to get decent reasults dont you need a bottle heater to keep constand bottle pressure?
depends on the size of the bottle.... they use latent heat (like LPG cylinders do) and take heat from the environment around them when liquid is being drawn off to "boil" the bottle contents and maintain cylinder pressure. the smaller the cylinder, the less surface area they have to draw heat from so the smaller bottles freeze up in no time, when this happens, you do get a pressure drop.
I have found that running a 25LB bottle, it's not really a problem.
