Hi,
I have a Ferroli optima 901 . I had problms with the DHW and foolishly adjusted this on the mod gas valve as it was varying from hot to cold all the time(after i did this i saw that it is factory set and not to be adjusted in the manual).
I now have constant hot water but evertime my central heating kicks in it rises to over 3 bar and opens the PRV .It then drops below 1 bar and stops the boiler working. I have checked the radiatiors for air and this is all ok. Should i try and vent the heat exchanger. Please someone help.

Monkey Hanger, May 2008

my pressure is at 3 bar carnt get hot water

andy, January 2009

Thanks for the fast answer. I have tried the red expansion valve, I pushed the needle and it let air out. The boiler seems to run ok if i do not put the central heating on. It stays at a constant pressure 1.5 bar uaually. As soon as the central heating comes on (when i turn the room stat from 0 to 18 degrees) the radiators will go to the correct temperature for about 1 to 2 hours and then the PSV kicks in as it has gone over 3 bar. Any suggestions anyone. Thanks for the reply ryan.

monkey hanger, May 2008

chek the expansion vessel. a big red thing usually round. it will hav a shrader valve, like a tyre valve. push the needle in and see if water comes out. if it does then its nakerd and needs to be changed

ryan, May 2008