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Help my woodburning stoves’ glass has gone black

Fire behind glass

This is definitely the most common question we get asked about and part of our 10 week series on this blog answering the most common solid fuel stove problems.  We will be writing one per week- if you would like the full guide in one handy PDF do sign up to our mailing list and you will receive the file automatically. Click here for the sign up.

But first if your glass goes black check out some of the reasons why and what you can do about it.

There can be several reasons why your woodburning stove glass is going black when using it.

The first thing to determine is how old your stove is and whether it has an air wash system. If your
stove is older than 10-15 years it can be possible that your stove does not have a modern air wash
system which means that it is prone to glass going black. Unfortunately in this scenario there isn’t
much to stop the glass going black and you may want to consider an upgrade to a more modern
stove. However if an upgrade is not possible if you follow the step for younger stoves you will still see
some improvement.

More modern stoves do have an air wash system and therefore glass should not be going black as
often.

Here are some of the steps you can take when it does occur and to prevent it from happening:

1. Build your fire towards the back of the firebox.
2. Use high quality dry wood. Green wood or wet wood can create more smoke and blacken the
glass
3. Make sure you get the stove up to temperature and hot right at the beginning. Let it burn hot for at
least 10 minutes- Bear in mind that stoves do vary and some may need less time and some might
need a little longer, your HETAS installer should be able to advise you when considering different
stoves. We highly recommend putting a stove thermometer on your flue pipe to help determine
that your stove has reached optimum temperature. This will also help heat your chimney which
makes for a better burn and ensure your stove is at its most efficient.
4. Before you go to bed or stop using your stove ensure that you put a couple of pieces of kindling on
any embers and let it burn hot i/e do not shut the airflow off completely. This ensures that any
fuel le burns away completely ensuring the stove doesn’t burn low too long.
5. Don’t let the stove burn below optimum temperature as when it burns low it can cause blackness
on the glass.
6. Don’t build your wood stack too high this ensures that no wood logs fall forward whilst your fire is
on.

If you find a log does fall forward or your glass has gone black you can remove this by making a really
hot fire and letting your fire burn for a while towards the end of the optimum burn range.
If the spots are very stubborn you can use a Stove cleaning sponge, stove glass cleaner paste or a
glass cleaner spray to get rid of them.

Please ensure you only use these products on a cold stove. It is
a good idea to clean the glass on a regular basis anyway. Smoke will also at times leave some marks
on the glass therefore it is always important to burn at optimum temperature and use high quality,
dry and hard wood.


Check back on the blog next Tuesday when we will be answering: ‘Why does smoke come out of my stove?’

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