Home/Are Flueless Gas Fires Safe? We Explain the Technology
Are Flueless Gas Fires Safe? We Explain the Technology 2018-11-30T12:20:24+00:00

Are Flueless Gas Fires Safe?

This is quite a normal question to ask as it seems unusual to put a gas appliance on a wall in a room without a chimney. There is a lot of false information available on forums and blogs normally lacking any technical back up as to how the modern flueless gas fires function. Here we try to explain the technology.


Let us explain……

The current GAD (Gas Appliance Directive) for the manufacture and design of flueless gas fires is very strict. This is not like it was back in the 60’s and 70’s when the first flueless gas appliances arrived on the UK market. Since then technology has moved on and so have the regulations. That is why there are only 4 manufacturers in the UK. Flueless gas fires are best sellers in countries like the USA and Japan however as they are still fairly new to the UK market we still hear negative comments regarding this new technology.

Flueless Gas Fires

We would not be able to sell them if they were not safe.

Like everything technology moves on and it is now 2013 and the modern flueless gas fires that are sold within the EU are designed to comply with a very strict set of regulations. This is why there are only a small number of gas fire manufacturers who can manufacture this style of fireplace in Europe. The modern flueless gas fires have very small levels of emissions – typically around only 3ppm of CO. These emissions are diluted by the fresh oxygen supplied into the room by the air vent. (PPP means “Parts per Million” and when you consider a smoker has around 100ppm of CO in their breath you can realise how small the emissions from a modern flueless gas fire are. You will not see that fact mentioned on the many forums and blogs that rubbish the technology.

What is the Safety Device?

All modern flueless gas fires have an ODS pilot system. (ODS = Oxygen Depletion System) This special part monitors the oxygen levels in the room. If the air vent is blocked or the wrong size the ODS will shut off the fire long before there is an issue over the emissions. For instance our flueless gas fire shuts down at only 25ppm, the CE maximum is 80ppm and it is reported that exposure to CO of levels of 800ppm and higher are considered hazardous.


Is Burning Wood Safer?

The emissions from a wood burning appliance are much higher than a flueless gas fire (they can be up to 50x greater). If they are installed with a faulty flue system or the door seal is damaged these emissions will come into the room. Wood burners do not have an ODS system, hence why it is law to have a CO monitor with a wood burner. There is a considerable amount of hype surrounding wood burners and on a like for like basis flueless gas fires are cheaper to run and have cheaper maintenance costs.

What is required to install a flueless gas fire?

  1. An Air Vent which supplies a fixed amount of fresh air. Typically 100cm2. Do not make the mistake of thinking this is the vent size. It is the “amount of fresh air” or “volume of air” that the vent supplies. Each vent has a different specified amount and you need to check with the manufacturer before buying. The most common mistake is to assume the 100cm2 quoted is the size of the outer vent (10cm x 10cm) it is not it is the volume of air passing through the slots in the vent. If you fit the wrong vent the fire will shut down and appear “unreliable” when it is actually trying to protect you. Always check the air vent against the air vent manufacturers stated “free air” and the gas fire manufacturers requirement. Better still buy an air vent from us when you buy your flueless gas fire.
  2. A Correct Gas Supply, the gas pressure must be maintained at the manufacturers stated level or the combustion will change – this is why a gas safe registered engineer must install a flueless gas fire in line with the instructions provided..

flueless gas fireThe most important factors when installing a flueless gas fire are:

  • Follow the manufacturers instructions.
  • There must be an air vent in the same room as the appliance.
  • The size of the vent must provide the volume, or more, of fresh air as stated in the manufacturers instructions.
  • The air vent must be over 1 metre away from the gas fire.
  • The minimum room size must be observed – larger is OK.
  • The gas pressure must be correct.
  • The fire must never be adjusted or tampered with.


Regardless of brand, in order to manufacture a Flueless Gas Fire within the EU the gas fire must pass the current CE standard for flueless appliances (EN14829:2007). To pass this the appliance undergoes a number of critical. The standard restricts the fires to a heat output of below 6kw.


Each of these tests must be passed:

  • The appliance is tested to ensure its construction meets the regulations.
  • The emissions from the appliance both in normal operation are checked – CO, CO2 and NOx.
  • The fire is then set up with the gas pressure 20% higher than normal and 15% lower than normal.
  • The fire is then tested with other “dirty” gas types to ensure it still operates safely.
  • Once all of these tests have been passed the appliance is placed in a sealed room and run on full power. In this extreme type of installation the fire must shut down “before” 80ppm CO or 1.5% CO2 is reached on the test meter. This is the CE maximum allowable level for safe operation. We designed our flueless gas fire to shutdown at 25ppm CO and 0.8% CO2 – well below the safe limit set by CE.
  • By testing the fire like this it is an absolute worst case scenario that is placed on the appliance to ensure it will still shut itself down in the event of being installed incorrectly or the air vent in the room being blocked.
  • Only after passing all of these strict tests is the appliance given a unique CE PIN number and a CE approval certificate.

However it does not stop there as CE also say that every fire that is manufactured must:

  • be identified by the manufacturer so it can be traced back to the original components.
  • Every fire must be individually tested to ensure it meets the regulations.
  • Every year we are visited by a CE appointed auditor to ensure we are still making the products to the approval standard.

At CVO Fire we take this a lot further and since starting manufacturing flueless gas fires in 2003 we have built up a reputation for high quality reliable fires. Here is what we do that’s different:

  • Every fire is hand made and individually tested with over 40 test results recorded.
  • For every 100 fires we build we select one at random and subject it to the CE test standard to ensure that everything is still perfect.
  • We also test every delivery of components “before” they are used, ignoring the manufacturer’s results, to ensure we are 100% confident of the quality before we use them on our fires.

Need some advice on Flueless Gas Fires and the safety factors? Call us for impartial advice: 01325-301020.