why does the pressure keep increasing on my bosch combi boiler?

ITS ONE OF 2 THINGS THE DHW HEAT EXCANGER OR ITS YOUR PRESSURE VESSEL,CHECK 4 WATER AT THE VESSEL AT THE BACK,IF NON U COULD RECHARGE IT WITH A BIKE/CAR TIRE PUMP......BUT U MUST ALSO HAVE THE BLOW OFF OPEN AT THE SAME TIME AS PUMPING......IF THE GUAGE IS CONTINUALY RISING WHEN THE HEATING SYSTEM IS FULL ITS YOUR HEAT EXCHANGER.GOOD LUCK!

PAUL THE PLUMBER
March 2008

if you have a plated heat exchanger it could be letting by

d..
April 2005