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Central Heating

Combi boiler high pressure


I got an ariston micro combi 23 mffi boiler which is 7yrs old. Last couple of days, once we turn on the boiler the pressure is going up. It is going beyond the red mark (3 bar) but, it won't cut off. I checked it for different temperatures, if the central heating temperature knob is on 4, the pressure showing is 3 bar. If the knob turn to 5 or higher the pressure is going over 3 bar but, not cutting off. the hot water is working fine. any suggestions on this fault. and a rough estimate for sorting it out.


2 Answers from MyBuilder Heating Engineers

Seems like a faulty expansion vessel, may only need recharging or may need changing. Call out an heating engineer.


Answered 5th Feb 2015

if its 7 years old boiler,the best option to change the expansion vessel,but the original my be very expensive and hard to change,usually what we do is to add extra expansion vessel on the return pipe,under the boiler.Its can cost much cheaper,and will do the same work.


Answered 8th Feb 2015

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