Advertisement
If you have a new account but are having problems posting or verifying your account, please email us on hello@boards.ie for help. Thanks :)
Hello all! Please ensure that you are posting a new thread or question in the appropriate forum. The Feedback forum is overwhelmed with questions that are having to be moved elsewhere. If you need help to verify your account contact hello@boards.ie

Air Supply to Room Sealed Stove and Carbon Monoxide

  • 14-06-2010 10:39pm
    #1
    Registered Users Posts: 648 ✭✭✭


    Hi,

    There is no such thing as an air tight stove, for a fire in a stove we need Fuel and Air.

    There are a number of different stoves manufactured to work with an external air intake for combustion.

    It is very important to bring your Mechanical Heat Recovery / Ventilation Supplier on board by getting an assurance from them that the air pressure in the room where the stove is installed is not compromised.

    One of the problems we have found in rooms without a permanent external air vent is the stoves can smoke when being lit or re-fuelled.

    Some suppliers / installers of mechanical ventilation understand how their system should be set up to ensure the air pressure is at least equal, others dismiss the potential problem as a non issue.

    Some consumers resort to opening windows when lighting or refuelling the stove to prevent smoke pouring into the room, it is not necessarily a bad stove or chimney / flue just a difference in air pressure between the sealed room and open flue.
    .


Comments

  • Registered Users Posts: 1,815 ✭✭✭imitation


    PeteHeat wrote: »
    Hi,

    There is no such thing as an air tight stove, for a fire in a stove we need Fuel and Air.

    There are a number of different stoves manufactured to work with an external air intake for combustion.

    It is very important to bring your Mechanical Heat Recovery / Ventilation Supplier on board by getting an assurance from them that the air pressure in the room where the stove is installed is not compromised.

    One of the problems we have found in rooms without a permanent external air vent is the stoves can smoke when being lit or re-fuelled.

    Some suppliers / installers of mechanical ventilation understand how their system should be set up to ensure the air pressure is at least equal, others dismiss the potential problem as a non issue.

    Some consumers resort to opening windows when lighting or refuelling the stove to prevent smoke pouring into the room, it is not necessarily a bad stove or chimney / flue just a difference in air pressure between the sealed room and open flue.
    .

    Your correct, the right term would be room sealed instead of air tight.

    I think this issue is a massive one, your dealing with carbon monoxide and poorly ventilated spaces by design. I`m amazed at how blase some vendors are about this, as it would be very easy for somebody to get killed.

    I have come across 3 types of stove, room sealed, non room sealed with external air and room intake stoves. I personally think the only real choice is the first one.


  • Registered Users Posts: 648 ✭✭✭PeteHeat


    Hi,

    There are lots different brands designed with external air intakes, it is not new technology, houses built in the 1940's had external air delivered under the hearth of standard fireplaces.

    The room still needed proper ventilation which served the obvious purpose of air changes and balancing the air pressure for the flue.

    Many people still remember the warnings about not closing or allowing doors to slam because the fire was being lit?

    .


  • Registered Users Posts: 472 ✭✭BigGeorge


    For a new build am looking to leave a duct(s) in the slab for the future install of an air supply to & exhaust from a room sealed stove

    2 questions
    (1) approx what size of ducting to I leave
    (2) can the supply also double up as the fire exhaust in the slab?


  • Registered Users Posts: 308 ✭✭clint_eastman


    BigGeorge wrote: »
    For a new build am looking to leave a duct(s) in the slab for the future install of an air supply to & exhaust from a room sealed stove

    2 questions
    (1) approx what size of ducting to I leave
    (2) can the supply also double up as the fire exhaust in the slab?

    I left a 4" duct in the slab and it's worked out fine. Although if you have a particular stove in mind then ask the vendor re the duct size.
    I've no idea regarding the exhaust, I just used a flue to the roof.


  • Registered Users Posts: 648 ✭✭✭PeteHeat


    Hi,

    Different manufacturers use different sizes and it depends on the stoves output, to be safe I would recommend 150mm (6").

    If you intend using an inset stove with ducts I suggest you plan the installation before you build the chimney.

    They work very well if you follow the manufacturers guides but can be a long term nightmare if you have to adapt chimney breasts and flue liners later.

    .


  • Advertisement
  • Registered Users Posts: 472 ✭✭BigGeorge


    Is the 150mm enough for the double flue & insulation? or would you suggest splitting the air inlet line & fire exhaust pipe.

    I would prefer to run it all though the slab rather than have to puncture the air tight membrane etc in the future


  • Registered Users Posts: 648 ✭✭✭PeteHeat


    Hi,

    Definitely split the two, the air supply is usually ducted under the floor, the size of the duct depends on the stove output and the distance from the stove to the outside air intake.

    The exhaust / flue pipe will usually be taken off the top of the stove because the max length of pipe from the back of the stove is 150mm and that will not take you through the wall unless the flue is fan assisted which it is not on standard stoves.

