Cold plugs in chimneys and Clearblue log/multifuel burners

[GreyCat]

Today I ordered a Grenadier hot- air blower fire starter. As for why.......

The wood burner in the office has issues at this time of year with a cold plug forming in the chimney. But this morning it was as bad as never before- to the point where I phoned the chimney sweep I use for advice, as I was concerned about potentially a bigger issue. He went through all the parameters, and given the stove type (Clearview with highest DERFA clean burn rating), install type (gable end, old chimney with liner, stove flue out back of stove not top) and the weather conditions (mist/cold, local "standard" chimneys showing spoke spill over from top and sink rather than rise) and usage pattern (the stove is not in constant use and is not lit over weekend when not in the office, door had been closed) he reckoned no fundamental issues. He did say that the Clearview stoves with multi baffles can be problematic if a cold plug forms, and today was an exceptionally bad day weather wise for it. He reckoned I'd get it going once the sun was up and warming the damp air. (He was correct).

.... bear in mind that at this point, I had tried all the usual tricks to get past a cold plug..... couple of firelighters to warm flue (bottom intake vent closed, door open as if the bottom intake vent is open the smoke exits through intake vents, DAMHIKT). Pre-warming the flue with a small butane blowtorch directed into the firebox......... ditto with my bigger butane weeding torch..... to no avail. (Usually the couple of firelighters thing maybe with persuasion from a small blowtorch works). Ended up with the smoke residue from the firelighters exiting via the rear intake vents when I opened them so see if it was starting to draw..... quickly closed them and gave up for a while.....

I have booked the sweep to call anyway next week as the chimneys are due sweeping end Feb, so may as well get him in a bit earlier as it's the first sweep since install last year. Stove draws fine once lit.

Still. Although the butane weeding gun is pretty good for pre-warming on a "usual" cold plug day (not least because I can sit on a stool to use it rather than crouch by the stove), I have ordered a Grenadier electric firestarter to pre-warm the stove/flue.

Be interested in other pre-warming methods people may use (bearing in mind at this point I have already tried all the "standard" options).

GC

 

[British Red]

I use a Dewalt hot air gun (advice of a HETAS inspector mate). We generally have no issues but the stove hasn't been cold since October

 

[Bhod]

Have no idea what a 'cold plug' is but I've never had an issue starting my multi fuel stove either top down burn or bottom up - for reference it is a Dunsley Yorkshire (without back boiler). Lay some oak down first, then some birch, top with hardwood kindling and a wood wool firefighter and away it goes. The firefighter and kindling preheats and then burns down to the birch which in turn raises the temp further and allows the oak to start burning nicely, once I've got a decent bed of coals I'll add more oak and then start shutting the air vent down.

Maybe the lighting sequence is different, I have to leave the door slightly ajar until the kindling is alight, very, very occasionally I've had to open either the front or back house door just to let an extra little airflow through but that can be counted on one hand over 20 years rather than being the norm.

 

[GreyCat]

Have no idea what a 'cold plug' is but I've never had an issue starting my multi fuel stove either top down burn or bottom up - for reference it is a Dunsley Yorkshire (without back boiler). Lay some oak down first, then some birch, top with hardwood kindling and a wood wool firefighter and away it goes. The firefighter and kindling preheats and then burns down to the birch which in turn raises the temp further and allows the oak to start burning nicely, once I've got a decent bed of coals I'll add more oak and then start shutting the air vent down.

Maybe the lighting sequence is different, I have to leave the door slightly ajar until the kindling is alight, very, very occasionally I've had to open either the front or back house door just to let an extra little airflow through but that can be counted on one hand over 20 years rather than being the norm.

It's the build up of a "plug" of cold air in a chimney which makes lighting a fire very difficult and can cause spillage into the room, see here; https://sandpitsheatingcentre.co.uk/why-is-my-wood-stove-smoking-cold-flue-winter-safety/ and here: https://www.homebuilding.co.uk/advce/HETAS-advice-on-cold-plugs-for-stoves

If you get a particularly severe case, even using the top down method and using dry wood (or event the jenga stack method described) will only achieve a smoky room..... and severity is dependant on the combination of flue, the stove and the weather- and also the use pattern (if the stove/flue never cools down you never have an issue).

