Okay, I've had them all and I'm kind of a nut when it comes to the safety of my family and home. I've also had foster children and had to provide true information about the safety factors of the types of heat we have had when homesteading; so here's the
real deal on the safety issues.
Woodstoves are wonderful (although soot is an issue) but you just can't stick a pipe through the wall and call it safe. There are a
whole bunch of factors there relating to that pipe (including the type of pipe) and where it is placed, how high, etc. You also have to be a certain distance from the wall, have the stove on a non-combustible surface, etc. You can't just stick a woodstove up and call it heat! Be sure and read up on those issues before going that route. Although your unit is all contained, you still open it to put in wood and you still have stray sparks and you always risk the chance of too hot a fire or a chimney fire. You also have to clean your chimney or, if you have stove pipe, it has to be replaced frequently to be safe. You can't skimp on that and be safe. More houses have had fires due to woodstoves than all the kerosene or propane heaters combined.
Kerosene heaters put off a lot of heat for the money. Those who get the geevies over them haven't seen them lately. They are a whole lot safer than just a couple of years ago. You just have to use common sense and think of them as an open flame in the middle of your room.
Don't buy one second hand, be sure keep it clean, and replace the parts as directions call for, and follow all the directions to the letter. If you do, they are as safe as any other heating unit. We have used them, but we limited them to day use only. Personally, I would not go to sleep at night with one on. Since they set on the floor (and although they will automatically shut off if they are turned over) it is too easy for something to blow against it, or get in it's path. I'm just kind of paranoid like that I guess.
Ventless Propane Heaters are wonderful! I heat my entire house right now with 2 of these and love them! They are also even safer than wood or other open flame because, since 1980, they are required to be equipped with a oxygen depletion sensor which will automatically shut down the unit in the event oxygen is being eliminated in the air at a harmful level of 18% - this is above unsafe levels as established by ANSI (American National Standards Institute). This would also include the fact if you had a propane leak; which you would know anyway because of the smell! Propane (and natural gas) are odorless. An agent is added to them to make them smell as they do so you will know if you have a leak. Running two of these heaters as our only source of heat for a two story 3,500+ sq. ft., 5 bedroom, 10 room home has been less than $400 a year here in SW Virginia. We do get them cleaned every year and checked (costs $30 for both). Another advantage to this unit is that it cannot be knocked over, kicked, or disturbed. It is also self-contained and the flame can't go other inside the unit. There is also safety features which will extinguish the flame should it get too high. When not in use, you can leave the pilot light on; but we do turn ours off just as a safety precaution and because it's just so easy to start when you want it. You also don't use a match to light them; it has an auto start button. Again, you have to use common sense. You won't put them next to where drapes would blow into them, etc. but you can set things next to it as long as it isn't going to touch the flame. Your safety zone is much more than with other open flame because of the "box" around it. Also, they sit up in the air higher where nothing is in the path of them. Here's a link to see some. I can't find one exactly like ours, but it gives you a better idea of what they are like (you can find better prices than these by the way too):
http://www.altapower.tv/z_heaters/St..._PH_Empire.htm
Note:
ALL of the above
WILL emit a certain amount of carbon monoxide! Again, you have to use common sense and you wouldn't use
any of the above in an airtight home. Note, however, that of all the above, only the ventless propane heater will shut itself off if oxygen is depleted in the air; which if your worried about air quality, is the safest of them all. If your worried about fire, none of the above is 100% safe.
We used them along with wood heat for 8 or so years.Other than the dry air we never had a problem.Never noticed any smell or fumes from our properly working heaters.But if the wick gets burned down low they are horrible smelling.If the wick is new replacement and to tall it will smoke like crazy on high.Turn it down or trim it off until it stops smoking while on high.Note you will still get some smoke for the first few secounds when lighting them.And maybe some smoke/fumes when you let them run dry to clean the wick.(never seen a need to let one run dry very often,it just burns out the wick that much quicker if you ask me.)But as i said before the liquid fuel still stinks to high heaven.And you will get it every where when refilling. :haha: 
