Change Monarch Add-a-Furnace Airflow direction

[newburner2]

Greetings,

I have a Monarch Add-a-Furnace with the blower set on top, pushing the air around the firebox and into the crawlspace of an old cabin. There used to be duct work in the crawlspace, but the rodents appear to have destroyed all of that. As such, it doesn't heat very well at all.

Pondering my options, it seems that replacing the duct work will likely lead to the same results unless I found some insulated, rodent proof duct work, which seems expensive.

My other idea is to close off the ducting under the furnace, and drill holes (or somehow add venting) to the lower1/4 of the furnace sides...allowing the blower to force the hot air directly into the living area.

Is that a bad idea or present any safety issues? Any other ideas to get some use out of this old furnace?

Thanks in advance for any guidance!

 

[coaly]

Does the furnace have a return air duct?
Blowing hot air into a building pressurizes the structure preventing flow of warm air into it. You need to return cool air to be reheated from the same area you're heating.
It is also difficult to move hot air which is lighter and buoyant into colder heavier air.
Metal ducts and wrap with insulation if needed. Control rodents and patch the insulation as needed?