Remember that this shelter is an EMERGENCY short term option. It is meant for LIFE and DEATH situations. Caution and care MUST be used when employing a fire with the shelter. The shelter will melt and burn if put in the fire. It is by no means fireproof.
Any fire will be dangerous and must be properly controlled regardless of the distance to the shelter. The shelter should only be used with a fire when the alternative is hypothermia or death.
Small sparks will melt through the front panel leaving little pin holes. These don't really affect the performance of the super shelter but they can be fixed with a little tape.
It is recommended that a fire be no closer than 3 feet from the front of the shelter and no larger than absolutely needed for warmth. Start with a very small fire, then build it up as necessary to heat the shelter while maintaining control and the proper standoff.