The condensate pipe leads from your boiler to the outside and expels acidic fluid. As the fluid is slightly corrosive it’s usual to use a plastic polymer pipe to take the fluid out safely. In cold weather it’s not unheard of to have a frozen condensate pipe and it blocks causing the boiler to perform poorly or not at all. Often on modern wall-mounted models this is accompanied by flashing error codes.
If you think this may be the case try pouring some warm water (not hot) over the exposed area of the pipe. This usually does the trick. If the pipe is at height or is difficult for you to reach just give us a call and we’ll help you out.