Replies

1. 
   Vince_McCauley | Dec 13, 2000 05:26am | #1

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   Robert

   With a gas furnace that old, it could be any number of things. It is way past time for it to be replaced. I doubt that you are getting 50 cents worth of heat for every dollar in fuel costs. It's time to replace it with a new fuel efficent system and will be cheaper in the long run that trying to track down the problem and fix it.

   vince

1. 
   David_Thomas | Dec 13, 2000 06:18am | #2

   *Not clear if you are talking about high carbon dioxide (CO2) or high carbon monoxide (CO). Also not clear if you are talking about CO/CO2 in the flue gases or in the house air (implied by the leaky heat exchanger theory). If either is in the house air, it is a definite health hazard because of CO. Have someone confirm that (your gas compnay might check for free). Or get a carbon monodixe detector. I wouldn't bother with the $39 P.O.S. Carbon Monoxide detectors without digital readout at Home Depot. Slightly better is the Kiddie Nighthawk with readout ($50), better yet is the AIM Safe-Air Products Model 935 Low-Level CO Monitor ($75) which avoids the damnable UL requirement that CO detectors not tell you about low levels of CO. (Fire Departments were getting too many calls back when units were more sensitive). I'd like to know if any detectable CO is there and see the concentration; that is very helpful in tracking down the source and route of CO. The first time I had a CO detector go off, I felt that it had been money very well spent. Here's a link with a lot of info on CO detectors: http://www.avweb.com/articles/codetect/ It has an aviation prespective - pilots are very concerned about CO, because they can't just step outside when the alarm goes off. -David

1. 
   David_Thomas | Dec 13, 2000 11:45am | #3

   *To answer another part of your question, Yes it is reasonable for a heat exchanger to develop leaks after 38 years and letting CO into the house. The heat exchanger is a single wall of metal that separtes flue gases from house air. On the hot side, it is exposed to acidic fumes (carbonic acid among others), high temperatures, and various energentic radicals (damn hippies). Not as likely to be "cracked" as to be corroded. If the leak is confirmed, REPLACE IT QUICKLY. Move ahead with checking this out. Or move out and check into a motel. -David

1. 
   Bob_Walker | Dec 13, 2000 01:11pm | #4

   *Ditto to everything David said.What did the tech do about it?Note, a cracked heat exchanger doesn't necessarily produce CO. And, doesn't necessarily mean flue gases will get into the house air (but it i couldand that's why cracked heat exchangers are dangerous.)In many, if not most cases, high CO in the flue gases can be corrected by properly servicing the equipment.Try to get a service technician who performs a Building Performance Institute Carbon Monoxide Analysis or BPI Combustion Anlysis.Please be aware, death isn't the only risk with CO. Chronic exposure to lower levels can cause disabling health effects. Just 'cause you ain't dead doesn't mean you don't have a CO problem.

1. 
   Jeff_Clarke_ | Dec 13, 2000 04:35pm | #5

   *Did he check the flue for draft? Does it tie into a masonry chimney and if so when was the last time you had the chimney cleaned?

2. 
   robert_p. | Dec 13, 2000 04:36pm | #6

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   i have recently had my gas furnace checked and the hvac tech found above normal co2 readings . he stated that it could be the heat exchanger . the furnace is 38 years old and i was wondering if it could be from the age of the unit and not a cracked heat exchanger . any ideas ?