False bottom height

[Bru]

What is the ideal height of a false bottom (space between the base of the pot and the fb)?

 

[Catt22]

What is the ideal height of a false bottom (space between the base of the pot and the fb)?

There is no ideal height that I am aware of. The general rule of thumb would be the lower the better. Usually the limitation when using a full width FB is the kettle drain port. The exception to this would be if you have a dip tube installed. IIRC, the FB on my Polarware kettle is about 1-1/2" above the kettle bottom and the volume beneath it is about one gallon. I also have a converted keg with a pie plate type FB which sits closer to the bottom, but it's not full width. The volume beneath that one is only about 1/2 gallon. So, IMO the height is not at all critical, but it's better to minimize the volume under the FB so that you don't have to up your water to grain ratio excessively for the mash. IOW, there's no advantage to installing the FB higher than necessary.

 

[Bobby_M]

The lower the better as Catt said. The more liquid volume you have below, the more "apparent" thickness you have in the mash above. This could be an issue in a recirculating system if you like to stick to ratios of 1.5qts/lb or lower. There are a lot of variables that affect whether you'd have a problem.

 

[Bru]

That makes sense - thanks.
I gather there are two ways to install a false bottom - either above the ball valve/drain tube with no dip tube (supported on nut and bolt "legs") or below the valve with a diptube.
It sounds like the latter may be the best option as it allows the FB to be lower and the dip tub can be used to keep the FB down.
Is there a concern that when using the first method the FB lift up allowing grain underneath and a potential stuck sparge or is there a way around this ?

 

[Catt22]

Much depends on the type of FB used. I prefer the full false bottom without a dip tube. The weight of full width SS FB is more than sufficient to keep it from lifting. The one I have for my Polarware kettle is a very snug fit. It has built in supports or legs. OTOH, the pie plate style FB for the converted keg is simply supported by it's rim resting on the concave kettle bottom. This one could move or lift very easily if not held down firmly by the dip tube. IMO, the very small advantage of the pie plate being closer to the bottom is far outweighed by the better performance of the full width FB with much more surface area. The larger volume below the full FB has proved to be no problem at all. I have no doubt that the full width FB is the better choice as it is much less prone to sticking. Lifting should not be a problem with either if they are constructed and installed properly.

 

[Bru]

Great, thats what Im going to use then (will be used in a 25 gallon pot with a diameter of 20").