Stoves and External air supply

StoveSearcher

Head is melted so hopefully somebody can help.

We're installing an inset stove into our large family room. The stove which has been recommended is 8Kw which should be well adequate.

Do we need an external air supply? Our kitchen is at one end of this room and on occasion I will have the extractor fan running full throttle. My understanding was that anything over 5KW should have it's own external air BUT, the supplier said that this only applies to air tight houses.

Ours isn't airtight - 2002 build and has a standard air vent in the room.

Can anyone enlighten me please

thanks

SS

heinbloed

Running a combustion in a room which is equipped with an independant air extraction is madness.
Pressure differential switches are an absolute must in such a case.
These have nothing to do with the presence of an independant air suply for the stove or open fire.
They avoid poisoning and flash backs by switching off any air extraction from a room as long as there isn't enough of a pressure differential between chimney and room.

The presence of an independant air suply to the room is useless if the extractor (kitchenhood) pulls out more air than this hole in the wall can supply, creating a negative pressure. The air or smoke would come down the chimney into the room. Plain physics.
Open the stove door and you'll have the flames and smoke in your face. This would cause a panic, life can be saved though.
But the smoke/CO will be sucked into the room even if the stove's door isn't opened. With a negative pressure in the room the airsuply won't be enough to guarantee a good combustion, plenty of CO would be created.

ALL serious stove sellers and manufacturers have these pressure differentials available,they are a legal requirement for situations like this (presence of an air extractor) in the entire EU.

Strange that your stove sellers haven't heard about this, you're now searching for advises on stoves in this forum since 8 month. Stay away from these 'shops', they'll sell you your own death.
What was the name of the shop you said?

heinbloed

Here one from Marley, there are others as well:

http://www.marley-germany.com/en/products/ventilation/exhaust_air_control/index.htm

creedp

heinbloed wrote: »

Here one from Marley, there are others as well:

http://www.marley-germany.com/en/products/ventilation/exhaust_air_control/index.htm

Problem is Heinbloed is that if you avoided all the stove suppliers who didn't mention this pressure differential switch the choice of supplier would be pretty poor! Maybe you would be better off not installing the stove though if your concern is the case. I would have thought though that having a stove with an external air supply is far superior to having a roaring open fire depending on a room vent for ventilation in the same scenario, i.e. also having a kitchen extractor fan going at full belt? Surely the latter scenario is one which many Irish homes find themselves in on a regular basis with no reported difficulties that I have heard to-date?

Having said that anything that improves on health and safety in the home should be seriously considered. Can you tell me how these switches actually work? Do they physically open a window to allow for additional ventilation when negative pressure scenarios arise or have I watched too much tomorrow's world type programmes?

heinbloed

@creedp:

There are various pressure differential guards available, working with different methods. They have one thing in common: they meassure the pressure differential between room(-atmosphere) and flue, be it a forced extraction flue like a kitchen hood or a chimney flue.
There are also plain things like the one linked above, these simply detect if the window is open or not.
But these plain guards are only usefull if the situation had been checked. Just opening a window - turning the alarm off - which would supply the kitchen hood OR the stove with enough air won't do. BOTH, the kitchen hood AND the stove have to have enough air flow to operate safely paralel.

The incompetence of stove installers I see here in Ireland is shocking.

On the continent stove installers (installers of combustion apliances as such) must have a minimum of 3 years training/aprenticeship, be examined (diploma) and so on. The same goes for chimney sweepers.

Hardly ever the pressure differential is meassured here, nor the capacity of the chimney, the draw, the capacity of the hole-in-the-wall.
Flung it in and cash it in and ride on.....

Here a link explaining the situation with the pressure differential guaranteeing a correct draw:

http://www.chimneys.com/burning_secrets/chapter_4.html

Note the comment about the hole-in-the-wall on the lee side!


About

Surely the latter scenario is one which many Irish homes find themselves in on a regular basis with no reported difficulties that I have heard to-date?

The beehive huts with no chimney at all had open fire places at the centre of the floor, camp fires - no reported problems at all.
Parents used to smoke in the presence of children and no reported problems at all.

Some things are simply criminal nowadays. No matter if "reported" or not.
And so are fire places in buildings equipped with forced air extraction systems. Reported or not. As long as the safety of the people in the building (the air quality) and the fire risk are an issue such structures are simply not habitable, illegal. Uninsureable.
Like a car without brakes. The operator is fully liable. And no insurance has to cover a faulty, dangerous installation or operation.

