As a homeowner, there’s a lot that goes into making sure your home stays as safe and as efficient as possible. But sometimes, you might not know what needs to be done for certain appliances in your home — like your gas or oil boiler/furnace and the system venting it — and who does what. We’re here to help by answering some common questions about these systems.
Let’s get started!
Who is qualified to service gas and oil boiler/furnace chimneys?
Gas/Oil boilers and furnaces are popular in the Mid-Atlantic and Northeast, and if you have an oil appliance, you have an oil company that delivers fuel and services your oil burner. The problem is, many homeowners think that their oil 
company takes care of everything, checking not just the boiler itself, but also the exhaust system that runs from the top of the furnace or the boiler to the outside.
Unfortunately, they don’t.
The exhaust system is something that should be taken care of by a Chimney Safety Institute of America (CSIA) certified chimney technician. Any CSIA certified chimney technician can service the chimney system for gas or oil burners.
The truth is, oil companies and gas companies do not sweep or inspect the exhaust system — they only work on the actual burners themselves. The certification needed to service the gas or oil boiler itself is different from the certification for servicing the exhaust system.
In reality, your oil or gas company won’t know what the condition of the venting system is like. They service the unit, make sure the unit comes on, and look at the gauge that tells them that it is adjusted correctly and that the exhaust is going out at the right rate.
But they don’t know what they’re exhausting into. It could be a pipe that’s full of holes like swiss cheese, and that pipe could be venting carbon monoxide into your wall space or chimney cavity, which could end up making you sick. Typically, if they notice a drafting issue they will instruct you to call a certified chimney technician to inspect the exhaust system.
The moral here? Don’t assume just because you have a maintenance policy with a furnace company that they are maintaining the exhaust system, because none of them do. It’s not their job.
Is there anything I need to be aware of when upgrading my gas or oil burner?
If you’re in an older home and it gets to a point where you’re going to upgrade your furnace or boiler, typically anything you’re going to purchase is going to be much more efficient than something that was manufactured 20+ years ago.
That’s good news, right? But, because it’s more efficient, the exhaust pipe coming off the top of the unit is going to be significantly smaller than the original unit’s. So, where that pipe taps into the chimney system, the venting system could now be overly large or oversized for what the new unit requires.
Note: The National Fire Code NFPA and International Residential Code (IRC), as well as the manufacturer’s installation guidelines for the boiler or furnace, all tell you what size that exhaust system needs to be.
Why does it matter if your new boiler or furnace isn’t matched up to the correctly sized liner?
If the liner is too large, the flue gases will slow down and condensate, meaning water vapor and soot will stay on the liner. The problem with that is that you get acid residue inside the chimney system and that acid residue is wet.
One of the byproducts of burning gas or oil is sulfur, and when you mix sulfur with water, you get sulfuric acid.
● Sulfuric acid will eat away at chimney liners and eventually eat through the piping system.
● Sulfuric acid will drip down into the crossover or connector pipe that goes from the furnace to the actual venting system. That connector pipe is usually a galvanized metal, and it’s very easy for very acidic flue gases with condensation to eat through, leaving a mess on your floor.
● Sulfuric acid will drip down into the furnace and corrode it. And we don’t have to tell you furnaces are very expensive to replace!
So if you’re thinking about upgrading your furnace or boiler, reach out to a certified chimney professional to find out if you need to have your exhaust system relined or resized for the new appliance.
How do clogs happen in oil and gas boiler/furnace systems?
Clogs can happen a couple of ways:
● When you have condensation and acidic flue gases in your exhaust system, this can weaken your mortar joints, the terra cotta tile, or the metal components, and things can shift or crumble and create a clog.
● If you don’t have a proper chimney cap and the chimney crown or exterior chimney is deficient for your furnace or gas exhaust system, water can come into the system and mix with acid residue, wearing things down and making them corrode, crumble, and clog up.
● If you don’t have a chimney cap or the proper screening on your cap, sticks and animals can invade the system, and clog or partially clog it.
The problem with clogs is that, when you have a clog, you’re not getting the right draft. And when you’re not getting the right draft, more and more soot starts to build up in your system. It’s like a snowball running downhill — your system will rapidly get more and more clogged from soot because it’s partially or totally occluded. And over time, that soot will only clog things further. As it gets clogged the dangerous flue gases such as carbon monoxide are not venting properly out of the home and staying in the home which can be deadly.
Do oil and gas burner chimneys need to be regularly maintained?
Yes, the NFPA 211 code does not discriminate. It says that all chimneys and all venting systems should be inspected and swept yearly. That means you need to have your chimney/venting system checked every year, regardless of whether we’re talking about wood, coal, oil, gas, or pellet chimneys. This also includes dryer vents.
So if it’s been more than a year since you had your chimney or dryer vent inspected by a certified chimney professional, give us a call. We’ll take care of it for you.
Have any other questions for us about your gas or oil burner chimney? Just give us a call. We’re happy to help!