Horizontal flues for condensing boilers must rise slightly in order for the acid water vapour to trickle back down the flue and be safely removed via the condense pipe. A vertical flue rises off the top of the boiler and can go through a flat or pitched roof or through the wall at a higher point.
Can you have a boiler with a vertical flue?
In cases where the boiler is not fitted to an external wall, a vertical flue may be installed. In this case, the flue goes upwards and then out through the roof. A vertical flue looks similar to a very small chimney and can be seen spouting out steam when the heating is on.
What size flue do I need for a new boiler?
As condensing boilers create much more visible steam I want to replace the boiler with one where a vertical flue can be taken straight up a dry riser to exit through the roof tiles. This would require a flue of around 24feet in length.
How to prevent flue gas condensation in boilers?
The best defense against flue gas condensation is having a qualified boiler company inspect your hydronic system and maintain the boilers per the manufacturer’s instructions. This will keep your facility energy cost low through total system efficiency of running condensing temperature in the hydronic loop.
What happens if you don't have a boiler flue?
Without a boiler flue, your heating system won't be meeting Gas Safe regulations. You'll be able to identify the flue as a white or black pipe installed either horizontally out of a wall or vertically from the roof.
Does a boiler flue have to be horizontal?
Boiler flues carry out the same job no matter whether they're installed horizontally or vertically.
Can a balanced flue be vertical?
A balanced flue normally exits a building horizontally, through a wall, or vertically, through your roof.
Does a condensing boiler need a flue?
All newly installed boilers must be condensing boilers, so if you're upgrading or replacing a boiler they will need to be a condensing boiler and the flue system must be suitable for that type of boiler.
How long can a vertical boiler flue be?
All of Baxi's, Main's and Potterton's system or combi boilers with a 60/100mm concentric flue fitted can be up to a maximum length of 10 metres. If you find that you do need a longer flue run, then the flue size can be increased to 80/125mm, giving you a maximum flue length of up to 20 metres.
What is a vertical balanced flue?
Vertical balanced flue kits share the same boiler connections as our high level kits and low level flues. The unique connection system on the vertical balanced flue ensures easy assembly thereby reducing installation costs.
Can a combi boiler flue go up a chimney?
definitely NO, you have to run the boiler manufacturers flue all the way out, checking the installation instructions on flue lengths number of bends and the termination of the flue, who ever is installing this boiler, GAS SAFE REGISTERED INSTALLER WILL BE ABLE TO ADVISE YOU ON THE BOILER AND THE INSTALLATION.
How long can a condensing boiler flue be?
10 metresAs a general rule, a flue should work effectively when it's up to 10 metres in length. This is usually based on a standard thickness of 60/100mm. For flues that need to be longer than this, it's a good idea to increase the thickness to 80/125mm to ensure that the gases are able to escape easily.
Do condensing boilers give off carbon monoxide?
Modern condensing boilers are very safe and produce less harmful gases than older models. Although they can naturally produce small amounts of carbon monoxide, this gas will be safely disposed of outside through the flue pipe — this is why a condensing boiler should be installed on an external wall.
Does a condensing boiler need ventilation?
All condensing boilers have a balanced flue pipe which gives the boiler all the ventilation it needs. Even if it's hidden away in a cupboard. And if you've had a new gas boiler fitted since April 2005 then it will be condensing. Any home with an older non-condensing boiler will need to think about boiler ventilation.
Are condensing boiler fumes harmful?
the gases you see are extremely unlikely to be carbon monoxide, new boilers run very clean and give of allot less harmful gases than older types. what you can see is plumage (water vapour or condensation, hence condensing boiler) and is pretty harmless. its just a visible nuisance but looks worse than it is.
What comes out of a condensing boiler flue?
The boiler flue is essentially the boiler's chimney, but instead of smoke and soot being channelled away from the inside of the home, it's mainly carbon dioxide and water vapour that's emitted.
How many bends can you have in a boiler flue?
If bends are unavoidable, then there must be no more than four bends in the length of the chimney. A bend should be no more than 45 degrees from the vertical, with the exception that 90-degree factory-made bends or tees may be treated as two 45-degree bends.
Does a balanced flue need a chimney?
Balanced flue gas stoves are very popular with homes without chimneys. They are designed for use with gas only, not solid fuel, and require much less work. To install one, a twin wall pipe is fit horizontally through an external wall. This is different from the twin wall pipe you would use to fit a log burner.
Can you have a log burner with a balanced flue?
Our Lundy stoves are a wood stove that can use a balanced flue (like a gas combi boiler) this offers so many advantages over conventional flues: Higher efficiency as the air is heated up which improves combustion efficiency and also reduces particle emissions.
