Vokera Compact 24 Pressure Going Up.

Dave_2002 · 25 Jun 2006

Pressure was on 3.5bar... Engineer drained boiler, recharged expanssion vessel to 1.5bar then put pressure to 1.5bar with cold water feed turned off to boiler (so no water coming out of hot water tap). Turned on heating and went to 2.5 within 20mins, so turned boiler off and now 24hrs later pressure has dropped to 0.5bar.

Earlier in the week he tried draining the boiler completely then turned on the cold water mains to combi, so heating side pressure was on 0 bar. The pressure within about 5 hours went up to 3.5bar (on heating side).

Could the water be mixing in the main heat exhanger into the heating side (as there is no seperate dhw heat exchanger on this boiler) or could it be a problem with the expanssion vessel (small hole possibly)?

Agile · 25 Jun 2006

According to the figures you have given he has not set up the expansion vessel correctly.

It should have been charged to 0.9 bar or about 60% of the cold pressure.

Try letting a little air out and then see what the effect is. There may well be another fault but until the EV is correct we will not be able to see what thay may be.

Tony Glazier

scatmanjohn · 25 Jun 2006

Dave_2002

Could the water be mixing in the main heat exhanger into the heating side

Thats exactly what it is. (very common on this boiler)

My money is on this senario.

Heat exchanger is kaput thus allowing mains pressure water to pass into the central heating.
(replace heat ex)
As the pressure has been rising above 3 bar the pressure relief valve has done its job and released the excess pressure. However it is now also kaput which is causing the pressure to drop when the mains water is isolated from the boiler.
(replace prv)

End of problem.

One good thing is they are the easiest heat ex to change that i have ever come across.

mmalone · 25 Jun 2006

Dave_2002 said:
Pressure was on 3.5bar... Engineer drained boiler, recharged expanssion vessel to 1.5bar then put pressure to 1.5bar with cold water feed turned off to boiler (so no water coming out of hot water tap). Turned on heating and went to 2.5 within 20mins, so turned boiler off and now 24hrs later pressure has dropped to 0.5bar.

Earlier in the week he tried draining the boiler completely then turned on the cold water mains to combi, so heating side pressure was on 0 bar. The pressure within about 5 hours went up to 3.5bar (on heating side).

Could the water be mixing in the main heat exhanger into the heating side (as there is no seperate dhw heat exchanger on this boiler) or could it be a problem with the expanssion vessel (small hole possibly)?

deffo sounds most likely the heat exchanger !!

if you shut off the cold supply to the boiler and it doesnt rise when the boiler is idle but rises when idle and cold supply open this is your fault.

diynot

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Vokera Compact 24 Pressure Going Up.

Dave_2002

Agile

scatmanjohn

mmalone

DIYnot Local

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