If you’re reading this in the US, you’re probably preaching to the converted, but you might be surprised to learn that chimney dampers are almost unheard of here in the UK. I have been involved in chimney/chimney consultancy for almost 15 years and am amazed that this simple technology has not yet become part of standard chimney and flue design in my country.
Most people have never looked down the chimney; Many have no idea that vast amounts of their expensive hot air flows through that chimney, up and into the atmosphere 24/7, whether the fire is burning or not. The fact is, leaving a fireplace open year-round is no different than leaving an upstairs window open, rain or shine.
Ironically, when the weather turns cold, people often start wandering around the house looking for gaps around doors, windows, and even keyholes that let in drafts and trying to plug them, without thinking. much where the current is. anger! More often than not, it’s the chimney that drives the draft, drawing that cool air into your centrally heated home.
In the UK, building regulations specify that a permanently open dedicated vent must be provided for each open fire with an area equal to half the cross-sectional area of the chimney. While homeowners are often horrified at the prospect of such a large hole in their living room, a fire needs to “breathe” and home heating efficiency improvements such as carpeting, double glazing, and drafts, mean that we can now rely on a purely adventitious air supply. Proper ventilation need not be a nuisance if it is correctly located, especially if a chimney damper is fitted to the flue, which prevents drafts and unnecessary heat loss when the fire is not in use.
When the fire is lit, a properly sized vent will supply the air needed for combustion and to allow the chimney to open; Ideally, it should not be inside the fireplace, but on the same side of the room as the fireplace, so that the cold air coming in doesn’t go through everyone’s ankles when it is directed to and through the fireplace opening and climb up the chimney. In fact, allowing the fire to easily “breathe” through this vent will tend to prevent it from having to draw in air from further away, through doors, windows or other chimneys on the property, and will improve comfort levels. Vents inside the fireplace are less desirable, as they can throw ash and smoke around and out of the fireplace; there is also a beneficial effect on the resulting suction of incoming air entering the chimney opening, tending to draw smoke with it.
As the cost of heating our homes skyrockets with rising fuel prices, and the effect our wasteful clothes are having on the environment becomes increasingly apparent, energy efficiency is no longer just an issue for green activists, but for all of us. For many, installing a wood-burning stove is the obvious choice, but in Britain we are fortunate to have a rich architectural heritage of splendid open fireplaces, and there is a strong case for preserving them, if we can minimize their negative impact on heating efficiency. home heating. Although wood-burning or multi-fuel stoves play an important role, installing them correctly often involves lining the flue, which is not only a costly operation for the customer, but can be irreversible, avoiding the use of the chimney as open fire in the future. and altering the character of the room forever. Those who have multiple fireplaces may well choose to have a stove installed in one fireplace as their primary supplemental heat source, and put dampers on their other fireplaces, especially if the alternative is to permanently cover the fireplace.
For fireplaces that are expected to be used very occasionally, DIY solutions can help. I often see fiberglass or bubble wrap plastic bags stuffed into flues! There are also purpose made balloons and the like on the market, but for more regular use, most would not choose to have to remove and store some kind of sooty chimney stopper every time they have a fire. It is also worth noting that it is good practice to allow a trickle of air to flow up the chimney, to avoid condensation, and/or a flue so cold that it will be difficult to re-establish an updraft when lighting a fire.
Whenever possible, the ideal solution is to install a specially designed chimney damper that the homeowner can instantly open and close at will, with no fuss or mess. The benefits of convenience and lower fuel bills will make this an investment that pays for itself much faster than most in the home improvement industry. Dampers can be installed at the top or bottom of the flue, and there are advantages and disadvantages to both styles, but often the geometry of the flue and chimney, and the relative difficulty of access to the top of the flue will be the deciding factor.
One of the reasons the UK has been slow to adopt chimney dampers is undoubtedly the variety and age of our housing stock, which means off-the-shelf products may not be suitable for many homes, and it should be borne in mind that if an improperly sized damper is installed, , in its open position it significantly reduces the area of the chimney, it can cause a fire with smoke.
There are also many British fireplaces that are struggling to draw by adding a chimney. Although many see them as “traditional”, they are actually a Victorian invention, suitable for the smaller fireplaces popular from that period. I’ve lost count of the times I’ve been asked to look at smoking chimneys, and looked up into the fireplace to see a well-constructed set and good-sized chimney, abruptly reduced to less than half its area by an 8″ pot. or 9″, which is often partially hidden by slates or whatever other supports the installer used during construction.
The combination of turbulence caused by the sudden change in section and the physical restriction of the small outlet often causes these chimneys to smoke unnecessarily. Another common “problem chimney” is the 3′ square opening revealed by enthusiastic homeowners who believe they have peeled back the layers of history to find the original chimney. What they have actually found is the builder’s opening, never intended to function as a fireplace, but to accept a kitchen or Victorian-style fireplace insert, built with a chimney to match these more modest proportions.
In chimneys where the flue is diverted to the smaller size, I would not recommend installing a damper on the existing terminal. If access and planning considerations allow, open it up and extend the stack if necessary, or install a larger pot if necessary, and put in a damper while you’re there. If not, try placing a damper in the ruffle just above the lintel chimney.
Chimney top dampers have the advantage of keeping birds and weather out of the chimney, as well as keeping a warm draft. Against it are the problems of access and working at height, and the possibility of mechanical failures in the “remote control” operating system. (usually stainless steel cable or chain)
Chimney dampers typically provide visible, fail-safe mechanical opening and closing, and can be installed without access to the top of the chimney, but they are deceptively difficult to design and position so they don’t foul the walls of the chimney. chimney when they are open, or excessively restrict smoke from the fire below. Fitting is a messy, sooty job…and if there isn’t good bird protection at the top, branches and soot displaced by weather and bird activity can collect and be blown into the home when you adjust. open the gate. By the way, the stretched mesh on top of the chimney is NOT a bird guard. It’s a perch/social amenity for our feathered friends to gather around while keeping warm, removing lice, defecating and practicing twig tossing! A good bird cover has a smooth, solid top that is ideally angled (to ward off rain or snow and make perching a chore) and mesh sides.
I look forward to the day when most UK homes have dampers fitted to all their open chimneys, and I predict that in the years to come these devices will become an integral part of responsible and astute home heating management. as is a well insulated loft or double glazed windows. .
Chimney flue dampers cannot be fitted to fireplaces operating on gas fires in the UK, nor can a gas fire be installed in a fireplace or chimney incorporating a damper unless it is made inoperable. The damper on a wood/solid fuel fire should not be closed unless the fire is out and cool!