Let's hope there are no reports of CO poisoning anymore, we have seen far to many already.

creedp

heinbloed wrote: »

@creedp:

There are various pressure differential guards available, working with different methods. They have one thing in common: they meassure the pressure differential between room(-atmosphere) and flue, be it a forced extraction flue like a kitchen hood or a chimney flue.
There are also plain things like the one linked above, these simply detect if the window is open or not.
But these plain guards are only usefull if the situation had been checked. Just opening a window - turning the alarm off - which would supply the kitchen hood OR the stove with enough air won't do. BOTH, the kitchen hood AND the stove have to have enough air flow to operate safely paralel.

The incompetence of stove installers I see here in Ireland is shocking.

On the continent stove installers (installers of combustion apliances as such) must have a minimum of 3 years training/aprenticeship, be examined (diploma) and so on. The same goes for chimney sweepers.

Hardly ever the pressure differential is meassured here, nor the capacity of the chimney, the draw, the capacity of the hole-in-the-wall.
Flung it in and cash it in and ride on.....

Here a link explaining the situation with the pressure differential guaranteeing a correct draw:

http://www.chimneys.com/burning_secrets/chapter_4.html

Note the comment about the hole-in-the-wall on the lee side!


About


The beehive huts with no chimney at all had open fire places at the centre of the floor, camp fires - no reported problems at all.
Parents used to smoke in the presence of children and no reported problems at all.

Some things are simply criminal nowadays. No matter if "reported" or not.
And so are fire places in buildings equipped with forced air extraction systems. Reported or not. As long as the safety of the people in the building (the air quality) and the fire risk are an issue such structures are simply not habitable, illegal. Uninsureable.
Like a car without brakes. The operator is fully liable. And no insurance has to cover a faulty, dangerous installation or operation.

Let's hope there are no reports of CO poisoning anymore, we have seen far to many already.

Listen Heinbloed, its all very well telling us all that unless we have pressure differential guards in our houses we'll die .. but whether you scoff or not about beehive huts etc the fact is I have never head of a person suffering harm in a house that has both an open fireplace and an extractor fan for the lack of one of these guards. I'll put the question to you - Do you have examples of such sad events? If so then this is your opportunity to raise the level of awareness here and maybe get people to do something about it. There is nothing like concrete examples to get people to sit up and listen!

I had a look at your link and it seemed to my untrained eye that the chimney problem related exclusively to open fireplaces and no where did it say that having a stove with an external air supply and an extractor fan was a no no. It was saying if you have a smoking open fire there are a number of reasons which it seems could be resolved but no where did I see mention of a pressure differential guard .. probably didn't sepnd long enough at it!!

I was interested in the bit about that an air pocket should be left between the flue and the brick/block chimney ... All I know is that my guy build 2 new chimneys for me and packed mortar between the clay pipe and the block in both cases:) Is this the wrong thing to do? I also noted that external chimney's are not a good idea so I'm spared on that one but of course if you go and line with as they described expensive liners that problem is cured. Does that mean that internal chimneys are OK?? It sure confusing is all I can say.

Now back to the pressure differential issue .. any other views on the importance of these especially in new houses?


Just to add you said that having a combustion appliance in the same room as an extractor is madness but surely it doesn't matter if the 2 are in different rooms .. seperate rooms are not sealed from each other so even if they are in seperate rooms then the problem also exists - now how many homes are we actually talking about here?

heinbloed

Sorry, creedp, the Irish building regulations do not ask for

concrete examples to get people to sit up and listen

.
They demand adequate ventilation. A legal binding expression that is, "adequate ventilation". Ask your local health and safety officer for an explanation.

How have you proven in your house that there is adequate ventilation when running fires and air extracts paralel?

Contact a civil engineer to explain you the risks of such stupid installations.

creedp

heinbloed wrote: »

Sorry, creedp, the Irish building regulations do not ask for .
They demand adequate ventilation. A legal binding expression that is, "adequate ventilation". Ask your local health and safety officer for an explanation.

How have you proven in your house that there is adequate ventilation when running fires and air extracts paralel?

Contact a civil engineer to explain you the risks of such stupid installations.

To be fair Heinbloed the Regs don’t ask people for concrete eg to sit up and listen but to my knowledge neither do they give direction on the use of pressure differential guards in cases when you have a combustion appliance and a kitchen extractor in your room/house or for any other scenario either. The Regs are pretty detailed in this area and they are also supported by detailed TGD and I have never come across a reference to such a device. Now Im not saying there isn’t one …….

