Airtight stoves, fact or fiction?

BarneyMc

I'm at the plastering stage of a new build and have installed airtight tapes, membranes, etc. I'm looking ahead at my one and only stove and want to keep this airtight also but is there such a thing?

I contacted the technical department from one leading stove manufacturer and got this reply: "The stove itself is not fully air tight, I don't believe that any stoves really are, as things like the hole in the stove body for the riddle grate control and the air manifold on the back of the airbox are not hermetically sealed, as well as the doors of course which will need to be opened when the stove is under fire to add fuel."

So my question is what impact does installing a stove have on your airtightness or does all this depend on the actual stove and installation detail?

There is one manufacturer who lets you filter for 'Room air sealed operation' stoves on their website (am I allowed to name them?) so I guess this is the best route to take for peace of mind? This is getting into the big money territory but I've just one stove and no fireplaces so I suppose I can splash out a bit here. Also, why spend so much money and effort on getting the airtight detail right only to have it compromised by a non-airtight stove?

By the way I could live with loosing some air up the flue each time the fire had to be re-fuelled. It's what's happening when the stove door is shut whether lit or not) that bugs me.

893bet

Still at it barney! As per our discussions it's not air going out that is the issue rather air, ie smoke, being pulled the other direction if your ventilation system becomes unbalanced.

I think in the next 5 years they will formalise standards a lot more for stoves regarding Airtightness but at moment......case in point I asked the same question to the same tech department of a large stove manufacturer twice, once recently and once 6 months ago and got too different answers.

BryanF

You got look outside of Ireland

893bet

BryanF wrote: »

You got look outside of Ireland

can you recommend a few brands?

Here or via PM.

BarneyMc

893bet wrote: »

can you recommend a few brands?

Here or via PM.

There's one manufacturer where you can filter for 'room sealed airtight' stoves. Can a moderator confirm if I can name the website here?

MizMix

I researched brands about a year ago and Brunner seemed to be one of the top (and they do modern looking ones too which is what I'm looking for)- there is an Irish supplier too. I found online prices from Germany much cheaper but you really would need to make sure whoever the contractor was knew what they were doing.

galwaytt

...was in a house on Friday last with one such 'room sealed' cassette fire, which they are moving into for Christmas. It was so badly installed - and incorrectly - the client had pulled it out of the wall and got on to the manufacturer to get the correct details. If the installers didn't even read the instructions that came with it then it's going to end in tears......it would seem to me that this level of details is above & beyond the capability of the majority.

stickybookmark

We also have an air tight house with HRV and 1 stove. I was told the stove had to have an external air supply, and the one I'll buy will have. Is the external air supply what you mean when you say 'Room air sealed operation' Barney?

BarneyMc

stickybookmark wrote: »

We also have an air tight house with HRV and 1 stove. I was told the stove had to have an external air supply, and the one I'll buy will have. Is the external air supply what you mean when you say 'Room air sealed operation' Barney?

No, it's not the external air supply which is a must. The easiest way to think about it is a stove not lit. Will there be a draught from it? This might come from the door seals, flue connection, etc. Surely it should be treated like any other part of your house, i.e. air tight?

As I mentioned above I have a website of a stove manufacturer (German) where you can filter for 'room sealed' stoves. I've yet to get a final price for it but I'm very interested as it guarantees air tightness.

BarneyMc

PM sent around.

corcadorcha

Please send me link to German website
Thanks.

BryanF

BarneyMc wrote: »

There's one manufacturer where you can filter for 'room sealed airtight' stoves. Can a moderator confirm if I can name the website here?

Mod note: Go ahead

IMHO Irish stove companies have designers still living in the 50's and their missing a trick! The European stoves are more modern looking and deal with Room sealed and air ducting better than the locals.

But the euros don't seem to do back boilers, there are Very limited options when you look for flush/ inset/ sealed/ external air/ boiler stove.

