My chimney is clear but blows smokes back into the room. Why?

I often get asked how can you stop a fire smoking back into the room. It can happen for a variety of reasons, one of which being that your chimney is blocked. That’s why it’s always important to have it swept regularly.

However, if you have had it checked by a professional and other potential causes such as bird’s nests, downdraughts or lack of ventilation into the room have been ruled out, it’s likely that the air pressure outside is literally pulling the smoke back down your chimney and into the room.

Picture the scene; it’s really chilly outside and you want to get your fire going. But if you’re cold, just think how your chimney will feel. It may not have been used for a while. It may not have any insulation. It may be on an outside wall – yes, even things like this can contribute to smoke blowing back into the room even when your flue is clear.

For chimney sweeps, we have the same problem when the air is too warm outside to produce a ‘draw’. That’s why it’s sometimes necessary for us to use a heat gun or blow torch to warm the flue before we conduct a smoke draw test as part of a normal sweep.

In both situations, the trick is to warm the flue before large amounts of smoke are produced. So let me introduce you to the Upside Down Fire or the Top-Down Fire method (Used in Europe alot).

Contrary to popular belief, starting off with small bits of wood and then adding more fuel onto a fire isn’t the greatest way of getting your fire going.

Let me take you through the method first, and then I’ll explain why it works:

Step One: Put a layer of your main fuel on the bottom (Can be coal or wood).

Step Two: Add some firelighters and light them.

Step Four: Add some kindling.

Step Five: After about 4-5 minutes, add some more kindling.

You can vary this slightly by putting kindling on top of the main fuel, then putting the firelighters on top if you wish, but the results are broadly the same.

So what’s happening? It’s simple – the flue is being warmed by the firelighters and kindling. Both produce predominantly flames and warmth, which is therefore warming the chimney and creating a good ‘draw’ or draught.

And because your main fuel has already been loaded onto the fire at the beginning, it will catch light eventually. By that stage the main fuel will have been ‘warmed’ as well (yes, cold fuel creates more smoke) and also, because it’s already in the grate, you’re not having to ‘smother’ the fire with the main fuel.

The net result is a fire which draws better and produces less smoke. This is good news because smoke, as it goes up the flue, can condense and leave deposits inside your chimney/liner. That’s why it’s important, if you are burning wood, that it is good quality, seasoned wood with a moisture content of around 20% or lower. Anything higher and you are simply sending more vapour into the flue, which is bad news and contributes to things like chimney fires and damaged liners.

Haven’t tried the Top-Down method yet? Why not give it a go and let me know how you get on? But remember, never light a fire if you suspect your flue is blocked. Give us a call, because smoke inhalation/carbon monoxide can be fatal.

Why do I need to have my chimney swept?

Chimneys need to allow for the free passage of dangerous gasses. Regular cleaning will remove soot and creosote, helping prevent dangerous chimney fires. Cleaning will increase the efficiency of some appliances. Bird nests, cobwebs and other blockages will be removed.

How often does my chimney need sweeping?

The sweeping frequencies below are for guidance. Frequency will depend on a number of factors including: Type of fuel, appliance used, duration of use, moisture content of wood fuel, type of chimney.

*Smokeless fuel: At least once a year
*Wood: Quarterly when in use
*Bituminous coal: Quarterly when in use
*Oil: Once a year
*Gas: Once a year

What is the best time of year for sweeping?

We would recommend getting your chimney swept after you have finished using it in the spring or summer months as the demand for sweeping peaks when the weather turns approaching Autumn and Winter which can lead to a longer wait for a Sweep to be available.

How long does it take?

A sweep usually takes 30 - 60 minutes, depending on the type of appliance.

Does it make mess?

Very rarely, a rare exception may be when the chimney is blocked with a bird’s nest when it is sometimes difficult to contain all dust, however, we use an Industrial HEPA Vacuum Cleaner that can deal with any situations that may arise.

What happens to the soot?

We leave the soot with the customer to dispose of in their general waste dustbin as advised to do so by NACS and the local authorities.

What should I do to prepare for the sweep’s visit?

In general we will need a clear passage to the chimney and adequate space to work in. Clear ornaments from the hearth and perhaps from the mantelpiece. If you have spare sheets, feel free to cover any light coloured soft furnishings in the room as this is not something we do as standard.

Do we offer certificated Sweeps?

Our Sweeps are certificated and trained by Rodtech, The industries leading Power Sweeping provider. Our sweeps are trained in the latest Power Sweeping Techniques and are experts with all of the different Rodtech Power Sweeping Equipment.

Are you insured?

Yes, we have £3,000,000.00 full liability insurance to cover any incidents that may occur.


How long will it take before the moss comes back?

Assuming that the roof isn’t under tree cover, the moss shouldn’t grow back for 2 to 3 years, so the chemicals should be re-applied every 2 years to prevent any moss growth. This application of chemicals to the roof is much cheaper than the initial cleaning as no elbow grease is required. Plus there is no need to physically get on the roof again, the chemicals can be applied from gutter height with a sprayer.

Can't I just use chemicals to clean the roof?

The short answer is no! You would need many gallons to try this as the moss would simply soak it up. In addition thick moss will prevent the chemical from soaking into the tile and the overlaps, which means the spores would not be killed, which means they would grow back quicker. Finally all the dead moss would eventually wash down into the gutters causing blockages and this would be ongoing for months so your gutters would need frequent cleaning to avoid becoming blocked.

Will manual removal of moss damage the roof tiles?

There is always some risk of damaged tiles whenever you disturb them, especially with very old roof tiles. However manual cleaning using a scraper or brush is much less likely to damage tiles than using a high pressure washer. In fact a number of tile manufacturers specifically state that pressure washers should not be used with their products to avoid damage and manual cleaning is often their preferred option.

Should I have moss removed as soon as it appears on my roof?

Despite scary horror stories told by unscrupulous tradesman, in the vast majority of cases some moss growth on roof is not a problem. In most cases even significant moss growth will not damage the roof tiles, but it can of course block gutters and drains. On certain very shallow pitch roofs, moss can potentially reduce the flow of water and in very damp conditions the roof tiles can be damaged over time. But in most cases, the removal of moss from roofs will be for mainly cosmetic reasons. 



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