What is a Class A Chimney?

Class A Chimney Pipe

Class A chimney pipes have many different names. You’ll hear double-wall chimney pipe, triple-wall chimney pipe, all-fuel pipe, or insulated chimney pipe.

Class A pipe is used to vent high-temperature exhaust released from wood, coal, and oil-burning appliances, such as fireplaces, stoves, boilers, and furnaces.

Not every venting system requires a Class A pipe, but it’s absolutely necessary for use with all wood-burning fireplaces and stoves.

Class A chimney pipe is UL-Listed, which permits its use with a range of different vent pipe manufactured by other fabricators and an even wider variety of fireplace, stoves, inserts, and furnaces.

However, it’s important to know that you should never mix and match different brands of Class A chimney pipes within a single chimney system (unless allowed by the manufacturer).

The different brands of pipe are all distinctly engineered and must be used as a complete system from beginning to end.

If you’re looking to extend or redesign your chimney system, you’ll need to know the make and model of your existing Class A pipe and buy the same type, if possible.

Unfortunately, if your current make and model is discontinued, you’ll ned to rebuild your chimney system from scratch.

Building codes prohibit the use of any adapters not approved by the manufacturer. These adapters are very rare and usually only offered by a manufacturer to link a very similar piping system to a currently offered system.

There are two types of Class A chimney pipe – solid-packed and air-cooled chimney.

Solid-Packed Chimneys

These pipes have a smaller inner diameter (usually between 5-8 inches) that have some insulation, either double-wall or triple-wall.

These pipes contain fiberglass or ceramic insulation to stay cooler on the outside and needs to maintain a 2-inch clearance to combustibles.

Air-Packed Chimneys

These pipes have larger inner diameters (usually between 8-24 inches) and no insulation.

These pipes rely on the air circulating within them to keep the outer wall cooler and needs to maintain a 1 or 2-inch clearance to combustibles.

Galvanized vs. Stainless Steel

When using a Class A chimney pipe, it’s important to plan or route the vent run wiselly to keep your costs ata minimum.

Class A pipe is usually manufactured with either stainless steel or galvanized outer walls.

When running CLass A pipe within a masonry chimney, a chase, an attic, or any enclosure inside your home, it’s economically wise to use a galvanized pipe.

It’s highly recommended if at all possible, to install your chimney in the interior of your home.

Having your chimney system exposed to the outdoors brings with it the risk of a cold hearth syndrome, which can hinder drafting and produce more creosote.

You’ll need stainless steel if your pipe will be exposed to the elements.

If the pipe is galvanized and exposed, it will be susceptible to eventual rust and corrosion. This is especially true in coastal areas.

If you must use a galvanized pipe, I recommend you paint your pipe with a high temperature, rust resistant paint to “trick” the pipe to last longer.

Class A Chimney Caps

Class A chimney pipes have their own specialized caps that fit right on top of the pipe at the point of termination above the roofline.

When terminating a class A system, you need to follow the 10-3-2 rule.

This means that the termination needs to be 2 feet higher than any portion of the building within a 10-foot horizontal distance, as well as 3 feet above the roof.

Here’s what the National Fire Protection Association says about it:

“A chimney for residential-type or low-heat gas utilization equipment appliances shall extend at least 3 ft (0.9 m) above the highest point where it passes through a roof of a building and at least 2 ft (0.6 m) higher than any portion of a building within a horizontal distance of 10 ft (3 m)” (NFPA ANSI Z223.1, Section 10.5.2.1).

Please know, this code must be met with the 10-foot radius, clear of any obstruction at the top of your pipe before your cap is installed.

This rule is in place to ensure proper draft for your unit.

How to Hire a Chimney Contractor

When you’re ready, you should schedule a time for a certified chimney expert to go to your home to take a look at the area you want your new class A chimney installed.

You can easily reach out to your local chimney company and have a done-for-you solution in no time!

But navigating through all of the chimney companies in your city can be a chore all on its own. And it makes sense, too.

Hiring anyone to come into your home to install a heat source involving fire shouldn’t be a task you take lightly. So I created a list that you can use to make sure you make the right decision when you need someone to help you in your home.

Questions to Ask

When you’re hiring a chimney company, you should always ask the following questions before allowing them to come into your home:

1. Can the company provide references? 
2. Does the company carry a valid business liability insurance policy? 
3. Does the company ensure that a certified chimney technician will be on the job? 

If they guarantee all three of those, then you are in a good spot. The technicians don’t necessarily need to be certified by the CSIA, but I do recommend putting in a bit more due diligence before accepting a certification that’s not by the CSIA. 

This is because certifications are a tricky thing, especially in an unlicensed industry like ours. Any company can craft a list of job-related questions and sell them as an exam and certify those who pass.

Certifications

I recommend you take a few extra minutes in your research before making your hiring decision to learn more about the certification the company has. Here are a few tips to make sure the certification is reputable: 

• Is the word “certified” just part of the business name or is it an earned designation? 
• Is the certifying body a for-profit business or non-profit? 
• Does the certification need to be maintained and renewed through continuing education as the industry evolves, or is it well enough to be certified through a one-time exam? 
• Is the certifying body well-established or are they relatively new to the scene? New doesn’t mean “bad” but you should make sure the requirements for certification are more or at least equally stringent as those of more established certifications
• Is the mission statement of the certifying body focused on educating and protecting homeowners or is it more focused on making it easier to earn a certification? 
• Does holding the certification require following a code of ethics? 

If you can answer all of these questions, then I think it will be safe to allow the company in your home to work on your chimney. 

Please note that If you are hiring a chimney company to install a cap for you, most of the time, they will need to buy the cap themselves. This is primarily for liability and insurance purposes. 

It doesn’t matter if you are in Roanoke, Lynchburg, Blacksburg, or some other city anywhere in the USA — if you have any questions about the safety of hiring a chimney company, please don’t hesitate to email me at mitchell@patriotchimney.net or call me at 540-225-2626. I’m happy to help!