Maintenance

A radiator that stays cold when the heating comes on.

The price cap moved on 1 October 2026, and the clocks go back on 25 October. A short run of the heating on a mild day shows which radiator is cold, and the pattern on the metal decides whether you check a valve, follow a bleed guide, or phone.

Checked 15 October 2026. Written for homes in England. Scotland and Wales use the same National Gas emergency number. Northern Ireland does not, and the Ofgem cap below does not set Northern Ireland bills. The Malta directory does not use these emergency numbers or Gas Safe.

This note does not inspect the radiators or the boiler. It is not a quote. You still choose a business and phone it yourself. Local Trades UK does not pass the job on.

Smell of gas, or a carbon monoxide alarm, comes first

If you smell gas, or a carbon monoxide alarm sounds while the heating is on, leave the radiator until the emergency line has been called.

National Gas publishes one line for that emergency in Great Britain, so England, Scotland and Wales use 0800 111 999. The call is free and open 24 hours, including a carbon monoxide emergency. Open doors and windows. Do not smoke or strike a match. Do not turn electrical switches on or off. Turn the meter off at the control handle unless the meter is in the cellar, and do not go into a cellar to reach it. If the alarm has sounded, National Gas also says to switch the appliances off, leave the property, and get medical help. Fresh air on its own does not treat exposure.

Northern Ireland uses a different number. nidirect says that if you smell gas, turn the supply off at the meter, open windows and doors, do not switch electrical equipment on or off, and phone 0800 002 001.

Either call is to the gas emergency service, not to a business on this directory. Who may work on the appliance afterwards is on who is allowed to work on gas in a home.

Why a cold radiator matters this fortnight

From 1 October to 31 December 2026, Ofgem says the price cap is 4% higher for a typical household on a default tariff who pay for electricity and gas by Direct Debit. On that tariff the average gas unit rate across England, Scotland and Wales is 7.97 pence per kWh, and the average daily standing charge is 29.68 pence. Both include VAT at 5%. Ofgem published the figures on 26 August 2026. A fixed tariff sits outside this cap. The bill still depends on how much gas the home uses, where it is, and the meter. These are the published averages. A repair price is the figure the business gives you on the phone. This page does not turn the average into a rate for one city.

Energy Saving Trust, in a guide dated 19 March 2026, says trapped air makes radiators less effective, and that turning the heating up to make up for it wastes energy. Finding the cold radiator on a mild day leaves time to book the repair before a cold week. National Gas’s general safety advice is to have gas appliances checked each year by a Gas Safe registered engineer. A first run that ends in a lockout is a reason to book that visit. Leave the boiler cover on.

The clocks go back one hour at 2am on 25 October 2026. GOV.UK lists that date for the UK. A programmer that does not change itself can leave every radiator an hour late after that Sunday. Energy Saving Trust describes a programmer as the control that sets when the heating comes on and off, and says the manual is the place for that model’s buttons. Read the timer before you treat a late start as a breakdown.

Read the radiator before you phone

Set the room thermostat above the temperature in the room and give the pipes time to warm. Then feel one radiator from top to bottom. Keep furniture and covers off the valve head. Energy Saving Trust says a cover can hold warm air around a thermostatic radiator valve, so the valve shuts that radiator while the room is still cool.

Cold only at the top

Energy Saving Trust says air collects at the top, and to check sooner if the tops stay cold or the pipes gurgle. Bleeding a cool radiator is a householder job. Their guide sets out the cloth, the key, and the moment you close the valve. This page does not repeat those turns. The safe range on the gauge afterwards is in the boiler manual. A combi can need a top-up after a bleed. If the gauge falls again over the following days, use a boiler that keeps losing pressure. If the gauge is already low when you start, read that note before you assume the radiator is the whole fault.

Warm at the top, cold across the bottom

Worcester Bosch describes the opposite pattern: hot at the top and cold at the bottom, usually sludge in the system water or poor circulation. Bleeding lets air out of the top. Worcester Bosch says only a heating engineer can confirm the cause in that house. Phone, and say which radiators are cold along the bottom.

Cold from top to bottom

Look at the thermostatic radiator valve before you book anyone. Energy Saving Trust says a TRV controls how much hot water enters that one radiator. A lower number means a cooler room, and the numbers are not one temperature on every model. A radiator in a room that has already reached its setting can feel cool because the valve has closed.

Phone a heating engineer when any of these are true:

  • The valve is open, other radiators are hot, and this one stays cold from top to bottom.
  • Several radiators stay cold on the same run.
  • The boiler locks out, or it shows a fault code, during the test.
  • The top goes cold again soon after a bleed, or the bottom stays cold.

HSE says a person who is not on the Gas Safe Register may install water pipes and radiators. Work on the gas boiler, and the final connection of the pipework to the boiler, has to be done by a Gas Safe registered engineer. Ask which part of the system they are coming to, and ask to see the ID card. The card shows the categories of gas work that engineer may do. A listing on this site prints Gas Safe only when the record already has it.

Where the phone number is

Open the plumbing and heating list, including London and Manchester. You phone, email, or use the website on the record. A reply is between you and the business.

If the engineer says the boiler should be replaced, what should be written on the quote is what sits inside a price for a replacement boiler. A heat pump grant in England and Wales is a separate question: whether the Boiler Upgrade Scheme is still open.

Sources

Questions on this fault

The top of one radiator is cold. Do I phone yet?

A cold top, or gurgling in the pipes, is the pattern Energy Saving Trust describes as trapped air. Bleed a cool radiator using their guide or the boiler manual, then look at the pressure gauge. Phone a heating engineer if the top goes cold again, or if the gauge will not stay in the range the manual marks. If you smell gas, or a carbon monoxide alarm sounds, call the emergency number in the first section before anyone looks at the radiator.

The bottom is cold and the top is hot. Should I bleed it?

Worcester Bosch says a radiator that is hot at the top and cold at the bottom is usually sludge or poor circulation, and that bleeding is the job for air at the top. Phone a heating engineer and describe which radiators feel cold along the bottom. This page cannot say whether the radiator, the pump or the system water is the part that needs the work.

The heating missed its usual time after the clocks went back. Who do I phone?

GOV.UK says the clocks go back one hour at 2am on 25 October 2026. If every radiator is late by about an hour after that Sunday, check the programmer before you book a breakdown. Energy Saving Trust describes the programmer as the control that sets when the heating comes on and off. If the timer and the room thermostat are both calling for heat and the radiators stay cold, phone a heating engineer.