Flue size

Go for it!

The original Convair’s were often installed in a brick fireplace with a concrete shelf fitted around 6 inches above the heater, there was a cast iron threaded flue section fitted between the heater and a hole in the shelf.
The chimney was simply open above this often one brick or more wide without a flue.

You should have no issues with your plan, apart from any legal requirements if installed in your house (if local laws require)

Originally Posted by droog

The original Convair’s were often installed in a brick fireplace with a concrete shelf fitted around 6 inches above the heater, there was a cast iron threaded flue section fitted between the heater and a hole in the shelf.
The chimney was simply open above this often one brick or more wide without a flue.

You should have no issues with your plan, apart from any legal requirements if installed in your house (if local laws require)

Thanks for an interesting post, droog. Two questions if i may;
how did they clean the chimney?
did the cast iron threaded section look like this?

Originally Posted by tiprat2

Thanks for an interesting post, droog. Two questions if i may;
how did they clean the chimney?
did the cast iron threaded section look like this?

Not sure on cleaning, the 15 year old unit at my parents house never had the chimney cleaned that I could remember.
The Convair that was in our current Cal Bung was also installed with open chimney, lots of ash when it was removed I doubt it had ever been cleaned after the heater was installed.

Yep that is the flue connector, there was also a cast iron ring that raised on the thread, if I remember the ring was put at the bottom of the connector while it was inserted through the hole in the shelf. Once the heater was in position the connector dropped into the receiver on the heater and the lock ring spun up the thread to push against the underside of the shelf. Fireproof mortar was used to seal it all up, or it may have had a nice asbestos rope for the seal.