Home › Boiler problems
Cold radiators, an error code, a kettle on the hob for the washing-up. Here's what you can safely check yourself, what you shouldn't touch, and the one rule that overrides everything else.
The short version: check power, thermostat, pressure (about 1 to 1.5 bar cold) and — in freezing weather — the condensate pipe outside. If you smell gas, forget the boiler: get out and call 0800 111 999 first. For everything else, ring 020 4577 2888 to be put through to a local plumber, day or night.
Before pressure gauges and reset buttons, the one that matters: if you smell gas, the boiler stops being a plumbing problem and becomes an evacuation.
And for planned gas work later: anyone touching the gas side of a boiler must be on the Gas Safe register. Ask to see the card. A genuine engineer expects the question.
Most sealed-system boilers sit happily around 1 to 1.5 bar cold — your manual has the exact range. Low pressure is the most common reason a boiler sulks, and often the cheapest to sort.
A slow leak that drops your pressure will eventually show itself as a stain on somebody's ceiling. Have it traced while it's still invisible.
The classic Tyrone winter call: first hard frost of the year, boiler dead at 7am. Very often that's the condensate pipe — the small plastic pipe that runs from the boiler to a drain, frequently along an outside wall. When it freezes, the boiler locks out to protect itself. Rural and exposed homes around Dungannon, with pipes on north-facing gables and outbuilding walls, get the worst of it.
If power, pressure, thermostat and condensate all check out and it's still dead, that's the end of the safe DIY list. Hand it over.
An error code is the boiler telling you exactly what's wrong — in a language only the manual and the trade speak. Your job isn't to decode it; it's to write it down. Tell whoever you ring the make, the model and the code, and you've saved everyone a diagnostic visit's worth of guesswork. Some codes clear with a single reset — low pressure and frozen condensate lockouts often do once the cause is fixed. Codes pointing at fans, sensors, ignition or anything gas-side are professional territory, and repeatedly resetting a boiler that keeps locking out just hides the evidence. One reset, then the phone. And as with any job arranged through this line: ask for a price before the work starts.
Around 1 to 1.5 bar when the system is cold, for most sealed systems — check your manual, models vary. Below 1 bar it's losing pressure, and topping up once through the filling loop is usually fine. If it keeps dropping over days or weeks, there's a leak somewhere and it needs finding, not endless top-ups.
Write the code down before you touch anything — it tells whoever you call a lot. Check the manual: some codes clear with a simple reset, others flag a fault that needs a professional. Reset once at most. If it locks out again, stop resetting and get it looked at.
Check the boiler has power, the thermostat is turned up, the pressure gauge reads above 1 bar, and — in freezing weather — whether the condensate pipe outside has frozen, which many boilers shut down over. Thaw a frozen condensate pipe with warm, not boiling, water. If none of that brings it back, it's a job for a professional.
Leave the property straight away with everyone in it. No light switches, no flames, no hunting for the leak. From outside, call the National Gas Emergency Service on 0800 111 999 and follow their instructions. Never ring a plumbing line first for a suspected gas leak, and only go back in when you're told it's safe.
The main page — how the line works and who it covers.
Go to home →Stopcock off first — the right order for the first five minutes.
Read the guide →What to try, what to never pour, when it's NI Water's job.
Read the guide →How the bill is built and what to pin down first.
Read the guide →Pressure, timers, tripped switches and the immersion backup.
Read the guide →Gentle heat from the tap end back — and never a flame.
Read the guide →Damp patches, dropping pressure and the honest stopcock test.
Read the guide →Any hour, any day — you'll be put through to a local plumber covering Dungannon and the surrounding towns and villages.
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