Is it an actual boiler?
You have those steam radiators throughout your "flat"?
I was picturing a swarthy euro with a big shovel heaving coal into some vast iron beast in the basement (then I remembered you said it was gas fired).
I guess you don't have a guy in the basement.
Or do you?
I have steam heat. Radiators are woat, but I don't want the expense of replacing them with something else.