Pellet Stove Glass: Sizing and Replacing the Glass Tube

Is the glass tube on your pellet stove cracked, broken or permanently sooted up? In most cases there is no need to replace the whole heater. The glass is a separate spare part: a straight borosilicate cylinder you can lift out and replace in a few minutes. This guide explains how to work out the right pellet stove glass size, why borosilicate glass matters, why glass cracks in the first place, and how to clean it without scratching it.

This is about replacement glass for pellet stoves and fire pits with a glass flame column – the outdoor heaters that give you a full view of the flame. Using another brand? Keep reading. Our glass cylinders are universal borosilicate tubes and fit many other heaters as long as the height and diameter match.

What size pellet stove glass do I need?

There is only one reliable method: measure. Do not rely on the model name or a photo, but on the two dimensions that decide the fit.

Measuring the height

Measure the glass tube itself from bottom to top – not the total height of the heater. If the glass is still in its holders, measure the free space between the lower and upper holder and add the insertion depth. Do not round up or down: 112 cm and 120 cm are close together but not interchangeable.

Measuring the diameter

Measure the outside diameter across the widest point of the tube. All Flamesa glass cylinders have a diameter of Ø 10.5 cm and a glass thickness of roughly 2 to 3 mm. If your diameter differs by more than a few millimetres, the glass will not seat properly in the holders.

Glass already broken?

Measure the remaining pieces in the lower holder for the diameter, and use the holder position or the manual for the height.

Sizes and compatibility

These are the sizes we supply separately. All borosilicate glass, all Ø 10.5 cm.

Sometimes the glass is not the problem – the holder is. If your tube wobbles or rattles, check the glass tube holder as well.

Borosilicate glass versus ordinary glass

Our cylinders are made of borosilicate glass, which is not the same as the soda-lime glass used in lanterns or vases. Borosilicate has a much lower thermal expansion, so it copes with large temperature differences without cracking. That is exactly what happens in a pellet stove: a hot flame on the inside, cold evening air on the outside.

A plain glass tube from a hardware store may look like it fits, but it is not built for this load and often fails within the first few burns. Always choose heat resistant borosilicate glass in the correct size. Background on the material is available on Wikipedia. One caveat: borosilicate is still glass, so it remains vulnerable to knocks and drops.

Why does pellet stove glass crack or break?

1. Mechanical damage

By far the most common cause. The heater blows over, knocks against a table edge, or the tube slips out of your hands during cleaning. Always place the heater on a stable, level surface and never move it while it is hot.

2. Thermal shock

Cold water on hot glass is the classic mistake. Let the glass cool down completely before cleaning. Never put out the fire with water – let it burn out instead.

3. Tension in the holders

Glass clamped too tightly or mounted at an angle can crack as it expands. Tighten the screws hand tight only, and check that the tube stands straight and free.

4. The wrong fuel

Always use clean, dry, good quality pellets and do not fill the pellet hopper above the mark. Damp pellets soot up the glass much faster.

5. Baked-on soot

Not a break, but often experienced as one. Regular cleaning prevents you from needing a new cylinder in the end.

Replacing the glass step by step

1. Let the heater cool down completely. Never work on a warm appliance.
2. Remove the top cap or reflector so the top of the glass is free.
3. Undo the holders. Usually a few screws. Keep the small parts together.
4. Lift the glass straight out with both hands, wearing gloves if it is broken. Clear away all shards carefully.
5. Fit the new cylinder straight into the lower holder, making sure nothing binds.
6. Refit holders and cap hand tight, then check that the glass is stable.

Before you light it again: check that the air intake is clear and the ash tray is empty. That keeps the new glass clear for longer.

Cleaning the glass without scratches

• Let the glass cool down completely first.
• Use a cleaner made for stove glass, such as the glass and soot cleaner, then rinse with water to avoid streaks.
• For tall cylinders, work with a long brush. The 120 cm glass cleaning brush consists of three 40 cm sections and can be attached to a drill via the threaded connector. The telescopic brush is the compact alternative.
• Never use steel wool, abrasive powder or a scraper. Scratches are permanent and become weak spots.
• Everything in one go: the cleaning kit.

We recommend storing the heater dry after the season. Staying outside? Cover it properly with a protective cover so moisture stays out of the pellet hopper and off the glass.

Will this glass fit another brand?

Often yes. It is a straight cylindrical borosilicate tube, and that is not brand specific. The rule is simple: if the height and the Ø 10.5 cm diameter match your heater or fire pit, the glass fits. We cannot confirm which other brands use exactly these dimensions, so always measure first and compare with the table above. If the diameter is off, do not settle for “almost right” – that causes play, rattling and eventually breakage.

Frequently asked questions

Can I replace pellet stove glass myself?

Yes. The glass is a separate part. You usually only need a screwdriver, a cold heater and a few minutes.

Which size does my heater need?

Measure the height of the glass cylinder and the outside diameter, then compare with the table above.

Is this glass heat resistant?

Yes, it is borosilicate glass, made for high temperatures and temperature swings. It stays breakable on impact.

Why has my glass gone black?

That is soot, usually from incomplete combustion or damp pellets. Clean the glass and switch to clean, dry pellets.

Can I use ordinary glass or acrylic?

No. Ordinary glass cannot handle the temperature differences and plastic does not belong near an open flame.

How long does the glass last?

With normal use and no knocks, a cylinder lasts a long time. Careful handling and regular cleaning matter most.

You will find all glass cylinders, holders and maintenance products with our outdoor pellet stoves.