Chimney Types

The main consideration when choosing a gas fire is you need to know what type of chimney or flue you have because certain gas fires will only work with certain types of chimneys or flues. Your property could have a flue, chimney or none at all, although it is still possible to purchase a fire for all of these situations. Flue type is the most important starting point, as this determines the depth that you have available for your inset gas or electric fire.

We have provided the following information with pictures to explain the different flue types and alternatives available to you, which can be determined by looking at your roof. However whilst the pictures and information below may be of help to you, the only reliable way of establishing what chimney or flue type you have is to have an on-site professional survey carried out by a GAS SAFE registered gas installer which we always recommend. This should be done in all cases to check the compatibility of your chimney or flue with the type of gas fire you intend to purchase, prior to making any final decision to avoid disappointment and additional unforeseen expense, which we cannot accept, any liability for on your behalf.




Flue Less

Most modern properties have been built without a chimney mainly to save the cost of construction. There are 2 types of fire which can be installed in a home with no chimney.

  • Gas Fire – Low Running Costs, High Heat Output, Easy to Operate, CE approved and Safe.
  • Electric – High Running Costs, no flame and fake lights etc, up to 2kw output. CE approved.

Flueless gas fires do not require a chimney and can be installed on any wall within a room. The result is a fire which is 100% efficient with very low running costs for a high heat output. Unlike all other flueless gas fires on the market, the CVO one does not have filters or a glass screen. Flueless gas fires can be easily installed into most rooms providing there is a gas supply, excluding bedrooms & bathrooms and the room meets the minimum size and ventilation requirements. An openable window or louvre is also required in the room into which the gas fire is installed. There is a choice of wall mounted, traditional style or recessed into the wall fireplace versions in our range.




Class 1 Flue

A brick chimney is easily recognised by a chimneystack, or chimney breast in your room, which relies on the natural circulation of air through the room and up your chimney to expel the products of combustion. The minimum internal diameter will be 7”(or greater) and it may have had a real solid fuel fire in previously, especially in the case of older properties sometimes identifiable by an existing chair brick at the back of the fire opening. If you have a chimney (class 1 flue) you will be pleased to know that you will be able to have all types of chimney fires within our range.




Pre Fabricated Flues (Class 1 & 2 Applications)

These are usually a metal interlocking single or twin wall flue pipe connected to a flue box, with a gas terminal on your roof. Creating the same circulation of air as a chimney. A flue pipe with a minimum internal diameter of 7” or more is recognised as a class 1 flue and a flue pipe of less than 7″ generally around 5” internal diameter is recognised as a class 2 flue. There is a large selection of gas fireplaces for class 1 & 2 applications available within our range, dependent on the size of flue and flue box you have in your property.




Pre-Cast Flue (Class 2 Application)

Many new properties that do not have chimneys are fitted with Pre-cast flues. This flue is manufactured into rectangular hollow concrete or clay blocks that travel vertically, up through the cavity wall of your property, to a ridge vent or metal flue terminal on the roof. These flues tend to be very shallow in depth, although suitable deeper, appliances may be able to be installed with the use of either a spacer kit or deeper rebate on the fireplace. Choose from a wide range of smaller <7kw appliances within our hole in the wall range.




Power Flue (No Chimney Application)

A power flue fire is available for new homes built without a chimney or older properties where the flue is no longer of sound integrity. The fire has an electronically driven fan system on the outside of the wall to expel the flue gases and as such a sound is to be experienced when the fan is turned on. When the fire is not in use, some natural air circulation may occur through the flue terminal, which is quite normal.

The downside of these fires is the noise and the fire has to be on an outside wall. For this reason, we do not manufacture any power flue fires as most clients choose a flueless gas fire which is generally cheaper and more efficient.




Balanced Flue (No chimney application)

A balanced flue is a glass fronted gas fire, which is completely sealed from the room into which they are installed and vents directly to an outside wall. Air is drawn in from the outside for combustion purposes increasing its efficiency

through an outer pipe whilst the inner pipe vents the combustion gases safely away to the outside of the property. The downside of balanced flue fires is that they need to be on an outside wall and are very expensive to buy and install. Most clients opt for a flueless gas fire with an open flame, higher efficiency and fraction of the cost.

Contact Firecraft
Our Details
Firecraft Stone Fireplaces
Units 2-4 Fleming Road, Hinckley, Leicestershire, LE10 3DU

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