Which pipe to join to 100mm wall outlet gravity flap

[benjiman]

Hi,

I've made a core hole for a new bathroom extractor. Bought a 100mm wall outlet gravity flap for the outside wall.

The hole is through a cavity wall so need a pipe to fit into the outlet that ive bought to bring it into the ceiling void, from where i can then connect a flexi to join to the extractor fan.

However cant seem to find that pipe in toolstation/screwfix. They sell a 100mm piece of short pipe. But that is the same size as the outlet of the gravity flap.

I know piece of soil pipe will fit onto the end of the gravity flap, but i dont want to buy a full length of pipe when i only need a 400mm piece.

 

[phatboy]

a 100mm flap is designed to fit inside a 100mm pipe. You should be fine.

Hopefully your hole is 105mm or thereabouts?

 

[oldbutnotdead]

Be prepared for disappointment with your gravity flap, they usually rattle in the wind & jam open. Whatever pipe you put in, keep the rigid as long as possible & give it a slight lift inside (so any condensation will run out). And get an extractor with a powered louvre- yes they"re dearer but they work.