Your right the Regs demand adequate ventilation which seems to be std requirements irrespective of whether you have a fireplace/stove/kitchen extractor/bathroom extractor/etc? As far as Im aware I don’t have to prove there is adequate ventilation when running fires and air extracts in parallel. In fact although I have 2 chimney’s neither will be hooked to a fireplace or stove for some time so Im not sure if I have to wait until they are, if ever, before I would have to prove anything in this regard. Anyway, Im still at a loss how installing a pressure differential device is required within this legally binding expression of adequate ventilation and all Im asking is for some concrete examples of where this is the case. In addition, how will the Regs help the tens of thousands of existing households out there with this arrangement in place? You refer to local H&S Officers, have they enforced these devices on householders? I have never heard of this so again if they have that would be useful knowledge. As you appear to be knowledgeable in this area I think we would all benefit from this evidence to ensure we do things right in the future and put right what is currently wrong.

You also say that these devices are the norm/mandatory in Europe and all reputable stove/fireplace/chimney installers would know this. Now I have spoken to quite a few stove installers both in Ireland and NI and I have never heard mention of such devices. They may be the norm in Europe but it seems to me their secret is pretty well maintained on this Island. Of course I may have been talking to the wrong people and if so then a whole lot of others will have been too. Can you give me some examples of quality installers who would give me such advice so I can talk to them about the most suitable set up for a stove in my circumstances (i.e. if I ever install one)

heinbloed

@ creedp:

You have a lot of questions concerning health and safety issues.
Pay a civil engineer who will be able to calculate the risks involved with your combustion devices running together with the air extracts.

Yes, you obviously are asking the wrong people. Otherwise your questions would have been answered in the planning stage.

Adequate ventilation means that the ventilation must be adequate. The Irish building regulations do not say how this must be achieved.
The EU continental building regulations (I can only speak for the German/Benelux language area) don't do so neither.
But there certain things have to be adhered to, for example when going for forced air extraction a pressure differential guard must be installed if combustion happens paralel.
Be this a gas hob or a stove with independant air suply or an open fire.
No one is forced to have combustion devices running there. So pressure diffeerential guards are not legally required when owning a building.

Has your building been planned by a civil engineer? Was he/she aware of the ventilation and combustion devices you've put in?

When safety belts became mandatory in the first EEC states it took Ireland another few decades to follow.
When driving tests became mandatory - ......
When smoke detectors became mandatory - the same story.
When radon protection became mandatory-....


Waiting for the law makers to tell us to adhere to logic shows a state of helplesssness, a mental state of childishness.

A vacuum (better: an evacuation) causes air to flow, creedp. Want it or not. Down the chimney, through the asbestos sealant of the stove door.
Carrying gas and fibres, small particles and sooth,ash and whatever the air holds.

Asking the stove seller if his device is good -- what do you expect to hear?
What does he/she know about the situation in situ? Has he/ she meassured air flows? Forget it.

The tire seller is not responsible for failing brakes.

The NCT for houses are civil engineers. Or in this case the fire safety officer, the health and safety officer.
The internet won't answer your questions. Nor would the stove seller.

So ask an independant payed person who does not want to sell you something if your funny installation ideas match reality. If adequate ventilation and a safe operation are guaranteed by his/her word and pocket. You or your relatives will sue the culprit if something goes wrong.

Let us know about the answer.


PS
Since it is quite windy today you could run a trial. Close all external doors and windows, turn on all extractors for a few minutes to allow for an underpressure to be created. And hold a burning newspaper into the stove pipe opening of your chimneys.
Do this with sober and healthy adults near by, teach them about the risks involved. Keep boron water for the eyes ready, buckets of water extinguishing the fire in case it goes wrong.

Maybe a cigarette or an incense stick first, start with a low risk experiment.
But keep in mind that burning a few kW of fuel (the stove capacity) demands a lot of fire - and air. So the cigarette/incense stick is just a first hint. The full risk scenario would be run under worst conditions.

Note the wind direction, wait for it to change and repeat.

StoveSearcher

Thanks guys - in the almost year we've been looking at doing this nobody has flagged an issue with pressure equalisation!!

I'm coming VERY close to calling the whole project off and going on a sun holiday:)

heinbloed - the link you sent me - is that just an alarm devide which warns you allowing you open a window or whatever? Have googled but my rather non technical brain isn't making sense of it.

Spoke to the stove supplier today (no, I've no intention of naming the shop) and mentioned your concerns. His view is that as the stove is going to be about 9m away from the extractor fan, this isn't going to be a problem. There are 3 internal and one expernal doors leading off this room and he reckons air for the extractor fan will come from a source other than down by the stove.

Anyone else have any opinions (including where wouldbe good for a holiday if I choose to blow the stove savings:D)

Thanks

SS

heinbloed

A holiday in a country with a building and heating culture?

