Are you sure of that without me looking? I have an oil and LP fired unit. Both into chimneys but we looked short at the direct vertical wall vented unit and was very quickly turned away by the installer.Energy Kinetics of System 2000 fame has a direct vent oil furnace.
Well I’ll be.I was surprised myself
Resolute RT and 90+ Resolute incorporate multi-fuel technology which allows for exceptional performance with high efficiency and nearly endless water!energykinetics.com
Huummm. My post went whackyThe only bad things about EK I have heard are dealer service issues. Up in my area they don't have a lot of market penetration so the service guys are bit less familiar with the more complex controls. They can work on the burners but not as good on getting the options to work. Both people I know locally both said they need to be cleaned yearly no matter how little they get used.
I had friends with power vents over the years and non were thrilled by them. The siding would get blackened by soot and during the summer with the windows open (no AC) they might get a exhaust smell on occasion.
FYI they are real small, the dealer usually hits you up for stand to get it up off the floor.
My backup oil furnace is getting to be 30 years old and was looking at them but I don't need all the features. If I found a used one I might spring for it but they are pricey since they only sell through dealers.