Boiler not heating water enough.

[assasin666]

Hi all can anyone advise me how to make my boiler heat water so it hurts to touch?

When I run a bath I do not need to put cold water in and yet it still is not hot enough. Sometimes I need to boil pans just to pour in which defeats the purpose of a boiler. Also the radiators do not seem to get hot to the touch.

My boiler is Viessmann. Vitodens 200. CE-0085 B00342.

Thank you.

 

[angusmcdangle]

Depending upon your plumbing, your bath's hot water tap may have a 22mm supply running to it (if the plumbing is 'old'), and if your boiler doesn't have a flow reducer fitted, it may be passing too many litres-per-minute through the tap for the boiler to heat properly.
Your instructions should give you an idea of what temperature rise your boiler should give for x amount of litres-per-minute.
Try just running a basin tap, slowly (but fast enough to bring boiler on) and see how toasty the water is then.
Also, does the CH flow pipe get hot during HW demand (when CH is off)? If so, there may be a diverter issue.
Also, if running HW results in the boiler reaching temperature, stopping, then restarting a few seconds later, then repeating this process, you may have restriction problems, probably in the HW hex.
Other than that, HW thermistor fault, PCB, etc?