auto ignition
blaze
blue
boiler
burner
button
carbon monoxide
checking
co
co2
combustion
control
copper
danger
death
device
equipment
exchanger
fault
fire
flame
fossil
fuel
gas
glowing
heat
heater
hot
house
invisible
kitchen
leak
malfunction
naturalgas
no color
no smell
old
poisoning
power
radiators
relay
repair
silent
spark
temperature
white
winter