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I purchased for a token fee the following Eltex Greenhouse Heater:



As can be seen the casing is totally zinc and it appears to work alright. I think the theory of operation is that the heat is directed from the wicks and travels up the windowed chimney from there it travels to either side of the of the bottom horizontal cylinder (heating that in the process) and then presumably to the vents located in the sides from where it heats the external air.

I wondered if anyone could throw some light on the following questions:

What would be the approximate year of manufacture of this heater?

Is the top horizontal cylinder connected to the bottom one ?

I was informed that the horizontal tray above the bottom horizontal cylinder should have water in it (which it has). I assumed this was to provide a moist atmosphere, but doesn't paraffin deposit moisture in the atmosphere of its own volition and if so then why place a dish of water there?

Can anyone tell me exactly how this heater is supposed to work?