After a boiler service, most of us breathe out, tick the “job done” box, and move on. That quiet confidence is lovely — until you remember carbon monoxide doesn’t play by tidy rules. The system’s been taken apart, re‑sealed, re‑lit. That’s exactly when a tiny check of your alarm matters most.
The kitchen smelt faintly of warm metal and wet wool, the kind of midweek smell that says “normal life”. The boiler hummed back into its steady rhythm; the radiators ticked like a polite metronome. A fresh yellow service sticker was squared up on the casing, cleaner than the fridge door ever is.
I watched the LED on the carbon monoxide alarm, the way you watch a baby monitor after a night feed — not panicked, just much more aware than you were an hour ago. The test button stared back like a dare. I pressed it and waited for the pattern I’d half memorised. Then it blinked.
Why that post‑service moment matters more than you think
Servicing is meant to make things safer, and it largely does. Still, any time an appliance is stripped down and put back together, seals are touched, flues are checked, combustion tweaked. That’s a mini‑disturbance in a system that runs on balance.
Gas pressure, draw in the flue, even the room’s air movement — all can shift after a visit. A carbon monoxide alarm is your independent witness in the hours that follow. **It’s the one device that doesn’t care what the paperwork says; it only listens to the air.**
There’s also the human side. We relax after a professional has been, as if danger clocks off with them. On a cold evening, doors get shut tighter, extractor fans kick in, and the boiler cycles hard. That creates new conditions. The safest habit is simple: test the alarm while the system is warm and the house is living as normal.
Real stories, real numbers, real life
I think of a neighbour in Leeds who reset their routine after a service — dinner on, kids’ baths, windows steamed. Their carbon monoxide alarm chirped once, then again, which they’d once have ignored as a random battery thing. They pressed test to be sure, called the emergency number, and a misaligned flue joint was fixed before bedtime. The sticker on the boiler still shone. The air in the house mattered more.
Public reports vary by year, but the theme stays stubborn: UK homes still see preventable carbon monoxide exposures, and winter brings spikes. Gas Safe Register inspections regularly find unsafe appliances across the country; it’s not rare, it’s just hidden. A working alarm turns the invisible into a decision you can act on.
We’ve all had that moment where a single beep leaves you wondering if you’re fussing over nothing. Here’s the trick: treat the test as the cost of calm. It takes seconds, it clarifies the noise, and it turns uncertainty into a clear signal. That’s not paranoia; that’s house sense.
How to test your alarm properly after the boiler’s been serviced
Do it the same day the engineer leaves. Power the boiler, run heating or hot water so the appliance is working, then press the test button on your carbon monoxide alarm. You’re listening for the exact pattern in your manual — usually a series of loud beeps and a flashing LED — then a return to standby.
Check the alarm’s position and age while you’re there. BS EN 50291‑compliant models typically sit on a wall at head height, 1–3 metres from the boiler, not tucked behind a plant or a curtain. Many units expire after 7–10 years, with a date on the back. **If it’s out of date, that button press is theatre, not protection.**
Soyons honnêtes : Let’s be honest — nobody presses that button every week. That’s why the post‑service window is gold. Never “test” with a lighter, candle, fumes, or a car in the garage. If you want to go beyond the button, use a dedicated CO test spray designed for alarms, following the label exactly. Keep windows in their normal position while you test; you’re checking real life, not a lab.
Common mistakes and kinder fixes
Don’t silence and forget. The hush button is a pause, not a cure. If your alarm sounds while the boiler is running, turn off the appliance if you can, open doors and windows, leave the property, and call the National Gas Emergency number: 0800 111 999. If anyone feels ill — headaches, dizziness, nausea — ring 999.
A few small missteps make alarms seem “annoying” rather than protective. Mounting too high above doorframes, parking them on top of the boiler, or placing them right next to an extractor can all skew how they sense the room. Keep them where they can “see” the air you actually breathe. *A tiny test, a huge difference.*
Remember batteries and lifespan. Many newer alarms are sealed for their lifetime, but older ones need fresh batteries and a calendar reminder. If you have multiple alarms, press them in turn — it’s quicker than you think, and it teaches your ear what normal sounds like.
What the pros wish you knew
One engineer told me the quietest wins happen when a homeowner tests an alarm right after servicing, then messages a photo of a faint fault light they’d never noticed before. Engineers are human; they want your home safe in the real world at 8pm, not just on a worksheet at 3pm.
“An alarm is your second set of eyes. I can’t stay through tea and bath time, but that little box can,” says a Gas Safe registered installer I spoke with in Manchester.
- Place an alarm near the boiler and another near bedrooms for layered protection.
- Know your model’s beep patterns: low battery, end of life, and real alarm sound different.
- Keep vents and flues clear; don’t box‑in appliances without proper ventilation.
- After any building work, repeat the test — airflow changes change risk.
- Write the install date on the alarm with a marker. Future you will thank you.
The peace-of-mind dividend
Testing your carbon monoxide alarm after a boiler service isn’t busywork. It’s a quiet handshake between the professional service and your lived‑in home, where doors slam, fans whirr, and the dog claims the warmest spot by the radiator. That’s where safety needs to hold.
Pressing one button re‑anchors the story in evidence. It also normalises a habit for kids, partners, even visiting relatives, the way smoke alarms became background routine. The more you hear that clean, confident test pattern, the less you’ll hesitate in a pinch. And if something’s off, you’ll know early.
So test it, log it mentally, and get on with your evening. **The reward is quiet — the good kind.**
| Point clé | Détail | Intérêt pour le lecteur |
|---|---|---|
| Test the same day | Run the boiler, press the button, listen for the correct pattern | Turns a service visit into confirmed safety at home |
| Position and lifespan | BS EN 50291 alarm at head height, within 1–3m; replace at 7–10 years | Makes the alarm accurate and trustworthy |
| If it sounds, act | Turn off appliances, ventilate, leave, call 0800 111 999 | Clear steps when seconds matter |
FAQ :
- Where should I put a carbon monoxide alarm near a boiler?On a wall at head height, 1–3 metres from the appliance, not blocked by cupboards, curtains, or extractors. Avoid corners and dead air spots.
- Is the test button enough to prove my alarm works?It checks the electronics and sounder. For extra confidence, use an approved CO test spray as directed. Never use flames or exhaust.
- How often should I test it?Weekly is the guideline. Real life? Do it weekly if you can; at minimum, make the post‑service test non‑negotiable and set monthly reminders.
- What are the symptoms of carbon monoxide exposure?Headache, dizziness, nausea, breathlessness, confusion, tiredness. If anyone feels unwell and the alarm sounds, get fresh air and call 999.
- When do I replace the alarm?Check the expiry date on the back. Most last 7–10 years; some give an end‑of‑life chirp. Replace sooner if damaged or unreliable.
