💧 Why Is There No Hot Water in My House? Causes & Fixes
There’s nothing more frustrating than turning on the tap or shower and discovering you have no hot water. Whether you rely on a combi boiler, system boiler, immersion heater or unvented cylinder — hot water problems are common. In this article, we break down why you might have no hot water and what to do next.
🛠️ Most Common Reasons for No Hot Water
- Boiler Pressure Too Low
Modern combi boilers stop heating water if pressure drops below 1 bar.
✅ Check the pressure gauge and repressurise using the filling loop if needed.
- Pilot Light Has Gone Out (Older Boilers)
If you have an older boiler with a pilot light, it may need relighting.
✅ Follow the boiler manual or call a Gas Safe engineer.
- Thermostat or Programmer Fault
Your thermostat may be set too low, off schedule, or unresponsive.
✅ Turn it up and test; if it doesn’t trigger hot water, it may need replacing.
- Diverter Valve Stuck (Combi Boilers)
If your heating works but you have no hot water, the diverter valve may be jammed.
✅ Needs a heating engineer to inspect or replace.
- Immersion Heater Not Working
For properties without gas, the electric immersion heater may be at fault.
✅ Check the switch, fuse and thermostat on the hot water tank.
- Frozen or Blocked Pipes
In winter, condensate or supply pipes can freeze and block hot water flow.
✅ Thaw gently or call for professional help if unsure.
🔎 Quick Checklist Before You Call an Engineer
- ✅ Boiler pressure is between 1–1.5 bar?
- ✅ Thermostat is set above 18°C and not on holiday mode?
- ✅ Timer or programmer settings correct?
- ✅ No fault code on the boiler display?
If all seems normal and you still have no hot water, it’s time to call a professional.
📞 Need Hot Water Repair in London?
At A&C Heating and Plumbing Ltd, we provide fast, expert help across North and West London:
- Water heater repairs
- Combi and system boiler faults
- Immersion heater troubleshooting
- Emergency hot water callouts
📞 Call us now: 0779 559 5757
🛠️ Book a Repair Online
❓ Frequently Asked Questions
My heating works but I have no hot water — why?
Likely a diverter valve fault in your combi boiler. It’s a common issue and requires repair.
Why is my hot water only working sometimes?
It may be a faulty thermostat, temperature sensor, or intermittent boiler pressure drop.
How quickly can you fix hot water problems in London?
Same-day service available across North and West London. Emergency slots also offered.
Do you repair both gas and electric hot water systems?
Yes — we handle gas boilers, unvented cylinders, and electric immersion heaters.