    If beside the outside wall (air source) 100mm duct should suffice but check with the manufacturer or retailer !

    The flue diameter could be as much as 180 > 200mm for twin wall to suit a stove with a 125 > 150mm spigot, take care to allow extra if you are going through the wall to allow an extra 30mm for the pipe sockets.

    .


  • Registered Users Posts: 12,740 ✭✭✭✭galwaytt


    :D..I've seen 3 ways to provide air to appliances in airtight houses lately:

    1. Duct under raft, directly up under willow-burning stove (not against a wall, hence the need...)
    2. Duct in plinth, over footings, under ffl, up under the grate (open fire)
    3. Duct built inside falsework chimney breast, up to ceiling level. In the attic the duct went to gable vent. Simple, effective, and no issues of dampness, or little furry guys !!

    Ode To The Motorist

    “And my existence, while grotesque and incomprehensible to you, generates funds to the exchequer. You don't want to acknowledge that as truth because, deep down in places you don't talk about at the Green Party, you want me on that road, you need me on that road. We use words like freedom, enjoyment, sport and community. We use these words as the backbone of a life spent instilling those values in our families and loved ones. You use them as a punch line. I have neither the time nor the inclination to explain myself to a man who rises and sleeps under the tax revenue and the very freedom to spend it that I provide, and then questions the manner in which I provide it. I would rather you just said "thank you" and went on your way. Otherwise I suggest you pick up a bus pass and get the ********* ********* off the road” 



  • Closed Accounts Posts: 2,389 ✭✭✭Carlow52


    There is a good reason for
    We are going with the Schiedel Air chimney system which brings air down a second channel in the stack alongside the flue.

    The provision of ground level external air supplies to stoves needs to be considered in the context of the risk of wind induced negative pressure on the air intake, with consequential flue problem.

    This negative pressure can occur if the air supply in on the leeward side of the house when a strong breeze is blowing across the house, particularly 2 storey.

    The recommended solution for ground level external air supplies is to provide an air intake from both sides of the house meeting at a tee or similar.

    The system mentioned above addresses this issue by have the air intake and flue exit at the same pressure, regardless of wind.

    PS I see 50mm dia mentioned as an air supply, if the run is anyway long the pressure loss will make it very ineffective.

    90 mm is the normal minimum


  • Registered Users Posts: 309 ✭✭Troy McClure


    Can an air intake pipe be put up the chimney parrallel to the flu? Would this work?


  • Advertisement
  • Registered Users Posts: 5,464 ✭✭✭creedp


    Carlow52 wrote: »
    There is a good reason for


    The provision of ground level external air supplies to stoves needs to be considered in the context of the risk of wind induced negative pressure on the air intake, with consequential flue problem.

    This negative pressure can occur if the air supply in on the leeward side of the house when a strong breeze is blowing across the house, particularly 2 storey.

    The recommended solution for ground level external air supplies is to provide an air intake from both sides of the house meeting at a tee or similar.

    The system mentioned above addresses this issue by have the air intake and flue exit at the same pressure, regardless of wind.

    PS I see 50mm dia mentioned as an air supply, if the run is anyway long the pressure loss will make it very ineffective.

    90 mm is the normal minimum


    Carlow52, Im assuming the same problem will occur if the external vent duct is taken straight out through the wall behind the stove. Duct would be the thickness of the wall plus about 400mm. I was proposing to have a 100mm duct. I didn't provide for an underfloor duct nor could I now retofit the option you are talking about, i.e. duct from both sides of house. My proposed duct will be on the west facing wall of the house.


  • Registered Users Posts: 1,691 ✭✭✭fclauson


    There is a lot of miss infomaiton about this topic

    REMEMBER CO (Carbon Monoxide) is tastless, oderless, and can kill - correct ventalation is critical

    Also having a practice of opening a window or stopping the MHRV while lighting the fire is really unacceptable - because - your cannot expect everyone to follow the procedure


    Finally certain external air kits do not meet the requirments of a MHRV, airtight house.

    Now read rhttp://www.boards.ie/vbulletin/showthread.php?p=71794885 - although h.... cannot reply currently - he has a lot of good advice here on the saftey of MRHV and stoves

    I also made an enquiry of SEAI on this topic - The relevant guidance is given below.

    Where MVHRs are being used room sealed stoves should be used(BR 398 below recommends that open flue applianaces are avoided). This means the combustion air is taken from outside the building.BS 5410 advises that the flue gas exit terminal is positioned on the outside of the building concentric with or adjacent to the combustion air inlet. This arrangement is designed to minimize the effect of wind on appliance combustion performance.

