No Hot Water But the Heating Still Works? Here’s Why
If your radiators are warming up fine but nothing comes out of the taps except cold water, the fault almost always sits with one specific part rather than the whole system. It’s a strange one to diagnose from the outside, because the boiler is clearly firing and clearly working, which throws a lot of homeowners off. We see this a fair bit on jobs across Southampton and Winchester, and it’s rarely as serious as it first feels. Here’s what’s actually going on, and what you can safely check yourself before calling an engineer out. Why This Happens: The Short Answer Most combi boilers use a single component, called a diverter valve, to switch between heating your radiators and heating your hot water. When that valve gets stuck, worn, or jammed in the “heating” position, the boiler keeps warming your radiators perfectly while sending nothing to the hot water side. Everything else in the system can be completely healthy, which is exactly why this fault confuses people. If you’ve got a system boiler with a separate hot water cylinder, the cause is usually different again, more often an immersion heater fault, a faulty cylinder thermostat, or a stuck motorised valve