Posting a message to the forum will remove the above advertisement
  1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.
  2. Checkout our Plumbers Insurance area - heavily discounted Public Liability Insurance and Van Insurance specifically designed for plumbers.

Discuss Which size gas terminal? in the Gas Safe Register Forum - Public Forum area at

  1. jrtrrror

    jrtrrror Member

    Originally, I though this was going to be a straight forward question and then just now I checked something.
    To cut a lengthy explaination short...a friend has what we thought was a living flame fire, which sits within a brick chimney breast. Work is being done on the chimney on the roof and it was recommended that the existing square chimney pot connecting to this particular fire be replaced with a gas terminal. I rang a friend who is a gas registered plumber, who back in the day of Corgi, used to be a trainer. He said that a 5" GC1 would meet regulations, however a 7" one would be better. He said there would be less chance of restricting the, well something. I can quite remember what he said. He described the 7" cowl as looking like a cheffs hat.
    Anyway, the gas fitter who actually came to check the fire (another person, not my mate) said that a 5" terminal is sufficient and that a 7" may restrict the flue more. Something to do with wind blowing.
    Who is correct?
    To complicate things further, I now wonder if I have given an accurate description to my mate. I now think the fire is actually a DFE fire not a LFE. I think Ive just found out they are two distinctly different fires. I can tell you that the fire in question has, simulated coals and you can clearly see right up the chimney flue, if you peer upwards. It is in no way sealed to the chimney breast.
    Would this change the requirements?
    What type of gas terminal is needed?
    Also, should the plumber have swept the flueflu part of 'signing off' the fire. It was not a new installation, just a service.
    Many thanks for your patience reading this.
  2. Darren Jackson

    Darren Jackson Plumber GSR

    Only specific terminals are suitable for use with DFE fires. Unless stated otherwise by the Manufacturer the minimum dimension is 175mm or 7" do not have a 5" terminal installed unless the Mi's allow it.
  3. jrtrrror

    jrtrrror Member

    Hi Darren. Thank you for your response. And taking the time to reply.
    From my original description, does it sound more like a DFE type fire.
    Does it matter? Are the regs the same for DFE and LFE. I.e. a 7" terminal is required.
    Also, as in my original post, should the flue have been swept during the service?
    I remember reading that it should be swept annually. I must confess, this information regarding sweeping came from a number of Chimney sweeping websites.
    Sorry, three more questions.
  4. sammathias

    sammathias Plumber GSR

    Should only be swept annually if it's a solid fuel fire or prior to installation of gas fire to a chimney which was previously used for solid fuel. As for the DfE fire. Depends what size the manufacturer recommended.
  5. jrtrrror

    jrtrrror Member

    Hi Sammathias.
    Thanks for the reply. The fire was already in place when they moved in, so instructions are not readily available.

    What size terminals are ordinarily fitted to DFE or LFE fires?

    Is there any sense in fitting a 7" terminal instead of a 5" just to be sure?

  6. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    need to find the instructions
  7. Darren Jackson

    Darren Jackson Plumber GSR

    Hi jrtrrror,
    1, Yes it does sounds like it is a DFE gas fire.
    2, Yes it does matter. As only specific terminals are suitable for use with DFE fires. (Unless stated otherwise by the Manufacturers instructions) the minimum dimension is 175mm or 7"
    3, The regs are different for iLFE minimum dimension is 125mm or 5" (Unless stated otherwise by the Manufacturers instructions)
    4, No, the flue does not need to be swept during the annual service, unless upon visual inspection & flue flow testing it is found to be in need of sweeping. Only solid fuel appliances need to be swept annually. Or before a new appliance is going to be installed.

    Also for your information chimneys fitted with a pot and above 170mm in diameter which were built originally for solid fuel appliances, do not require any other terminal when they serve a gas fire or circulator. A suitable guard may be required when a terminal is not fitted on a chimney outlet where there is a likelihood of birds nesting or or other forms of wildlife entering the chimney; or to stop the ingress of rain water if it is a problem.

    I hope this clarifies things a bit better for you.
    Kind regards Darren.
    • Like Like x 1
Similar Threads - size terminal Forum Date
Size of metal header tank for multifuel stove Oil and Solid Fuel Forum Saturday at 3:35 PM
Potterton statesman 45/50 nozzel size? Oil and Solid Fuel Forum Feb 8, 2019