Worcester heatslave 15/19 oil fired 'high pressure'

[Hotfish]

My 12 year old Worcester heatslave 15/19 oil fired combi boiler has been misbehaving recently. A few months ago the pressure started rising initially about 1 bar over a period of a week & so I checked the expansion vessel & when I pressed the valve water came out so I trotted off & bought a new one, fitted it, problem fixed or so I thought but no that was too easy. Pessure is still rising its now taking 24 hours to increase by 1bar & I'm getting fed up draining it off every day! The detachable water pipe is NOT connected so the increase is pressure is not comming from there.
Any help please!!

 

[outinthestix]

Make sure the new vessel is OK. Could be a problem with the heat exchanger passing mains water through to the heating water.

 

[oilman]

Heat ex is most likely.

 

[Hotfish]

Thanks, new vessel pressure is is holding at 0.8 bar so I think its time to buy a heat exchanger looks like i'm going to have fun fitting that!

 

[bab]

It wants doing sooner rather than later as u are introdicing fresh water with oxygen in all the time diluting your inhibiter & increasing corrosion in the system.U could turn off the mains water at night to prevent more fresh water entering heating but dont open taps or flush w/c or it will allow contaminated heating water will backfeed into watermain.

 

[Hotfish]

Cheers bab for the extra information,yes as soon as I can I'll be rushing off too get a replacement exchanger!

 

[oilman]

try people like inspiredhating and discountheating (or discountedheating poss) online.

 

[Hotfish]

Replacement heat exchanger now fitted pressure is now holding & correct.Strait forward job it took about an hour & a half with a cup of tea & a cig! Thanks to all that gave advice.