Painted last year, bubbling noticed, plaster a bit crumbly

do I have blown plaster? its happening just above the skirting boards in one area of the room about 1 meter wide and 1 inch or 2 high. I have recently changed my central heating system!

It doesn't bother me too much but
my main concern is that I would scrape the paint off and re-paint only to find that it bubbles again in 3-6 months time.

I think the plaster may have previously been damp and has now dried out!
Is there some treatment I can apply to the plaster once scraped off or a way I can paint allowing it to breathe? or has it already breathed? or do I need to leave the plaster bare to equilibriate or do I need pva or should I just forget about it and go for a curry?

many thanks in anticipation..

its hard to tell really without seeing it. you could try usein an oil based primer on it, but make sure the surface is dry and sound

How old is the house ?

Is the wall solid plaster or plasterboard ?

What type of emulsion are you using ?

Is the problem in an downstairs or upstairs room ?

30 year old ground floor flat (of 4 stories)
the bubbling is about 1-2ins high and intermittantly over about 1.5 meters just above the skirting boards

would say the plaster was dry/flakey underneath and could probably scrape off with medium force!

Check to see if the air vents in the bricks are somehow blocked (outside).