7 Boiler Checks to Do Before Winter (UK Homeowners’ Guide)
When cold weather hits, the last thing you want is a boiler breakdown. A few simple checks before winter can keep your system efficient, safe, and ready for the months ahead.
At Parallel Plumbing Solutions, we help homeowners across prepare for the colder season with expert servicing and advice.
Here are seven essential checks to help you spot small problems before they become costly emergencies.
1) Check boiler pressure (when cold)
Look at the gauge on the boiler front.
Low (<1.0): you’ll likely need to top up via the filling loop.
High (>2.0): bleed radiators, then recheck pressure.
If it keeps drifting, it could point to an expansion or valve issue — book a professional inspection.
2) Bleed cold or patchy radiators
Air pockets prevent radiators from heating evenly.
Use a radiator key until you hear hissing air, then close when water appears.
After bleeding, recheck boiler pressure — it may drop slightly.
3) Test your thermostat and timers
Turn the thermostat up and check if the boiler fires up.
Review schedules to ensure heating only runs when needed.
Smart thermostats can cut energy use by up to 10% if used efficiently.
4) Protect your condensate pipe from freezing
The small white pipe that drains from your boiler outside can freeze during cold spells.
Make sure it’s insulated and not blocked.
If it does freeze, gently pour warm (not boiling) water over it and reset the boiler.
5) Keep the flue and ventilation clear
Ensure nothing is blocking the flue outlet or air vents — no boxes, foliage, or debris.
Good ventilation prevents harmful gas build-up and keeps combustion efficient.
If unsure, get a Gas Safe engineer to inspect it safely.
6) Listen for unusual noises
Whistling or banging sounds (“kettling”) can signal scale or sludge inside the system.
This reduces efficiency and can cause breakdowns.
A system flush or magnetic filter installation can help prolong your boiler’s life.
7) Book your annual Gas Safe boiler service
Manufacturers recommend a yearly service to maintain efficiency and safety — and keep warranties valid.
Our engineers inspect key components, clean parts, check pressure, and test flue gases to ensure your boiler runs perfectly through winter.
When to call an engineer (don’t DIY these)
Ongoing pressure loss or leaks
Boiler not igniting/locking out
Unusual smells or CO alarm sounding (turn off and call emergency gas line)
No hot water or intermittent heating
Why a professional service saves money
Efficiency: clean burners = lower gas use
Reliability: minor faults fixed early
Safety: CO and flue checks prevent hazards
Warranty protection: most warranties require a service every 12 months
Winter offer — stay warm with Parallel Plumbing
Avoid breakdowns this winter with a professional boiler service from our team.
We offer reliable same-week appointments and fixed pricing.
Call or book online to secure your slot before the rush.