Review on Natural Gas Heater: Mr. Heater Vent-Free 20,000 BTU Blue Flame - Multi-Size Option by Leon Yulharmanto

the heater itself seems fine, but I REALLY REALLY would've liked a heads-up regarding permit issues. I don't know if this is the same everywhere (I'm in Eugene, OR), but because this appliance uses combustion, and is ventless, the building codes do NOT allow it to be the only heat source.so after spending $2400 to get the gas lines installed, I learned the city requires an alternate heat source as well before they would issue the permit/give me a 'certificate of occupancy', so I ended up paying to have electrical heat installed as well.and another possible heads-up: the contractors tell me (and directed me to an article online) that condensation on interior surfaces tends to be a problem with ventless gas heaters. I have used the heaters for a few weeks now and have not observed an obvious condensation problem, but longer term issues (mold?) are still a concern.so before you decide to go with ventless gas heat, do your research!(and if do you decide to go with it, then this heater seems perfectly fine :-)