Am having an problem with my sealed HW system pressure.
Recently I noticed water dripping through the tundish from the relief valve on the cyclinder. What seems to be happening is that the pressure in the HW cylinder rises to 6-7 bar and the pressure relief valve (7 bar) starts to drip/vent via the tundish. The cylinder is meant to operate at 3.5 bar and has a pressure reducing multibloc on the inlet. I have two pressure gauges fitted one on the multibloc and the other on the cylinder expansion vessel both read 6-7 bar.
The symptoms are that as soon as I pressurise the system by turning on the mains, the pressure immidiately raises to 3.5 bar (as one would expect) but then slowly rises to 6-7 bar over a period od 10-15 minutes. Interestingly the expansion vessel gauge rises to 6 bar first then a few minutes later the inlet (multibloc) catches up. This happens whether the boiler is on or not or whether the water in cylinder is hot or not. I am assuming is the mains pressure is 6-7 bar.
My first thought was the pressure reducing multibloc was faulty or not seating properly. I have replaced the cartridge in the multibloc and cleaned it. I have checked the expansion vessel and its pre-charge pressure (3bar). The CH and cyclinder coil is pressurised to 1bar.
The only other thing I can think of is that somehow water is bypassing in the multibloc body but having replaced the cartridge it seems unlikely as it has no other moving parts than in the cartridge but the whole unit will be a nighmare to replace and costs almost £200 so I do not want to do it until I am sure this is the problem.
Any other ideas as to how or why the pressure could be rising in the cylinder?
Thanks.
Giles
Recently I noticed water dripping through the tundish from the relief valve on the cyclinder. What seems to be happening is that the pressure in the HW cylinder rises to 6-7 bar and the pressure relief valve (7 bar) starts to drip/vent via the tundish. The cylinder is meant to operate at 3.5 bar and has a pressure reducing multibloc on the inlet. I have two pressure gauges fitted one on the multibloc and the other on the cylinder expansion vessel both read 6-7 bar.
The symptoms are that as soon as I pressurise the system by turning on the mains, the pressure immidiately raises to 3.5 bar (as one would expect) but then slowly rises to 6-7 bar over a period od 10-15 minutes. Interestingly the expansion vessel gauge rises to 6 bar first then a few minutes later the inlet (multibloc) catches up. This happens whether the boiler is on or not or whether the water in cylinder is hot or not. I am assuming is the mains pressure is 6-7 bar.
My first thought was the pressure reducing multibloc was faulty or not seating properly. I have replaced the cartridge in the multibloc and cleaned it. I have checked the expansion vessel and its pre-charge pressure (3bar). The CH and cyclinder coil is pressurised to 1bar.
The only other thing I can think of is that somehow water is bypassing in the multibloc body but having replaced the cartridge it seems unlikely as it has no other moving parts than in the cartridge but the whole unit will be a nighmare to replace and costs almost £200 so I do not want to do it until I am sure this is the problem.
Any other ideas as to how or why the pressure could be rising in the cylinder?
Thanks.
Giles