Reply by Gene Howe

My shop is 36X28 with a 10’ ceiling. Like Sumpynubs, I use a ventless gas heater. Mine’s propane, and does have a blower, tho I’d agree, it’s not needed.
While it seldom get’s REEELY cold here, it has been -8 and the heater kept it toasty.
Our home’s well water pressure tank and pump is in the shop, so it MUST be above 30 at all times.
We are seriously considering installing one in the house, also.
Here is the one I use in the shop. ProComm

-- Gene 'The true soldier fights not because he hates what is in front of him, but because he loves what is behind him.' G. K. Chesterton