If your cylinder looks like a giant, shiny metal barrel with pipes everywhere, you probably have an unvented system. These are common in newer homes. The shut-off valve is almost always on the cold water supply pipe, often near the bottom of the unit.
But here’s the crucial part: unvented cylinders have a pressure-reducing valve and a safety relief valve. Do not try to unscrew anything or mess with those valves. Just turn the little lever or wheel on the cold water supply—nothing else. If you touch the pressure valve, you might get a surprise fountain, and not the romantic kind.
If you feel unsure, remember: there’s no shame in calling a plumber. They’ve seen more cylinders than a factory tour guide. Your pride is not worth a flooded hallway.
How To Turn Off Hot Water System at Erin Wright blog
The “After You Turn It Off” Dance
So, you’ve turned the valve. Now what? First, run the nearest hot water tap to bleed the remaining pressure and water from the system. Water will come out for a bit—maybe just a trickle, maybe a small gush. Let it finish, then close the tap.
Congratulations! You’ve officially turned off the hot water supply from your cylinder. You’re now a certified home hero. Feel free to pat yourself on the back, do a little victory shimmy, or text your partner a poorly lit photo of the valve for proof.
When you need hot water again, simply reverse the process: turn the valve counterclockwise (or parallel to the pipe for a lever). Wait a few minutes for the cylinder to reheat, and boom—steamy showers are back on the menu.