Is a balanced flue better?
Balanced Flues – Balanced flue fires are more efficient than their conventional flue counterparts as the fires are totally sealed from the room. Essentially there is no drawing of air from the room, which has an impact on the efficiency.
Is a balanced flue an open flue?
A balanced flue – or 'closed' system – has one significant difference to an open flue. Instead of drawing in clean air from your room, it takes it in from outside the house, via a pipe.
What is a boiler flue?
A boiler flue pipe is an essential part of any heating system that burns fossil fuels. As well as producing heat, the process of burning fuels creates harmful gases. If breathed in, these gases could prove harmful to those in the property. Simply put, boiler flues do the same job as an exhaust pipe on a car.
Why don’t electric boilers need a flue?
As opposed to gas and oil boilers, electric boilers don't burn any fuel which means that they don't produce any waste gases that need to be emitted out of the home . Electric boilers are typically best suited to smaller properties, such as flats, that have a single bathroom and low demand for central heating.
How much do boiler flues cost?
This is because it will be included in the cost of the boiler. Should you need to replace your existing flue pipe, you could expect to pay around £100.
How do you know if a flue is blocked?
Being outside, there's a chance that various bits of debris can make their way into the flue and cause a blockage. Should this happen, waste gases will be unable to leave the property and could lead to the boiler overheating or carbon monoxide leaking into the property.
How to tell if a boiler is in operation?
When the boiler is in operation, you will notice steam leaving the flue – this is condensation and waste gases being emitted away from your home.
Why do you need a flue pipe?
Any boiler that burns fossil fuels, such as gas and oil, will need a flue pipe. This is because burning fossil fuels produces waste gases that would be harmful to the occupiers if emitted into the home. One of these gases is carbon monoxide. Carbon monoxide is a potentially harmful gas that can't be detected without a carbon monoxide alarm as it's both colourless and odourless. It's important to be aware of the symptoms of carbon monoxide poisoning, which includes: 1 Headaches 2 Dizziness 3 Breathlessness 4 Nausea 5 Collapsing 6 Falling unconscious
Why do you need a boiler service?
As part of the service, the engineer will check the flue to ensure that it's free from obstruction. When there's a fault with your boiler, the issue will commonly be displayed as an error code (or fault code) on the unit's digital display.
What is a boiler flue?
A boiler flue is a pipe or duct that's attached to gas boilers which allows waste gases produced during the heating process to safely leave the building. You might recognise them as those black or white ducts that stick out of buildings expelling gas.
Why are boiler flues required?
Boiler flue regulations have been brought into place for new boiler installations to keep you and your neighbours safe from potentially harmful gases. In this guide, we're going to break down the regulations to give you the peace of mind that your boiler flue is in a safe place.
Why are boiler flue regulations in place?
Boiler flue regulations ensure that the gases being expelled don't re-enter the home, which would instantly make the flue redundant.
What happens when a boiler is burning?
Temperature. The harmful gases are produced when the boiler is burning fuel, which means that the gas exiting through the flue is hot, so this needs to be taken into account when positioning the flue. Keeping it away from any plastic gutters as they could end up melting is one of the considerations to be made here.
How to ensure boiler flue meets the regulations?
The best way to ensure that your boiler flue meets the regulations is to seek the expert advice of a Gas Safe registered engineer. Fill in our simple form today and to get FREE quotes from up to 3 trusted engineers in your area.
What is a condensing boiler?
Condensing boilers are highly efficient units that have 2 internal heat exchangers meaning that less heat is lost through the flue. When a non-condensing boiler is replaced with a condensing boiler, the different flue arrangements could mean that the current flue has to be relocated.
How far away from the window should a boiler flue be?
How far this is will depend on the size of your boiler but is typically between 30-60cm above , below or to the side of an opening.
What are the Current UK Boiler Flue Regulations?
The regulations that determine how a boiler flue must be installed are part of the UK building regulations, that ensure buildings are built in a safe and legal manner.
What are the Specific Location Requirements of a Boiler Flue including Separation Distances?
The distances discussed within this next section are suitable for fan-assisted, room sealed boiler flues. Please note that open flues will require differing rules.
Distances Away from Other Property Features
In addition to regulations regarding distances that a flue must be installed away from windows, doors and air vents, there are further regulations that require the positioning of a boiler flue to be installed:
Distances from Neighbouring Properties or Local Features
Further to the regulations that stipulate the specific location and distances that a boiler flue must be installed inside the property, there are also regulations that relate to the surrounding neighbouring properties or local area.
