O/T Woodburner Flue Issues

[geoffbeaumont]

On 1/12/2023 at 7:39 PM, Retroanaconda said:

There’s no requirement for building control sign off in Scotland so that isn’t an issue.

I’d say the idea has merit for sure, read up on the regs in terms of where the flue must terminate in respect of ridge line etc. though.

That's because the HETAS certification takes care of that - it doesn't mean you aren't required to comply with the building regs.

Flue must be above the ridge (and any windows in the vicinity - possibly other roofs too, but not sure about that).

On 1/12/2023 at 7:19 PM, Nonimouse said:

The probelm with HEATAS is that if you've got £3k and you've got the ticket, you may not have the knowledge.

...but this is the reality. When we bought our current house the stove was HETAS installed but didn't comply with regs (inadequate heat shielding to wooden beam, flue top too low, hearth too small). It was dangerous and didn't draught.

We couldn't find anyone prepared to touch an existing installation and had to have the whole installation replaced with new.

[reb78]

4 hours ago, geoffbeaumont said:

 

...but this is the reality. When we bought our current house the stove was HETAS installed but didn't comply with regs (inadequate heat shielding to wooden beam, flue top too low, hearth too small). It was dangerous and didn't draught.

We couldn't find anyone prepared to touch an existing installation and had to have the whole installation replaced with new.

See it in all trades. We thought we would give a young chap a chance who had set out on his own as a qualified electrician. The amount of bodge work that became apparent after he left was crazy. Qualified or not I could have done a better and safer job. 

[Gazzar]

Sadly all too common. I prefer to do my own wiring, and get it certified. I'm slow, but thorough.

[reb78]

1 hour ago, Gazzar said:

Sadly all too common. I prefer to do my own wiring, and get it certified. I'm slow, but thorough.

I was really disappointed. I just cleared up his mess. No point having him back as it still wont be right. 

[reb78]

Back on topic... this was the back boiler on my rayburn after 6 weeks of wood and anthracite. I'm burning it too low I think. Its all clear now but the wood will only be going on when i have the flames going well rather than banking down overnight with a mix of anthracite. Chimney has some residue but not a lot compared to the boiler. 
 

 

there should be five channels there. The left two were pretty much blocked. The wood is two dry and seasoned for two years mostly. 
 

So depending on what the OP is burning it may be worth running brushes up the chimney and certainly checking the baffle plate is clear and clean. 

Edited January 15, 2023 by reb78

[Nonimouse]

13 hours ago, reb78 said:

Back on topic... this was the back boiler on my rayburn after 6 weeks of wood and anthracite. I'm burning it too low I think. Its all clear now but the wood will only be going on when i have the flames going well rather than banking down overnight with a mix of anthracite. Chimney has some residue but not a lot compared to the boiler. 
 

 

there should be five channels there. The left two were pretty much blocked. The wood is two dry and seasoned for two years mostly. 
 

So depending on what the OP is burning it may be worth running brushes up the chimney and certainly checking the baffle plate is clear and clean. 

It needs to be hotter - what wood are you burning? It looks ot very resinous

I would also suggest putting potato peelings on, at least once a week. As they burn, they produce a chemical that breaks down the tar

[Nonimouse]

19 hours ago, geoffbeaumont said:

That's because the HETAS certification takes care of that - it doesn't mean you aren't required to comply with the building regs.

Flue must be above the ridge (and any windows in the vicinity - possibly other roofs too, but not sure about that).

...but this is the reality. When we bought our current house the stove was HETAS installed but didn't comply with regs (inadequate heat shielding to wooden beam, flue top too low, hearth too small). It was dangerous and didn't draught.

We couldn't find anyone prepared to touch an existing installation and had to have the whole installation replaced with new.

This is the problem with any form of competance training 

[Gazzar]

1 hour ago, Nonimouse said:

It needs to be hotter - what wood are you burning? It looks ot very resinous

I would also suggest putting potato peelings on, at least once a week. As they burn, they produce a chemical that breaks down the tar

Wow, excellent tip! Thanks.

[Nonimouse]

1 hour ago, Gazzar said:

Wow, excellent tip! Thanks.

