Originally Posted by Vulcanus
I would create a unique big lower air intake, but the intake tube must be put directly under the centre of the fire basket (not laterally).
I would create a simple air diffuser to prevent the ash clogging the air intake tube and also for better air distribution like a chimney cowl
I personally think there's no difference where and the direction the intake air is coming from. I have seen UDS's like you described with intake beneath the fire basket. Different, but no benefit. I've modified my ECB in this manner.
Also an elevated ash pan attached to your charcoal basket will make cleanup a lot easier instead of attaching a cowl or barrier over the intake to keep ash away.