Theory and troubleshooting using short modules packed with images to make learning quick and easy.
Combustion is a rapid chemical reaction when oxygen combines with the fuel to produce heat. Lighting a match is combustion.
You require three things to produce combustion; heat, fuel, and oxygen. Since the air we breathe is only about 20% oxygen and 80% nitrogen, we end up having to supply much more air to get the oxygen we need.
Natural gas has the chemical formula of CH4. Natural gas, also known as processed natural gas, is a dry gas which means it has all the heavier hydrocarbons removed and stored in underground storage tanks for use. Natural gas has no color, no taste, no odor (your distributor adds mercaptan for safety which gives a rotten egg smell), is non-toxic (although you may die from insufficient oxygen if there is too much natural gas in the air), and is transparent.
Gas requires quite a bit of air for proper combustion since the air is made up of mostly nitrogen and only contains about 20% oxygen. For adequate combustion to happen, you require combustion air, excess air, and dilution air when using a draft device.
Combustion air is made up of primary and secondary air when speaking about perfect combustion. Since we strive for complete combustion in the real world, excess air is added to ensure combustion.
Combustion is a rapid chemical reaction when oxygen combines with the fuel to produce heat. By modifying any of the three, oxygen, heat, or fuel, you create an imbalance and can produce incomplete combustion.
Carbon monoxide (CO) and aldehydes are products of incomplete combustion.
Carbon monoxide is the most harmful product of incomplete combustion. It’s colorless, odorless, tasteless, and toxic. In large quantities, it can be combustible.
Boyle’s Law is a law for an ideal gas. An ideal gas is a perfect gas that follows all the gas laws. Ideal gases are hypothetical.
Boyle’s Law states that for a fixed amount of an ideal gas at a fixed temperature, P (pressure) and V (volume) are inversely proportional, which means at a fixed temperature, when pressure increases, the volume will decrease. If the volume increases, pressure decreases.
A combustion analyzer measures and gives out results to you based on what’s taken place after combustion has happened.
Understanding exactly what your combustion analyzer is telling you is arguably one of the most important pieces of information to understand as a technician nowadays.
An essential step is running a combustion analysis in commissioning a newly installed appliance, troubleshooting, or even just on routine maintenance for both efficiency and safety.
An essential step in commissioning a newly installed gas appliance or even just on routine maintenance for both efficiency and safety includes clocking the meter, running a combustion analysis, checking temperature rise, verifying stack/venting draft, and setting manifold pressures.
A 94% gas furnace installed fresh out of the box could be running at quite a bit less when not set up correctly. You’re not doing your customer any favors when not finishing an install as you could add thousands of dollars in gas usage and repairs that could be avoided over the life of the appliance.