Help with log burner

[saveasteading]

What interesting responses. Please excuse me challenging or testing some. and argue back of course.

For clarity we are talking sealed , high quality stoves here, not open fires/gas fires/ leaky cast iron stoves.

 

23 hours ago, epsilonGreedy said:

your "understanding of these things" tends to decline when your brain is starved of oxygen.

 

I am not proposing that there is no air intake. But if I was:

The stove sucks in air, not oxygen then expels dirty, low oxygen air out to the sky. The air in the room remains of the normal gaseous proportions. There is no shortage of oxygen in the room or my brain, unless the room is very small.

If it is very small, then the fire is also going to be small.

Replacement air is drawn in through  vents or gaps at doors etc. If there isn't enough air intake then the fire and I both dim slightly, but not a lot.

The air intake on the stove I am referencing is about 100mm x 3mm when fully open. the gap under the nearest door (after allowing brush-strip) is 900 x 1mm.

When closed down to normal burning, the air intake is very small indeed. 100 x 0.5?

I checked the seals to the glass last week and pushed one back into place.

 

If air is being expelled through the flue then an equivalent amount will be dragged in through gaps unless the room is completely airtight.

 

When I fall asleep in front of an open fire, there might well be a lack of oxygen and a surfeit of nasties. In front of the stove it is just heat....and the intellectual stimulus of this forum.

 

22 hours ago, Iceverge said:

 

I think the need for any external air for a stove is really just theoretical overcaution by the building regs

 

Nobody knows what heating might be installed , so design for gas and then we are safe whatever.

I have installed an air vent to an aged family member's house where there was none...and a gas fire.  I could sense the unpleasant atmosphere which was sleep-inducing and very dangerous.

 

22 hours ago, Iceverge said:

combustion will continue in the flue which it wasn't designed for.

Have the manufacturer's not considered that their fires will have flues? Every catalogue shows a flue up to the ceiling, almost as a necessary feature.

My reference stove has a top chamber to carry fumes away and extract heat from them, and I don't think it is so precise that the same does not continue in the flue.

 

22 hours ago, Iceverge said:

a full heat suit to approach the stove

Are these readily available, or a shield?

 

22 hours ago, Iceverge said:

you haven't minimised the exhaust gas temperature from the combustion chamber or maximised it within.

Taking this to extremes, we could build a wall around the stove to keep the heat in and maximise the internal and exhaust temperatures.

 

 

I am assuming, until further advised, that the upmarket stove manufacturers have tested their stoves twice. Once in a lab for best spec figures for publication. Again for everyday use, with a flue of about 2m, perhaps more.

 

[ProDave]

Building regs only require an air vent for stoves 5kW and over.  If your stove was only 4kW then you could argue with your BC incpector that no air vent into the property was needed.

[saveasteading]

 

I hadn't realised that...rather kills my argument that the BCO has to assume you might install a gas fire.

I can't find that reference quickly but will search later. But did come across the lovely term "Fortuitous ventilation":   also known as leaks and draughts.

 

5kW is quite a lot, especially in a new house, so that should be that.

[SteamyTea]

40 minutes ago, saveasteading said:

23 hours ago, Iceverge said:

a full heat suit to approach the stove

Are these readily available, or a shield?

Can't these also be just as effective, if made from to tin foil, and placed on head, like a hat.

42 minutes ago, saveasteading said:

For clarity we are talking sealed , high quality stoves here, not open fires/gas fires/ leaky cast iron stoves.

But this is the problem.

44 minutes ago, saveasteading said:

checked the seals to the glass last week and pushed one back into place

PM 2.5s and 10s are smaller than a visible gap. Shall see if I can find the report about indoor air quality when I get home (and if I remember).

46 minutes ago, saveasteading said:

Have the manufacturer's not considered that their fires will have flues? Every catalogue shows a flue up to the ceiling, almost as a necessary feature

Always struck me as odd, like getting a kettle, but no lid.

But they are selling a feature, not a function in reality.

[bassanclan]

Would recommend Clearview stoves. Size and output to be determined!

[Cpd]

1 hour ago, bassanclan said:

Would recommend Clearview stoves.