Works really well

As do waxed card milk cartons as fire starters, or pistachio nut husks

[reb78]

3 hours ago, Nonimouse said:

It needs to be hotter - what wood are you burning? It looks ot very resinous

I would also suggest putting potato peelings on, at least once a week. As they burn, they produce a chemical that breaks down the tar

I agree. Its the first year we have had it installed here (moved it from my mums last spring so have used it for 30 years) and I was going easy on it to try and eeek out the wood and anthracite and I think I have been running it too cool as you say. As well as cleaning it this weekend I repaired the cooker/heating air flap so now i can get it to sit part way between the two which helps with draw and making sure the firebox can run hot but still provide heat. What i need to do is cut the wood out from the overnight banking too as thats when i imagine a lot of these deposits form.

Wood wise - its mainly a mix of elm and ash, with some oak. I dont think there is any pine/conifer type stuff in there. Its all been seasoned for around 2 years (the Elm was chopped up in Feb 2020 - this was a fallen limb so had been down some time before I cut it up too) so I am surprised by the amount of resin seen.

Potato peelings are a useful suggestion! I bought some chemical to put on twice a week to reduce the tar build up but that clearly didnt do much!

[Happyoldgit]

Lots of sites on the internet with useful info. Particularly relevant to the UK [ok England-shire] is this one...

https://www.stovefitterswarehouse.co.uk/pages/do-i-need-an-air-vent-for-a-wood-burning-stove

On the subject of external vents...

"The air vent aperture required increases in size depending on the KW output of the stove (this being very approx. equivalent to a 50p piece for each KW – so a 5kw stove requires an area equivalent to 5x50p pieces).

The exact figure is 550 square millimetres of vent hole per kw of stove.

A square hole 3cm x 2cm is 600 square millimetres. A 50p piece is 594 square millimetres.

In older properties “that are not deemed as particularly airtight” then the rule is the same but you get the first 5kw free. In other words a 5kw stove has no air vent requirements, whilst a 6kw requires one 50p sized hole, a 7kw two 50p sized holes (or equivalent) etc."

Trying to find a reliable HETAS registered installer seems particularly problematic around here at present as everyone and their granny is scrambling to get wood or multi fuel burners installed as they think they will save money on their energy bills. Consequently installers are raking it in at present and seem loathe to commit quotes to paper before starting the job. We have a new multi fuel stove / range on order to replace a Hunter Herald wood only stove so are looking to get the 10 year old 316 stainless liner replaced with a 904 as I want to use up a bunker load of anthracite left over from when the AGA was solid fuel prior to its conversion to 'electric.

As an aside, as the cost of living rises there appears to be a whole load of folks who believe they can tour the countryside chopping and hacking in places they have no right of access to in order to gather free wood that they can chuck on their stoves along with anything else burnable.

[reb78]

Whats the lifespan of a liner out of interest and what are the reasons for replacing them? We have one lined chimney and other that isnt but will get that done this spring. I kinda figured that if the liner does not have a hole in it, it must be ok but are there other reasons for failure?

[Nonimouse]

4 hours ago, reb78 said:

I agree. Its the first year we have had it installed here (moved it from my mums last spring so have used it for 30 years) and I was going easy on it to try and eeek out the wood and anthracite and I think I have been running it too cool as you say. As well as cleaning it this weekend I repaired the cooker/heating air flap so now i can get it to sit part way between the two which helps with draw and making sure the firebox can run hot but still provide heat. What i need to do is cut the wood out from the overnight banking too as thats when i imagine a lot of these deposits form.

Wood wise - its mainly a mix of elm and ash, with some oak. I dont think there is any pine/conifer type stuff in there. Its all been seasoned for around 2 years (the Elm was chopped up in Feb 2020 - this was a fallen limb so had been down some time before I cut it up too) so I am surprised by the amount of resin seen.

Potato peelings are a useful suggestion! I bought some chemical to put on twice a week to reduce the tar build up but that clearly didnt do much!

Avoid elm if you can, if not burn it as hot as you can. It produces a lot of smoke, but not pitch smoke like pine. It also holds moisture. I think your worst culprit is the anthracite though, I would opt for the smokelss fuel nuggets

[Happyoldgit]

19 minutes ago, reb78 said:

Whats the lifespan of a liner out of interest and what are the reasons for replacing them? We have one lined chimney and other that isnt but will get that done this spring. I kinda figured that if the liner does not have a hole in it, it must be ok but are there other reasons for failure?

Depends on the grade of stainless the liner is made of. "They" reckon 316 is ten years minimum [burning wood only] but can last longer. 904 is recommended for multi fuel.

