Central Heating Not Working? 7 Things to Check First
There's nothing worse than waking up to a cold house on a winter morning. Before you panic and call for emergency heating repairs, there are several simple checks you can do yourself. For homeowners across Crawley, Horsham, Redhill, Reigate, Horley, East Grinstead, Haywards Heath, Burgess Hill, Brighton, Epsom, and throughout West Sussex and Surrey, this troubleshooting guide could save you time and money.
Many heating problems have simple solutions that don't require a Gas Safe engineer. We'll walk you through 7 common issues and their fixes, plus help you identify when professional help is needed.
✓ Check 1: Thermostat Settings
Why Check This: It sounds obvious, but incorrect thermostat settings cause countless unnecessary callouts across West Sussex and Surrey.
What to Check:
- ✓ Is the thermostat set to "Heat" or "Auto" mode (not "Off")?
- ✓ Is the temperature set higher than current room temperature?
- ✓ Are batteries dead? (Digital thermostats)
- ✓ Is the timer programmed correctly?
- ✓ Has someone accidentally changed settings?
Quick Fixes:
- Increase thermostat temperature by 5°C
- Replace thermostat batteries if display is dim/blank
- Check timer hasn't been bumped to "Off"
- Try turning thermostat completely off, then back on
✓ Check 2: Boiler Pressure
Why This Matters: Low pressure is one of the most common reasons heating systems fail to work.
How to Check:
- Look at your boiler's pressure gauge (usually has a green zone)
- Normal pressure: 1.0 to 1.5 bar (in the green zone)
- Too low: Below 1.0 bar (needle in red zone)
- Too high: Above 2.0 bar (also in red zone)
If Pressure is Too Low:
You can top up pressure using the filling loop:
- Turn off your boiler
- Locate the filling loop (usually two valves connected by a flexible hose)
- Open both valves slowly
- Watch the pressure gauge rise to 1.0-1.5 bar
- Close both valves tightly
- Turn boiler back on
✓ Check 3: Pilot Light (Older Boilers)
Applies to: Older boilers with visible pilot lights (most modern boilers use electric ignition).
What to Look For:
- Open the boiler panel (consult manual)
- Look for a small blue flame
- If flame is out, the boiler won't fire up
Relighting a Pilot Light:
If safe to proceed:
- Follow manufacturer's instructions exactly
- Usually involves holding down a button while using a spark igniter
- Flame should light and stay lit when button is released
Frequent Pilot Light Failures? This indicates a faulty thermocouple or gas valve needing professional boiler repair.
Heating Still Not Working?
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✓ Check 4: Radiator Valves
Common Issue: Individual radiators not heating even though boiler is working.
What to Check:
- Thermostatic Radiator Valves (TRVs) - Make sure they're turned up (usually numbered 1-5)
- Lockshield valve - Covered by a cap, should be open (needs adjustment wrench)
- Stuck valve - TRVs can stick closed; try removing head and gently tapping pin
If individual radiators remain cold after checking valves, they may need bleeding or have internal sludge requiring a powerflush.
✓ Check 5: Frozen Condensate Pipe
Winter Problem: Very common across West Sussex and Surrey during cold snaps. Modern condensing boilers have an external condensate pipe that can freeze.
Signs of Frozen Condensate:
- Boiler won't start
- Gurgling sounds from boiler
- Error code displayed (check manual)
- Problem started during freezing weather
How to Thaw:
- Locate the condensate pipe (usually white plastic, exits externally)
- Pour warm (NOT boiling) water over the frozen section
- Alternatively, use a hot water bottle wrapped around the pipe
- Once thawed, reset your boiler
- Consider insulating the pipe to prevent recurrence
For homes across Crawley, Horsham, Redhill, and surrounding areas, we recommend lagging condensate pipes before winter arrives.
✓ Check 6: Power Supply & Fuse
Simple but Often Overlooked: No power = no heating.
What to Check:
At the Boiler:
- Check boiler switch is ON
- Look for any lights/display
- Try the reset button
- Check fused spur switch nearby
At the Fuse Box:
- Check heating circuit breaker hasn't tripped
- Look for switch in OFF position
- Try resetting any tripped switches
- Check RCD hasn't tripped
✓ Check 7: Timer/Programmer Settings
Especially After Power Cuts: Timer settings can reset or become incorrect.
What to Verify:
- ✓ Current time is correct
- ✓ Heating schedule is programmed
- ✓ Not set to "Off" or "Holiday" mode
- ✓ AM/PM set correctly (common mistake!)
- ✓ Boost function works when pressed
Try setting timer to "Constant" or "All Day" mode temporarily to test if heating works at all.
When to Call a Professional
If you've checked all 7 items above and heating still doesn't work, it's time to call a Gas Safe engineer. Contact us immediately if you notice:
Urgent Issues:
- Gas smell
- Carbon monoxide alarm sounding
- Water leaking from boiler
- Unusual burning smells
- Boiler making loud bangs
Non-Emergency Faults:
- Error codes displayed
- Boiler keeps shutting off
- Pump not working
- No hot water
- Strange noises
Mend Your Home provides comprehensive heating system diagnostics and repairs across Crawley, Horsham, Redhill, Reigate, Horley, East Grinstead, Haywards Heath, Burgess Hill, Brighton, Epsom, and all West Sussex and Surrey. Our Gas Safe engineers diagnose and fix all makes and models.
Preventing Future Heating Problems
Regular Maintenance Tips:
- Annual Boiler Service - Catch problems before they cause breakdowns (Book your service)
- Bleed Radiators Yearly - Improves efficiency and prevents cold spots
- Insulate Pipes - Prevents frozen condensate pipes in winter
- Check Pressure Monthly - Spot leaks early
- Replace Batteries - In thermostats and programmers
- Keep Vents Clear - Don't block air bricks or flue terminals
Frequently Asked Questions
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