Also, if there is no vent, then a flu pipe (vertical pipe coming straight from the appliance and out into the opening, usually straight out of the roof or through an existing chimney) must be fitted in the UK.
Back in the late 1980s, our flu pipe from the boiler was found to have cracks in it, and we suffered carbon monoxide poisoning. We knew we were experiencing symptoms, but not a great deal was known back then. We kept saying something was wrong, but the local authority (council), who then owned the house, said there was nothing wrong.
We later called British Gas out, the former nationalised UK-wide gas company (privatised in 1986), and they immediately shut the boiler down, put a “Condemned” sticker on it and insisted that we get the flu pipe replaced, which was a nasty concrete-like thing. It was replaced with a solid metal pipe, and we have had no problems since. A yearly inspection is required for all central heating systems, although this is only a legal requirement in the UK for landlords. If you own your own home, like we do, you do not have to service your boiler, which is silly because we all need to, so regular publicity is issued to warn homeowners.
Anyway, hello – I’ve not spoken directly to many of you yet!
Play it safe with appliances – get them serviced regularly and always ensure they are operated correctly. (Nag nag nag! ;-))
Take care.
Carl