You need somehow to get the flue warmed up, which with modern "Clearview" type multi-baffled stoves can be a challenge..... and if the heat doesn't rise up enough when using something which emits smoke to do so, that smoke ends up in the room. When this chimney had an old Parkray (and no liner), it was not a problem, as the heat from initial kindling/firelighters could easily find its way up the chimney.

This morning, we had a sudden dip in temperature (and dew point) about the time I was trying to light up, I had not lit the fire for a few days and had left the door on the stove shut, and there was little wind. Physics was against me and it was particuarly bad today.

This is something I was not aware of until I learned the hard way..... but yeah the sweep knew all about it and gave me some good advice.

GC

 

[Bhod]

Thanks for that never knew there was such a thing. Unfortunately Dunsley no longer make the Yorkshire, too many hoops and too much money to satisfy DEFRA needs nowadays, at least ours is "grandfathered" in with the exemption.

 

[Broch]

Ours, a Charnwood, can be very sluggish to get going on those foggy damp days when smoke just falls to the ground and goes rolling off down the hill.

I light a small fire using a firelighter and softwood kindling (called morning sticks around here) - I find softwood lights faster and produces heat quickly. For our stove, the door has to be cracked open. Before that dies down fully, i.e. when there's still flame, I add more softwood then some smallish dry split logs and keep the door open. After about 5 minutes I can add a couple of logs, close the door, with the air fully open. I only close down the air when the stove is up to full temp - probably a bit wasteful but it prevents me having to start all over again

 

[Keith_Beef]

I'd not heard the phenomenon called "cold plug" but the description in the first post is very familiar.
We had a fireplace insert fitted, the chimney raised by about 40cm and a liner put in when we bought this house. At the time there was a lot of noise about changing laws and insurance rules but in the end the ideas seem to have been abandoned.

On cold days the smoke doesn't rise up the chimney and can smother the fire before it gets going well. The smoke can even manage to leak out into the room if it gets really bad.

I've found a way to get a good updraught going. I lay two split logs across the hearth, one at the back and one at the front. Between the two I put loosely crumpled balls of newspaper, then a few handfuls of kindling (mix of papery bark from birch or kolkwitzia, grapevine trimmings, maple and buttonwood twigs). Over that, front to back between the two split logs, I add a layer of bigger twigs about as thick as my thumb. Finally I add a few more loosely crumpled balls of newspaper.

The idea is to get a really hot fire going as quickly as possible, even it isn't long lived, to get the updraught going. Sometimes I might need to light the fire a second time, but at that point there will be some charring on the logs and some embers, so a few more twigs, thumb-thick pieces, one paper ball and a few blows down the bouffadou get it going properly.

Bouffadou — Wikipédia

fr.wikipedia.org

 

[Toddy]

I don't have a stove, but I grew up with coal fires.....on days when they did not 'draw' when being lit, we built a small starter fire, surrounded it with kindling, and then covered the entire front of the fireplace with a sheet of newspaper. That forced the draught and smoke up and not out, if I make myself clear ?
The fire pulled itself alight.
I know that our fires were built to have airflow from below, I'm presuming that the airflow control thing at the bottom front of a stove performs that function ?

This must sound very odd to those who didn't grow up with open fires in every house, but it worked....too well sometimes, I mind neighbours who left the paper on too long and it was pulled in, it flared in the fire and flew up the lum....one wasn't very good at keeping her lum swept.
A burning chimney roars like a dragon

 

[Keith_Beef]

Open fires were still around when I was a wee bairn. I can just about remember the Yorkshire range at my grandparents house where we lived at the time, but that was replaced by a gas fire in the back room, the fireplace in the front room likewise, and a had cooker replaced the two ring hob in the kitchen, but those in my grandparents' room and in my room were never replaced. They were boxed in with a removable wooden contraption.

I remember the fireplace in my great grandfather's house, too, and in the first house where my mum's sister lived with her husband, I think that they were still burning coke when they moved to a more modern house in about 1975.

I remember the newspaper technique that you describe to her the draught going, and building the fire with kindling.

 

[Broch]

Yep, my job as a kid was to go down and light the fires - the newspaper trick was very successful but I had to be a dab hand at crumpling it up fast and throwing it into the fire when it caught alight

 

[GreyCat]

@Toddy : you have reminded me that when I was a bairn, we had a steel plate with a handle called a "bleezer" (Geordie slang) which one held against the (coal) fireplace when lighting up to get it to draw. If you couldn't afford a bleezer, a sheet of newspaper also worked, but a proper bleezer was the thing to have. A gas poker was also quite common although we didn't have one of those. The gadget I bought appears to be the successor to the old gas poker....

