Can anyone help with a query about boxing in a gas boiler?

Discussion in 'Engineers' Talk' started by Eddy120, Aug 8, 2023.

  1. Eddy120

    Eddy120 New Member

    Long story, but I have to box in a very large boiler cupboard with a combi boiler in it and put fireproof lining/doors where the old wooden doors were. My problem is I am getting lots of contradictory advice about ventilation holes. Combi boilers apparently are not actually a fire risk but the electrical supply can be and Building Control understandably want venting to the outside to prevent gas build up should there be a leak. I also get that the holes have to be at least 300 cm from the outlet duct. However, can anyone clarify whether this needs both a top hole and a bottom hole and how big do they need to be for a standard residential duct? Or doesn't it matter? Thanks:)
  2. Bob Rathbone

    Bob Rathbone Screwfix Select

    My Worcester 42CDi combi is in a double IKEA cupboard, it has no back and is fixed with the supplied brackets on the top allowing it easily to be removed for service. I cut a panel in the bottom to allow access to the valves, it has a couple of holes in the panel to get to the top up valve. It's been like that for 15 years, never given any trouble, never caught fire, not even warm. If you insist on ventilation, adjust the hinges and put spacer buffers on the doors to give a gap all round the door edge, this will not be visible from the front.
    Eddy120 likes this.
  3. Eddy120

    Eddy120 New Member

    Thanks, bob. That seems reasonable. I'll give it a try.
  4. Davie

    Davie Active Member

    Your boiler installation manual will state the required distances around the boiler
  5. Paul pilpo

    Paul pilpo New Member

    I have seen loads of boilers in cupboards but as long as it's safe on electric and flue, so they can test them when they want it's ok I guess
  6. Eddy120

    Eddy120 New Member

    Thanks, Paul. Having chased round and round in circles, I eventually came back to the same conclusion so I am glad you said that. The only thing that they did say in the end was to ensure that there was no combustable material stored in the cupboard and perhaps put a piece of fire board under the plugs so that if one did start smouldering, it could not ignite the floorboards. I totally get how Grenfell happened. Dozens of different authorities (building control, fire service, gas safe) with stacks of different guidance all saying different things:)
  7. Bob Rathbone

    Bob Rathbone Screwfix Select

    Chip board or MDF sheet is difficult to set fire to when it is in sheet form. I don't see where the high temperature will come from to start a fire as the boiler combustion chamber is contained in a closed metal box which is cooled by the incoming combustion air. I would agree that a fire risk exists if it was an 'open to room' appliance, taking the combustion air from the room or cupboard.

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