Space Heater Fire Cause

Recently, we were asked to investigate a fire involving a newly purchased space heater. Space heaters tend to be small heating appliances meant to heat “small” spaces inside a home or other building. In this particular case, the heater was intended for use with propane gas and rated with a capacity of 30,000 BTU/hr. The homeowner had purchased the heater from a local Home Depot store and installed the heater himself. The installation amounted to connecting the heater to a gas supply line. After approximately three days use, a fire occurred. Luckily, the fire was quickly extinguished with minimal burn damage to the floor and smoke damage throughout the remainder of the home. Upon visual examination of the gas line connection, it was noted that the shutoff valve had been attached to the heater gas line fitting. The proper position for the shut off valve was in the gas supply line from the home at the point where the line was accessed above the floor. The outlet of the valve is then supposed to be connected to that part of the gas line that is connected to the heater. However, the main problem was found to have been in the connection of the valve to the heater fitting. The shut off valve appeared to have been cross-threaded onto the fitting. The pipe joint compound used to seal the threaded connection was also scorched and was indicative as well as a confirmation of a gas leak at that point. In should be noted that since propane is heavier than air, an accumulation around the heater while it was in operation would have ignited, which is what actually happened. The photographs below show how the shut off valve was misaligned with the heater fitting and the resulting damage to the heater.

About R.J. Hill, P.E.
R. J. Hill is the author of two blogs: R.J. Hill Consulting and the Descendants of James Alexander Hill. Mr. Hill is a registered professional (mechanical) engineer with over 39 years of experience, 34 years in private practice. Please visit www.rjhill.com to see the kinds of forensic investigations that Mr. Hill performs.

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