incubus 1 Posted July 22, 2009 Report Share Posted July 22, 2009 Hi. Last year i had a Fluless Gas fire fitted in the living room. The room has a vent as regs state, But the problem is because of the nature of such fires there is now no ventilation in the chimney and i'm getting damp patches in the Kitchen behind the living room wall. The old gas bar type fire was obviously self venting. I have not altered the chimney pot in any way.. So the question then is this...What is the best way to vent the Chimney..Should i put in an Air brick in the kitchen breast or is there any other way round this issue..??Thanks in advance. Link to post Share on other sites
verne 1 Posted July 23, 2009 Report Share Posted July 23, 2009 seems you have a couple of problems here. as you have a flue i would question the wisdom of installing a flueless gasfire; usually considered only to be a way to have a gas fire where there is no flue or external wall (where a balanced flue fire would be more suitable)!even though natural gas is a lighter than air gas it is still a hydro carbon fuel in the same way as petrol, diesel, propane and butane...in other words it contains hydrogen and burning it mixed with oxygen will produce H2O (water (vapour)) in copious amounts and ready to condense on any cool surface if it is not extracted by some means...a further problem is the chimney. a certain amoumt of rainwater will always find its way into an uncapped chimney. heat from a coal or wood fire meant this would hardly ever be a problem and the use of a gas fire instead at least provided some assissted ventilation. even an unused fireplace provides some natural ventilation as long as it remains open. to minimise the possible problems of rainwater causing or aggravating damp it is a good idea to fit ventilation caps to the chimney pots of unused chimneys and gas caps to those where a gas fire is fitted.a fireplace should never be totally bricked up or otherwise left without a vent of some sort but it must also be considered that to be an effective part of a ventilation system air must be able to enter the room from elsewhere in order to find its way through the vent and up the chimney by natural convection currents. this is why rooms with a coal fire were often draughty unless fitted with an underfloor vent.even though a flueless gas fire through the action of its catalytic converter does not produce poisonous gases, it does consume oxygen and produce carbon dioxide. the purpose of the vent required by the regs is to replenish the oxygen so the fire can continue to burn for safety reasons only. it is hardly adequate enough to be a useful contribution to proper ventilation enough to combat your problem of damp... Link to post Share on other sites
incubus 1 Posted July 23, 2009 Author Report Share Posted July 23, 2009 seems you have a couple of problems here. as you have a flue i would question the wisdom of installing a flueless gasfire; usually considered only to be a way to have a gas fire where there is no flue or external wall (where a balanced flue fire would be more suitable)!even though natural gas is a lighter than air gas it is still a hydro carbon fuel in the same way as petrol, diesel, propane and butane...in other words it contains hydrogen and burning it mixed with oxygen will produce H2O (water (vapour)) in copious amounts and ready to condense on any cool surface if it is not extracted by some means...a further problem is the chimney. a certain amoumt of rainwater will always find its way into an uncapped chimney. heat from a coal or wood fire meant this would hardly ever be a problem and the use of a gas fire instead at least provided some assissted ventilation. even an unused fireplace provides some natural ventilation as long as it remains open. to minimise the possible problems of rainwater causing or aggravating damp it is a good idea to fit ventilation caps to the chimney pots of unused chimneys and gas caps to those where a gas fire is fitted.a fireplace should never be totally bricked up or otherwise left without a vent of some sort but it must also be considered that to be an effective part of a ventilation system air must be able to enter the room from elsewhere in order to find its way through the vent and up the chimney by natural convection currents. this is why rooms with a coal fire were often draughty unless fitted with an underfloor vent.even though a flueless gas fire through the action of its catalytic converter does not produce poisonous gases, it does consume oxygen and produce carbon dioxide. the purpose of the vent required by the regs is to replenish the oxygen so the fire can continue to burn for safety reasons only. it is hardly adequate enough to be a useful contribution to proper ventilation enough to combat your problem of damp...Absolutely spot on Verne.. Thank you for your response..The reason i fitted the fire was because there was an old Back boiler behind the Breast which we replaced with a combi, and because of its modern looks with little thought of the old Flu.. I think now i'm gonna replace with a balanced flu Gas fire..So my next question then..is it a straight forward replace or do i have to do anything with the Flu to accept a Balanced Flu gas fire...???Thanks again Verne... Link to post Share on other sites
verne 1 Posted July 25, 2009 Report Share Posted July 25, 2009 i am no gas engineer but to the best of my knowledge a balanced flue gas fire can be fitted anywhere there is a gas supply and an outside wall. the wall is pierced and a terminal is installed at a place where the products of combustion can be dispersed without re-entering the building... so there are regs with distances from external doors, windows, other buildings and so on. then it is a matter of laying something fireproof as a hearth and removing (combustible) wall covering from behind the fire and then just enjoy... Link to post Share on other sites
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