No Hot Water
Boiler, immersion heater, or hot water cylinder issues
4 free DIY guides · 18 total
Waking up to no hot water is one of the most common plumbing callouts in the UK. Whether your boiler is firing but not producing hot water, your immersion heater has tripped, or your hot water cylinder has lost pressure — most causes are diagnosable without calling an engineer straight away. Modern combi boilers, unvented cylinders, and gravity-fed systems all have different failure modes, and the fix for one won't apply to another. These guides walk you through the most likely faults for your system type, what to check yourself, and when you genuinely need a Gas Safe registered engineer out.
Expansion vessel failure — boiler pressure keeps rising
System pressure rising above 3 bar when heating is on — expansion vessel fault
Unvented cylinder pressure relief valve dripping
What a dripping PRV on a megaflo or unvented cylinder means and what to do
How much does it cost to replace a diverter valve in the UK?
UK costs for replacing a stuck or faulty diverter valve on a combi boiler — the most common cause of hot water failure.
The diagnosis is different depending on your system — this helps us point you to the right guide.
Can't find your problem?
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