Heating contractors all have different approaches to inspecting furnaces. Some invest in the best equipment to do the job right while others just guess. Combustion problems come in various sizes and shapes, and individual tests may not by themselves prove if the house is actually safe.
As we mentioned in previous articles, it's critical to understand the signs, and know what and when to test, in order to ensure that a small oversight does not result in a long-term health problem for homeowners.
To understand the risk of carbon monoxide to you the homeowner we recommend you watch this video.
Knowing some simple facts about combustion will make analysis easier. The problems with combustion appliances, like furnaces are not simply with the equipment themselves, but how they work within the home or building.
The safety of the units depends on their installation, operation, and maintenance.Other concerns such as competing air sources, house tightness, and effects of remodeling all can be important to the overall operation of your furnace.
The policies and procedures at Sims Heating And Cooling were designed to use the most advance testing equipment to check for the safety of furnaces and boilers.
Homeowner Safety - The concern is for the short- and long-term safety of homeowners. Visual inspection of the house and the furnace mechanism is extremely important in this analysis.
Checking for Carbon Monoxide - Are there any signs of carbon monoxide being created? Is there any carbon in the burner area, flue or vent? How are the flames burning? Are there any visible signs of a problem, such as flames burning erratically, no flames visible on part of the burner, weak flames, or white tips on the flames? Regardless of the visual inspection, a test must be performed to verify that there is no CO in the combustion gases.
The sample should be taken from each flue (where the exhaust leaves the home), before additional dilution air is added to the gases. In a furnace with four burners, at least four tests should be taken.
Our field experience has shown that problems with most units that create carbon monoxide(CO) in excess of 25 ppm in the flue can be corrected. Most field standards are higher than this (less than 100-200 ppm).
One of the key components of this step is to determine why CO is being created, since CO is a symptom of something being wrong with the home or the heating system.
In a previous article, we discussed the heating process is chemical equation and CO was one of the potential by-products when something wasn't working right; which is what creates the threat to carbon monoxide poisoning.
Draft and Venting - The draft of the furnace measures the power of the venting system to exhaust. Is it getting enough air(O2). The measurement of the draft is coupled with a visual inspection of the venting system to determine the probability that all of the combustion gases are getting out of the home. If the draft is measured in cold weather, it can provide an indication of the ability of the appliance to exhaust in warmer weather (if the draft is weak in cold weather, it will be weaker in hot weather). The standard we use was developed from both technical analysis and field testing .
Cracked Heat Exchanger
There's the potential for contractors to condemn a heat exchanger which creates all sorts of emotional reactions by homeowners and the BBB warns homeowners about this.
Examining furnaces for a breach or hole in the heat exchanger is potentially significant, but of lesser importance than the previous tests. Checking for cracks is done by examining the flames for interference when the blower is operating and by direct inspection of the heat exchanger.
Bacharach is the manufacturer of our testing equipment. This is what they say:
Combustion testing today is no longer an option. It’s a necessity.
It used to be that fossil fuel-burning home appliances could be adequately serviced by conducting visual tests. But with today’s regulatory, environmental and safety concerns – as well as the risk residential service technicians now face with possible liability – “eye-balling the flame” is no longer a sufficient way to test. The truth is, an appliance that shows a nice blue flame is probably not burning efficiently. It could, in fact, be burning more fuel than is necessary, adding soot to the system, or more importantly, emitting toxic gases that could eventually put your customers, you – and your business – in real danger.
Here are their guidelines:
To test for cracks using a combustion analyzer, after drilling a hole in the flue, we simply watch the O2/CO2 readings and the CO reading when the blower comes on - usually several minutes after the burner(s) ignite or fire up.
Typically, the O2/CO2 or CO readings will stabilize within 30 to 60 seconds after ignition. If a crack is present, when the blower energizes, air (at 20.9 percent O2) may be blown through the crack in sufficient quantities to raise the O2 (or decrease the CO2) reading on the combustion analyzer.
Using a combustion analyzer to test for cracks in a heat exchanger has limitations; however, there are some distinct advantages:
- It tests under actual operating conditions.
- It may provide additional information as to how dangerous a crack is. For example, if a crack is visually observed and a combustion test finds that when the blower comes on the carbon monoxide reading rises to excessive levels, a service contractor can be more confident that a dangerous situation exists and has the documentation that the unit needs to be immediately condemned and taken out of operation.
- It can be easily done during the normal course of a service call where combustion testing is performed.
- It is important to keep in mind that changes in combustion test readings may also be caused by other factors:
- Depressurization of the mechanical room due to leakage in the return side of the distribution system may be sufficient to change the readings when the blower is energized.
I know this is a little technical in nature, but it is a key to the testing equipment we use and the training of our technicians.