BarneyMc

BryanF wrote: »

Mod note: Go ahead

Thanks Bryan. It's http://www.spartherm.com/en/products/stoves/

Under 'Features' you can select 'Room air sealed operation'.

It seems like the elephant in the room but if you have an airtight house but install a stove that's not then are you not fooling yourself?

hesker

So if it's room sealed how is the fire fed with air (oxygen). Is there a pipe drawing external air to it with a flow control valve or something? Or is it just fed with air from the room though a similar valve?

BryanF

hesker wrote: »

So if it's room sealed how is the fire fed with air (oxygen). Is there a pipe drawing external air to it with a flow control valve or something? Or is it just fed with air from the room though a similar valve?

usually >150mm pipe sub-floor that comes up under the stove, this requires planning at an early stage, they often have a max length, it should be sloped to avoid water ingress and suitably covered to avoid moisture and insects etc

Calahonda52

BryanF wrote: »

usually >150mm pipe sub-floor that comes up under the stove, this requires planning at an early stage, they often have a max length, it should be sloped to avoid water ingress and suitably covered to avoid moisture and insects etc

There is also a consideration that the air intake pipe should be brought to both the leeward and wind-ward side of the house so as strong winds, such as we have right now, will not cause neg pressure in the intake if on the leeward side only.

The is also a prefabricated block chimney on the market that has the air intake along side the flue up to top of the stack..

Of course on the web u will find arguments
http://www.imbrandon.com/burning-in-the-fireplace-see-how-important-it-is-to-bring-air-into-the-fireplace/
and surprise surprise
counter arguments
http://www.woodheat.org/the-outdoor-air-myth-exposed.html

The key thing here is to comply with the Irish regs so the links above is just for an alternative view

galwaytt

BryanF wrote: »

usually >150mm pipe sub-floor that comes up under the stove, this requires planning at an early stage, they often have a max length, it should be sloped to avoid water ingress and suitably covered to avoid moisture and insects etc

..in a bungalow I've seen an inlet in the soffit outside, across the attic, and dropped down behind studwork in the firebreast to feed the fire. No need to worry about dampness up there !

air

In my opinion stoves just aren't compatible with modern homes.
Notwithstanding the aforementioned air tightness issues, you're introducing so much fumes and smoke into your home which have negative health effects. Also they are a relatively uncontrolled heat source which means that they aren't compatible with well insulated modern homes that need a small amount of controlled heat input.
On top of this you have the hassle of sourcing, storing and moving solid fuel, dealing with ashes and cleaning both the flue and the stove itself.
Time people moved on from flames IMHO.

fclauson

No stove with an opening door can be "certified" airtight - it will take just a small twig sticking out over the seal to cause problems

That being said many stoves can be very close

Exeternal air is critical

On smoke into the room I reckon (no science here) that the chimney and external air would need to be blocked before MHRV could drag smoke into room - and as in a well insulated house it will be timber rather than coal then you will smell the smoke before it kills you - coal would be different

So after three years and around 50 fires our almost airtight well ventilated timber only stove works v well

BarneyMc

fclauson wrote: »

No stove with an opening door can be "certified" airtight - it will take just a small twig sticking out over the seal to cause problems

That being said many stoves can be very close

So after three years and around 50 fires our almost airtight well ventilated timber only stove works v well

For the final blower test then do you have to have your stove installed or can you just cover pipes, flues, etc. and assume a decent air tightness?

The first paragraph here throws a bit of light on standards in this area: http://www.danskan.de/index.php?id=16&lang=en

fclauson

Not sure what the official line on that is

ht9zni1gs28crp

I would assume the Stove needs to be installed, as that is the final build up per se...The stove itself is the Airtight line...

BarneyMc

miller_63 wrote: »

I would assume the Stove needs to be installed, as that is the final build up per se...The stove itself is the Airtight line...

To give a realistic air tightness result then yes I agree. In practice though installing a stove after the test is a leap of faith.

