Got Gas ... Heat?

Got Gas…Heat ?
 

Many of the homes in our area are heated with natural gas.  Simply put, flame equals heat.  Although the concept is simple, the application can be complex.
In the last article we discussed forced air units (FAU) in general terms that applied to both gas and electric models.  This article addresses the issues related to gas fired heating systems.  While most homes have FAU systems, others have wall furnaces or floor furnaces.  Some have hydronic boilers or steam boilers used with radiant systems.
As with any source of power or energy, certain precautions are in order.  The gas that is piped to our homes is naturally odorless.  The gas company adds an odorizer for safety.  When we “smell gas” it’s the odorizer we detect.  Call the gas company for a free safety check.
At each gas appliance, the gas valve should be easily accessible in case you need to turn it off.  Older units may have flexible brass or solid aluminum tubing connections that are no longer approved due to potential leaks.  A new connection is not very expensive and could be a life saver.
In order to burn the gas efficiently and get the maximum heat the right amount of combustion air is required.  Excessive production of carbon monoxide can be avoided with an adequate supply of air for complete combustion.  In general, the combustion air should not come from the living area and never from a sleeping area.  For safety, only outside air is used for combustion.
When natural gas is burned, the products of combustion include carbon monoxide, carbon dioxide and water vapor.Most of the safety issues associated with gas heat deal with the exhaust venting.  Flue draft hood, size, material, clearances, connections, slope, length, and termination point all contribute to the safe disposal of exhaust gases.
 Except on high efficiency units, the gas exhaust vent can get extremely hot and is usually made of galvanized metal.  Required fire safety clearance to combustible materials for single wall pipe is six inches, for double wall pipe it’s one inch.  Single wall pipe should not be used in an attic.
Some older homes have exhaust venting made of transite, a concrete-asbestos product that requires one and a half inch clearance.  Although the asbestos in a transite pipe is encapsulated, and poses little threat to health, there is another problem.  The exhaust gases tend to condense on the relatively cool inner surface of the pipe and become a corrosive liquid.  Any metal components below the transite are subject to rapid deterioration.  If you see powdery white streaks on the metal or corrosion on the heater, call a heating professional for evaluation.
Adequate venting of the products of combustion to the exterior is critical. Because of the production of potentially deadly carbon monoxide, the termination of the exhaust vent must be away from windows or other openings into the living space.  This applies to all gas heaters including pool heaters.
If there is sooty blow-by around the FAU registers, it may be caused by poor maintenance. But it could also be caused by a cracked firebox.  As the name implies, the firebox contains the flame.  Air to be heated is passed over the firebox.  If the firebox is cracked, combustion gases including carbon monoxide can enter the conditioned air stream and be distributed throughout the house.
The good news is that if you have to replace your gas furnace, the new models are more efficient.  A high efficiency furnace can pay for itself in lowered gas bills.
Last but not least.   If you are experiencing flu-like symptoms or regular headaches during the heating season, you may be feeling the effects of carbon monoxide poisoning. Be safe. Be healthy. Get that safety check!