I have replaced doors in my house and would like to replace a plain boiler cupboard door — standard 1981mm x 762mm (6½ft by 2½ft) door — with a 6-panel door matching the others.

The thing is that the boiler is a natural gas condensing combi boiler and therefore needs vents?

The current door has a 225mm x 150mm (9in x 6in) louvred vent at the top and bottom of the door and these won't fit aesthetically within the panelling of the door. However, I could fit two 9in x 3in louvred vents at the top and bottom to match the amount of ventilation.

Seeing as the boiler (a Potterton Promax Ultra Combi 28 ErP) is much newer than the central heating boiler previously fitted and the new boiler is fitted with a flue expelling exhaust gases outside the building, is ventilation actually needed any more? I cannot seem to find any information on it online.

If it is still required, how large is ventilation needing to be?

  • 2
    Make and model of boiler would help answer this question. One point though is most modern condensing boilers get combustion air from outside, often via a separate passage inside the exhaust vent...mine are like that. Mar 13, 2020 at 16:13

2 Answers 2


Page 16 of the boiler installation guide PDF (Section 7.3 - Ventilation of Compartments) points out that no air vents are required in cupboards or compartments with your boiler.

This is because although the boiler requires oxygen in order to burn the gas correctly, your boiler has a double walled (balanced) flue and takes in all the air it needs through the outer part of the flue, drawing the oxygen it needs from outside the building.

See this OFTEC page for more information on balanced flues and cupboard air venting.

  • Thanks for pointing this out. This gives the reason why air vents are not required which is why I accepted this answer. I have suggested an edit to add the installation guide page @Jack pointed out in the comments in case that gets deleted. Mar 14, 2020 at 7:15

If you locate the make and model of your boiler, and look it up on the internet, there will most certainly be an install guide available on the makers website.

If you posted a picture of the label on your question if you have had difficulty in finding what I mentioned, we can look it up for you.

The guidelines listed by the maker MUST be followed, there is no general information out there to simply say do this or that and expect it to be safe to operate.

  • Thanks for your answer. See my edit for make and model as I cannot find anything online Mar 13, 2020 at 18:50
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    An intersearch got me this result mediacdn.potterton.co.uk/-/media/websites/pottertonuk/files/… It is the install guide for the unit you have. I gave a quick look at the pages and it details all the different parameters you need to follow for the install. There are 2 lines that need to go out, one is an exhaust flue and an over flow line is the other
    – Jack
    Mar 13, 2020 at 20:09
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    It was an easy find, curios why you could not find it. I simply copied and pasted the name you gave and the search came up with it right away, with many choices. And on section 7.3 it says it needs no ventilation
    – Jack
    Mar 13, 2020 at 20:16
  • Thanks for that @Jack Mar 14, 2020 at 7:11

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