Plumbing

Worcester boiler losing hot water - whats the problem / solution?

Anonymous user 09/03/2024 - 3.04 PM

Hi - thanks in advance. We have a Worcester combi boiler that’s about 12-15years old and is serviced annually. For the past six months we’ve had problems with hot water only lasting a few minutes in the shower or bath, before it runs cold. I would appreciate advice on trouble shooting the issue. Here’s the detail: - Turning the shower off and then on again, normally restarts the hot, but it turns cold again approx. a minute later. - Some taps in the house – such as the kitchen (downstairs, while shower is upstairs)– do not experience this problem. Sometimes if we leave a hot tap running while we run the shower, the water stays hot in the shower – but this doesn’t always work. Sometimes the water will run hot with no issues in the shower - it's intermittent. - We have another issue with the boiler losing pressure every approx. 2 weeks (naturally I turn the valves to top up the pressure). An engineer fitted a new external expansion vessel 2 months ago but that hasn’t resolved the problem with the pressure dropping, or the hot water stopping. *The problem with the failing hot water occurs even if we have the correct pressure in the boiler.* The reason I’m asking advice is because different engineers have recommended contrasting solutions. One has suggested a system flush (which is costly at £400+ if it’s just a hunch). Another suggested it may be a part that detects the temperature inside the boiler, which may have furred up (we have v hard water) so the part cannot detect the temp any more. I’m no expert, but the temp is displayed on the boiler so the system is detecting the temp. I basically don’t have the cash to try every solution until one works, but understand troubleshooting is a fine art. Any advice appreciated. Thanks UPDATE: Thanks for your advice - particularly Nottingham Boiler Services for their detailed response. I'm going to speak to the original engineer about replacing the heat exchanger. The boiler is also running hot - which I hadn't even stated but you guessed correctly - so I'll turn the temp down for the time being. Will update to say what fixed it, once it's done!