two traps. This is normally provided by the sink waste.

Don't those two contradict each other?

NT

[John Rumm]

Not quite (although it could have been worded better)! What they are seeking to avoid is having the condensate drain connected directly to a second trap without any air break. So into an open waste pipe before a trap is fine, and into a waste pipe that is open at the far end but after a trap is also ok.

(I find that a washing machine stand pipe waste is often a handy place to take a condensate drain - but a tee on the top and a reducing bush to take the 22mm pipe, then the side branch can be left open for the hose from the washing machine etc)

[tabbypurr]

ahh, makes sense :) Cheers.

NT