My Vaillant Aqua plus is loosing pressure and needs topping up every 5 to 6 hours. (Gauge reading zero). There is no discharge from the two pipes going through the wall to the outside. When the heating is on, the pressure never gets to 3mbar although it does rise slightly indicating that the pressure vessel is working. There doesn't appear to be a leak in the system (with the flow and return pipes closed at the boiler, the pressure still drops). A heating engineer came yesterday and pumped up the system which had no pressure in it. Today after bleeding the system several times, I am still loosing pressure. Can anyone advise?
Could be water leaking back into the heatexchanger. Top up system,set to 1.5 bar isolate the valves under the boiler on the flow and return. Leave the system 24 hours, if pressure has dropped then heat exchanger is knackered.
Hetic here, just reread your post, you have already confirmed it, but one other came to mind the pressure vessel if the pressure goes above 3 bar, then it need recharging or replacing & heat exchanger might be ok. Don't think the prv is the problem, as no discharge. Where is Dave.
Baffled. The pressure has never gone above 3 bar and I can confirm that because the bag on the overflow is still bone dry after a week. Could this simply be air escaping from the top of the pressure vessel? There are definitely no signs of a leak in the boiler. The isolating valves at the boiler for the flow and return pipes are functioning ok.
Had time to think abit, I still think it's heatexchanger leaking, because if a pressure vessel was leaking through it's diaphragm, it would cause pvr to dump the water, when you topped up system. Can't find manual here or remember, if there is condensate trap on your boiler, if there is brown rust in it, then it's heat exchanger. If heat exchanger, then any water would just burn off, hence no visiable signs of a leak.
Don't even know if certian spares are still available, your boiler is at least 14 years old. Where is Dave.
Unfortunately, with the flow &a return valves closed and the central heating off by removing the battery from the room wireless thermostat, the heat exchanger would not be able to burn of any water?
If it is the heat exchanger, & the part is still available, I hope you on good terms with your bank manager.
With the boiler being 14 years old, if it is the heat exchange then it's possibly time for a new boiler.
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