    The stove manufacturers instructions should also be followed.
    Ref. BS 5410 code of practice for oil firing —Part 1: Installations up to 45 kW output capacity for space heating and hot water supply purposes.
    "4.3.2 Room sealed appliances It may be desirable, or indeed preferable in some circumstances, to avoid taking air for combustion or for draught control from within the habitable space. To meet this need, room sealed appliances are available that take their air directly from outside the building."

    and
    "11.1 General
    A room sealed balanced flue appliance is an appliance with the flue gas exit terminal positioned on the outside of the building concentric with or adjacent to the combustion air inlet. This arrangement is designed to minimize the effect of wind on appliance combustion performance. Room sealed balanced flue
    appliances may discharge flue gases at high or low level. An appliance designed to burn class D fuel should discharge its flue gases at a height of 2 m or greater from the outside ground level. No such limitation is required for an appliance designed to burn class C2 fuel. NOTE Further information on room sealed oil fired appliances is given in BS EN 303-1, BS EN 303-2, OFS A100 [11] and OFS A101 [11]."



  • Registered Users Posts: 14,538 ✭✭✭✭Poor Uncle Tom


    Moderator Post:

    Following a prompt from fclauson and a discussion between the moderators it was decided to start a new thread here using the off-topic posts from a thread in the prices/costs forum called "Airtight Stove for House with HRV" which was actually looking for prices.

    Anyway, please read through the posts above before contributing and stick to the topic which is in the title and the posts above.


  • Registered Users Posts: 648 ✭✭✭PeteHeat


    Can an air intake pipe be put up the chimney parrallel to the flu? Would this work?

    Hi,

    You need to be careful with this type of air supply, it would need to be very well insulated and in a seperate duct to the flue because warm air rises and the air pressure in the room could "push" the air out instead of allowing down the pipe.

    It will work on fan assisted stoves such as wood pellet because they have a fan, there are also wood burners designed with fans for such situations.

    .


  • Registered Users Posts: 648 ✭✭✭PeteHeat


    creedp wrote: »
    Carlow52, Im assuming the same problem will occur if the external vent duct is taken straight out through the wall behind the stove. Duct would be the thickness of the wall plus about 400mm. I was proposing to have a 100mm duct. I didn't provide for an underfloor duct nor could I now retofit the option you are talking about, i.e. duct from both sides of house. My proposed duct will be on the west facing wall of the house.

    You might want to look for an anti draft vent.


  • Registered Users Posts: 5,464 ✭✭✭creedp


    PeteHeat wrote: »
    You might want to look for an anti draft vent.

    Would this defeat the purpose of having an external air supply, i.e. to supply a fresh air supply direct to stove or are you advising to install it in reverse so that it allows air in but not a back draft out?

    Sorry I'm just confused!


  • Registered Users Posts: 648 ✭✭✭PeteHeat


    Hi,

    The vent is designed to allow air in but not a howling gale if the wind is blowing against that side of the house.

    While we can sell many of the brands I see posted on Boards I do not push them as most are designed to take primary air ducted from outside the house but the secondary air is fed from the room.

    Anyone using a wood burning stove should know that the primary air is only used when lighting the stove, when the fuel is burning you close the primary air and use the secondary air inlet also known as the air wash.

    Some models have a third air inlet to allow a secondary burn which when used with good fuel can appear like gas jets burning at the back of the stove.

    Carlow52 makes a very good point about positive and negative air pressure, this Must be addressed by the supplier of the Mechanical Ventilation / Heat Recovery system if they don't give a straight answer find another supplier.

    These systems (including a properly installed stove) are too important and expensive to get wrong.

    I believe the more air tight the house is makes for a more compelling argument for the compromise of one vent in the room where the stove is installed.

    The number of people who are enquiring about stoves for air tight homes and in the next breath are asking about banking the stove down for the night leaves room for enforced legislation because a stove (shut down) set to burn overnight leaves the real danger of carbon monoxide poisining.

    fclauson has rightly pointed out the dangers of carbon monoxide and the relevant standards, I shudder when I hear people asking about a stove burning overnight because that is the perfect environment for Carbon Monoxide.

    A properly fitted stove adds far more to the BER than the loss from one vent.

    The majority posting here are not professional developers building to sell, they are people building homes who have no intention of selling in the short term, I believe the rating on a piece of paper that will not be used unless the house is being sold should not over rule the safety and comfort of a persons home.

    .


  • Registered Users Posts: 14,538 ✭✭✭✭Poor Uncle Tom


    Doesn't TGD Part J cater for this adequately? or is it a case of Carbon Monoxide being produced rather than having adequate ventilation?


  • Registered Users Posts: 5,464 ✭✭✭creedp


    The vent is designed to allow air in but not a howling gale if the wind is blowing against that side of the house.

    Thanks PeteHeat. Can you suggest a brand or where I could get one of these?

    While we can sell many of the brands I see posted on Boards I do not push them as most are designed to take primary air ducted from outside the house but the secondary air is fed from the room.