Does Your Boiler Meet the Current Regulations?
Should you have any concerns that your currently installed boiler and flue does not meet the current UK regulations, please seek professional advice from qualified heating engineer.
Boiler Flue Regulations Summary
In this short guide we have covered the core boiler flue regulations within domestic properties.
What is a flue in a boiler?
Put simply a flue is a tube that runs away from your boiler to the outside of your home and gets rid of harmful gases, such as carbon monoxide. As Gas Safe Registered engineers we have strict regulations to meet when installing your new boiler flue, such as where the flue is positioned. As a result, the type of flue you have currently may influence ...
When do you install a flue on a boiler?
More often than not, if your boiler is less than 15 years old it will have a horizontal boiler flue.
What does a square flue mean?
A square flue usually means an older system with a small 15mm gas pipe. A gas upgrade to a 22mm gas pipe would be needed to meet modern Gas Safe regulations.
What is a vertical flue?
Vertical boiler flue. A vertical boiler flue on the other-hand tends to be found in homes where the boiler isn’t on an outside wall, or when the property is a more unusual shape. Both reasons make it tricky to run a flue out of the wall straight in to the open air, like we do with a horizontal flue. Instead we might run the boiler flue up and out ...
How old is a boiler flue?
More often than not, if your boiler is less than 15 years old it will have a horizontal boiler flue. To find out for sure, nip outside and take a look at the outside wall where your boiler is located, if a pipe pops out then you have a horizontal flue. Vertical boiler flue.
Do you need a flue for a boiler?
There are also boilers that use an open flue which sucks in air from inside the room instead of from outside, in this case there will be a boiler vent as well as a boiler flue. It is only boilers that are installed behind fireplaces, that don’t need an additional flue.
Why does a boiler have flue gas?
Flue gas condensation can occur in any hot water boiler. The causes of this condensation and the importance of properly mitigating it are easily misunderstood. Flue gas condensation is also part of the reason why condensing boilers can have efficiencies up to 99% whereas a typical non-condensing boiler will max out around 80–85% efficiency. However, many a boiler have been sent to the scrap yard due to failure from corrosion of flue gas condensation. Let’s dig deeper into how condensation can cause metal failure in a boiler heat exchanger.
How does flue gas condense?
How Condensate Forms. Flue gas will form and condense on a heat exchanger and in the boiler stack when it falls below its dew point , and this occurs when the return water temps of the system are around 135°F. The vapor of the flue gas undergoes a phase change into a liquid which is now acidic with a pH typically between 2–5.
What material is used in a condensing boiler?
Manufacturers design condensing boilers to handle the acidic nature of condensate by building the heat exchangers out corrosion-resistant material such as stainless steel. As an example, Fulton uses duplex stainless steel in all of their condensing boilers. Duplex stainless steel has some of the highest tolerances to corrosion and thermal shock, making it an excellent material to handle the condensate loads of a condensing boiler. A traditional boiler that is non-condensing has a heat exchanger constructed of copper, carbon steel, and/or cast iron, which are not resistant to corrosion. Because these boilers are not designed to handle sustained condensate loads, if the system return water temps are below 140°F, the flue gas condensate will eventually wear down the metal, causing a leak in the heat exchanger. For this reason, it’s important to identify what kind of boiler is installed in a facility and make sure that the system’s temperatures are within the manufacturer’s design specifications.
How to prevent flue gas condensation?
The best defense against flue gas condensation is having a qualified boiler company inspect your hydronic system and maintain the boilers per the manufacturer’s instructions. This will keep your facility energy cost low through total system efficiency of running condensing temperature in the hydronic loop.
Why is my boiler going to the scrap yard?
However, many a boiler have been sent to the scrap yard due to failure from corrosion of flue gas condensation. Let’s dig deeper into how condensation can cause metal failure in a boiler heat exchanger. A pit and staining on concrete where a stack was allowed to leak.
What is the pH of flue gas?
The vapor of the flue gas undergoes a phase change into a liquid which is now acidic with a pH typically between 2–5. The boiler now needs to be able to manage this condensate by draining it from the bottom of the heat exchanger and out to the drain in the boiler room.
Is flue gas condensation a good thing?
Flue gas condensation is a good thing when going for record efficiencies in a hydronic system, but the boiler and stack must be designed to handle the condensate. If either are incorrectly selected for the application or are not installed properly, flue gas condensation will be the silent killer. It will eat the boiler from the inside out, which will surprise most facility managers whose budget doesn’t include replacing a boiler that is only a couple years old.