BarneyMc

I came across this list of stoves with the DIBt certification: https://www.dibt.de/de/zv/NAT_n/zv_referat_III5/SVA_43.htm

I suppose you have to question the DIBt certification but it's certainly some standard to work to.

galwaytt

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air wrote: »

In my opinion stoves just aren't compatible with modern homes.
Notwithstanding the aforementioned air tightness issues, you're introducing so much fumes and smoke into your home which have negative health effects. Also they are a relatively uncontrolled heat source which means that they aren't compatible with well insulated modern homes that need a small amount of controlled heat input.
On top of this you have the hassle of sourcing, storing and moving solid fuel, dealing with ashes and cleaning both the flue and the stove itself.
Time people moved on from flames IMHO.

Sorry, but that's your opinion. I see a lot of new houses to high standards built - successfully - with room sealed stoves and there is no evidence of any 'health' issues. Many use it as their sole form of whole-house heating.

And think about it: if it's room sealed, how is there anything from the stove entering the room ??

air

Yes, I did preface it with "in my opinion".
Smoke will inevitably enter the room whenever you open the door of the stove to light it or add fuel.
You also can't avoid introducing ash and dust into the room when you remove the ash after a burn or get the chimeny cleaned.
One of the great advantages of modern airtight builds is how much cleaner they stay due to the filtered incoming air, you're throwing out a lot of that benefit by introducing all that dust which will also block your HRV filters quicker than without.
Finally a flue or chimney is a big cold bridge whether or not the stove is in use.

On the health impact this should be much reduced with room sealed ones however that doesn't help your neighbours if you are living in an urban area.

FrontDoor

galwaytt wrote: »

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Sorry, but that's your opinion. I see a lot of new houses to high standards built - successfully - with room sealed stoves and there is no evidence of any 'health' issues. Many use it as their sole form of whole-house heating.

And think about it: if it's room sealed, how is there anything from the stove entering the room ??

Could you expand on that a little.

I see a lot of modern houses with UFH, where the stove is never lit.

On the other hand, I know of one house with 2 sealed stoves and back-up of oil and rads. The oil is hardly ever used.

Are stoves compatible, or at least an extravagance, with UFH? It must be a minimum of 5k off a house budget by removing stove+chimney+extra associated detailing?

BarneyMc

FrontDoor wrote: »

Are stoves compatible, or at least an extravagance, with UFH? It must be a minimum of 5k off a house budget by removing stove+chimney+extra associated detailing?

Why are stoves not compatible with UFH but seem to be with rads?

FrontDoor

BarneyMc wrote: »

Why are stoves not compatible with UFH but seem to be with rads?

They are certainly compatible with both.

Just that UFH generally seems to be on all the time and the need for a stove is then removed?

It is not a rapid response system like rads, which can be turned off and on quickly.

Take a house with no occupants 9-5. Do you leave on UFH constantly and maintain a certain temp, or use rads/stove to lift temp again a little in the evening.

Do rads + oil + stove go together better that UFH + stove?

ht9zni1gs28crp

From experience of living in our house since August its been one of the best decisions ever to ditch the stove. I couldn't ever have imagined lighting it, the house would be unbearable.....

Plus a few less jobs to do in fuel prep and stove clean....

€6k+ better spent elsewhere....

FrontDoor

miller_63 wrote: »

From experience of living in our house since August its been one of the best decisions ever to ditch the stove. I couldn't ever have imagined lighting it, the house would be unbearable.....

Plus a few less jobs to do in fuel prep and stove clean....

€6k+ better spent elsewhere....

Do you miss the centre-piece idea of a stove/fire in a room?

What solution have you installed?

ht9zni1gs28crp

FrontDoor wrote: »

Do you miss the centre-piece idea of a stove/fire in a room?

What solution have you installed?

Why is it a centre piece? or rather why should it be a centre piece? Breakaway from traditional thinking on a modern solution. Think of the reasoning behind why it became a centre piece of a room....when the need/funtion is removed then form will follow....

I'm on Air source heat pump to UFH in a passive house...

