Risk to boiler of backfilling through condensate trap

[SydDenham]

Hi

I have a condensing boiler recently installed with a small bore pipe taking the condensate into the internal waste drainage.

Does the Valliant boiler have protection in it to stop any back flow from a feed that enters the same condensation pipe? The feed into it will naturally flow away from the boiler due to the fall but there could be a risk of it temporarily backing up.

Any thoughts gratefully received..

 

[Scott_D]

Any pictures?

 

[Harvest Fields]

Sounds like it is just connected to a sink waste. Vaillant say that this is perfectly acceptable. But a picture would help.

 

[Last Plumber]

The Vaillant trap is good but it is not designed to prevent back-flow.

 

[Harvest Fields]

The Vaillant trap is good but it is not designed to prevent back-flow.

Nope but the boiler does lock out when it does.

 

[SydDenham]

Thanks for your input so far.

I've no photos but the proposal is to feed the flexible pipe of one of those half height dishwashers into the pipe that takes the condensate from the boiler. The boiler is under the worktop so (from memory) 150mm off of the floor.

The pump on the dishwasher is (according to its instructions) very weak (it won't pump vertically more than 100mm) and the condensate pipe is the only pipe that is low enough to feed it to.

The condensate pipe is 1.8m long and falls until it enters a 40mm waste pipe in the adj. bathroom. The dishwasher would enter into the condensate pipe about 600mm from the boiler.

The 40mm pipe junction with the condensate pipe is not easily accessible.

 

[ShaunCorbs]

No you can't fit a diswasher into the condense overflow pipe

 

[johnduffell]

That pipe will be too small for the dishwasher waste, needs to be 40mm minimum.
Otherwise your own would also need an air break between the boiler trap and the connection to the washer, which is doable.
My recommendation would be to check the dishwaterd instructions as usually the pipe has to raise up to just below worktop height to avoid sink water flowing into the dishwasher and the dishwasher from draining by gravity.

 

[SydDenham]

Thanks for your inputs - although the dishwasher instructions said it would only pump 100mm vertically, it seems to be happy (15 washes now) with pumping up around 500mm so it's been plumbed into the sink waste above it. Therefore no need to try for the condensate pipe.

Thanks again