Chimney balloons are a simple solution that can prevent warm air from escaping through open chimneys, improving comfort in your home while reducing energy use and carbon footprint.

In many older UK homes, chimneys are hidden funnels that draw warm air directly from your living space and pull in colder air through draughts. According to the Energy Saving Trust, an open chimney can cause unnecessary draughts if you don’t use your fireplace, and draught-proofing it can save around £60 a year in Great Britain and £65 in Northern Ireland.

Chimney balloons are inflatable devices that block draughts at their source and are a low-cost fix for energy-conscious households. They seal the throat of the flue, stopping warm air from escaping and cold air from entering. Unlike permanent chimney caps or dampers, they’re quick to install and removable when you want to use the fire.

Chimney balloons allow you to plug the draught, save on energy bills, and make rooms more comfortable, making them an easy win for many homeowners. However, effectiveness depends on chimney shape, ventilation, and maintenance, and there are alternative solutions worth considering.

This guide examines how chimney balloons function, their advantages and disadvantages, cost, and whether they’re the right choice for your home.

Quick Takeaways on Chimney Balloons:

• Chimney balloons cost from £16 and are one of the cheapest ways to draught-proof an unused fireplace.
• A properly fitted balloon can reduce heat loss and improve comfort, paying for itself within one or two winters.
• They’re best suited for chimneys that you rarely or never use and are easy to install, removable, and reusable.
• The lifespan is typically 2–5 years, although regular checks are necessary to ensure they remain inflated.
• Alternatives include Chimney Sheep (wool-based plugs), permanent chimney caps or dampers, and other specialist draught excluders.
• Potential downsides include deflation, damp risk if overinflated, and safety issues if forgotten before lighting a fire.
• For renters or listed properties, chimney balloons offer a non-permanent solution compared with professional caps.

What is a Chimney Balloon?

Chimney balloons are also called chimney draught excluders. They’re inflatable devices that stop warm air from escaping and cold draughts from entering through an unused fireplace. It sits just above the fireplace opening, inside the flue, and expands until it seals against the inner walls of the chimney. Once in place, it acts like a temporary barrier, blocking the airflow without causing permanent changes to the structure.

Most chimney balloons are made from a durable plastic or specialist laminate that resists punctures and can withstand minor variations in chimney size. They come in a range of shapes and diameters, from small round balloons for narrow Victorian flues to larger rectangular versions for modern chimneys. When you need to light the fire, deflate the balloon and remove it. Then, re-inflate it once the fireplace is no longer in use.

Chimney balloons are flexible and low-cost, making them a suitable draught-proofing option for UK homes. They offer a middle ground between makeshift DIY fixes, such as stuffing the opening with cardboard, and expensive, permanent solutions, like a chimney cap or damper system.

A draught is defined as a cold vortex of air and is a major cause of heat loss and inefficiency.

How Does A Chimney Balloon Work?

The principle behind a chimney balloon is simple: warm air rises, and an open flue acts like a funnel, drawing that heated air straight outside. This “stack effect” doesn’t just waste energy. It also creates a suction that pulls cold air back into the room from gaps around windows, doors, or floorboards. A chimney balloon breaks this cycle by physically sealing off the chimney throat.

When inserted into the flue and inflated, the balloon expands until it presses gently against the inner walls. This stops air from moving freely through the chimney, reducing the upward pull of warm air and the downward flow of cold draughts. In practice, the effect is noticeable almost immediately: rooms feel warmer and less drafty because they’re retaining heat instead of letting it escape.

Chimney balloons don’t make a chimney airtight. Most have a small safety vent, allowing a tiny amount of airflow to continue, which prevents moisture buildup. This is important because a fully sealed chimney could encourage damp if the masonry traps condensation. The vented design ensures the chimney stays dry while still blocking the majority of airflow.

Are Chimney Balloons Effective?

The effectiveness of a chimney balloon depends on the shape of the flue, the condition of the chimney, and how well you fit the balloon. In most cases, they help reduce draughts within minutes of installation. Rooms stay warmer for longer because the balloons slow the constant upward pull of warm air and reduce the return of cold air through gaps.

Guidance by English Heritage notes that disused fireplaces and flues cause unnecessary heat loss and draughts and recommends chimney balloons as one of the quickest and simplest solutions. Blocking an unused flue can significantly reduce draught-related heat loss, making rooms feel warmer and decreasing reliance on central heating.

It’s worth noting that chimney balloons are not perfect. If the flue has an unusual shape or is heavily sooted, air can still circulate the edges. The balloons can also lose pressure over time, especially if they are not checked regularly. Despite these limitations, for a small upfront cost, they remain one of the most cost-effective ways to stop an unused chimney from acting like an open window.

What are the Pros and Cons of Chimney Balloons?

