Before You Call: Safety First
Call a Gas Safe engineer immediately if:- You smell gas
- The flame is yellow/orange instead of blue
- There's black soot around the boiler
- Anyone feels unwell (headaches, dizziness)
These could indicate carbon monoxide - ventilate the room and call for help.
Simple Checks You Can Do
1. Check the Power
It sounds obvious, but check:
- Is the boiler switched on at the wall?
- Has a fuse tripped? Check your consumer unit
- Is there a power cut in your area?
- Is the programmer/timer set correctly?
2. Check the Thermostat
- Is it set higher than the current room temperature?
- Has someone turned it down?
- Do the batteries need replacing? (wireless thermostats)
- Try turning it up a few degrees
3. Check the Pressure
Look at the pressure gauge on your boiler:
- Normal: 1-1.5 bar (green zone)
- Too low: Below 1 bar - needs topping up
- Too high: Above 2.5 bar - needs bleeding
How to repressurise your boiler:- Find the filling loop (two taps with a braided hose)
- Open both taps slowly
- Watch the pressure gauge rise to 1-1.5 bar
- Close both taps
- Reset the boiler
If you're unsure, your boiler manual has specific instructions. 4. Check the Condensate Pipe (Winter)
In freezing weather, the condensate pipe (white/grey plastic pipe outside) can freeze, causing the boiler to shut down.
To thaw:
- Locate the frozen section (usually where it exits the wall)
- Pour warm (not boiling) water over it
- Or hold a hot water bottle against it
- Reset the boiler once thawed
5. Check Gas Supply
- Is the gas meter turned on?
- Do other gas appliances work? (hob, gas fire)
- Is there a supply issue in your area?
- If you have a prepay meter, has credit run out?
6. Check for Error Codes
Modern boilers display error codes. Note the code and:
- Check your boiler manual for meaning
- Search online for '[your boiler model] + [error code]'
- Tell the engineer when you call
Try a Reset
If basic checks are OK, try resetting:
- Find the reset button (often has a flame symbol)
- Press and hold for 3-5 seconds
- Wait for the boiler to restart
- Check if heating/hot water works
Important: If you need to reset more than 2-3 times, or it keeps tripping, there's an underlying fault. Call an engineer - repeated resetting won't fix it and could cause damage.
Common Boiler Problems & Likely Causes
| Symptom | Possible Cause | Can You Fix? |
|---|
| No heating or hot water | Thermostat, timer, or diverter valve | Check thermostat & timer |
| Heating but no hot water | Diverter valve stuck | Engineer needed |
| Hot water but no heating | Diverter valve or motorised valve | Engineer needed |
| Boiler keeps losing pressure | Leak in system | Top up, then engineer |
| Boiler making noise | Kettling, pump, or air in system | Engineer needed |
| Boiler keeps turning off | Low pressure or thermostat | Check pressure first |
| Pilot light won't stay on | Thermocouple fault | Engineer needed |
| Radiators cold at bottom | Sludge buildup | May need powerflush |
| Radiators cold at top | Air in system | Bleed radiators |
When You Need a Gas Safe Engineer
Call a professional if:
- Basic checks haven't fixed it
- You've reset more than twice
- There's a persistent error code
- You smell gas or suspect CO
- There's a water leak from the boiler
- The boiler is making unusual noises
- You're not comfortable doing checks
Information to Give the Engineer
Help them diagnose faster:
- Boiler make and model
- Age of boiler (if known)
- When it last worked
- Any error codes displayed
- What you've already tried
- Any unusual sounds or smells
Written by the My Home Heroes Team
Our engineers have 12+ years experience serving North East England. Gas Safe registered, NICEIC approved.
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