The previous fire insert (a Parkray roomheater from the 1970's) straight into the unlined chimney didn't have an issue, although a similar roomheater in the old parlour was a pain to light. The sweep did say that the baffling arrangements on modern clean burn stoves make it that much more difficult to get the cold flue warmed due to the various baffles and secondary and tertiary air paths- and certainly I found that was the case, even directing a blowtorch into it takes a heck of a while to get the flue (where it exits the stove) even hand warm.

This morning it's gone straight away (admittedly I did leave the door open overnight and I also gave a a few minutes pre-warm with the blowtorch).

Weather is different today- not so cold and it is windy.

It's a pity that it's not clearer in the stove instructions, but then again it's another case of the environmental controls making it more of a challenge- even though the main driver of smoke cleanliness is what you burn (dry wood or approved fuel) and how you burn it (optimal temp).

Hey ho. Will report back after the sweep visits next week!

GC

 

[Toddy]

I didn't know what that was called

We had one of those, shaped to fit the opening of the fire, slightly curved iirc, but it was an awkward thing to have about for those few days when the fire wouldn't draw....ours lived in the coal bunker outside the back door. It got hot too and had to be moved with care.
I think they used the newspaper because it was quick and to hand.

We had a gas poker, wouldn't be done now, but the gas was piped around the downstairs of the house and we plugged things into it (bayonet fitting) like the poker, the fridge and the portable fire that heated the kitchen.

The fireplace gleamed. The tiles were wiped and polished every day, and 'whitened' once a week to keep the grout looking clean and smart.

Sorry, gone off topic

 

[TLM]

Last summer when the outside temps climbed somewhat high (for us) we had air conditioning on keeping the inside at comfortable 22-23 C. Our kitchen stove (wood) refused to light up, totally, pushing all smoke in, lots of it. I had to take the smoldering wood out and take them outside. I took an electric blower and blew out the cooled air, after that we got the fire going but just barely and the blower trick had to be used every time when lighting up. I gave up and we used electric stove for the rest of the heat wave.

 

[Chris]

My Great Aunt used to live in an old but fairly big cottage in some woods in Devon and she had a proper fireplace and she cooked on an old always-on Aga. I can remember the smell of the fireplace (both cold and when lit) which she burned wood and coal in. It was delightfully cosy in there on cold, wet evenings.

She used to breed Westies (Wistmill is her breed) and at one point she had 23 of them in the house. Sitting in the lounge with that many Westies an hour after their dinner, I am not sure the open flame was all that safe.

I do remember her occasionally having to light a small but fast fire when initial attempts had smoke falling into the room, but I’d never really thought about it as I was so young at the time. This is interesting and helpful to know about.

 

[MrEd]

I get this now and again due to geographical location, I use a hot air gun and top down with the door open - usually works.
If bad then I use both in conjunction

 

[Danceswithhelicopters]

A gas poker! Flamethrower fun for a' the family!

Had one in our house when e moved in with 1950s style red rubber tubing that had cracked and rotted and leaked like a bagpipe chanter.

 

[GreyCat]

Aye well my butane weed killer flame gun is I guess the direct successor to the gas poker!

It is easier than a blowtorch as I can sit comfortably on a stool whilst using it.

New fire lighting gadget arrived today, will unpack and test tomorrow.....

GC

 

[Woodland explorer]

I feel your pain, my stove can be bigger for smoking
I usually light a twisty type fire lighter and chuck it up on the top battle plate then shut the door and open the bottom vent, sometimes if it’s really bad I have to crack the door for a few seconds to maintain enough air so the fire lighter doesn’t go out.
I no my brothers was that bad that my method wouldn’t always cut it

 

[Danceswithhelicopters]

A small tealight in the hearth for 30 minutes or so?

 

[slowworm]

We don't really get this problem with our stove which is probably down to such a good draw on the flue (one advantage of living on a windy hill).

When it is a bit sluggish to get going I just use lots of fine kindling and shavings if I have them, often without any paper as that can cause smoke.

I also remember using a sheet of news paper to get an open fire going in previous houses. I also experienced the bottom of the sheet being drawn in and catching alight!