How Much Heat will a 1800 Watt Bulb Produce?
1800 Watts at 25% efficiency means 75% is wasted or 1350 watts is being radiated as heat. Let's be very very inaccurate and say 1/4 of that heat is heading towards you. That's 337 watts of direct heat to you. The human body produces 100 watts of heat on its own. You've just added 3X that amount.

If you're already in a room temperature environment (70F), then yes, you'll get toasty fast. If you're in a 40-50 degree room, it might actually be somewhat comfortable on your face, although your feet will probably go numb.

Keep in mind that these numbers are extremely rough and there's a lot of guestimates in here. I would say my margin of error may be around +-100%...

Ask a vague question...get a vague answer I guess. Hope it helps a little though.