Philip-
There's no "setting" you can change. It will simply depend on making sure you don't get a heater where the load is too high for your wiring. Typical home wiring is usually 14 gauge, with the circuits controlled by 15 amp breakers/fuses, which means that a typical circuit can handle a power load of about 1800 watts. Many of the smaller heaters draw 1500 watts, so, as long as you buy one this size and -- don't have the same circuit loaded up with other stuff, like lights and appliances -- you should be fine. If you overload the circuit it will, hopefully, cause a breaker (or fuse) to blow. But, there is also a small risk of fire if your system isn't up-to-snuff. Do you have old wiring? Do you know what the amp rating is for this circuit? (If you have breakers it will be printed on the breaker switch for that circuit).

Thanks for kudzu9's explanation!

The heater will be used in the basement, I have old wiring. I really don't have any idea about the amp rating for this circuit, which should be shared with my media (TV, hi-fi) and recesse lights. If I use the lower wattage heater, Do I have any risk of fire?

If there is a properly sized overvoltage protector (circuit breaker / fuse) and the wiring is in good shape, there is little fire risk from an overload. What you may do is find yourself with a blown fuse / breaker. A bigger issue is to make sure that combustibles are kept away from the heater. Also make sure the cord on the heater is in good condition and NO EXTENSION CORDS should be used.

let's see, TV, hi-fi, and recessed lights. are you sure they are all on teh same circuit or are you just assuming since they are int eh same room? if you know for a fact they are, then simply check which breaker it is and see what the current rating is on it. a 20A circuit handles up to about 2400W, while a 15A handles only up to about 1800W. both of these are TOTAL loads, so lights, tv, etc plus the heater.

if you absolutely MUST use an extension cord, then spend the extra 5.00 to get an appliance rated extension cord. regular cords will not handle the current and eventually melt. appliance cords are rated for higher current draw and actually the only recommended extension cord for heaters. our local fire dept says not to use ANY extension cords, but if you must they recommend the appliance cords.

you ALWAYS have a risk of fire with a heater. read the directions, follow them, and use common sense to minimize this risk. growing up we had those old roudn heaters that would cook an egg a few feet away. i can't tell you how many jackets i burnt up standing too close to one. newer heaters use fans to move teh heated air, so lower wattage units cna heat a room more evenly.

if you really wnat good even heat with lowest power consumption, get an oil filled radiator heater. they use less power and therefore minimize the risk of wiring issues/overloaded circuits. they run longer, but once the oil heat ups they heat evenly and safely.

i can't tell you how many jackets i burnt up standing too close to one.

Many, many years ago I was involved in a little "accident" with a space heater. The girl I was seeing at the time was staying with her grandmother. The grandmother kept the thermostat pretty low a and used space heaters in the bedrooms. The girl had a heck of time explaining to her grandmother how the comforter fell off the bed in the middle of the day ended up right next to the heater. Damned cats... ;-)