September 25, 2026
Autumn has a habit of arriving politely and then turning sharp. One week you are eating outside, the next you are reaching for a jumper at four in the afternoon. The first proper cold snap usually lands in November, and it tends to arrive at the worst possible moment: the boiler that has idled all summer, the radiator that has been warming at the bottom since March, the back door that has been letting in a thin stream of air for months.
None of these jobs are difficult. Most take minutes rather than hours, and none of them need special equipment beyond a radiator key and a tube of sealant. Work through them over two or three weekends and you will spend the cold months warm instead of waiting in a queue for an engineer along with half your street.
1. Book the boiler service before the rush
Your boiler does very little between May and September. Then, within a fortnight, it is asked to run for hours a day, every day. That sudden change in workload is when tired pumps, worn seals and tired fans tend to give up.
An annual service is the cheapest insurance you can buy. It keeps a manufacturer's warranty valid, checks combustion and safety, and catches small problems while they are still small. Gas appliances must be serviced by a Gas Safe registered engineer, and oil boilers by an OFTEC registered technician – this is not a job for a general handyman, and it is certainly not a DIY one.
While you are at the boiler, look at the pressure gauge. On a sealed system it should usually sit somewhere around 1 to 1.5 bar when the heating is cold. If it has dropped below 1, top it up via the filling loop, following the instructions for your model. If the pressure keeps falling, you have a leak somewhere and should mention it when you book.
2. Bleed the radiators before you need them
Trapped air is the most common reason a radiator feels hot at the bottom and cool at the top. It also makes the system noisy and wastes heat. If yours gurgle when they come on, or take an age to warm through, start here.
- Turn the heating off and let the radiators cool completely. Bleeding a hot radiator means risking a scalding jet of water.
- Find the bleed valve – a small square spindle at the top corner of the radiator – and hold a cloth or small container underneath.
- Turn the radiator key a quarter turn. You will hear a steady hiss as air escapes.
- Close the valve the moment water trickles out rather than spitting. Do not over-tighten it.
- Check the boiler pressure afterwards and top it up if it has fallen.
Work through the whole house, starting with the radiators on the top floor. If one radiator needs bleeding every few weeks, air is being drawn in somewhere – worth flagging to your engineer rather than simply repeating the job.
3. Check valves and thermostats in every room
Radiator thermostatic valves often seize over summer. The pin underneath the head can stick down, which leaves the radiator permanently cold. Take the head off and press the pin gently with pliers to free it; if it will not move, the valve needs replacing.
Why one room stays cold
If the radiators nearest the boiler get scorching while the far end of the house barely warms, the system is probably out of balance. Balancing means adjusting the lockshield valves on each radiator so the hot water is shared out evenly. It is fiddly but effective, and many engineers will do it as part of a service. Two things worth remembering: open the valves fully in the rooms you actually use, and never turn off every radiator in the house with the heating running.
4. Hunt down the draughts
On a windy evening, walk slowly round the ground floor holding the back of your hand near the edges of doors, windows and skirting. You will feel the culprits quickly enough. The usual suspects are:
- Gaps under doors, including the internal door to an unheated hallway or garage.
- Letterboxes, keyholes and cat flaps.
- Frames and sashes of older windows, and the cords on sash windows.
- Loft hatches that sit slightly proud of the ceiling.
- Open chimneys in rooms with no fire in use.
- Holes where pipes, cables and cooker hoods pass through external walls.
Brush seals, self-adhesive foam strips and a little silicone sealant cost very little and take an afternoon. Two cautions. Never block a vent that supplies air to a gas appliance or an open fire – that air is there for safety. And leave trickle vents on windows open, because a sealed-up house collects moisture that has to go somewhere.
5. Set the thermostat for how you actually live
Most people are comfortable somewhere between 18°C and 21°C. Turning the dial to 25 does not heat the house any faster – it simply overshoots and costs more. Instead, set a comfortable daytime temperature and let it drop to around 15°C or 16°C overnight and when the house is empty.
Use the timer properly. Two shorter heating periods, one in the morning and one in the evening, suit most households better than one long block. In a hard frost, keep a little background heat on even when you are out, particularly if pipes run through a cold loft or garage. Also check where the thermostat itself sits: away from radiators, direct sun, draughts and heavy curtains, or it will read the wrong room entirely.
6. Lag the pipes and look after the condensate
Foam lagging on the pipes in your loft, garage or outbuilding is one of the best-value jobs on this list. Pay particular attention to any pipe running along an external wall or close to a draughty loft hatch.
If you have a condensing boiler, find the white plastic condensate pipe that carries water away, often to an outside drain. In a hard frost, this is the pipe that freezes and stops the boiler dead. Where possible, ask your engineer about rerouting a long external run, increasing the pipe diameter or fitting a trace heater. If it does freeze, thaw it carefully with warm water – never boiling, never a naked flame – and take care on steps and ladders.
Doing it in the right order
Book the service first, because that is the one job with a waiting list. Bleed the radiators next, so the system is working properly before you start adjusting controls. Then deal with draughts, set the thermostat and timer, and finish with lagging before the first frost is forecast. Any work involving gas, or anything you are unsure about, belongs with a registered professional rather than a weekend DIY attempt. An afternoon or two now buys you a winter of quiet, even warmth – and no phone calls to an emergency plumber at midnight.
Photo: Géo / Pixabay
