Questions and Answers About Carbon Monoxide (CO)

Do all furnaces, space heaters, boilers, water heaters, fireplaces etc. produce carbon monoxide?
All gas, wood, oil and coal appliances can produce acceptable levels of CO. Appliances that are vented properly should never produce levels that are detected in the living space and should produce less than 100 ppm of CO internally.

Should unvented appliances only operate for short periods?
Unvented appliances to vent CO into the living space, therefore the level of CO they produce should be 50 ppm or less. These should only be operated with proper ventilation.

Do ovens or cook stoves produce carbon monoxide?
All ovens produce carbon monoxide, even electric ones. Proper ventilation is recommended, especially during warm-up and self-cleaning operation. Carbon monoxide increases on gas ranges every time the door is opened.

If my equipment is producing high levels of carbon monoxide, does it have to be replaced?
Most appliances that are producing high levels of CO can be repaired or adjusted. Based on age or efficiency, repairs need to be compared with replacement costs and overall savings and safety.

Do cracked heat exchangers make carbon monoxide?
Usually the small cracks that are found in heat exchangers do not cause CO to be produced, while larger holes or openings can. A cracked heat exchanger is a sign of poor operation and is a defect that needs to be repaired before it becomes dangerous. As long as the furnace is making minimal levels of CO and not spilling into space, the equipment is safe to operate.

I had someone look at my furnace and water heater, and they said it looked like they were operating correctly. Are they safe?
Anyone who evaluates the operation of equipment by sight alone is negligent and ill advised.

Are most contractors properly trained in carbon monoxide testing?
Unfortunately, there are many contractors that are not trained in the proper procedures for CO testing, and many that do not even have the proper test equipment. (Digital CO Analyzer)

How do I know if the person checking or servicing my equipment is qualified to do CO testing?
· They must have a digital CO analyzer
· They will have CO testing listed on the work ticket or invoice
· They may ask if you have other appliances to be tested
· They will show you the actual readings that they take
· They will be listed with C-MAC and/or have proof of training

Do fire departments, utilities and heating contractors all have the same abilities to test for carbon monoxide?
They all have the same opportunity to have the same knowledge, but a heating contractor should have more qualifications to pinpoint the exact problem and repair it, because that is their main area of expertise.

Is rust on the equipment normal? Does it indicate a CO problem?
Rust is a sign of an appliance not venting properly; overtime, the can cause a serious CO problem to develop.

I had someone check in my house for carbon monoxide without checking the appliances. Am I safe?
Carbon monoxide is an intermittent problem in many cases. Normally it occurs at its highest levels at night when the home is closed up and little traffic goes in and out. Checking for CO in the space provides only minimal information and guarantees very little.

Carbon Monoxide Testing
Carbon Monoxide Monitors