About the pressure differential warning device (Marley) linked:
This is a very simple design, it gives off an alarm if the kitchen hood is working but the window isn't open. A few plain rules have to be adhered to, ask the manufacturer for an installation manual.
This device from Marley does not guarantee that there is enough air or pressure in the house/room to run the stove safely.It is only a warning device saying that there is something seriously going wrong.

The better, more safe devices contain a pressure differential sensor. Or several of them. These are legally demanded for public buildings like hotels, restaurants etc.. And cost more than a stove,much more and demand regular maintenance and testing by ventilation specialists.
But do guarantee that the pressure in the room is compared to the pressure outside permanently and will give off an alarm if the discrepancy/difference is too big. If a situation is created where the air of the room is evacuated beyond safe meassures. Since room sizes differ and more then one ventilation system might be involved these very accurate devices are nothing for the DIYers.

B.T.W.:
Are there still restaurants running open fires and kitchen hoods parallel ?

I know one here in Youghal which had to close down, the smoke and ash coming into the guest area ruining the table clothes. And not only these.
A new build. Expensive, 5 meter ceiling height. A waste of money thanks to bad design and engineering. It's an Off-licence now, near the Green Park.

heinbloed

Stove Searcher wrote:

Spoke to the stove supplier today (no, I've no intention of naming the shop).....

Why not? Good advice speaks for good quality.


And

.....and he reckons air for the extractor fan will come from a source other than down by the stove.

Reckons?! Why?

heinbloed

...maybe both?

There is a PH village in Austria, some passive show houses have stoves installed. So you could check out how this works: airtight building envelopes in combination with stoves, build according to very stringent national building regulations. The houses are cheap for a few days and Grossschoenau is a nice place.

http://www.probewohnen.at/lang_en/page.asp/index.htm

http://www.youtube.com/watch?v=OjgizzH7iCw

creedp

StoveSearcher wrote: »

Thanks guys - in the almost year we've been looking at doing this nobody has flagged an issue with pressure equalisation!!

I'm coming VERY close to calling the whole project off and going on a sun holiday:)

heinbloed - the link you sent me - is that just an alarm devide which warns you allowing you open a window or whatever? Have googled but my rather non technical brain isn't making sense of it.

Spoke to the stove supplier today (no, I've no intention of naming the shop) and mentioned your concerns. His view is that as the stove is going to be about 9m away from the extractor fan, this isn't going to be a problem. There are 3 internal and one expernal doors leading off this room and he reckons air for the extractor fan will come from a source other than down by the stove.

Anyone else have any opinions (including where wouldbe good for a holiday if I choose to blow the stove savings:D)

Thanks

SS

For the 2nd time today Ive posted a long [unweildy] response on this thread and both times it got lost in transmission so Im not going to try again. Im with you on this OP .. with the latest serious concern raised here relating to the dangers of stoves Im thinking to hell with the stove and just crank up the HP (oops another foolish installation!) when needed. Given that it would cost about €2k to install a good quality stove and as much again for this latest device, the payback on the investment would be seriously long.

Again I'll just say if anybody out there, civil engineers, etc have a view on this topic I would welcome the discussion. Also Heinbloed you have asked the OP to name his supplier so why would you name a few of these quality suppliers you refer to so we can have the benefit of their expertise?

OP you may be right blow the money on a holiday and as least then you won't die of CO or other nasty substance floating around your house. Alternatively don't cook and therefore you won't have to turn on your extractor. I don't know which is the better solution.

roy rodgers

StoveSearcher wrote: »

Head is melted so hopefully somebody can help.

We're installing an inset stove into our large family room. The stove which has been recommended is 8Kw which should be well adequate.

Do we need an external air supply? Our kitchen is at one end of this room and on occasion I will have the extractor fan running full throttle. My understanding was that anything over 5KW should have it's own external air BUT, the supplier said that this only applies to air tight houses.

Ours isn't airtight - 2002 build and has a standard air vent in the room.

Can anyone enlighten me please

thanks

SS

OP, Every burning appliance will need oxygen to burn the fuel and to be able to remove the products of combustion in a safe manner.

There is no limit on the size of the appliance, providing that it has the correct ventilation and flue.

How big is the rooms the stove is going into?? and how many vents are already in the room?? If memory serves me right a 8 kw fire in a 15m2 room will need 9500mm2 which is about a 5inch round hole.
A smaller hole would do as the house would have a certain amount of advantitious air but your better to be safe than sorry!

heinbloed

Roy rodgers wrote:

If memory serves me right a 8 kw fire in a 15m2 room will need 9500mm2 which is about a 5inch round hole. A smaller hole would do as the house would have a certain amount of advantitious air but your better to be safe than sorry!

