PS - a comment on the heater for future reference ...
You should not need to remove the heater when doing pwc's. Just unplug it so it doesn't turn on "dry". (Otherwise the glass will overheat & crack.) If you must remove the heater, make sure it had cooled a bit in the water after unplugging ... that would have prevented the carpet burn and also prolong its life.
Oh, well, see what happened was this: The glass top didn't crack from the heat of the heater; what we did was remove the glass in order to access the surface of the water to do the change, and I placed the glass top wrapped in a towel toward the side of the tank, where my wife accidentially stepped on it when assisting me with doing the water change. The top cracked in half on one side, but it fits on top of the tank okay right now in two pieces together, like a puzzle, until the new top that we ordered yesterday from the store we ordered the tank itself from comes in.
As for the heater, what happened was, I didn't remove it just to do the water change -- I figured that because we're not treating for Ich anymore, I could remove the heater altogether because I decided to leave the tank at room temperature. When I did this, I unplugged the filters and bubble wands and heater, but I placed the heater, like an idiot, directly on the carpeting without taking the plug of the heater out of the extension cord plug it was connected to, and then I plugged everything back in once the water was replaced -- suddenly, smoke started to come out of the heater while it was on the carpet, and it was burning right into the floor -- we have a carpet repair guy coming tomorrow to fix this, but I just can't believe I did this...I should have just left the darn thing in the tank and just unplugged it.
Instead, I took the whole heater out of the tank to store under the tank's stand housing because we're not using it right now, and thus almost caused a fire by placing it on the carpet.