    Would a Clearview Stove be one of those brands to which you refer? Can you suggest a free standing stove(s) that does not rely so heavily on internally supplied secondary air ?

    The majority posting here are not professional developers building to sell, they are people building homes who have no intention of selling in the short term, I believe the rating on a piece of paper that will not be used unless the house is being sold should not over rule the safety and comfort of a persons home.

    I accept this view and equate it to people spending €1000's of euro extra to buy an economical diesel car when they are doing less that 10k miles a year. However, in my case I was going to install a woodburning stove but with a HP it not only harms my BER rating but it means I don't comply with the renewables requirement. So its not as case of wanting the best possible BER - I've already had to downgrade my BER even without the addition of the stove - but not being compliant if I install one!!

    Any views you might have on best option in terms of stove - wood or multi-fuel woulf be very welcomed.


  • Registered Users Posts: 648 ✭✭✭PeteHeat


    Doesn't TGD Part J cater for this adequately? or is it a case of Carbon Monoxide being produced rather than having adequate ventilation?

    Hi Poor Uncle Tom,

    Part J is a guidance document from 1997 which was probably based on the UK experiences of the previous ten years (our version is a copy of the UK document) which they have since ammended / added to our Government haven't even bothered to copy and paste.

    A lot of the posts on boards refer to installations that don't even comply with the 1997 document which is why I seldom post on the subject anymore, people are taking serious chances with their families safety thinking the regs mean nothing because they are not enforced or because someone else says their stove works without complying.

    Ventilation is needed to complete the "Triangle of Fire" providing the air source for the burning process, it is also needed to make a solid fuel stove work properly, air enters the room, it's pulled over to the stove due to the fact that the warm air around the stove rises it gets heated and rises / dissipates and the new air continues the process.

    The Carbon Monoxide danger comes from people loading fuel into a badly installed stove and "banking" / shutting it down for the night to provide background heat and avoid the need to re-light the stove the next day.

    When a stove is shut down the burning process is being starved of oxygen which makes for incomplete combustion which in turn is where we get dangerous amounts of carbon monoxide produced, any minor fault in the flue or change in the room > external air pressure (as covered by Carlow52) can lead to the Carbon Monoxide entering the home.

    The supplier / installer of any mechanical ventilation system should factor in the use of a solid fuel appliance in the particular room and program the system to suit that room.

    I have been asking various stove manufacturers for the certificate or test data that states their stoves are room sealed that way if the flue is right no products of combustion such as Carbon Monoxide can enter the room.

    To date only one has been able to do so, their product one in a wide range from the same manufacturer starts at €3,000.00 and requires a lot of pre-planning during the house build or a major job for retro-fit so we passed on stocking it because I know we might sell one a year if we are lucky.

    .


  • Advertisement
  • Registered Users Posts: 648 ✭✭✭PeteHeat


    creedp wrote: »
    Thanks PeteHeat. Can you suggest a brand or where I could get one of these?

    They are (or should be) available from most builders providers / stove suppliers.

    creedp wrote: »
    Would a Clearview Stove be one of those brands to which you refer? Can you suggest a free standing stove(s) that does not rely so heavily on internally supplied secondary air ?

    I can't answer for Clearview as I do not represent them, however it is very unlikely that any stove with an "Air Wash" is room sealed, it is impossible to have this feature working from the primary air intake but very few do.

    creedp wrote: »
    I accept this view and equate it to people spending €1000's of euro extra to buy an economical diesel car when they are doing less that 10k miles a year. However, in my case I was going to install a woodburning stove but with a HP it not only harms my BER rating but it means I don't comply with the renewables requirement. So its not as case of wanting the best possible BER - I've already had to downgrade my BER even without the addition of the stove - but not being compliant if I install one!!

    I would equate it to a person sourcing a new car today without ABS Brakes, I am coming from the side of safety and good installation practice.

    Whatever stove you install must be safe for the long term, IMHO safety over rules conflicts in the two building regulations.

    It will take a long time for our Government Departments to cop on to what they are specifying in the documents, for example in the UK to comply a stove can only burn wood and can not be retro fitted to burn other fuels, in Ireland a steel box with glass in the door self certified by the manufacturer can be called a wood burner and so complies (doesn't appear to matter that it will burn everything from coal to shredded tyres as well).

    All building regulations can be and are over ruled by the manufacturers installation sheets provided the product has been independentantly tested.
    creedp wrote: »
    Any views you might have on best option in terms of stove - wood or multi-fuel woulf be very welcomed.

    Sorry, the rules prevent me from making such recommendations (advertising).


  • Registered Users Posts: 14,538 ✭✭✭✭Poor Uncle Tom


    PeteHeat wrote: »
    Sorry, the rules prevent me from making such recommendations (advertising).

    You can PM the information if you wish....


Advertisement