The point is that an air extractor is installed as well, a kitchen hood.

How does that work, roy rodgers, how is the safety calculated and guaranteed?

Remarkable it is that no stove seller or stove installer has joined the discussion.


O.k., we gonna ask the OP the vital question which no one seems to have done before: What capacity(m3/minute) has the extractor?

Stove Fan

I'm surprised that no stove suppliers or stove installers have come into this discussion:(.

I am not either but I could ask someone who is although he is a company owner and stove installer in the UK, so regs may be different.

I have only seen that a stove must not be fitted in the same room as an extractor fan.

Stove Fan:)

roy rodgers

The extractor fan should treated as a just another appilance and the manufacture's instruction should be referrred too as always.

If the exhaust pipe from the extractor fan is 4 or 5 inch, well a 4 or 5 inch additional vent would also be needed to replace the discharged air, so if OP had two 5 inch vents in his room one for the 8kw stove and one for the extractor fan he'll be well covered.

heinbloed

Well, Stove Fan :
You have refered to a sales man who said that the extractor would get it's air from anywhere but not from the stove/chimney.... that should be a reference worth to investigate.

heinbloed

Roy rodgers wrote:

The extractor fan should treated as a just another appilance and the manufacture's instruction should be referrred too as always.

No. We have here a system which units can't be run independantly and parallel. The one thing influences the other, a system.
Therefore "the manufacturer" has no clue and can't be taken serious with any statement about the safety of the system.
He simply knows nothing about the other items and the circumstances they influence.

heinbloed

Roy rodgers wrote:

There is no limit on the size of the appliance, providing that it has the correct ventilation and flue.

Well, that's correct. But how is the correct dimension calculated, tested? There are international standards for this calculation but these can fail in situ, Murphy's law.
What would save the operator/homeowner if the wind changes direction, for example not blowing onto the house' air inlet (hole-in-the-wall) but sucking at it ? And the extractor working at full tilt? And the stove blazing away- hopefully ... all at the same moment?

roy rodgers

Air is all around us if you haven't noticed its one of them miracles of nature.

It doesn't matter if a extractor fan is horsing out 250m2/h and a chimney creating 7 air changes to a room an hour as long as there is adequate ventilation thats the laws of physics.
I have worked in workshops on a big scale where there was open flued steam gas boilers and extractors fan going and it was all working on it own adequate ventilation.
If the system is designed right there is no problems.
Plumbing is not rocket science its common sense!!

good night some of us have to work in the morning:p

creedp

heinbloed wrote: »

Roy rodgers wrote:




Well, that's correct. But how is the correct dimension calculated, tested? There are international standards for this calculation but these can fail in situ, Murphy's law.
What would save the operator/homeowner if the wind changes direction, for example not blowing onto the house' air inlet (hole-in-the-wall) but sucking at it ? And the extractor working at full tilt? And the stove blazing away- hopefully ... all at the same moment?

What would actually happen in this precise scenario?? Would the person keel over from the lack of oxegen or would they be poisoned by the CO being sucked out of the stove? I have often been in a house with a stove/open fireplace and a kitchen extractor operating at full tilt in parallel and no one keeled over but maybe these people are all living on borrowed time? If so I would like the warn them of the impending doom. So if this is a real rather than a theoritical problem, i.e. if the wind is blowing above a certain speed and the vents are located at the wrong location and the stove is at absolute full tilt and the extractor is on full tilt and you have no window/door open anywhere in the room and all of this goes on for a 'x' period of time then you could be in real danger. I don't mean to make light of this but unless it is explained and supported by fact very few people will take this seriously in my humble opinion.

I know of 2 houses with this scenario, in the 1st house there are window vents which are pretty limited in any case but even so half of them have been blocked up to stop drafts. In the second house there is no vent at all in the room and yet these people are still standing. I already have advised the people in the 2nd house to put a hole in the wall vent in but as yet they haven't. However with this new issue arising I might go back and try again!!

Putty Man

I'm reading this thread looking for an answer to the OPs original question, if you have an external air supply into a stove, is an extractor fan still a problem?

I would think that it could be, in that no matter how good the supply of air from outside, the extractor fan wouls still cause a draw into the room. This draw could be more that what the chimney is producing.

creedp

Putty Man wrote: »

I'm reading this thread looking for an answer to the OPs original question, if you have an external air supply into a stove, is an extractor fan still a problem?

I would think that it could be, in that no matter how good the supply of air from outside, the extractor fan wouls still cause a draw into the room. This draw could be more that what the chimney is producing.

