damp in upstairs chimney breast

HI All
This is my first time with a question after finding many segments on this site useful, so I hope my question will help others aswell.
After living in my 1930's semi for a year, I started to notice damp making the plaster bubble on the upstairs chimney breast (Along the ceiling line) This has got progressively worse(approx 3cm in 6 months). There is no moisture running down the chimney breast section in the loft.
I think the flashings are ok.
The only other place that i think the damp could be coming from is condensation. I still have the old style fire back boiler in operation down stairs. The upstairs fire place has been sealed - badly. I am unsure whether the chimney is capped. ( I think it is)
Would putting an air brick in the upstairs section of the chimney breast stop the condensation? Also is there any chance of carbon monoxide leaking through from the downstairs back boiler?
I look forward to hearing from you soon
Thank you

A back boiler should be fitted with a flue liner ( although a few early ones probably were not ).

Yours might have failed and if so that could be quite dangerous and would be best checked by a competent CORGI.

If its just a capped chimney then a ventilation grill should be fitted just above floor level although a ventilator in the loft usually works as well.

Tony

thanks for the reply i thought nobodey was going to ancewer me
The boiler was checked 6 months ago and all was ok so i am guessing a failed flue would have been spotted and the damp was there then. How can i tell if it is capped as I carnt tell from the ground and would i be best to put an air brick in anyway.

I replied to your posting under the plumbing and heating heading.

It has now been deleted from there and as I dont look in the building section normally I would never have seen it.

Because of the safety implications it is very lucky that as a CORGI I did see it and give the appropriate safety advice.

If Mod 8 had been in at the beginning then that safety advice would not have been given!

Tony