BarneyMc

FrontDoor wrote: »

They are certainly compatible with both.

Just that UFH generally seems to be on all the time and the need for a stove is then removed?

I would have thought if a stove was lit then the room stats would tell the HP to remain switched off?

FrontDoor

miller_63 wrote: »

Why is it a centre piece? or rather why should it be a centre piece? Breakaway from traditional thinking on a modern solution. Think of the reasoning behind why it became a centre piece of a room....when the need/funtion is removed then form will follow....

I'm on Air source heat pump to UFH in a passive house...

I'd agree completely with that sentiment.

FrontDoor

BarneyMc wrote: »

I would have thought if a stove was lit then the room stats would tell the HP to remain switched off?

Would the heat thrown out by a stove in an air-tight, well insulated home not quickly overwhelm the place though?

Thats really my query I suppose. Do people living in such houses use their stove much? Fclauson says about 50 times in 3 years or once every 3 weeks. Miller sees no need for one.

air

UFH is often coupled with a heat pump and if the heat pump is sized correctly it will only meet the maximum heat demand about 90% of the time. This ensures it runs with best efficiency most of the time.
The downside is that you need a supplementary heat source to provide the additional heat input requried to maintain temperature in extreme conditions. Stoves are often put in to serve this purpose.
I don't think it's possible to justify stoves over simple electrical resistive heating for this application - the capital costs are very high vs the likely lifetime energy output.

On stoves with rads vs stoves with UFH, I woudl think the reason for it is this:
Stoves are a pretty uncontrolled heat source with highly variable heat output. UFH is far slower to react than rads so it's not possible to regulate room temperature with it as effectively as with rads when trying to deal with the peak of heat output from the stove.

I think the main reason people install stoves in modern homes is because they like looking at them, which is fine but they're certainly not a good option from an economic or environmental perspective.

FrontDoor

air wrote: »

UFH is often coupled with a heat pump and if the heat pump is sized correctly it will only meet the maximum heat demand about 90% of the time. This ensures it runs with best efficiency most of the time.
The downside is that you need a supplementary heat source to provide the additional heat input requried to maintain temperature in extreme conditions. Stoves are often put in to serve this purpose.
I don't think it's possible to justify stoves over simple electrical resistive heating for this application - the capital costs are very high vs the likely lifetime energy output.

On stoves with rads vs stoves with UFH, I woudl think the reason for it is this:
Stoves are a pretty uncontrolled heat source with highly variable heat output. UFH is far slower to react than rads so it's not possible to regulate room temperature with it as effectively as with rads when trying to deal with the peak of heat output from the stove.

I think the main reason people install stoves in modern homes is because they like looking at them, which is fine but they're certainly not a good option from an economic or environmental perspective.

Interesting. Thanks.

BarneyMc

air wrote: »

I think the main reason people install stoves in modern homes is because they like looking at them, which is fine but they're certainly not a good option from an economic or environmental perspective.

From an environmental perspective is it not better to burn logs (stove) locally sourced and sustainable rather than electricity (HP) generated from burning imported fossil fuels (mostly oil)?

From an economic perspective I've a bit of land and plenty of logs. Surely not to use this 'free' fuel would be a missed opportunity?

FrontDoor

BarneyMc wrote: »

From an environmental perspective is it not better to burn logs (stove) locally sourced and sustainable rather than electricity (HP) generated from burning imported fossil fuels (mostly oil)?

From an economic perspective I've a bit of land and plenty of logs. Surely not to use this 'free' fuel would be a missed opportunity?

Use the logs to run some sort of gassification boiler? Drive ufh from there?

ht9zni1gs28crp

for extra warmth just do some cooking, washing, drying or invite people around....

Our main (open plan) room sees a 1 deg temp rise within 20 mins if two or more extra people are in there. Imagine what one log on a stove would do!

In response to Barney, by offsetting the HP demand by producing enough via PV panels per annum satisfies the renewable side of things.