Im presuming this wouldn't be a problem with a recirculating extractor fan. However, if you have a MHRV system will the draw from that also be a problem even if the room has both an extract and supply source and the system is supposed to balanced? In my case the room is 13m long with the extractor on one side and the stove location on the opposite side with the MHRV extract beside the extractor and 2 MHRV supply vents between it and the stove. The MHRV installer said the room is balanced so no draw.

creedp

Putty Man wrote: »

I'm reading this thread looking for an answer to the OPs original question, if you have an external air supply into a stove, is an extractor fan still a problem?

I would think that it could be, in that no matter how good the supply of air from outside, the extractor fan wouls still cause a draw into the room. This draw could be more that what the chimney is producing.

Sorry for constantly coming back to this one but it is a important issue that seems to be largely ignored. In the above scenario I presume that a problem will only arise if the air being removed by the extractor in not being replaced by air coming into the house from other vents/leaks/windows/doors. The problem here is of course how can you determine this in all cases. Heinbloed says get a civil engineer for this task. Is this the way to solve the problem and again I ask the Q did anybody here ever get this analysis done on either their own home or one that they are involved in constructing?

Putty Man

creedp wrote: »

Im presuming this wouldn't be a problem with a recirculating extractor fan. However, if you have a MHRV system will the draw from that also be a problem even if the room has both an extract and supply source and the system is supposed to balanced? In my case the room is 13m long with the extractor on one side and the stove location on the opposite side with the MHRV extract beside the extractor and 2 MHRV supply vents between it and the stove. The MHRV installer said the room is balanced so no draw.

I would say that if the room is balanced, no draw, then a stove with external air would be fine.

I'm not sure I would be 100% happy tho about depending on this in real life, simply because of the potential danger if something wasn't up to scratch.

One thing not mentioned yet is the airtightness of the stove itself. If it was fully airtight, ie air from outside, flue to outside, and no other air allowed in or out. Then surely that would negate the danger of smoke getting into the room. Might cause issue when the doors are opened for refilling tho..


..yeah I'm outta my depth here, best leave this to the experts (if such a person exists).

heinbloed

Here another type of pressure differential switch/sensor:

http://www.brunner.eu/steuerungen/br-steuerungen-usa.iterra

In combination with a chimney fan (automatic operation) like

http://www.kutzner-weber.de/gb/products/chimney-fans.html

the operation should be safe. If the electricity supply doesn't fail.
The OP has an independant air supply planned. In principle this should be calculated as well, the volume of air which can be supplied.
As putty said already, the closed system won't be closed if the stove is re-fuelled or de-ashed. In this case the suction force of the air extractor would suck the smoke and ash into the room, the hot combustion gases as well. Risk of injury, panic, fire....

Open fire places and stoves where relativly harmless to operate in times when air extractors where unknown. But nowadays these devices are found in many homes and they are used.
In the old times it was o.k. to have a few drinks and take the horse finding home. But nowadays this would be a risky aproach.

DoneDL

Advice from the Solid Fuel Association, as mentioned by Stove Fan.

EXTRACTOR FANS

Where extractor fans are fitted into a property then
additional ventilation will be required in the same
room. This will avoid the extractor fan creating a
negative pressure in the property that may interfere
with the operation of a chimney.

Extractor fans must not be sited in the same room
as a solid fuel appliance.

creedp

heinbloed wrote: »

Here another type of pressure differential switch/sensor:

http://www.brunner.eu/steuerungen/br-steuerungen-usa.iterra

In combination with a chimney fan (automatic operation) like

http://www.kutzner-weber.de/gb/products/chimney-fans.html

the operation should be safe. If the electricity supply doesn't fail.
The OP has an independant air supply planned. In principle this should be calculated as well, the volume of air which can be supplied.
As putty said already, the closed system won't be closed if the stove is re-fuelled or de-ashed. In this case the suction force of the air extractor would suck the smoke and ash into the room, the hot combustion gases as well. Risk of injury, panic, fire....

Open fire places and stoves where relativly harmless to operate in times when air extractors where unknown. But nowadays these devices are found in many homes and they are used.
In the old times it was o.k. to have a few drinks and take the horse finding home. But nowadays this would be a risky aproach.

I've looked a the blurb relating to the 2nd attachment above and it selling point seems to be improving the draw in a chimney so that the stove operates more efficiently and with less emissions. I don't see it promoting its use to aleviate problems of negative pressure cause by forced extract ventilation. But i suppose anything that encourages smoke up the chimney helps in that regard.

