We recently had a small flood in our apartment. I found that the metal-sheathed rubber hose connecting the cold water supply to the blue cold water expansion vessel had a wide split in it. The water supply had already been turned off by someone else; when I turned the water back on gently, water gushes out of the split.
Can/should I replace this hose myself? I have no plumbing qualifications, although I do have a solid grasp of physics and engineering, an eagerness to learn and I know how to turn off the water supply to my flat...
The tank is a Zilmet Ultra Pro 8 litre. Note that the water connection of the expansion vessel is at the bottom; the air valve is at the top - other similar products I've seen online seem to have them the other way around.
- I unscrewed the hose at the mains water end, a little water dribbled out. As I started to unscrew the hose at the vessel end, it gurgled a bit as if air was getting in and started to leak water (exactly as you'd get if you slowly unscrewed the cap on an upturned water bottle). I started to worry that I was letting air in to the water side of the expansion tank and that this might be bad - eventually I decided that the air pressure must be too low as I'm assuming that when the tank is pressurised correctly but there is no water pressure, the diaphragm will be pushed against the water inlet, so to re-expel that air I was letting in all I ought to do was to repressurize the tank. Is that correct? I attached a bike pump to the valve and the pressure was zero, worryingly. As I pumped it up to the factory pre-charge level (1.5 bar = 22psi), loads more water was expelled. Is this normal? It sounds like the expansion tank has been running depressurized for some time.
- The water coming out of the tank, especially towards the end, was a bit smelly, and had a few black bits (rubber?) swimming in it. This doesn't seem great - I think this feeds the rest of the taps in our house including the drinking water! The tank claims it has a (replaceable) 'food grade membrane' and is advertised as being for potable water.
- The rubber hose does not appear to have perished, nor the metal sheath on it corroded - I have no explanation as to why it split. I'm concerned it burst due to some pressure surge (would the expansion tank have absorbed this, had it actually had some air in it?), and that other parts of the system may be damaged.