That's very true. Mine uses 2000watts!...
So that means that heater will draw 16.7 amps (if it's running on 120 volt). That pretty much uses up a 20 amp circuit breaker. So if you've already got a 5 amp light ballast and a couple of 1 amp fans running on that circut and the heater comes on,
pop goes the breaker.
Most of those cheap electrical timers we're all using (I've got 3 of them in my set up) are only rated for 15 amps. You wouldn't want to use one of them to regulate a 2000 watt heater. And even the timer it's self uses some amperage. Maybe not very much but when you start getting several of them it all starts adding up.
Another word of caution....Don't just go installing a higher amperage breaker. The size circuit breaker that's there has been used to protect (from over heating) the size wire that's been used to run to the outlets. So if you start tripping breakers
do not simply put a larger breaker in. You need to get another 20 amp breaker and run another 20 amp rated piece of Romex wire to the area you need more power.
They way most houses are wired they are not set up for you to be running 30 amps worth of electrical equipment in your bedroom closet from the closest outlet to it.
I ran another dedicated 20 amp line to mine (to supplement what was already close at hand there) just to make sure I didn't burn my house down in the process of growing my own weed to save a little money.
Jack
Wattage divided by your voltage (120) tells you how many amps something draws.