In relation to references to the old days of huts and horse transport I personally don't think that helps people to take your point of view more seriously. When you say open fireplaces and stoves were safe prior to kitchen extractors coming on the scene, that's like saying they were fine before the advent of electricity. There has been fireplaces and stove not to mention solid fuel/oil fired ranges in houses alongside kitchen extractors for years now and I for one have never heard of lads eyebrows being singed when they were refueling/cleaning them out because their extractor happenned to be on at thesame time. If this is the extent of the problem then all the danger and fear can be avoided by telling people to turn off your extractor when you are opening your stove.

One concern I would have of course is the use of technology for ventilation control that can go wrong and depends on electricity to operate, i.e. what happens if the MHRV system dies and the extractor fan is operating at full swing then some kind of a device to warn the householder would be important and maybe this is where these devices are needed.

creedp

@Donedeal. Now that's the first time I've seen this piece of advice (sorry before you raising is Heinbloed) and if it is the case then why isn't it more generally promoted. It seems a bit strange to have Building Regs which insist on adequate ventilation but do not insist that this situation should be avoided.

Of course the only problem with this advice is that it is more appropriate to traditional houses which have a standalone kitchen is seperated by a closed door from other parts of the house but how does it work with modern open plan design or simply two small adjacent rooms with an open door between them?

DoneDL

creedp wrote: »

@Donedeal. Now that's the first time I've seen this piece of advice (sorry before you raising is Heinbloed) and if it is the case then why isn't it more generally promoted. It seems a bit strange to have Building Regs which insist on adequate ventilation but do not insist that this situation should be avoided.

Of course the only problem with this advice is that it is more appropriate to traditional houses which have a standalone kitchen is seperated by a closed door from other parts of the house but how does it work with modern open plan design or simply two small adjacent rooms with an open door between them?

It is difficult to define a traditional house, I would say that the advice stands. Some stoves will mention in the Installation instructions that an extract fan is not allowed, extract from Esse stove MI`s

2. Do not fit an extractor fan in the same room as

the appliance.

I for one would think that a large open plan area would not be considered a room but as heinbloed has pointed out the variables involved from the output of the fan to the air requirements of the room combined with what the stove requires to burn safely is difficult to calculate. Factor in adventicious air, outside temperatures and weather influences on the behaviour of the chimney. So to be safe and within the regs it`s best to go with manufacturers instructions.

StoveSearcher

And still more to think about:(

To give a bit more info. This is an open plan kitchen/living room measuring 9m long and 5m wide with two passive air vents on each end - one beside the extractor fan and one about 4m from the proposed stove installation (on the same wall)

There is an external door and three internal doors and as we have two smallies, at least one of these internal doors is pretty much always open!!

I really don't know. Spoke to the supplier again this morning and he really feels that pressure equalisation will not be an issue given the size of the room, the location of the extractor fan and the position of the air vents. But then, he wants to sell a stove.....

But back to my original question - in a non air tight house in a room space this size with an extractor fan at one end, is an external air supply a necessity or a nice to have? The stove doesn't come with one as standard but can be suppliesd as an add on kit

SS

creedp

I for one would think that a large open plan area would not be considered a room but as heinbloed has pointed out the variables involved from the output of the fan to the air requirements of the room combined with what the stove requires to burn safely is difficult to calculate. Factor in adventicious air, outside temperatures and weather influences on the behaviour of the chimney. So to be safe and within the regs it`s best to go with manufacturers instructions.[/QUOTE]

I agree its always prudent to err on the side of caution but if your house is deigned with a large open plan kitchen/dining/living room with a chimney/stove then you either don't have an extractor fan or dont have a stove or I suppose you can't have MHRV. The alternative may be to install one of these negative pressure guards as outlined by Heinbloed. I just don't know .. all I do know is that I have all of these in place except stove at present!

Stove Fan

Hi:)

This is the reply I had from a professional stove installer in the UK with fitting a stove in the same room as an extractor fan. I dont know if the regs here are the same?

There isn't anything actually stating you can't have an extractor in the same room as a stove. All it says is that it should be avoided. Basically so long as there is enough air coming into the room to replace the air being extracted then everything should be fine. We've installed stoves in pubs with extractors and we've simply installed plenty of ventilation. Basically close all doors and windows, turn extractors to maximum and then install enough vents until appliance doesn't spill smoke. Another way to combat the problem would be to install a stove with a direct air kit to outside. Although what would happen when you open the door to refuel I'm not sure. I'd imagine you may get some smoke spillage.

