Hi all,
My friend and I have recently built a 5" BBR from 2 drums and split fire bricks.
Everything is exactly to spec. The riser is square with the rear chambered to just above the height of the port. From the height of the top of the fire box upwards it is a 5minute riser. No ramp the same as the 2017 BBR on Peter's site.
The thing heats the house very well, however it is pulsing very badly like others I've seen. A few flames per second pulsing out of the primary air.
I read somewhere that Peter said these are usually caused by a restriction down the line. The flue is also 5" so it
should be fine.
The possibility that comes first to mind is perhaps the transition area fell barrel to flue needs to be larger than 5" diameter?
Opening the door a little stops the pulsing, but that is no doubt due to poorer efficiency of the burn and therefore less air requirement and poorer draft so it no longer suffers from the restriction causing the issue.
There is definitely an efficiency problem because the bricks never clean like my ones at home do shortly after lighting it. They stay black.
Am I on the right track with the transition area? Or is something else worth checking first?