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    Servicing Denver, Arvada, Westminster, Northglenn, Thornton, Wheat Ridge, Sheridan, Lakewood, Englewood, Centennial, Littleton, Aurora, Castle Rock, Highlands Ranch and surrounding communities. Counties served are: Douglas, Arapahoe, and Jefferson Counties.

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TESTING A FURNACE FOR CARBON MONOXIDE.

Here in Denver, Colorado most home sales will require that the seller of the home have the heating equipment " Certified ". This certification is different than simply having the furnace checked! When a reputable company certifies the furnace, they are saying in writing that the furnace is in proper operating order and is safe to use.

The first step in doing this certification for us is to use a high quality test meter which measures carbon monoxide in parts per million ( PPM). This is a $ 500.00 meter and is extremely sensitive and accurate. It's accuracy will be affected by temperature, battery condition and the fact that it travels in a protected case but is none the less in a service truck  which is hitting bumps, potholes and the like. The meter has a calibration adjustment on the front of the instrument that must be calibrated in fresh outdoor air before each use! Please note in the picture below, our initial reading was 004 PPM in fresh air. The next shot will show the calibration procedure.

Below we have calibrated the instrument to 000 PPM in fresh outdoor air. Some service companies forget this important step and therefore condemn a furnace as being "cracked" when in reality they didn't follow the instruments manufacturers instructions. 

The furnace we are checking is in a crawl space which has no combustion air ducts.
The first test involves taking a reading at the furnace burners. We would expect to see a reading around 020 PPM. As you can see, below we read 184 PPM. This is the first sign of a more serious problem or problems. This could be a problem of dirty burners, a dirty or collapsed heat exchanger, obstruction in the flue system, a cracked heat exchanger, insufficient combustion air and several other causes.

Below is a shot of where the instrument probe is inserted near the burners.

Now we like to get a general feeling if the carbon monoxide levels are indeed not being vented up the flue pipe to out doors. So we take a sample of the air over the furnace itself. As you can see below, the air is contaminated slightly. Note: The instrument manufacturer says 000 PPM - 003 PPM is considered the lowest reading you can get since no meter can be within zero tolerance no matter how expensive. So 006 PPM is not much, but remember it is under the floors of the home! Also this furnace is 30 years old and well beyond it's life expectancy.

Now to the all important consideration. Below we are taking a sample at the register     ( vent ). As you can see we are reading 040 PPM. This is telling us - Yes the furnace is making carbon monoxide and it in fact is entering the living area through the duct system. This furnace MUST be replaced. Also combustion air ducts  need to be installed.

Note the brass shut off in the gas line. The new codes say this has to be changed to a lever type. The one pictured requires the use of a wrench. In an emergency there will be no time to find a wrench! Also note the silver box. This is a fan-limit switch. It's function is two fold. It starts the furnace blower when the furnace gets up to temperature, and it also shuts the burners back off if the furnace over heats. This is your last line of defense if a blower motor was to burn out. Without this switch operating correctly the furnace would get red hot and ultimately probably start a fire or an explosion.

Below is the furnace blower wheel and motor. There is supposed to be a furnace filter to the right of the blower assembly. Do you see one? Also note the wheel and the end of the motor is FULL of dirt. There are supposed to be openings all around the end of the motor so that the motor can be cooled! Obviously, this dirt didn't just happen. This furnace has had NO maintenance for years and as a result the motor runs a while then overheats and trips an internal overload within the motor. However the burners are still burning. The furnace gets red hot and eventually the fan-limit switch shuts the burners back off. Good thing for this homeowner because if it didn't he or she might be homeless or dead! Change your filter monthly and have the furnace inspected yearly for safety! The service call is NOTHING compared to your life. Not to mention the cost of replacing a furnace before necessary or the added costs of higher fuel prices.

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