The $220 oil heater I bought in November nearly burned my house down in January
I got one of those oil filled radiator heaters from a big box store in Lewiston to cut down on propane use in my workshop. Worked great for two months, quiet, kept the place at 55. Then one night I left it on and went inside for dinner. Came back out and the whole unit was tilted against a stack of cedar planks, the plastic feet had melted into the floor, and the cord was hot to the touch. Turns out the wheels were cheap and one had cracked off. I didn't notice because I never moved it after setup. Cost me 220 bucks for the heater plus 80 to replace a scorched extension cord and a ruined tarp. The fire department guy said these units tip easy and people don't bolt them down. If you use one of these in a shed or garage, put it on a solid base and strap it to the wall with a ratchet strap. I'm now back to my old kerosene unit and just wearing more layers. Anyone else had a space heater fail on them after a few months of regular use?
Wait, actually most of those oil filled radiators don't put out a ton of heat from the bottom. The heat radiates from the fins, not the base plate. The plastic feet melting is more about the unit tipping over and the hot metal touching the floor directly, or the cord shorting out. So a cement board underneath wouldn't have stopped the wheels from cracking, that's just a cheap part failing. I do agree about strapping it down though, that's the real fix. And honestly, if you're leaving it on all night unattended in a workshop full of cedar planks, you're playing with fire no matter what surface it's sitting on.
Funny thing is nobody talks about the floor or surface under these heaters. You said yours melted into the floor, and I bet most people just set them on concrete or carpet without thinking that the heat goes straight down. A piece of plywood or a cement board under the whole thing would've saved you both the heater and that tarp. I strapped mine to a pallet after reading this, cheap insurance for something that gets left on all night.