two stoves - some chimney questions

I'd be grateful for some advice on the following.

I'm planning to put a multi-fuel stove in the kitchen, where there used to be one several years ago (now there's just a wall); and a smaller woodburning stove in the living room, where currently there is a bashed-out fireplace.

The chimney breast is in the living room. There is a single chimney stack, and two chimney pots. If the two cavities join somewhere, I'm not sure where.

I know I've got to do some more bashing out in the living room, to change the bottom end of the chimney so that it's suitable for a woodburner, possibly even widening the opening sideways and putting in a new lintel, although the latter work would only be for aesthetic reasons.

But will it be OK to have two lined flues? Or does that depend on where the cavities join and become a single cavity?

Is it even advisable to have two lined flues? Should I have one, or maybe none?

In the past, the living room fireplace and a big kitchen range were used without any chimney lining.

Thanks for any help with this!

Harry

Reply to
Harry Davis
Loading thread data ...

It's highly unlikely that the two flues will join anywhere, it's a really bad idea. Smoke/fumes from one fire could well end up in the other room under some wind/temperature conditions.

eh, stoves with no flue? Ideally each needs it's own lined flue or chimney of some sort. Installation of a solid fuel appliance is covered in detail by the building regs and such work is notifiable to building control. So you either employ a HETAS installer or DIY and tell building control yourself.

Reply to
Dave Liquorice

"Dave Liquorice" wrote in news: snipped-for-privacy@srv1.howhill.co.uk:

I meant no lined flue in the chimney. Many old chimneys are unlined.

Yes I know :-) Document J. That's not what I was asking, though! :-)

Harry

Reply to
Harry Davis

Modern woodburner stoves have considerably higher flue temperatures than the original fireplace, hence the need for lined flues. And if you have a thatched roof, prepare to dig really deep into your pockets.

Reply to
Davey

Its all very interesting as in this house the old chimney is still there and four items, being two original coal fires and two gass fires used to be in the same chimney space. It was built in 1939, but was still operational in the first few years i was here and no cross fumication seemed to occur at all. Brian

Reply to
Brian Gaff

Are you sure the 'chimnet space' does not contain more than one flue? How many chimney pots are there at the top of the stack.

Reply to
djc

Actually it is the other way round. Modern wood burners and multi-fuel stoves are very efficient and have a very low flue temperature. This in turn means that there is a very high risk of condensation in the flue, which in turn leads to acids eroding the mortar and tars seeping through the chimney into the house. This is generally not a good thing.

Old style open fires chuck a lot more heat up the chimney and this in turn pushes the moisture and tars out into the open air and keeps the chimney dry.

So with modern wood burners and multi-fuel stoves you do really need a flue liner to protect the rest of the house, unless you have a very good ceramic liner in your chimney. Which frankly is very unlikely even if you have a modern house.

Even with this stainless steel liner, you need to run the stove flat out from time to time to make sure that condensation products are cleared from the flue liner. Also you should really burn dry seasoned hardwood - damp softwood will leave both moisture and tar in the chimney and flue liners are good but they aren't invulnerable. Too much tar and you can get a chimney fire inside the liner.

So if you are considering installing a wood burner or multi-fuel stove you need to grit your teeth and have a reality check. Yes you can buy a modern stove for as little as £300. No you can't install this into an old style chimney with just a register plate and avoid long term major problems. Ignore the headline price of the stove and budget £1,000 for the liner and then add the cost of the stove. In some cases it will cost more, but at least you are starting in the right area.

If this looks like too much money then look at alternatives such as a Tortoise style efficient open fire which circulates a lot more heat onto the room.

Ignoring reality may seem like a good idea at the time. It generally isn't.

Cheers

Dave R

Reply to
David WE Roberts

In message , Harry Davis writes

Not so important with an open fire due to lower flue temperatures and less condensation of tars.

Victorian kitchen range installations may have used coke and not been so susceptible.

Things have probably moved on since your house was designed and built. One consequence is less chimney fires.

There is a lot of information on the stove manufacturers sites and well worth a delve.

Reply to
Tim Lamb

"Brian Gaff" wrote in news:k9frq1$ilq$ snipped-for-privacy@dont-email.me:

Indeed.

On a related point, I am sceptical about the need for a lined flue. In our house, there used to be a huge kitchen range and a fire in the living room fireplace, and the chimney was swept once a year and there were no chimney fires.

Today, "not having a lined flue is risking your life - and, er, the insurance companies don't like it" seems to be used as the main advertising line, or enforcement line, or whatever we want to call it.

As for a tortoise fire, that someone has recommended, well they are nice, but they have to be watched (they are basically a 'woodburning' or 'multi-fuel' stove' without a door), and I doubt they throw out waste in different quantities or mixes or at different heats from what closed-in stoves do.

What is remarkable is that a single day's work of putting in a lined flue tends to cost around £1000, which tradesmen only get away with because of building regulations, the way the licence system works, and the culture of not undercutting each other. Unless there's a more convincing answer to the question as to why the price for the said labour is so extraordinarily high.

