I have to install extractors in the kitchens of several HMO's.

I requested from the local BCB guidance on what they would require in terms of operation (manual or automatic) and extraction rates and they of course referred me to AD F which today, is making my head hurt!

I'm thinking of installing a constant trickle fan with humidity boost but the 4inch fans (eg Vent Axia Lo Carbon Centra) don't seem to meet the 60 l/s extraction rate stated in AD F, or am i misinterpreting the figures?!

Then we get on to being referred to AD J re: open flue appliances....

Any guidance much appreciated!

"I have to install extractors in the kitchens of several HMO's."

What does the commander making you install these specify?

Regards

BOD

As I read it, if you're having a simple intermittent extract, it's 60 l/s - usually achieved with a 6" fan (or 30 l/s using a cooker hood).

If you're having constant low-level extract, with boost, it's 13 l/s at high rate - the low rate depending on the whole dwelling rate (based on number of bedrooms etc.)

Not sure if it's different for HMOs though.

- Andy.