The whole 'free' fuel is a misnomer IMHO. You still need to collect, cut it, store it, dry it, fetch it in, clean it out. I have plenty of other stuff to be at than collecting firewood! I lived with a stove in a previous house and never again.....

If I were to employ you BarneyMc on a hourly rate what would it be?

Carawaystick

Also cutting firewood warms you twice, which no heat pump will do...

ht9zni1gs28crp

Carawaystick wrote: »

Also cutting firewood warms you twice, which no heat pump will do...

All I can hear with that quote is a grandfather heckling a young fella to keep cutting while a house up the yard has windows frozen over in the inside.... :o

monkeynuz

air wrote: »

Yes, I did preface it with "in my opinion".
Smoke will inevitably enter the room whenever you open the door of the stove to light it or add fuel.
You also can't avoid introducing ash and dust into the room when you remove the ash after a burn or get the chimeny cleaned.
One of the great advantages of modern airtight builds is how much cleaner they stay due to the filtered incoming air, you're throwing out a lot of that benefit by introducing all that dust which will also block your HRV filters quicker than without.
Finally a flue or chimney is a big cold bridge whether or not the stove is in use.

On the health impact this should be much reduced with room sealed ones however that doesn't help your neighbours if you are living in an urban area.

What a load of cobblers, the smoke into the room is eliminated by opening the air flow up before opening the door, therefore no smoke comes into the room and the issue of dust is a very minor one if at all you can avoid all but the tiniest amount of dust by just being careful, it isn't rocket science. And what harm is it doing o the neighbours?

fclauson

So is the stove an economic, environmental, practical or sentimental choice

economic - you are right - they are expensive - an electric fan would definatly be cheaper

environmental - depends - your own timber makes it so - and burning timber is supposed to be "ok" from a green perspective

practical - dust is a microscopic issue (pun intended) - but my stove has cause no heart aches in terms of dust or smoke in the time I have had it - and I enjoy splitting the logs to fill it

sentimental - this sits outside any of the other choices - a room is heartless without something to sit around while one enjoys a wee dram. A flickering fake fire from the TV might suffice, or one of those fake log flicker fires

but watching a real fire with its ever changing shapes and faces within it is hugely therapeutic and for that reason alone is why I decided to fit one.

fclauson

Why not (see pic)

MizMix

Yes it's the sentimental element that makes me really want one- I know we don't need it but I can't imagine the Xmas period without one! It's also a lovely focal point to a room.

ht9zni1gs28crp

That's the beauty of design, not everyone will agree and at the end of the day it is what you want.

But sometimes its good to challenge the 'norm' or challenge 'what everyone does' syndrome.

Good design can mean a room doesn't need a 'focal' point in itself. This can be design by layout, feel or material use....A good Architect will recognise this freedom and revel in it.

air

I'm sure stoves will be a future for a long time to come, much as horses are still bred despite the advent of cars. I think solid fuel burning of any sort in urban areas will be outlawed in the coming years however.

As regards the cobblers comment above, there is always some smoke released into the room and smoke will adversely affect the health of anyone living in the immediate vicinity.

dathi

air wrote: »

. I think solid fuel burning of any sort in urban areas will be outlawed in the coming years however.

smoke will adversely affect the health of anyone living in the immediate vicinity.

http://www.contracostatimes.com/breaking-news/ci_29002369/ban-wood-burning-heating-devices-considered-new-bay
nordic countries are looking at a similar ban after several court cases where neighbours took smoke nusance cases and won .

fclauson

on other thing to think about is that our house is Passive - but it hates the damp miserable days with no solar gain

over the past 3 or 4 weeks the house has felt (but the temp gauge has not shown) cold - the stove was a wonderful thing for changing the feeling

air

Surely heat input from any other source would have had the same effect though, not withstanding the nostalgic pleasure of the dancing flames etc.
Do you have underfloor heating also? I've found that it provides a nice radiant feeling similar to that which you get from stoves etc.