Warm Air & Radiant Heater Repair | Factories & Warehouses

Q: How do I book or get a quote?

Call 0800 0996 007, WhatsApp 07947 578332, or email estimates@fastcommercialboiler.help with the site, fuel, make if known, mounting height if the heaters are suspended, and what is happening. A photo of the data plate and any fault code helps. Rates can be negotiated.

Heaters we work on

Gas-fired and oil-fired warm air heaters, floor-standing and suspended
Unit heaters in warehouses, loading bays and workshops
Radiant tube and plaque heaters in high-bay buildings
Space heaters and their controls, zone thermostats and time clocks

Common makes include Reznor, AmbiRad, Powrmatic, Benson, Space-Ray, Winterwarm and Combat. We are an independent engineer, not a manufacturer's appointed agent.

Typical faults

Lockout on ignition or flame failure, fans not starting or overheating, limit stats tripping, flue and combustion air faults, tube burners failing to light, and controls calling for heat that never arrives. Heaters in dusty production areas need regular cleaning, so an annual service makes a real difference.

See factories & warehouses for the wider picture, or commercial oil heating for oil-fired units.

Heater types in commercial buildings

Factories, warehouses, workshops and loading bays are often heated by warm air, unit or radiant heaters rather than a wet boiler system. The plant is usually mounted at floor level or suspended from the roof structure, and it heats the space directly instead of sending hot water around the building.

Floor-standing warm air heaters (gas, oil or LPG) draw air through a heat exchanger and discharge warm air into the space, often through ductwork or directional outlets. Larger units sit in a plant bay or at the end of a workshop.
Suspended warm air and unit heaters hang from the roof or wall brackets in warehouses and loading bays. They are compact, fire into a heat exchanger and blow warm air down into the working area.
Radiant tube heaters burn gas or LPG along a tube that radiates heat onto people and surfaces below, which suits high-bay buildings where heating the whole air volume would waste energy.
Radiant plaque heaters use a ceramic or metal plaque face that glows, giving localised heat for workstations, doorways and cold spots.
Destratification fans and controls push warm air that has risen to the roof back down into the occupied zone. Zone thermostats, time clocks and BMS signals decide when heaters fire; a healthy heater that never runs is often a controls problem, not a burner fault.

Common makes on commercial sites include Reznor, AmbiRad, Powrmatic, Benson, Space-Ray, Winterwarm and Combat. We are an independent engineer, not a manufacturer's appointed agent, so we diagnose and repair across those families rather than pushing one brand.

Symptom and fault guide

Ignition lockout: the heater tries to light, fails, and locks out. Causes include a dirty burner, weak spark or ignition electrode, gas valve not opening, or a flame sensor that cannot see the flame.
Flame failure during run: lights then drops out. Often combustion air restriction, flue issues, unstable gas pressure, or a failing flame detection probe.
Fan or limit trip: the overheat limit or fan proving switch has opened. Blocked filters, a seized circulation fan, closed discharge louvres, or a heat exchanger packed with dust are typical on warehouse units.
Flue and combustion air faults: terminals blocked by debris or nesting, flues crushed or disconnected, or intake air starved in a sealed plant enclosure. These are safety-critical and should not be reset and ignored.
Radiant tube not lighting: one burner on a multi-burner tube fails while others run; injectors, electrodes, gas solenoids or the local flue/air path for that section need checking.
Zone calling with no heat: thermostat, time clock or BMS is asking for heat but the heater never starts. Interlocks, enable relays, remote kill switches and wiring faults are common, especially after other contractors have been on site.
Dusty heat exchangers: production dust coats the exchanger and burners, raising flue temperatures, causing limit trips and cutting heat output. Cleaning on a planned service stops a lot of winter call-outs.

How a repair visit usually runs

Phone triage. When you call 0800 0996 007 we ask for the make and model if known, fuel (gas, oil or LPG), whether the heaters are floor-standing or at height, any fault code or lockout light, and whether access equipment is already on site.
Make safe. The engineer isolates the heater, checks for gas smell or oil leak, confirms the flue and combustion air path look intact, and only then starts diagnosis. Unsafe plant is left isolated with a clear note for the site.
Access. Suspended unit heaters and radiant tubes often need a MEWP, scissor lift or tower. We either use your site access or bring our own arrangements so work at height is planned, not improvised.
Combustion and safety checks. Ignition, flame detection, gas train or oil burner, fans, limit stats, flue integrity and combustion readings are checked before parts are condemned.
Repair. Faulty electrodes, fans, gas valves, burners, controls or flue components are repaired or replaced, the heater is fired and proved, and lockout history is cleared only when the cause is fixed.
Advise on PPM. You get a note of what was found and whether an annual service or a planned preventative maintenance visit would reduce repeat lockouts, especially on dusty sites. See commercial boiler servicing and planned preventative maintenance.

Engineers come from our team of over 10 local engineers, based at CO10 8NN near Sudbury and covering commercial sites across Suffolk, