Wood Burner Flue query.

However you do it *IF* you are considering a sale at some point then beware that Building Regs will apply to the installation and may cause problems if its not 'signed off' by an Inspector or a friendly HETAS registered person

Your proposal does sound a little rough and ready when you talk about telescopic flue sections and may well lead to CO into the room.

My sweep simply pushes his brush up past the flue damper and into the flue. No disassembly necessary.

Our newer one is similar but the old one has to have a top baffle plate removed to give access though its not a difficult job. I guess some old models may need firebricks removing but designs have improved a lot since those days.

Telescopic sections are a standard fitting and acceptable to allow removal of stove in case of issues without having to dismantle the entire chimney/flue stack.

Yes, it would be better to have a removable section to give access both up and down the remaining flue. Then the bit removed could be cleaned externally. With all of this zero carbon stuff going on, it might actually mean such stoves become illegal very soon. Brian

Looking at fitting a second floor woodburner using an existing chimney, I hit an issue with floor to flue exit minimum height of 15'

snipped-for-privacy@stovesonline.co.uk gives an explanation of BR part J which might be of interest to you.

With an enclosed unit, I thought drawing the inlet air from lower than floor level might be a way around this but haven't investigated further.

Given that our house is upsidedown the wood-burner is effectively being fitted in a "bungalow" even though it's a 2 storey house.

I had quite a lengthy chat with the flue-man who designs the flues for the company I purchased the stove from as the stove in question has a recommended flue length (top of stove to ferminal) of 5 metres rather than the recomended 4.5m. Presumably down to cooler flue gas due to the water jacket extracting heat.

His response was: the standard 4.5m (15') length is "recomended" as it was advised to cover the majority of installations, i.e. poor locations, surrounding buildings, obstacles etc. It is purely a recommended height and not a regulation height.

When I detailed our location i.e. on top of a hill exosed to S.W. and the flue being virtually straight up and out next to the ridge tiles he said that as an ex-installer it would have been a "dream install" knowing the flue would "pull like a train" and he could walk away knowing there would never be a problem. He also said that he lives in a bungalow and his own flue is shorter than 4.5m and doesn't give any problems.

The Local flue merchant also said the same thing and added that of course if there is a problem you can always add an extra length to the top but the general feeling of both is that if it draws, it draws and that's all there is to worry about.

Ok, so I thought the best solution is to check properly. The top plate when fitted still allows access to the bleed valve so wouldn't need to be removed.

I then started to go through the removal of the fire bricks process to gain access to sweep from stove. Obviously everything is clean and un-burnt but taking out the first fire brick after removing the grate, and a bit of the corner chipped off, confirming my original suspicions.

With that in mind, I'm going back to the plan of a 500mm section with inspection/sweep access door and another 500mm section followed by 2 30 degree offset bends to go through the ceiling without having to cut and frame the ceiling joist.

The stove isn't coming out anytime soon as it's all plumbed in and worst case scenario I can simply dismantle the flue from above as the roof is easy access with a step ladder.

Going to cost a bit more for the twin-wall access section but will ensure sweeping is carried out regularly, or when necessary as visual inspection will be quick and simple.

:)

Ok. Ours is a chalet bungalow with an included attic so the ridge height is lower than a normal house. Conventional 9" chimney pot so not easily extended:-(

Mine has a plate above the stove for access, but my sweep has so far been able to work a brush through the superheaters and up into the chimney without too much difficulty. He only used the top pipe access the very first time he did it. I have it swept once a year.

His recommendation is twice yearly. OTOH I've never had any bother and the deposits removed are always dust like and not at all risky. I am very good at running a hot fire and managing the vents.

Which fire bricks? My back boiler multi-fuel stove has no fire bricks at all. Some tar condenses on the water jacket but otherwise it burns clean and smokeless once it is properly alight. I have to be a bit careful in a power cut since it could boil the water in the superheater tubes without the pump on.

