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Understanding CO, Part Three

As we complete our discussion on the fundamentals of Carbon Monoxide in this segment, I want to point out that two other symptoms of low-level CO poisoning are headaches and confusion. And one example of these specific symptoms involves this case study of a situation involving an elderly resident. The factors in this case are as follows:

Complaint: Frequent headaches.

Observation: Elderly resident seems to be confused and disorientated at times, lucid at other times.

Building Type: New, energy efficient construction, one-bedroom, elderly housing unit.

HVACR Equipment: Heat pump.

Kitchen Equipment: Electric range and standard exhaust vent system.

Water Heater. Natural gas, in laundry room adjacent to kitchen.

Fuel-Burning Equipment Operation and Ambient CO Measurements: An initial test showed normal draft of water heater and no CO emissions from the vent into the living space. However, a secondary test with vent fan operating in the kitchen showed a significant loss of negative draft pressure in the water heater vent, resulting in a carbon monoxide spill, emanating from the laundry room.

To put it simply: Complaints from a resident of this specific type of housing unit could have easily been written off as a condition and/or other health issue related to advancing age. Instead, the actual source of the problem was insufficient combustion relief in the laundry room that wouldn’t allow the water heater to vent properly in the event of a drop in building pressure in the room adjoining the combustion appliance zone.

The two instruments necessary to accomplish the test procedures in this case study were a draft gauge, used for measuring the pressure in the vent system, and a device designed to measure ambient levels of CO in a building.

In addition to accomplishing ambient measurements of CO in a living space to determine if fuel-burning appliances are operating properly in regard the vent system as mentioned in the case study above, a more advanced level of testing, known as a combustion analysis, can be accomplished to further evaluate the operation of equipment. This process requires a more sophisticated device, one that is capable of  evaluating the overall operation of the burners. In the example in Figure Two, we’re showing the factors that are evaluated when device that is capable of these simultaneous measurements is employed.

Figure Two

The equipment in this case is forced-air gas furnace with an 80% efficiency rating, and the procedure for obtaining these measurements is to drill a hole in the equipment vent (re-seal it with a high temperature silicone once testing is completed) and inserting the instrument probe into the opening. While this analysis print-out is showing the measurement several factors, note the two listings that are highlighted, the Oxygen level shown at 10% and the Carbon Dioxide measurement shown at 6.1%.

In this specific instance, a furnace of this type should show an Oxygen reading of 6 to 8 percent, and a Carbon Dioxide measurement between 8.25 and 9.5 percent. When comparing data regarding what the measurements should be, and the actual measurements recorded by the device, we know that the Oxygen level is higher than it should be and the Carbon Dioxide level is lower than it should be. This means that the furnace is not operating properly, with the burner is functioning in a condition known as under-firing. What this analysis leads us to is a diagnosis that the fuel pressure being supplied to the burners in this equipment is lower than it should be, and an adjustment is necessary to bring the pressure up to a proper level. This will ensure the correct ratio of fuel to air, and the proper operation of the burner.

In addition to vented appliances, non-vented appliances such as the gas range shown in Figure Three, could also be responsible for a CO spill in a building if the burners are not operating properly. To be certain that a residence is not experiencing excessive CO levels and that fuel-burning equipment is operating properly, ambient measurements in the building, and a combustion analysis of vented equipment, are necessary.

Figure Three

Until Next Week….

Learn from yesterday….Live for today……Look forward to tomorrow.