Check out page 23 here: http://www.specflue.com/regulations/DOC_J_2010.pdf

Stove Fan:)

heinbloed

It is dangerous advice to tell some client that a separation with a door will avoid the risk of an underpressure.
These people should be reported.

A standard door within a house or flat is not airtight.

If the closed house is depressurised by an air extractor like a kitchenhood then this depressurisation effects all rooms. And toilets and cup boards and cabinets ....

I gave you the sample of the closed restaurant in Youghal. That is what exactly happened. The kitchen hood was in use, the entire restaurant was depressurised. The smoke from chimney sucked into the very large premise, the smell from the toilets as well.
Despite that these rooms where all seperated from each other by doors.
The only way to get the thing sometimes working was to leave the major entrance door open. as soon as the wind started to blow from the sea(the prevailing wind direction here in Youghal) this open door was increasing the depressurisation effect, making things worse.

Another sample is Burger King in Cork, Patrick Street: Despite having the large doors towards Patrick Street open all day long the depressurisation of the kitchen hoods is so strong that the kitchen hoods do not work properly. They have to keep the emergency door at the side of the building open as well.
Go and have a look, it's a public building, entrance free.

Relying on a row of holes in the walls is simply not good enough. As soon as the right wind directions prevail these holes would increase the depressurisation effect of the extractor!

@ Stove fan:

You have written in your last post that you have installed stoves in pubs and punctured the walls.

We've installed stoves in pubs with extractors and we've simply installed plenty of ventilation.

Since pubs are 'public spaces' a fire engineer/safety officer would have to comission these installations - as far as I know.
Anyhow: give us some adresses so we can go there and have a look, a pint. Good quality jobs can be published, why not.....

"If it can't be meassured it can't be calculated"

Air flows can be meassured !

Uk Flue Flow Test For Gas Appliances:

Because of the high volume of smoke produced by a smoke pellet, it is advisable to first check that the primary flue is pulling, by using a smoke match placed at the opening to the combustion chamber. Once it has been established that the primary flue is pulling using a smoke match:-

Place a smoke pellet in the combustion chamber of the appliance. The smoke should enter the flue system and be discharged from the terminal. No smoke should emerge from the draught divertor.

If the flue test result is not satisfactory repeat the test after a further ten minute warm-up period.

If the flue fails the second test, check for any obstruction within the flue system, or the need for additional ventilation to the room. If any extract fans (i.e. Cooker Hoods, Room Extract Fans, Warm Air Heating Fans, Tumble Dryers, vented to outside) are fitted within the room containing the appliance/s repeat the test with the fan or fans running at full rate.

If any extract fans are fitted in an adjoining room, the test should be carried out with the room connecting door/s open. If the flue now fails the test, but works satisfactorily when the extract or appliance fans are not in operation, this indicates that there is not enough ventilation air. The air ventilator (if fitted) must therefore be enlarged, or a ventilator fitted preferably direct to outside. Current standards recommend, as a guide, that 50cm2 (8ins2) of air vent free area will be sufficient for most situations.

If all tests fail, and the defective ventilation cannot be corrected, make safe the installation and advise customer or owner of property in accordance with the current standards and regulations.

Billy Bunting

gary71 wrote: »

If all tests fail, and the defective ventilation cannot be corrected, make safe the installation and advise customer or owner of property in accordance with the current standards and regulations.

Then give them the bill and pray they pay it :rolleyes: been there done that

Stove Fan

heinbloed wrote: »

@ Stove fan:

You have written in your last post that you have installed stoves in pubs and punctured the walls.



Since pubs are 'public spaces' a fire engineer/safety officer would have to comission these installations - as far as I know.
Anyhow: give us some adresses so we can go there and have a look, a pint. Good quality jobs can be published, why not.....

"If it can't be meassured it can't be calculated"

Air flows can be meassured !

Hi I have never fitted any stove for a customer, I am not in the stove fitting or stove supply trade, just interested in stoves.
. It was a professional UK based HETAS registered heating installer that I asked and that he had fitted stoves in pubs etc with extractor fans using the method above. The original text below mine in my previous post was his reply.

Are there any online links to building regs in Ireland covering stoves and extractors?



Stove Fan:)

heinbloed

Stove Fan asked:

Are there any online links to building regs in Ireland covering stoves and extractors?

Try a search engine for "Part F, Building Regulations"

JoyceL

Could somebody please help.... I currently have oil central heating.. it heats rads and water.. I want to install a boiler stove but my plumber informs me that my fireplace is too far away from my hot water cylinder.. Is it possible to install a new cylinder on a ground floor to link up to the boiler or to run pipes from the stove out through the back wall and then up to the tank on a first floor bedroom ?? any suggestions