I live in an area where most houses have unlined chimneys and living-room fireplaces, and most have large kitchen ranges (or 'stoves' as people call them here), which were not bought for reasons of fashion or to copy TV chefs paid to promote equipment, but to burn what was once cheaply- available coal and also cheaply-available peat, although nowadays some people also burn wood.

It is also interesting that lined flues have short lifetimes (you're doing well if you get one that lasts 25 years), and although they themselves are fairly cheap (but a lot dearer than paying a chimney sweep), the labour to keep on fitting new ones is expensive.

Funny how not a great number of houses burned down years ago.

'Just stick in a register plate', and make sure everything's sealed properly and at the right angle, may be the way I go.

Harry

Reply to
Harry Davis

Harry Davis wrote in news:XnsA11E57AE2638Bharrydavis@88.198.244.100:

Also how in many other countries where the majority of people have run large ranges in their houses for generations, most chimneys are unlined.

There is this assumption in Britain that the natives are really stupid and will blow themselves up or burn their houses down by accident unless 'Sir' brings in regulations to 'help' them, which funnily enough causes the poor 'natives', who are also being conned into paying high prices for very simple objects made from inexpensive materials, to spend loads of money which, in many cases, they haven't got - so they get ever further into debt.

See also how most gas cookers nowadays require an electricity supply to work, and when you call up the manufacturers to enquire, you get told by some 16-year-old girl that it's really dangerous to use matches.

There are many many other examples.

Harry

Reply to
Harry Davis

That =A31000 ball park figure is not just labour. You have obviously not= looked at the cost of stainless flue liner suitable for a woodburner. It= ain't cheap single skinned ali alloy stuff that you'd use for a gas appliance.

See above it's not the labour but the liner.

Meh, up to you.

But stoves do chuck out a very different flue gas mix and much higher temps than an open fire. Open fires get a lot of flue gas dilution/cooling going on due to their open nature, this doesn't happen =

with a stove. I also wonder about how much CO is produced when you reduc= e the burn rate of a stove. CO is a rather insidious toxin low levels migh= t not kill you but they ain't good for your health. I'd much rather know i= t and other gases weren't percolating through the chimney sides into bedrooms...

I also doubt that an ordinary chimney will still be gas tight after 25 years.

Reply to
Dave Liquorice

With respect, I don't think you are really listening.

The performance of MODERN stoves is vastly different from the traditional fires and ranges that you are talking about. They have been extensively engineered to throw nearly all the heat into the room, and as little as possible up the chimney. Heat which on old stoves and fires went straight up the chimney.

We had two Tortoise style open fires in traditional fireplaces without any problems. However it was obvious that a lot of heat was going up the chimney and not into the room. We had an old Raeburn cooker in a traditional fireplace and again this ran without problems (unless the wind was in the wrong direction). Again the stove design was very unsophisticated compared to modern stoves. We ran a modern Stovax Stockton in a ceramic lined flue in a 1950s house and after about a year tarry liquid was seeping out through the top of the chimney into the loft. We should have had a liner fitted but baulked at spending £400 on the stove and £1,000 on the liner. Had we not removed the stove it would have needed a liner to stop the tar running further down into the bedroom.

A few things to note:

(1) The cost of installing a liner is mainly the cost of the stainless steel liner. It does seem a lot of money but liners were expensive before HETAS and Building Regs made them compulsory for most installs.

(2) IMHO you just haven't taken on board that the cost of a decent installation includes the cost of a liner and you are still searching for specious arguments to justify not spending the money. e.g. "As for a tortoise fire, that someone has recommended, well they are nice, but they have to be watched (they are basically a 'woodburning' or 'multi-fuel' stove' without a door), and I doubt they throw out waste in different quantities or mixes or at different heats from what closed-in stoves do." Trust me - they do. They are vastly different from a closed in stove. They don't have the air controls, they don't have the secondary airwash, they don't radiate nearly as much of the heat from the fuel, they don't have the stove flue, most of the fire is inside the chimney breast instead of out in the room. They are basically a slightly more efficient open fire where a 'box inside a box' design allows air to be drawn under the fire, up the back, and out over the top to circulate warm air into the room.

(3) You do still have to sweep stainless steel flues - they get soot in them just like an unlined chimney and are thus susceptiible to chimney fires if not swept.

(4) I don't think anyone here has suggested "not having a lined flue is risking your life - and, er, the insurance companies don't like it" - this seems another 'justification' for you not spending money. You are risking your chimney structure if you don't use a liner and repairs may well be very expensive. There is a risk to life if you don't install the stove correctly but AFAICS this has nothing to do with using a liner - it is more to do with ensuring there is enough draught, enough ventilation, and a properly sealed installation which does not allow carbon monoxide back into the room. A competent DIYer can install a stove safely, but (as with many things) an incompetent DIYer can kill people. [There was a thread a while back about a stove a man installed in a garden room that killed his son.] A HETAS installation should avoid these pitfalls. Obviously if you do cause damage or have a chimney fire then I doubt any insurance company would be sympathetic.