Like most energy-saving products, chimney balloons come with advantages and limitations. Understanding both helps homeowners determine whether this solution is appropriate for their property.

Pros

• Low upfront cost: Typically priced between £20 and £40, far cheaper than installing a chimney cap or damper.
• Quick to install: No specialist tools or professional help required; most installations take under 10 minutes to complete.
• Removable and reusable: Easy to deflate when you want to use the fireplace, then re-inflate afterwards.
• Immediate comfort improvement: Reduces draughts instantly, often making a noticeable difference in room warmth.
• Non-permanent solution: Suitable for listed buildings or rented homes with restrictions on permanent modifications.

Cons

• Potential for deflation: Balloons can lose air pressure over time and should be checked periodically, typically every few months.
• Chimney shape limits effectiveness: Irregular or huge flues may not seal properly.
• Risk if forgotten: Lighting a fire without removing the balloon can damage it and release unpleasant fumes.
• Moisture concerns: If fitted too tightly without ventilation, chimneys may be more prone to damp.
• Shorter lifespan than alternatives: Average lifespan is 2–5 years, depending on usage and care.

Chimney balloons work best for homeowners with unused fireplaces who want a fast and low-cost draught fix. They’re less suitable if you use the fireplace often, if the chimney has an unusual shape, or if you need a long-term maintenance-free solution.

Chimney Balloon Installation and Maintenance Guide

Fitting a chimney balloon is a straightforward DIY job, but a few simple checks make all the difference between a secure seal and wasted effort. The process typically takes less than 15 minutes and doesn’t require special tools.

Step 1: Measure Your Flue

Before buying, measure the width and depth of the chimney throat with a tape measure. Balloons come in different sizes, and an accurate fit is crucial to stop draughts. If in doubt, choose a slightly larger size rather than a smaller one, since you can adjust it to fit more snugly.

Step 2: Position the Balloon

Insert the deflated balloon into the chimney throat, about 30–50 cm above the fireplace opening. This is usually the narrowest part of the flue and provides the best seal.

Step 3: Inflate Carefully

Use the supplied pump or your breath to inflate the balloon until it presses lightly against the chimney walls. It should be firm but not overly tight. Most balloons have a small vent hole to allow a trickle of airflow, preventing condensation.

Step 4: Check and Adjust

Once inflated, make sure the balloon sits evenly and doesn’t shift. If air escapes quickly, remove it and inspect the chimney for sharp edges or debris that may be causing a puncture.

Step 5: Ongoing Maintenance

• Monthly check: Gently press the balloon to ensure it’s still inflated.
• Cleaning: Wipe down with a damp cloth before storage to avoid soot buildup.
• Storage: Deflate fully and store in a cool, dry place when using the fireplace.
• Safety tip: Always place a small reminder card or tag near the fireplace so you don’t forget to remove the balloon before lighting a fire.

A well-fitted balloon is virtually invisible, requires only occasional checks, and should last a few years with basic care.

Are there Alternatives to Chimney Balloons?

Chimney balloons are not the only way to draught-proof a fireplace. Homeowners seeking a more durable, natural, or low-maintenance option have several alternatives worth considering. Each comes with its own strengths and drawbacks.

1. Chimney Sheep

A “Chimney Sheep” is a thick, felted wool pad that blocks draughts while still allowing the chimney to breathe. Because wool is breathable, it reduces the risk of condensation and damp, making it a popular, eco-friendly option.

• Pros: Long lifespan (10+ years), made from natural materials, allows ventilation.
• Cons: More expensive than a balloon, bulkier to store when removed.

2. Chimney Cap or Top Damper

A chimney cap or top damper is a permanent solution you install at the top of the flue. It blocks draughts from above and also prevents rain, debris, or birds from entering. Once fitted, it requires little ongoing maintenance.

• Pros: Lasts decades, improves weather protection, and prevents wildlife entry.
• Cons: High upfront cost (£150–£300 with installation), not reversible, usually unsuitable for renters or listed properties.

3. DIY Draught Stoppers

Some homeowners use improvised solutions such as stuffing the chimney opening with old cushions, plastic bags, or cardboard. While this can temporarily block airflow, it is not recommended for safety reasons, as forgotten material in a working fireplace can catch fire or produce toxic fumes.

• Pros: Almost free, instantly available.
• Cons: Unsafe, untidy, short-term, poor draught seal.

4. Specialist Draught Excluders

There are also purpose-made chimney draught excluders, such as covers or plugs, that fit directly into the fireplace opening. These are less common but can be effective in certain types of chimneys.

• Pros: Easy to remove, reusable, and designed for safety.
• Cons: Limited sizing, can be visually intrusive, and less effective than a well-fitted balloon or cap.

