Fire officials in
Minnesota are often questioned by the public as to the performance of smoke detectors versus heat detectors when installed
to provide early life saving warning in the residential environment. State Fire Marshal Division personnel also receive similar
questions concerning the requirements for smoke detectors in residential buildings as required by the 2003 Minnesota State
Full-scale fire tests
conducted since the 1960’s have shown that smoke detectors are more reliable than heat detectors for early warning to
provide live safety in homes. In the January/February 1993 NFPA Journal, Bukowski summarizes 10 independent studies comprising
over 200 experiments that prove this point.
The following text
is extracted from State Fire Marshal Division Fact Sheet titled Fire Alarms in Group R Division 3 Residential Buildings. Local
fire officials are encouraged to develop similar policies to provide guidance in dealing with the issue of smoke and heat
detectors in residential buildings.
SMOKE DETECTORS IN RESIDENTIAL OCCUPANCIES
Experience and full
scale testing has shown that typical residential fires produce detectable quantities of smoke prior to detectable levels of
heat in nearly all cases. In addition, slowly developing, smoldering fires may produce incapacitating and even lethal levels
of smoke and toxic gases without any significant increase in room temperature. The Minnesota State Fire Marshal acknowledges
that approved heat detectors installed in areas not appropriate for smoke detector installation such as furnace rooms, garages
and unfinished attics, may provide some additional warning in the case of a fire confined to these areas. The State Fire
Marshal will not accept heat detectors as an alternative or equal to smoke detectors in locations requiring the installations
of smoke detectors.
IONIZATION VERSUS PHOTOELECTRIC DETECTORS
In cases where smoke
detectors are subject to frequent false alarming due to cooking, smoking or similar causes, the State Fire Marshal encourages
the installation of photoelectric smoke detectors as they are not as susceptible to these types of false activation.
Studies have shown
that ionization detectors are better at detecting small, invisible particles of combustion that are typically present from
fast, hot, flaming fires. These studies have also shown that photoelectric detectors are better at detecting larger, visible
smoke particles that are more commonly seen from slow, smoldering fires. Both types of smoke detectors have been shown to
be effective in detecting typical residential-type fires. Some research seems to indicate that photoelectric detectors may
activate slightly sooner as many residential fires start out as slow, smoldering fires.