It can just about run the entire central heating when run flat out which may prove useful this winter given the price of kerosene.

I wouldn't want anything that wasn't gas tight on the exhaust. YMMV

If it does invest in a high quality CO alarm - your life may depend on it!

Mine you also have to take out the top baffle plate but that is a part of routine maintenance anyway so hardly worth mentioning.

You may be over egging this:-)

I installed a *smoke eater* type log burner in the farmhouse. The spec. called for a 7" flue not available in stainless flexipipe so I used 8" with a 1" rockwool insulating sleeve.

Installed in 2009. Kept burning throughout the heating season, hardwood only. Flue never swept. Checked when we sold in 2019 and found about 6mm of grey ash adhering to the flue wall!

That's what I'm hoping for. The gas boiler will maintain the heat store at 60 degrees C so the house will always have a fail-over to bring it up to temp. when wood burner isn't alight but with the wood burner giving 4 kWh in the main living room and more to the the central heating it will at least significantly reduce gas consumption... Just remains to be seen if wood works out much cheaper. :)

Quite a bit of paranoia over "wood fumes". It's not like gas/oil. What about all the people that have lived with "open fires" all their life, Don't recall ever seeing anyone suffer CO poiconming from an open fire and open fires are perhaps the most inefficient way of burning wood so theorestically significantly more CO is produced in an open fire than a sealed and high combustion efficience wood-burner. Plus the flue is at a lower pressure than the room otherwise the fire wouldn't burn so the risk of CO poisoning isn't actually a thing. And.... unlike natural gas, you know about wood fumes coming into the room both visually and by the effect on eyes, lungs etc, far from the "silent killer" of other devices.

Smoke alarm will alret you WAYYYYYYY before a CO alarm could.

When it is down to burning charcoal in the embers overnight it is exactly like gas/oil and the CO is odourless. The alarms are not expensive and are worthwhile as an insurance policy.

We used to have an open fire. The through draft from it pulled in plenty of cold air to replace the stuff going up the chimney. Big improvement of a stove is that less cold air is pulled through the room.

Once the fire is down to embers it is still burning hot but without any obvious warning signs. Most deaths from CO poisoning in countries where it still happens are from burning charcoal.

No it won't. Charcoal burns with a clean smokeless flame but under ash it can also burn with a fair proportion of CO emission.

I think you might be right Tim. Only thing is, although I've now half filled the wood-shed with 2 x builders bags of split/seasoned Ash which should burn cleanly, no doubt less than prime wood will also find it's way into the boiler so the traditional " sweeping once or twice a year " perhaps not required with the current clean burning regulations might be more of a requirement.

Having just gone into the local Flue Wholesaler and he's advised that no-one stocks or generally sells twin-wall with access hatch so I've now got to re-design the flue once again!

Got to be right but I'd much rather have an access/sweep port than having to remove all the fragile vermiculite blocks every year.

No way of sweeping from the flue top?

Our farmhouse had triple flues, each about 12" x 14" so the stack top was something you could stand on! With the cap taken off the new liner it would have been simple to sweep downwards from a roof ladder hooked over the house ridge.

We had cracking of the firebrick fireback with one replaced over the 10 years. With no back boiler, our fire probably ran hotter than yours will.

I suppose it is always in the Sweeps interest to recommend more than the minimum cleans:-)

I did wonder about sweeping from te top down. That would be a simple job but what would happen to all the soot and crap that ended up in the top of the burner/boiler ? I'm presuming it would just re-burn being at the hot end of the flue and most of the loose soot would travel up the flue and out.

Hmmmm perhaps that is the best way to go. :)

Cheers Pete

No way of getting there with a vacuum cleaner?

Kindly don't sue me!

That is the standard way of sweeping chimneys and flues in mainland Europe and in Scotland. The rest of the UK seems to be an exception in sweeping from the bottom up.

That would be a simple job

Why do you assume that it would remain above the burner/boiler or stove/fireplace and not fall into it, where it could be removed?