Not without knowing what it sits on. A valve can be the isolation for a single tap, for a whole flat, for a heating circuit, or for a system that cannot be left standing — and from the outside they look much alike. A closed heating or circulation circuit can cause frost damage or stagnant hot water long after you have forgotten you touched it.
If it is urgent and water is running: close it, and say afterwards what you closed. If it is not urgent, find out what it does first.
In detail
What the valve sits on, not what it looks like. A pipe feeding a single draw-off point is one thing; a valve on a riser, a heating circuit, the expansion, or a safety line is something else entirely. Safety valves and valves on an expansion vessel must never be closed.
Follow the pipe with your eyes in both directions and see where it goes. Look for markings, labels or colour coding. Note whether the pipe is warm or cold, whether there is an identical valve next to it, and whether the handle sits in the "open" position parallel to the pipe.
It can be. Old valves that have sat untouched for decades can seize or start weeping precisely when they are moved, and a valve that will not reopen turns a small problem into a large one. In a block of flats, closing a circuit can also affect neighbours.
Write down which one it was and when. If you reopen it, do so slowly and listen for noises, then check that hot water and heating work where they should. Tell whoever attends that the valve has been closed — it explains symptoms that otherwise look like a new fault.
The valve close up with any marking, and a step back so it is visible where the pipes run. A photo of the handle alone can rarely be answered. Say where in the building it sits and what you suspect it belongs to.
What this page is not
This page describes what the symptom usually comes down to. It is not an assessment of your particular installation and it does not replace a professional who can see it. If water is running, you can smell gas, or anything involving electricity is in play: shut it off and call a professional now.
Other symptoms
Partly, and the part that is settled is the application key. An ECL Comfort 210 or 310 is an empty shell without one: the key carries the software layout, such as A266 for heating plus domestic hot water. Keys are not locked to a serial number and move freely between controllers of the same type.
Read the answer →Almost always air in the radiator. Hot water comes in and heats the lower part, but air has collected at the top where it cannot escape on its own, so the top stays cold. Bleeding the radiator is the first step and usually fixes it.
Read the answer →There are three common sources, and they can be told apart without tools. The trap and its connections only leak when you run water. The supplies to the tap leak continuously, including overnight, because they are under pressure. The dishwasher hose or connection leaks during and just after a cycle.
Read the answer →Condensation spreads evenly along a cold pipe, often as many small droplets on the underside, and gets worse when it is warm and humid indoors. A leak has a point: the damp is heaviest at a joint, a valve or a weld, and runs from there.
Read the answer →The heating working while the hot water does not already says a good deal: the fault is usually in the part that only concerns hot water, not in the heat source. The most common are the cylinder or the heat exchanger, a broken or misadjusted mixing valve, or a stopped hot water circulation pump.
Read the answer →One thing to do next
Write a few lines and send a photo or a short video. You get a written first assessment of your own case — what it most likely is and what the next step is — for €9.99. A professional reads it, not just a machine.