I have the small 5kw one, been in 10 years and is still awesome! 

[epsilonGreedy]

2 hours ago, bassanclan said:

Would recommend Clearview stoves. Size and output to be determined!

 

 

I have yet to install one but I can recommend a trip to their HQ in Ludlow where they have many working displays. The staff are very knowledgeable as well plus you get free parking in the centre of a tourist town.

[Gus Potter]

@saveasteading

 

Just made a few comments in line with your text in italic

 

What interesting responses. Please excuse me challenging or testing some. and argue back of course.

Yes interesting stuff..

 

For clarity we are talking sealed , high quality stoves here, not open fires/gas fires/ leaky cast iron stoves.

ok

 

I am not proposing that there is no air intake. But if I was:

The stove sucks in air, not oxygen then expels dirty, low oxygen air out to the sky. The air in the room remains of the normal gaseous proportions. There is no shortage of oxygen in the room or my brain, unless the room is very small.

If it is very small, then the fire is also going to be small.

Folk do daft things..and burn things they maybe should not.

 

Replacement air is drawn in through  vents or gaps at doors etc. If there isn't enough air intake then the fire and I both dim slightly, but not a lot.

The air intake on the stove I am referencing is about 100mm x 3mm when fully open. the gap under the nearest door (after allowing brush-strip) is 900 x 1mm.

When closed down to normal burning, the air intake is very small indeed. 100 x 0.5?

I checked the seals to the glass last week and pushed one back into place.

 

If air is being expelled through the flue then an equivalent amount will be dragged in through gaps unless the room is completely airtight.

 

Yes.. but if you rely on the gaps under the doors, around the windows etc then you'll need some warm slippers as the cold air has to pass throught the room on it's way to the stove. If you live in the country then the farmers not only spread muck from time to time but also lime and other bits and pieces which kick up a lot of dust. Even during harvest the air can carry a lot of small particulates. You may find that you start getting a lot of outside dust on the window cills etc.

 

Assuming you live in the country then you have a couple of choices. Enjoy the countryside, learn to live with it and enjoy the odd smell of wood smoke in the house.. or try and isolate the interior. If you duct the air supply to just under the stove then any PM2.5 s will just get sucked up the flue even when the stove is not on? Passive ventilation. Practically if the room gets too hot folk just open a door or a window.

 

When I fall asleep in front of an open fire, there might well be a lack of oxygen and a surfeit of nasties. In front of the stove it is just heat....and the intellectual stimulus of this forum.

 

 

Nobody knows what heating might be installed , so design for gas and then we are safe whatever.

I have installed an air vent to an aged family member's house where there was none...and a gas fire.  I could sense the unpleasant atmosphere which was sleep-inducing and very dangerous.

 

Each appliance should be checked for leakage and the ventilation checked to ensure any appliance comply with the venting. yes you can future proof..?

 

Have the manufacturer's not considered that their fires will have flues? Every catalogue shows a flue up to the ceiling, almost as a necessary feature.

My reference stove has a top chamber to carry fumes away and extract heat from them, and I don't think it is so precise that the same does not continue in the flue.

 

Are these readily available, or a shield?

 

Taking this to extremes, we could build a wall around the stove to keep the heat in and maximise the internal and exhaust temperatures.

 

 

I am assuming, until further advised, that the upmarket stove manufacturers have tested their stoves twice. Once in a lab for best spec figures for publication. Again for everyday use, with a flue of about 2m, perhaps more.

 

Yes on point one under lab conditions. Point two.. keen to see any data.

 

Edited November 29, 2021 by Gus Potter
italic missing

[epsilonGreedy]

4 hours ago, saveasteading said:

I am not proposing that there is no air intake. But if I was:

The stove sucks in air, not oxygen then expels dirty, low oxygen air out to the sky. The air in the room remains of the normal gaseous proportions. There is no shortage of oxygen in the room or my brain, unless the room is very small.

 

 

My point is there is a fundamental and dangerous fallacy behind the claim "I am a smart dude and will recognise when my stove is malfunctioning before it gets dangerous". Air starved combustion leads to incomplete combustion and CO production. CO makes you non smart with little warning.

