Presumably the tea candle will produce enough heat to equal that radiated by the typical human bod. That might help in a small, enclosed space.
Fortunately,my living room sports a fireplace and I have a stack of firewood. That will produce a lot more heat.
I've heard that too but a check on Wikipedia seems to indicate that it would take
3 tea candles to equal the BTUs an adult male will generate. I hear that a number of people will burn a candle in a snow shelter/Quinzee to bring the temp up to near the freezing mark. (Hotter than that would ruin the shelter and cause drips.)