You should contact emergency help lines,

• If you smell gas;
• If you suspect the presence of carbon monoxide;
• If you hear a loud noise whenever the furnace turns on
• If the furnace won't shut off
• For all new homes that have gas appliances installed – inspection must be completed prior to occupancy
• For inspection of natural gas appliances that have been given a "warning tag"
• If you convert appliances from one fuel source to another
• If you 'self' install gas appliances without a qualified licensed technician