[ProDave]

3 minutes ago, epsilonGreedy said:

Air starved combustion leads to incomplete combustion and CO production. CO makes you non smart with little warning

Which is of course why building regulations demand a room containing a stove and a room that the flue passes through, have CO alarms.  I trust those to let me know if something has gone wrong.

[saveasteading]

48 minutes ago, epsilonGreedy said:

Air starved combustion leads to incomplete combustion and CO production

Which goes up the chimney. All of it?

My fire goes out when starved of air. 

 

I also have an old and clunky woodburner, with vent into an old chimney. That does have problems, which were demonstrated  when I put some chipboard in...the smell of the chemicals was noticeable in the room so it must leak smoke at joints.

With the modern ducted stove there isn't even a smell of wood burning.

[saveasteading]

1 hour ago, epsilonGreedy said:

staff are very knowledgeable

Will they know about the benefits of exposing or encasing ducts?

| see that their brochure is all with fireplaces, so of course should be insulated all the way in the chimney.

Very expensive. What does the extra £600 bring as benefit?

[Gus Potter]

9 minutes ago, saveasteading said:

Which goes up the chimney. All of it?

My fire goes out when starved of air. 

 

I also have an old and clunky woodburner, with vent into an old chimney. That does have problems, which were demonstrated  when I put some chipboard in...the smell of the chemicals was noticeable in the room so it must leak smoke at joints.

With the modern ducted stove there isn't even a smell of wood burning.

 A few thoughts..

 

Yes, if you put in a stove and stick the pipe into an old brick chimney rather than installing a liner all the way up you get "smells". Now you wonder.. is it the new short length of metal flue that is leaking (my new stove) or are gases escaping out through the mortar joints and the register plate?

 

For all the register plate is the bit of of metal that the stove pipe disappears into when it goes into an old chimney.. you see this a lot with older Aga installations. Also you may find that someone has been "modernising".. and stripped the plaster off the chimney breast, and replaced it with cable ducting for the massive inch TV .. and dot and dab plasterboard causing the old brick flue to leak.

 

By their very nature you will aways get incomplete cobustion in a stove for part / all of the time.. even with a gas appliance when say it starts up.. see a yellow flame for example.

 

As an a side when we used to design open fires and match them with the brick flue size required we used to say. One storey.. area of flue need 1/8 of the fire place opening, two storeys 1/9 of fire place opening..Glasgow tenements.. well they just had to make do. I installed a wood burner a few years back in our 1955 is house, two storeys. I measured the door opening area of the stove and looked at the flue cross section area.. but remember the two areas (door opening vs flue area) seemed uncannily like 1/9!..of course my maths may be rubbish.

 

In the past I have done a few stoves on 4 story historic buildings.. you are confined by the 9 inch brick internal flue size and lots of twists and turns. Remember that in old buildings the basement would be at this level. The maids / servants would pretty much have the fires running all the time so the flues were always hot and drawing. Now with modern living we need to adapt and recognise that a cold flue can smell a bit. A stove is just not for Christmas!

 

Now if you are doing say a steading the flue may have a bend in it.. you can insulate by pouring vermiculite down.. but it can be horribly messy if it leaks!

 

 

 

 

 

 

[Iceverge]

6 hours ago, saveasteading said:

Have the manufacturer's not considered that their fires will have flues? Every catalogue shows a flue up to the ceiling, almost as a necessary feature.

My reference stove has a top chamber to carry fumes away and extract heat from them, and I don't think it is so precise that the same does not continue in the flue.

 

I think this has more to do with aesthetics rather than anything else. People don't like the look of chunky twinwall flues. 

 

6 hours ago, saveasteading said:

Nobody knows what heating might be installed , so design for gas and then we are safe whatever.

I have installed an air vent to an aged family member's house where there was none...and a gas fire.  I could sense the unpleasant atmosphere which was sleep-inducing and very dangerous

 

Wise to be cautious, however without measurement did you figure out if the sleepness was causes by low oxygen levels, high CO or CO2 or just the heat? The building regs has to cover all bases so a hole in the wall will suffice. In specific instances objectively it may not actually remedy the problem but just hide the symptoms. 

