i am a hvac engineer and i have a pressurization problem with my boiler at home, i fill the boiler to 1 bar pressure and switch the heating on and the pressure goes up to 3 bar and the pressure relief valve blows after about 20-30 mins, i have checked the expansion vessel and the diaphram is pressurized, i dont kno what else can be causing such high pressure, the boiler is a halstead ace high boiler

lee walsh, April 2009

what should the pressure be on halstead ace high

kym, October 2009

If you're sure the expansion vessel is not faulty and is fully charged to one bar (air pressure) then check the small bore braided hose that conects it to the boiler. this is likely to be blocked

andy gas man, April 2009

most common problem with heating on and pressure rising means expansion of water is not been accomodated in expansion vessel. replace exepension vessel or add anywhere in heating system and this should solve this problem.

Mr K, April 2009