So:

You are like a crocodile - in de Nile ;-)

There are many ways to justify not spending money and blame people for wanting to rip you off for things which are obviously not necessary. However these justifications are convenient but usually not accurate. In your case your arguments as stated do not hold up and I think you should step back, take a deep breath, and then do some more research which does not start with the position that you want the stove but can't stomach the cost.

As I said further up, I went down that route and managed to 'justify' not fitting a liner becasue the chimney was built with a ceramic liner. One year down the line and a massive tar seepage into the loft it was obvious that we should have fitted a liner or not fitted the stove.

Cheers

Dave R

Reply to
David WE Roberts

"Dave Liquorice" wrote in news: snipped-for-privacy@srv1.howhill.co.uk:

I have. Couple of hundred pounds.

The requirement for CO detectors in completely unnecessary circumstances is something else I could have mentioned.

In the US, the big scare is radon. This is the second biggest cause of lung cancer, so I could hazard a guess at which business sector is involved in talking up the practically non-existent danger from radon.

In some parts of Cornwall, professionals (builders, solicitors) recommend a special kind of survey when people buy houses, because of a risk of possible subsidence caused by mining. Of course in many areas there is such a risk. But the professionals still recommend such surveys even in areas where there's never been any mining and so there is zero risk of subsidence caused by mining.

Most of the time I switch off when I hear the word 'environment'.

In Ireland, it's literally illegal to burn stuff in your garden. You're supposed to take it down to the official tip, where you PAY them to burn it for you.

Fear sells. So does unnecessary compulsion.

Sufficiently so, so as not to be a problem. I'm not trying to be trite. Millions of chimneys are still in use, and there isn't a problem from people getting gassed. I can't prove a negative, but I can't identify a problem either. Regular cleaning is all that is required, which isn't expensive even if you get someone in to do it.

Harry

Reply to
Harry Davis

"David WE Roberts" wrote in news: snipped-for-privacy@mid.individual.net:

I understand about heat going up the chimney. There isn't much difference between a stove from 2010 and one from 1990.

What were you burning?

Most stoves using unlined chimneys don't cause that problem.

I know. Then you need to replace them, unlike with an unlined chimney.

You're mistaken. I saw one website where company was advertising lined flues with the line that you wouldn't want to be standing by the graveside of a "loved one" thinking you wished you'd got an unlined flue, and many places talk about insurance.

"Usually not accurate" - really? How much of what an average person buys do you think is "necessary"?

Harry

Reply to
Harry Davis

But that wasn't here, was it? Not on this esteemed NG :-) Nobody here is pushing the unscrupulous commercial angle or scare stories. You have to look beyond those.

Reply to
David WE Roberts

Just a thought on flue temperatures. I've been saying that the flue temperatures from modern stoves are low. Others have been saying that they are high.

I think that both are true. The very efficient combustion gives high gas temperatures at the exit point of the stove. However the very efficient combustion also extracts all the heat with the minimum air. So the absolute amount of heat which goes up the chimney is relatively low, and the temperature at the top of the flue is also relatively low.

The amount of heat going up a chimney is a combination of the gas temperature and the gas volume, so a large volume of warm air going up the chimney will heat the chimney more than a small volume of hot air, and also carry more of the combustion products out of the top of the chimney.

Look at the size of the opening for an open fire - room enough for a small child with a brush.

Look at the opening size for a modern stove when it is throttled back - room enough for a small pencil :-)

Cheers

Dave R

Reply to
David WE Roberts

"David WE Roberts" wrote in news: snipped-for-privacy@mid.individual.net:

My apologies! I didn't mean to say it had ever happened here, but unfortunately that's what I mistakenly typed!

It is quite common elsewhere, though.

Harry

Reply to
Harry Davis

I had a quick google to see if I could find anything about stove flue temps but didn't find much.

formatting link
half way down the first has some guidnace as to acceptable temp ranges for flue gases from a wood burner. The second says more or less the same for those ranges.

Agree.

Possibly, they could be the same or reversed. Remember heat transfer is proportional to the temperature difference the bigger that difference is the more heat is transfered.

Agree, you don't want the top of the chimney to be below the condensation point.

So you gets lots of dilution thus cooling as well as lots of volume.

True enough but the starting temperature is higher, there is no dilution so the volume is lower.

Then bring into the equation how fast those gases are traveling up the flue. The lower volume hotter ones from a stove are goiong to be slower due to the restriction of air supply by the stove than the higher volume cooler ones from an open fire.

I think I can argue this either way but the stove gases certainly start hotter, well maybe what about stoves with boilers. B-)

Reply to
Dave Liquorice

Hah. Every weeknight as you drive around in the dark, you will smell people burning rubbish in the countryside. A regulation that's only honoured where people can't avoid it.

Reply to
Grimly Curmudgeon

Liner segments installed upside down? They shoud be female up.

The last one is probably the most important. Should the worst happen and chimney fire gets out of hand and spreads to the roof or floors (and it can without escaping the the chimney, just by the temperature the chimney stack can get to) one of the first questions the insurance co will ask is was the installation installed to Doc J. and where is the documentation to prove it.

Reply to
Dave Liquorice

HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.