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Troubled Houses - A Home Owner's Resourcesm - C O Tests

We see many interesting adverse conditions during our inspections, partly because of the unlimited number of ways people can mess up a house, but also because we do a thorough inspection to reveal these adverse conditions. We hope these stories and illustrations help home owners avoid these costly conditions by learning about causes, preventions, and remedies.

NOTICE TO BUYERS & SELLERS: This site does NOT encourage or discourage the purchase of any individual house, or style, age, location, or condition of house.  Conditions shown and/or described herein may have been remedied at the house where these conditions were found.  These conditions typically can be remedied by qualified contractors. The presence of these conditions in any house is comparable to any other real estate consideration such as price, size, or location.  Consult a qualified home inspector before purchasing any house, and consult a qualified real estate agent for more information on how to handle a real estate transaction where adverse conditions are reported in a home inspection.   This site does not describe any house by address or knowingly show a readily identifiable exterior image.  Further, no home actively listed for sale on the Twin Cities MLS will be described on these pages at the time the article is posted.  

Copyright All rights reserved.  "Troubled Houses - A Home Owner's Resource" is a SERVICE MARK of Hankey & Brown Inspection Service Inc.  Click here for the list of topics and all articles in this resource.

THANK YOU for visiting   Click here to learn more about our services, which now include IR Thermography, radon testing, and carbon monoxide tests.

Why we test for Carbon Monoxide

Hankey & Brown Inspection Service includes carbon monoxide testing of heating systems (furnaces & boilers), gas water heaters, gas clothes dryers, and indoor ambient air.  We also test gas fired direct vent fireplaces.

Our tests are done with Bacharach single gas detectors and measure the carbon monoxide levels in the vents of the equipment and the indoor air near the equipment.  Typically, the readings indicate the equipment is operating properly (less than 100 parts per million) of carbon monoxide and no carbon monoxide is present in the indoor air.   We issue a separate memo listing the test results.

Occasionally, the tests reveal either that the equipment is making excessive levels of carbon monoxide, OR that carbon monoxide (regardless of the level) is leaking from the equipment, or spilling from the vent connector or its draft regulator. 

      Troubled Houses, Carbon Monoxide Test on rusted boiler 44 ppm carbon monoxide fumes leaking out of boiler  (C) 2010  ASHI Certified Inspectors, Eden Prairie, MN

Carbon monoxide test of 53 year old boiler, leaking 44 ppm of  carbon monoxide into the indoor air.   Immediate repair or replacement was recommended.

The production of elevated levels of carbon monoxide, or the spillage of any combustion fumes into the house are both very serious adverse conditions that have the potential to cause deaths to people in just a few hours.  Exposure to lesser amounts of carbon monoxide can cause chronic illness, headaches, and loss of mental & physical functions if the exposure is lengthy.   

For more information on the health effects of carbon monoxide see

Testing is not required by ASHI┬« Standards, but our view is that in Minnesota, carbon monoxide (CO) is an essential part of a complete home inspection.

One of our CO testing experiences is told in the Sept. 2006 ASHI┬« Reporter article entitled: Misunderstanding and Communication

Hot water with Carbon Monoxide

We test furnaces, water heaters, gas ovens, and indoor air for carbon monoxide (CO).  Water heaters usually make very little CO and usually all the CO goes up the vent, but not on this 16 year old water heater.

                        Water heater making high levels of carbon monoxide Troubled Houses (C) 2009 ASHI Certified Inspectors, Eden Prairie, MN

The level of CO at this water heater was over 2200 parts per million since the test instrument does not read higher than the level shown.  The heater was also SPILLING carbon monoxide at its burner door.

                                   High level of carbon monoxide at water heater burner door Troubled Houses (C) 2009 ASHI Certified Home Inspectors, Eden Prairie, MN

The CO level at the water heater burner door was over 800 parts per million.   Opening the burner door revealed that the main gas burner flame was actually touching the bottom of the tank.  This cools the flame, makes poor combustion and creates the CO. 

                          Mirror image of gas water heater flame Troubled Houses (C) 2010 ASHI Certified Inspectors in Eden Prairie, MN  

Our inspection was done for the buyer, but we left a warning note for the seller indicating the potential for carbon monoxide poisoning.  We learned two days later that the seller was purchasing a new water heater.

Fear of Carbon Monoxide is often used as a scare tactic by furnace service technicians to encourage the replacement of furnaces with "cracked" or damaged heat exchangers.  There can be several ways that carbon monoxide enters the home, but heat exchanger cracks rarely introduce CO into the circulating air of the house.  For more information on this topic, link to Carbon Monoxide Myths