Radiator Replacement & Installation in North West London

Cold at the top, cold at the bottom: what is the radiator telling you?

Where a radiator is cold tells you what is wrong with it. Feel it with the heating fully on. Cold at the top and hot at the bottom means air is trapped. Bleeding it with a radiator key usually fixes it. If one radiator needs bleeding every few weeks, air or gas is getting into the system, and that needs finding. Hot at the top and cold at the bottom means sludge, the black iron oxide that builds up inside steel radiators when a system has run without enough inhibitor.

Bleeding will not help. The radiator can be taken off the wall and flushed through outside, or replaced if it is badly corroded. Cold all over while others are hot is usually a valve. A TRV pin can stick shut after a summer off, or the lockshield valve at the other end may be closed. If every radiator is cold, the problem is at the boiler or pump, which is a heating engineer's job.

Like-for-like swap or a bigger radiator?

Replace like for like if the room was warm enough before. Measure the existing radiator's pipe centres, the distance between the two valve connections, because a radiator with the same centres goes straight onto the existing valves with no pipework changes. Upsize if the room never reaches a comfortable temperature. Radiators are rated by heat output in watts, and output depends on the panel type as much as the size. A double-panel radiator with fins gives far more heat than a single panel the same size.

We work from the room's dimensions, its outside walls and its windows to check the output needed before ordering, rather than guess from the old one. A bigger radiator in a cold room is worth considering if the house might move to a heat pump later. Heat pumps run at lower water temperatures, so radiators sized more generously suit them better.

Moving a radiator: what is involved?

Moving a radiator means new flow and return pipes to the new position, so the cost depends on the route. On a suspended timber floor, which most interwar semis have downstairs, we lift boards and run new pipe between the joists. On a solid concrete floor, pipes are run along the skirting, chased into the wall or brought down from above. We also check the size of the existing pipes. Some houses fitted out in the 1960s and 1970s use microbore pipe, which is much narrower than standard 15 mm pipe and limits how much heat a radiator on that branch can deliver.

A larger replacement on microbore may not perform as its rating suggests. GOV.UK lists adding extra radiators to a heating system as work that may need building regulations approval. If your job falls into that category, we tell you at quote stage.

TRVs, lockshields and balancing

A thermostatic radiator valve turns the radiator down as the room warms up. The other valve, the lockshield, sets how much water the radiator can take and should only be adjusted when balancing. Approved Document L, the building regulations guidance on energy use, says that when a boiler is replaced in an existing home each room should have thermostatic control, typically a room thermostat in one room and TRVs on the other radiators.

TRVs should not be fitted in the same room as the thermostat, or the two fight each other. Balancing matters most after new radiators go in. Without it, the radiators nearest the boiler take most of the flow and the furthest ones stay lukewarm. We balance by closing the lockshields down on the near radiators until each one heats evenly.

Draining down, inhibitor and sludge

Most radiator swaps involve draining at least part of the system, and every drain-down dilutes the inhibitor. Inhibitor is a chemical added to the heating water to slow the corrosion that turns into sludge. We add fresh inhibitor after refilling. Approved Document L asks for central heating circuits to be cleaned and flushed, with a suitable inhibitor added, before a new heating appliance is installed, and for systems to be prepared and commissioned to BS 7593. That standard is the code of practice for treating water in domestic heating systems.

Where sludge is confined to one or two radiators, flushing them off the wall works. Where the whole system is heavily sludged, a system clean that involves the boiler circuit is a heating engineer's job, and we will refer you to one. We also check whether the system is sealed, topped up from the mains to the pressure set by the boiler maker, or open-vented, fed from a small tank in the loft.

Landlords: what heating must a rented home have?

Landlords must keep the installations for space heating and heating water in repair and proper working order, under section 11 of the Landlord and Tenant Act 1985, for most tenancies under seven years. A radiator that will not heat is a repair the landlord pays for. The health and safety rating system councils use for rented homes treats excess cold as a hazard. The government's landlord and agent guide to the system, published in June 2026, gives a baseline: heating in good, safe condition that can warm all habitable rooms, bathrooms and toilet rooms, with the main living room at 21°C and other habitable rooms at 18°C when it is minus 1°C outside, and heating the occupier can control and time.

The guide says these baselines are not mandatory standards, but anything below them will not generally be considered acceptable. The same guide gives an excess cold hazard caused by the lack of a properly installed heating system as an example that may warrant an improvement notice. A room with no working radiator, or one too small to warm it, is best put right between tenancies.

What decides the price of radiator work?

The number of radiators and whether they go onto existing pipework. A like-for-like swap with matching pipe centres is the simplest job. Different centres mean the tails or pipework must be altered. Moving a radiator adds the pipe run, and floor type matters: lifting boards is quicker than working round a concrete floor.

Draining a large system, valves seized onto old pipework, and designer or column radiators that need extra support also add time. A defined radiator job is priced as a fixed price before we attend.

Certificates and defined jobs are a fixed price confirmed before we attend; repairs are charged by the hour, with the rate and an estimate confirmed before we attend.

Radiator work across Harrow and north west London

We replace and move radiators across Harrow, Kenton, Stanmore and Edgware, and in Pinner, Hatch End, Harrow Weald, Wealdstone, Kingsbury, Queensbury, Wembley, Mill Hill and the neighbouring areas. Many homes here are interwar semis whose heating was added decades after they were built, so pipe runs and radiator sizes vary room to room.

Rooms over garages and in loft conversions are often the cold ones, and a correctly sized radiator usually fixes them. Between tenancies is the easiest time to swap radiators in a let property.

Plumbing by area: Plumbers in Harrow, Plumbers in Kenton, Plumbers in Stanmore, Plumbers in Edgware, Plumbers in Bushey, Plumbers in Colindale, Plumbers in Hendon, Plumbers in Mill Hill, Plumbers in Northolt, Plumbers in Northwood, Plumbers in Pinner, Plumbers in Ruislip and Plumbers in Wembley.

What we do not do

We do not service, repair or install boilers. If no radiators heat, the boiler shows a fault code, or the pump or controls have failed, you need a Gas Safe registered engineer for gas boiler work, and we will tell you so. We do not install underfloor heating or heat pumps. A whole-system clean that involves the boiler circuit is also referred to a heating engineer. Damp in a cold room is a separate question, and we do not carry out damp investigations.

Why people trust us

• Repairs tested before we leave, and the area left clean
• A walk-in office on Kenton Lane, not a serviced address
• We diagnose first and tell you what we have found before doing more
• A time slot rather than a morning-or-afternoon window
• Work photographed before and after, and reported
• We tell you when you do not need something we sell

We are building a review profile under this name and would rather show you none than borrow someone else's. Ask us for references from landlords and we will put you in touch.

Official sources

• GOV.UK: When you need building regulations approval (adding radiators, heating systems)
• GOV.UK: Approved Document L, Volume 1 Dwellings (2021 edition incorporating 2023 amendments)
• MHCLG: Landlord and agent guide to the Housing Health and Safety Rating System (published 23 June 2026)
• legislation.gov.uk: Landlord and Tenant Act 1985, section 11

Last reviewed October 2026 by EliteShires Property Services.