 

6 hours ago, saveasteading said:

Have the manufacturer's not considered that their fires will have flues? Every catalogue shows a flue up to the ceiling, almost as a necessary feature.

My reference stove has a top chamber to carry fumes away and extract heat from them, and I don't think it is so precise that the same does not continue in the flue.

 

Thermally your best bet is to get the flue out of the heated envelope as soon as possible. Manufacturers certainly don't consider that.  Combustion probably does continue in the chimney, especially if an already very hot fire is over stoked. A chimney won't last very long if that continues. 

 

6 hours ago, saveasteading said:

Are these readily available, or a shield?

 

Yes readily. Probably overkill for a 5kW logburner though!

6 hours ago, saveasteading said:

Taking this to extremes, we could build a wall around the stove to keep the heat in and maximise the internal and exhaust temperatures.

 

Yes. I contemplated doing this with a boiler stove and using the back boiler to extract heat only at a rate to ensure that combustion continued optimally. 

 

6 hours ago, ProDave said:

Building regs only require an air vent for stoves 5kW and ove

All stoves in Ireland AFAIK.

 

 

 

After this discussion last evening I was overcome with a desire to start playing with matches so went to my parents house sparked up their rayburn and also the woodburner in the living room, both of which I installed.

 

It was of course fun. Especially playing with the cooker and it's myriad of controls.  

 

The rayburn has a 150mm twinwall flue right from the damper box at the top of the cooker. It drafts really easily, even in a cold house. ( Fires draft better in warm houses due to the hot air buoyancy). Once the chimney was up to temp (the outside of the twinwall was getting warm to touch (10mins) ), i closed the damper while keeping the draft wheel open until the whole body of the cooker was warm ( took about 45mins) then I closed the wheel most of the way to throttle the fire.

In this mode the twinwall will barely be hot but the cooker will make plenty of heat for DHW and cooking. If you forget to close the damper the cooker will burn lots more blocks and try to melt the chimney but not produce any more useful heat in the ovens or boiler. The previous rayburn had a change of "driver" about 15 years ago and the damper was subsequently rarely closed. It ruined a cast iron stove pipe and a concrete chimney and did more damage in that decade than in the previous 55 years.

 

When refuelling it was almost impossible to do it in a method that prevented some smoke coming into the room. They are not precision bits of equipment and if you forget to open the damper when opening the firebox smoke comes out from every joint between every panel and from under the hotplate. cough cough. De-ashing is a mess of a process. Ash dust is extremely fine too. It can't be good for you. 

 

 

The wood burner is a far cruder affair and is connected directly to a concrete chimney. It takes a heap of kindling and newspapers to get it up to temperature. Once running it uses far more timber than the rayburn for less output, I assume due to the energy needed to keep the chimney warm enough to draft. ( A cold chimney may be able to cool the flue gasses to sufficiently to loose their bouyancy).  This woodburner comes with a wide grate, maybe 500mm and a low height firebox, about 200mm. Rubbish design really for burning timber. The centre of the fire often burns out leaving unburnt logs at the sides meaning more pokering and prodding.  

 

The rayburn's tall and narrow firebox is superior as when the fire burns out only a tiny few embers will remain at the bottom. 

 

Anyway, after a hour or so I had burnt the basket of timber I had brought from the shed and the novelty had worn off so I shut down both the appliances and retired to out nice dust free passive house for the evening.

[epsilonGreedy]

11 hours ago, saveasteading said:

Will they know about the benefits of exposing or encasing ducts?

| see that their brochure is all with fireplaces, so of course should be insulated all the way in the chimney.

 

 

I don't know, my two stoves will be situated in traditional fireplaces.

 

Why don't you treat yourself to a short break in the Welsh Boarders then you could pop into Ludlow and subject the staff to your technical proficiency test.

 

11 hours ago, saveasteading said:

Very expensive. What does the extra £600 bring as benefit?

 

 

I don't know but when buying a manufactured item with an expected 20 to 40 year life span people tend use non technical assessments of a business because a human life is not long enough to run a sequence of 30 year product test experiments.