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These days, more and more people prefer that a boiler remains concealed within their home. A study conducted by Npower reveals that a whopping 57% of people will knock off  £5,000 from the asking price of a property if it has a boiler out in the open. The study also shows that about 68% of Brits would consider not purchasing a property if the boiler is visible.

The good news is, the availability of different models and sizes of boilers has made it easier to conceal it in kitchen cupboards. Now the question is what sort of ventilation will be required in an enclosed space like a cupboard for a boiler to operate properly. 

Know that a boiler doesn’t need any ventilation although the waste gases produced by it need an out. This is normally taken care of with the help of a flue as it expels these gases out in the open. 

But when it comes to flue ventilation, are there any regulations that you need to be aware of? Will it help if you positioned your boiler in a certain way?

Let’s find out.


If your boiler is installed inside a cupboard, there are some clearancing rules that you need to stick to. A gap of 300 mm has to be maintained between the top of the cupboard and the top of the boiler. A gap of 100 mm must be maintained between the cabinet and the base of the boiler. 

The boiler cupboard itself doesn’t need ventilation, the boiler does require oxygen to correctly burn the gas. The ambient air within the cupboard will suffice for the boiler to perform this function as long as the clearance measurements mentioned above are in place. This tells us that the cupboard space shouldn’t be too cramped or airtight. Lack of oxygen will end up producing carbon monoxide which is harmful.

Boiler Accessibility

For boiler servicing, repair and maintenance it’s important that the system remains easily accessible. For this, the cabinet door should open up without any hindrances while a gap of at least 700 mm should be maintained between the boiler and the wall around it. This will help the heating engineer to properly service the boiler.

Flue Positioning

More than the boiler, it’s very important that the air flue is positioned correctly with proper ventilation. The flue is the only way for the waste gases to be released from your home so its positioning counts for a lot. 

A horizontal flue system should have a gap of at least 300 mm below an air vent, window or other ventilation opening. For a vertical flue system, a gap of a minimum 1,000 mm from an adjoining opening is ideal. 

This regulation is enforced to keep any waste gases from entering your home back again. 

Flue Terminal Accessibility

Boiler installation should be such that the flue terminal has access to ambient external air. It’s crucial that this terminal isn’t obstructed or blocked in any way and it must allow the air to flow freely through it at all times.

These regulations are in place for your safety to ensure that you follow it thoroughly when installing a boiler cupboard.

Get in touch with us today for expert and regulated boiler installation service