Having decided on a Sterling for my new GH, I was reading about them on the ACF website, when I noted the fairly small difference in cost between the single and separated combustion models, as the separated unit is priced with the necessary exhaust system, while the other is not.

I spoke with ACF's Heating & Venting guru, who told me the separated combustion would allow for a really tight seal in the GH, as it draws in fresh air for combustion and heats it in one of the dual vent chambers, as opposed to using the air in the GH, which sounds rather like our direct vent house furnace.

That has appeal, as we do intend to seal the GH as much like a tomb for the really cold months of winter as we can.

He also said separated combustion extends the life of the burners in GHs, as the dry winter air coming in, helps to offset the effects of damp air in the GH on the burners, which makes sense.

It might also increase fuel effeciency a bit too, with all that oxygen being fed to the combustion chamber.

I can't rely entrely on plants for that, as at least half the space in the GH will be devoted to fish tanks.

It SOUNDS like a better idea for a year round use GH in a cold climate. BUT: is there a downside?

Opinions?