If you’ve recently purchased a new wood-burning or multi-fuel stove, or are considering an installation, you may be wondering if you need to install a chimney liner. Of course, you want your new stove to heat your home efficiently and safely. A chimney liner helps ensure proper performance and reduces safety risks. This guide will explain what a chimney liner is, why your older home likely needs one retrofitted, and the potential consequences of skipping this important component. 

What is a chimney liner?

A chimney liner is a flexible, stainless steel tube that lines the inside of your chimney. It creates a smooth, properly sized passage for the smoke and combustibles from your stove to flow up and evacuate safely out of your home. You can think of it like the central hole through a polo mint sweet. The liner is the hole, and the chimney is the overall structure (the polo mint itself). 

The liner itself is called the flue. The chimney is the complete system, including the outer masonry or bricks encasing the flue passage. If you peek inside your chimney, you’d see the flue liner running up the inside. 

Product Guides: How to Choose and Measure for a Chimney Liner

Why your older home likely needs a retrofit

If your house was built before 1968, it likely does not have a proper flue liner installed. Earlier chimneys were commonly made of brick or stone masonry. While this works, it leaves the flue passage rough and inconsistent. The masonry absorbs heat, cooling the smoke and reducing draught. And gaps between the bricks or stones create opportunities for smoke to leak into the home. 

After 1968, building code standards improved. Homes built after this year had to include flue liners, usually made from clay tiles or pumice concrete. While better than bare masonry, these liners still left rough surfaces and opportunities for heat loss. 

Even if your chimney was properly lined with tiles or pumice, these materials can deteriorate over decades of use. Cracks and gaps in the liner let heat escape, reduce draught, and allow tar build-up. Your chimney likely needs a modern stainless-steel liner retrofit. 

How a liner improves stove performance 

You might be wondering why a liner is needed. “My old fireplace worked fine without one!” While this may be true, there’s an important reason: old open fireplaces are extremely inefficient, while modern stoves burn much more efficiently. 

An open fireplace is only about 15-20% efficient, meaning 80-85% of the heat goes right up the chimney! This large amount of heat creates a strong draught up the chimney. Modern stoves are 70-80% efficient or more, losing only 15-30% of heat up the flue. With so much less heat, they rely on a smooth, properly sized liner to maintain draught strength. 

A liner does this by keeping the smoke and gases warm as they rise and exit the chimney. Cool smoke stops draughting and can even flow back down in extreme cases. A liner insulates the gases and prevents cooling draught-killing voids. This helps your new, efficient stove perform as intended for clean combustion and heat output. 

Liners prevent safety hazards 

Along with improving performance, a liner also prevents the serious safety hazards that can occur with older unlined chimneys. Gaps in the masonry let smoke leak back into the home, filling interior air with dangerous carbon monoxide. Children and pets are especially vulnerable to CO poisoning. 

The smooth stainless-steel liner fully contains smoke and gases, keeping your indoor air safe. Liners are also necessary for insurance coverage on wood-burning stoves in many cases. Protect your family and home with a properly installed liner. 

316 vs 904 grade stainless steel?

Chimney liners are available in different grades of stainless steel. The grade refers to the composition of the steel, with 904 being a higher quality than 316. For most homeowners, 316 grade provides an affordable and durable option. 904 grade is best for very heavy use such as burning coal or smokeless fuels. It has maximum corrosion resistance and strength. 

Even if you only burn wood, choosing 904 grade provides an extra degree of longevity and safety. While 316 grade will suffice for average wood burning, upgrading to 904 is a good investment if it fits in your budget. You likely only want to do this liner installation job once, so using the best materials makes sense for peace of mind. 

Consequences of skipping the liner 

Given the clear benefits of including a chimney liner, you may be wondering: what happens if I don’t install one? There are a few potential consequences: 

  • Safety hazards from smoke or CO in the home 
  • Underperformance of your stove due to weak draught 
  • Tar buildup that can stain interior walls and damage the chimney 
  • Higher risk of a chimney fire since gaps provide oxygen 

In summary, an unlined chimney prevents your stove from heating properly, risks contaminating interior air, and damages the chimney itself over time. The nominal upfront investment is worth it. 

Do I need a liner?

If your chimney was built after 1968 and already has a proper clay tile or pumice liner, you may be able to safely install your stove without a liner. Be sure to inspect the existing liner thoroughly for any cracks, gaps, or deterioration first. 

However, most UK homes built before the late 1960s will require a new stainless-steel liner for optimal safety and performance. The project doesn’t require special skills, and the liner kits available make DIY installation feasible in most cases. Take the time to install quality flue liner before enjoying your new stove this winter. Your family, home and wallet will thank you. 

DIY Guides: How to install a chimney liner