A chimney balloon is the most cost-effective short-term fix, while a chimney sheep suits those seeking a natural, breathable solution. For homeowners wanting a one-time investment with no ongoing effort, a chimney cap or damper is the most robust option.

How Much Do Chimney Balloons Cost?

One of the main appeals of chimney balloons is their affordability. A standard balloon can cost as little as £16, depending on the size and supplier. For most households, this makes it one of the most affordable draught-proofing products on the market.

When compared with other solutions, the value becomes clearer:

Draught-Proofing Method	Typical Cost (UK)	Lifespan	Maintenance	Best Suited For
Chimney Balloon	From £16	2–5 years	Needs occasional reinflation	Renters, occasional fireplace users
Chimney Sheep (wool plug)	£35–£60	10+ years	Minimal, but must be removed for fire use	Eco-conscious homeowners, irregular flues
Chimney Cap / Top Damper	£150–£300 (installed)	20+ years	Low once fitted	Long-term fix, homes with permanently unused fireplaces
DIY Stuffing (e.g. plastic bags, cardboard)	~£0–£10	Short-term	Needs frequent adjustment	Temporary draught stop, not recommended for safety

In practice, a chimney balloon can pay for itself within one or two winters by reducing heating bills. For example, a detached or semi-detached UK home with an open unused flue could be losing hundreds of pounds in wasted heating each year, depending on the property size, home insulation and efficiency. Even if the balloon only reduces a fraction of that loss, the return on investment is quick.

The main trade-off is durability. Unlike a permanent chimney cap, a balloon won’t last decades and will eventually need replacement. However, for tenants, homeowners with listed properties, or anyone needing a reversible solution, it remains the most budget-friendly option.

Final Thoughts on Chimney Balloons

An open chimney can be one of the most significant hidden sources of heat loss in a home. For households with a fireplace that’s rarely or never used, a chimney balloon offers one of the simplest and most affordable ways to improve comfort. With prices starting at just £16, the savings on reduced heating bills can quickly outweigh the upfront cost, making it an attractive option for both tenants and homeowners.

That said, chimney balloons are not a one-size-fits-all solution. Their effectiveness depends on the shape and condition of the flue, and they do require occasional checks to ensure they remain properly inflated. For long-term, maintenance-free protection, alternatives such as a chimney cap or a wool-based draught excluder may be worth considering.

For many households, though, the chimney balloon strikes the right balance between cost, convenience, and performance. It plugs a problem that most people don’t even notice until they feel the difference through a warmer, draught-free living space.

FAQs on Chimney Balloons

What Is The Alternative To Chimney Balloons?

Alternatives include Chimney Sheep (wool-based plugs that allow ventilation), chimney caps or top dampers (permanent, long-lasting solutions), and specialist draught excluders that cover the fireplace opening. Each option varies in cost and durability. For most homeowners, a chimney balloon is the most cost-effective short-term solution, while a chimney cap is the most permanent.

Do Chimney Balloons Cause Damp?

Chimney balloons have a small vent or breathable material to allow airflow, which helps prevent dampness. Problems can arise if you overinflate the balloon or if the chimney already has moisture issues. In most cases, damp is not caused by the balloon itself but by underlying ventilation problems.

How Long Do Chimney Balloons Last?

On average, chimney balloons last between 2 and 5 years. Lifespan depends on the condition of the chimney, frequency of use, and how carefully they are inflated and stored. Regular checks and gentle cleaning can help extend their life.

Which Is Better, a Chimney Sheep or a Chimney Balloon?

Both products reduce draughts, but they work slightly differently. A chimney balloon creates a tight seal, making it an ideal solution for a quick and inexpensive fix. A Chimney Sheep, made from felted wool, is more breathable, longer-lasting, and better for damp-prone chimneys. The “better” choice depends on whether you prioritise cost or longevity.

Is A Chimney Balloon Worth It?

Yes, for households with unused fireplaces, a chimney balloon is often worth the investment. With prices as low as £16, it can pay for itself within one or two winters by reducing heat loss and lowering heating bills. It may not be ideal for irregularly shaped flues or a chimney that you use frequently.

What Is The Cheapest Way To Block A Chimney?

The most affordable option is DIY stuffing (such as cardboard or plastic bags), but this is not recommended due to fire risks and poor performance. Among safe products, a chimney balloon is the most budget-friendly option, offering an effective seal at a low upfront cost.

Can I Use The Chimney Balloon When The Fire Is On?

No. You should only use the chimney balloon when the fireplace is not in use. If you light the fire while the balloon is in the chimney, it will likely shrink, melt, or fall into the fireplace. It’s not typically a significant safety hazard (especially for modern balloons designed to fail safely), but it can damage the balloon or produce an unpleasant odour. A visible tag or reminder can help prevent this.

Sources and References

Energy Saving Trust – Draught proofing

English Heritage – Open fires, chimneys and flues