Energy Coach Corner:Carbon Monoxide – A Cautionary Tale and Another Reason to Get a Home Assessment

Written by: Lauren Brois on Feb 17th 2015

February 17, 2015 by Norm Jen, the Energize Energy Coach

I was recently attending a training class with a friend (and fellow member of the Chappaqua Volunteer Ambulance Corps) when she mentioned that she was concerned about a low level of carbon monoxide in her house.  Diane had had two different contractors at her house and neither one of them seemed to be able to fix the problem.  While most of us think of a home energy assessment, as channel to improving energy efficiency or improving comfort, combustion safety (i.e. carbon monoxide issues) are also addressed during the assessment.  What follows is a conversation about carbon monoxide and what we found at Diane’s house.

This article is a bit longer than others I’ve posted in the past, so for those of you who are looking for the short version, here is my summary:

  • Typical carbon monoxide detectors are set to alarm at levels well above what we consider “safe” in the home performance world.
  • Many carbon monoxide issues frequently arise during heating season when we use our furnaces and boilers.
  • BPI certified home performance contractors can properly assess carbon monoxide issues in a home and recommend appropriate repairs if necessary.
  • In Diane’s case, the problem was a very simple fix, although two prior contractors had tried and failed to properly address the problem.

Here is my bottom line:  a Comprehensive Home Assessment can check for carbon monoxide issues and provide homeowners with peace of mind.

For those of you seeking the extended (geeky) story, here it is…

Every year, my ambulance corps and those in neighboring towns receive calls about building occupants exposed to carbon monoxide.  Many of us know carbon monoxide as a “silent killer” because it is colorless and odorless, and therefore undetectable without proper equipment.  In low concentrations, carbon monoxide can cause headaches, lightheadedness and nausea.  In higher concentrations, serious things like memory loss, loss of consciousness and even death can occur.

How does carbon monoxide (CO) occur?  In the world of building science, we say carbon monoxide is the byproduct of “incomplete combustion.”  The “combustion” portion of this phrase tells us that carbon monoxide can only be generated when something burns.  Any “appliance” in our home where combustion takes place is capable of generating carbon monoxide.  For most of us, the common culprits would include furnaces, boilers, water heaters, gas stoves, and fireplaces.  The “incomplete” portion of the phrase refers to improper tuning.  While we rarely see anything burn without generating at least some small amount of carbon monoxide, a poorly tuned furnace, for example, is capable of generating lethal amounts of carbon monoxide.  With the exception of stoves, the other appliances mentioned above have a “vent” which directs combustion gases to the outside.  So even if we have high levels of carbon monoxide generated, the vent directs most (but not always all) of the combustion gases to the outside, often via a chimney.

Carbon monoxide concentration levels are measured in “parts per million” (ppm).  Properly equipped homes have at least one carbon monoxide detector, mostly likely UL listed.  Under UL standard 2034, you are allowed to breathe CO levels of 30 ppm for up to 30 days, 70 ppm for up to 4 hours, or 400 ppm for up to 15 minutes.  [I might add that this assumes a “healthy adult.”  Children, pregnant mothers, elderly, and those with chronic cardiac or respiratory conditions may be more susceptible to carbon monoxide poisoning.]  A BPI certified contractor will tell you that the 24 hour limit is 9 ppm, and if CO levels rise above 35 ppm at any time, they are instructed to terminate a home inspection and ask all occupants to vacate the building immediately.  In other words, by the time a household carbon monoxide detector sounds an alarm, CO levels in a house are extremely high.

In Diane’s house, I used a device known as a combustion analyzer which, among other things, measures CO concentrations.  We observed a reading in excess of 2000 ppm in her furnace exhaust!  Luckily for Diane, her chimney was venting that highly toxic exhaust properly to the outside, but if her chimney should become obstructed for any reason, the results could have been fatal [Perhaps some of us recall a story where this happened at a restaurant on Long Island last year.].  There are still appropriate reasons why some of those gases may spill into my Diane’s house and as a result, she was observing a small amount of CO in the house.  Using the combustion analyzer, we were able to determine that my Diane’s furnace simply needed an adjustment and after it was tuned, the CO levels in her furnace dropped from over 2000 ppm to under 2 ppm.  Another mystery solved using building science!

Amazingly, neither of the two HVAC contractors Diane had hired used a combustion analyzer.  They tried tinkering with other items like caulking some duct work and a minor adjustment elsewhere, but it is clear that neither one knew enough to check the furnace for improper combustion.

Did I resort to some kind of wizardry to diagnose Diane’s problem?  Hardly.  Any contractor in New York State’s Home Performance with Energy Star program is required to check the combustion appliances in your home during a home assessment.  If an elevated carbon monoxide issue is identified, an appropriate repair is recommended (and should be considered a high priority matter).  Perhaps that alone may make it worth everyone’s while to have a Comprehensive Home Assessment performed. 

So this winter, please stay safe.  If you haven’t already done so, PLEASE consider this story another reason to get a Comprehensive Home Assessment. Sign up today on the Energize NY website or call the Energize NY Office 914-302-7300 and ask for Lauren.