 

 

[reb78]

13 minutes ago, Nonimouse said:

Avoid elm if you can, if not burn it as hot as you can. It produces a lot of smoke, but not pitch smoke like pine. It also holds moisture. I think your worst culprit is the anthracite though, I would opt for the smokelss fuel nuggets

Interesting. The Elm is nearly gone so that's easy to avoid now. Interesting to hear about the anthracite though. Before it came to me this Rayburn only burnt anthracite and very little else and it was usually very very clean. I should have clarified though - i am using one of the smokeless manufactured (anthracite derived) alternatives now but I thought anthracite was also considered smokeless and ok in smoke free zones as a result (not that that applies out here in the sticks). Its become harder to get and I don't think will be available in raw form next year.

[reb78]

12 minutes ago, Happyoldgit said:

Depends on the grade of stainless the liner is made of. "They" reckon 316 is ten years minimum [burning wood only] but can last longer. 904 is recommended for multi fuel.

 

 

Thanks - I dont know what grade this current liner is. Used to be on a woodburner before I put the Rayburn in but I dont know its age. How do they fail?

[Happyoldgit]

48 minutes ago, reb78 said:

Thanks - I dont know what grade this current liner is. Used to be on a woodburner before I put the Rayburn in but I dont know its age. How do they fail?

Bits of liner come down when it is swept ...if not before.

[reb78]

24 minutes ago, Happyoldgit said:

Bits of liner come down when it is swept ...if not before.

Haha. Yep. I can spot that. None when i ran the brushes up on sunday.

[Blanco]

14 hours ago, Happyoldgit said:

Thanks - I dont know what grade this current liner is. Used to be on a woodburner before I put the Rayburn in but I dont know its age. How do they fail?

over 40 years ago now we put a Selkirk flue in the central brick and concrete 'core' of a timber frame on Mull. It was backfilled with lightweight concrete which used vermiculite as agregate. The flue failed over 20 years ago but the concrete 'liner' still works perfectly. Only soft wood is available on Mull and my Father used very brutal methods to clear the resin once a year , but then we didn't know about potatoe peelings!  I helped clear a couple of flues in more recent years and found resin can build rapidly where a lined flue exits the roof, and the smoke cools. one such was reduced to  a finger sized hole in the middle, ... it did draw much better when cleaned!

[reb78]

34 minutes ago, Blanco said:

over 40 years ago now we put a Selkirk flue in the central brick and concrete 'core' of a timber frame on Mull. It was backfilled with lightweight concrete which used vermiculite as agregate. The flue failed over 20 years ago but the concrete 'liner' still works perfectly. Only soft wood is available on Mull and my Father used very brutal methods to clear the resin once a year , but then we didn't know about potatoe peelings!  I helped clear a couple of flues in more recent years and found resin can build rapidly where a lined flue exits the roof, and the smoke cools. one such was reduced to  a finger sized hole in the middle, ... it did draw much better when cleaned!

We had one of the aggregate (?) I guess vermiculite (?) pumped flues installed at my mums... bloody thing popped bricks out everywhere as they pumped it in - particularly in the attic! All fine once we filled the holes and let it set! I guess it proved it needed lining!

I had to get quite brutal with that back boiler at the weekend - used a 22mm bit of old copper pipe to punch down through the blocked channels. Its burning cleaner now. Maybe some of the first wood I used on it was resinous and i didnt realise but I dont think it was. I am running it hotter now though and only smokeless fuel when I damp it down overnight.

Edited January 17, 2023 by reb78

[Nonimouse]

17 hours ago, reb78 said:

Interesting. The Elm is nearly gone so that's easy to avoid now. Interesting to hear about the anthracite though. Before it came to me this Rayburn only burnt anthracite and very little else and it was usually very very clean. I should have clarified though - i am using one of the smokeless manufactured (anthracite derived) alternatives now but I thought anthracite was also considered smokeless and ok in smoke free zones as a result (not that that applies out here in the sticks). Its become harder to get and I don't think will be available in raw form next year.

They are funny things to get just right. I had an pre war 'Royale' that I converted from solid fuel to gravity fed oil. It just about broke me, then I found out about an old boy in Hemyock, who specialised in sorting out old rayburn issues. One of the problems I had was that we had recently fitted double glazing to our cottage. Not enough draft. to create a draw. He got it burning beautifully, then a couple of months later offered me the gravity oil system. That was brilliant. Basically burnt anything oil based. I had a Parkray 77 as a back up, which I carried on using wood on