Vokera Linea 24 Combi Boiler - water Pressure keeps dropping error 04 why?

the water from the heating system is passing through the domestic hot water valve when the diverter valve is changing from heating to hot water the valve is not fully operating this means some of the water from the heating is passing through the domestic hot water the pressure will not drop because the boiler is hot and the pressure rises when the boiler is operating you will not see the drop in pressure until the boiler is really cold

john consett have proved this is the problem many times
December 2013

i also have a pressure problem and my engineer says it looks like the heat exchanger is at fault but he can't change it because the hood is no longer available from vokera. boiler is 6 years old! i am now looking at having to replace it!

BRYAN
January 2011

Had the same problem, loosing pressure over a couple of days. In the end it turned out to be the preasure relief valve weeping into the drain outside, spotted it whilst sitting in the garden.

David Orrell
October 2010

I have the same problems a Vokera Linea 24 Combi Boiler, has a new expansion vessel, no problem with the radiators no leaks their and they get hot, the small heat exchanger is new and a magnetic filter fitted to the rad system. The pressure gauge drops in about 4 to 5 days, the large heat exchanger is badly corroded at each end, so it looks like it could be leaking but never shows external leaking on the floor. The shower fluctuates from freezing for 40 sec to hot 2 minutes and so on. All valves and sensors have being changed yearly to correct the above problems but never satisfactory. We have very high water pressure and have to turn the shower tap to nearly off so the water screams past the regulator to get constant hot water, if we turn regulator full on the shower is near flat cold at all times so the system can't cope with the fast flow of incoming cold water. Is their a better system to cope with high mains water pressure or is it the large heat exchanger that is silted up, but then I would have thought the radiators would not be so hot. Thanks in advance.

Graham - Hot & Cold flushes
February 2010

The hot and cold water problem may be the domestic hot water plate heat exchanger (part 8036). I have had to change mine twice in the last 3 years. I had it cleaned out once but only lasted for a couple of months. I changed mine last week and hot water is working a treat. Costs about £90 and once system drained easy to fit.

CJC
October 2009

Hello i have got the same 04 code flashing up and my domestic hot water keeps going hot and cold. the pressure is at 1.5 bar so no problem with the pressure dropping ? any ideas on the problem. thanks Andy

Andy linea 24
February 2009

Check all your radiators for leaks at the valves where the copper pipe goes in. If no leaks evident then fault most likely lies with the expansion vessel on the boiler. This should have air pressure of 0.7-0.9 bar in it which sometimes needs recharged. Any heating engineer can do this for you using a car foot pump in about 5-10 minutes. If the vessel needs to be replaced because it wont hold the air, then it will take about 45 minutes to change it. If your vessel is part no 2204, the Vokera retail price is £65.26. Hope this helps.

Scott Clapperton
April 2006