Special Feature Article


Jeffrey May,B.A.,M.A.
Author, Inspector, Teacher

Former Chairman of Education Committee, ASHI-NE.

Former Member of Council of Representative at ASHI National.

1999 Recipient of the ASHI-New England President's Award.

1996 Recipient of the ASHI-New England Frank Long Award. T

 

"One rather dangerous defect that I have observed in several new homes has to do with the improper venting of furnaces and water heaters. Some furnaces today have powerful fans to suck the combustion gases out of the furnace."

 

 

 



 

 

 

 

 

 

 

Healthy Heating System

by Jeffrey C. May, J. May Home Inspections, Inc.

Winter is hard upon us and snow blowing and shoveling have me thinking about being inside a warm home and having adequate heat (which I do not!). Since I have already written about the difference between a boiler and a furnace and I have described how boilers and furnaces work, this month I will look at combustion equipment from the perspective of safety.

People are generally cautious about things with visible fire because they can see the flame and associate the danger with it. Unfortunately, the heat that we experience upstairs from the boiler or furnace in a home is not very intense; it does not make us think about the actual flame that may be burning somewhere to provide that hot air or water. Out of sight and out of mind, a boiler or furnace chugs on, but can deteriorate to quite a hazardous condition if ignored long enough.

Combustion equipment, just like a car, should be checked annually by a qualified technician. Neglect produces the most common safety hazards associated with combustion equipment. For example, and this is most common in older homes, chimney flues are often deteriorated at the interior, containing crumbling bricks or liner tiles. These can create piles of masonry debris at the bottom of the chimney flue.

In addition to masonry blockages, I have also seen raccoons, squirrels, birds, and even a football and a tennis ball blocking a flue. Expect the worst. Should a flue become completely blocked, as is the case in approximately 5% of the homes I inspect, all the combustion gases will vent into the interior of the house, creating potentially lethal condition should carbon monoxide be present in the combustion gases. (A client told me that his entire family was poisoned by carbon monoxide because the family cat fell asleep on top of the chimney and, dreaming of catnip, rolled into the flue, blocking off the furnace vent.)

Oil burning equipment is in need of regular maintenance, far more so than gas burning equipment. Oil burners flames tend to be dirtier than gas burners, and combustion chambers in oil-fired equipment can rapidly build up so much debris (from rusting of iron and deposition of flame-soot) that draft can be significantly reduced, resulting in a spillage of combustion products into the home.

Note that oil-burning boilers are supposed to be cleaned every year at the interior, but only rarely is this done. Most boiler service technicians appear only to change the burner nozzle regularly. Allowing debris to build up on the interior of the boiler can result in a loss of up to 10% of fuel efficiency.

Gas-fired boilers and furnaces are also subject to problems as a result of the accumulation of rust collecting on burners. The gas burners in a gas-fired boiler should be checked regularly and brushed clean as necessary by a gas technician, to prevent build-up of rusts on gas ports.

In nearly all homes with combustion equipment in the basement for heat, there is a metal vent pipe between the boiler or water heater and the chimney. The metal pipe conducts the combustion gases from the boiler to the chimney flue. It is not uncommon to find the vent pipe poorly supported, disconnected, or rusted through in many locations. Be sure to have your vent pipe checked regularly; a fallen or blocked vent pipe can result in either a fire or combustion gas poisoning.

My wife was a real estate agent for a few years, and she sat one winter day at an open house. No one showed up, and after an hour, she began to feel quite nauseous and dizzy. She decided to wait outside the home. The house sold and on the home inspection, it was discovered that there was a large hole in the vent pipe; most of the combustion products from the antique furnace were entering the house. As it turned out, the sellers were not affected because they never stayed in the house with the heat on unless all the windows were open.

One rather dangerous defect that I have observed in several new homes has to do with the improper venting of furnaces and water heaters. Some furnaces today have powerful fans to suck the combustion gases out of the furnace. These fans blow the noxious gases into the vent pipe and into the chimney flue, creating pressure in the vent pipe. Should there be an opening in that pipe for a vent from an ordinary (gas-fired) water heater, there is the possibility of combustion gases from the furnace or water hea ter blowing out through the water heater draft hood.

If you are buying a home, you should be aware of a new requirement in Massachusetts as of January, 1995: all new gas installations must be vented into lined chimney flues. This means that if you are planning to replace the boiler in a Victorian home, you should probably add about another $l500 to the cost of the boiler for installation of a metal chimney flue liner.

Maintain your combustion equipment and you will sleep well.

From "JUST PROPERTY"


Jeffrey May (M.A. organic chemistry, Harvard University) is founder and principal of J. May Home Inspections, Inc. located in Cambridge, MA.

 


 


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