Why do radiators get hot when hot water is on?

The reason your radiators heat up – even with the heating off – is because the valve doesn’t close off the heating side of it fully. This means water can still pump around the radiators when the heating should be off. There’s not much you can do when a mid position / 3 port valve does this, except to change it.Click to see full answer. Keeping this in view, why is my heating coming on when the hot water is on?A frequent and likely cause is a faulty or jammed three port valve. In a typical central heating and hot water boiler system, the valve sends water to either the radiators, the hot water cylinder, or both. In the list of possible repair costs for a heating system, your problem is a fairly economical one to rectify.Furthermore, why is my boiler giving me hot water but no heating? Intermittent or no heat and hot water can often be due to either broken diaphragms and airlocks, faulty motorised valves, a broken thermostat or low water levels. You can start by checking if the boiler problem is caused by fault of the boiler pressure or thermostat, as these are easily accessible. Similarly, you may ask, why are my radiators getting hot when the heating is off? When a diverter fails or gets blocked with debris, hot water intended for the hot water circuit can get into the radiator circuit. Then the radiators will be hot even though the heat is turned off. You do not have to live with constantly hot radiators. If you are experiencing this specific issue with your radiators.Is it OK to turn boiler off at night?If you do decide to turn your boiler off at night, then it might actually be the less efficient option. Turning your boiler off at night would mean that you have to turn it back on every morning, something which takes time and effort when you are half asleep and freezing cold.