November 1997 Edition

Hazardous Furnace Vent Pipes

We have a high efficiency furnace with plastic vent piping. Can you tell us about the current problems some people are having with their furnace vent pipes and which brands are included?                       
Homeowners are taking legal action against vent pipe manufacturers to recover the cost of removing and replacing allegedly defective vent pipes from their homes, which if left uncorrected can result in flu gases leaking into living spaces - a significant health hazard. 
High-temperature plastic vent pipes are installed to vent some home heating appliances and equipment. The plastic pipe is sold under various brand names: “Plexvent”, “Spirolite”, “Selvent” and “Ultravent.” Some plastic vent pipe products refer to being made of “Ultem.”                       
These vent pipes, when used to vent high-temperature flu gases, are alleged and reported by consumers to be prone to premature failure because as the plastic pipe is heated and cooled, it expands and contracts, causing the vent pipe to prematurely crack and deteriorate.          Anyone owning a home which contains any of the above named products, should have their systems inspected by a licensed heating and air conditioning contractor and repaired or replaced as needed. 

White Powder On Metal Furnace Vent Pipes 

Our furnace vent pipe has white powder around some of the joints in the pipes. Is this normal and will it hurt the piping?                       
Natural gas is about the cleanest-burning fuel around. But it’s not perfectly clean. Along with water vapor and relatively harmless carbon dioxide, the exhaust from gas appliances contains trace amounts of sulfur and nitrogen compounds. If the water vapor cools enough to condense in the vent pipe or flue, these sulfates and nitrates condense along with it, forming a weak solution of nitric and sulfuric acid that can corrode metal or masonry.
A southern California heating contractor told about a case where the problem went beyond corrosion. Called to a house to investigate a malfunctioning furnace, he found the unit connected to a metal vent pipe that was completely plugged with a white crystalline precipitate. Exhaust condensing in the long run of vent had not only corroded the metal, it had reacted with elements from the pipe to form a crumbly mass that collected in an elbow.                         “
This happens when a new, more efficient furnace is hooked to a vent that’s too big,” said the contractor. “In the old furnaces, the stack temperature ran about 400 degrees F. In the new models, the exhaust is cooler, and it condenses instead of going up the chimney.”                       
Worse, after the furnace began to shut itself off automatically - as it should when the vent is blocked - someone came back and tinkered with the burner until it would operate properly without proper exhaust venting. When the homeowner called, it was only to complain that the house would not heat properly - they didn’t realize that their furnace posed a serious health hazard and safety risk.
The lesson: Each of the many gas appliances on the market today has specific exhaust vent requirements. Don’t take those requirements lightly. Make sure each burner is installed by a qualified professional in strict accordance with the manufacturing instructions. If the professional says he will need to replace the vent pipe with a smaller one, don’t argue. He probably knows what he is talking about. 
Source: Journal Of Light Construction-April 1997

Insulating The Garage

Our attached garage, which keeps relatively warm in the winter, is connected to the house on two sides. The builder insulated above the ceiling in the rest of the house but not in the garage. Should I insulate the attic area above the garage to retain the heat? Would it help keep the garage cool in the summer?                       
Since you are not heating the garage space directly, you will not save on your heating costs. The only payback you will get will be a bit of extra comfort inside the garage. The few degrees of heat retained on cold days may be appealing, but you will spend more than $250 just to insulate the ceiling area. You will have to decide if that would be money well spent.                       
If the garage gets hot in the summer, insulating the attic will keep the garage somewhat cooler. Simply venting the garage roof would be a big help too.
Source: The Family Handyman June 1995 

Class Action Law Suits

They are many class actions today against siding manufacturers. Would you list the names and addresses so we will have the information to give our clients?                       
The following list is for siding and plastic pipe class actions that I am familiar with. If any of you have information on other companies, drop me a line and I will list them.
Georgia Pacific Corporation - Jarratt & Catawba Siding
Web Site: 
Masonite Corporation - X-90 Siding
Web Site: 
Louisiana Pacific Corporation - Inner-Seal Siding
Web Site:
Cox v. Shell Oil - Polybutylene Piping
Web Site:
US Brass - Quest Polybutylene Piping-Nonresidential
Web Site:

If you have a question, change of address, comment, home tip or would like to send Home Tips to your clients, send your letter to Home Tips, Christian Building Inspectors, Inc., 3697 Habersham Lane, Duluth, Georgia 30096. You can E-Mail your questions to us at We reserve the right to edit questions for length.

Quote of the Month

“A man is not finished when he is defeated. He is finished when he quits”

- Richard Nixon

A Tip Of The Hat To:

Ausker & Barbara Morris

Northside Realty

Marietta, Georgia

**** Thank You****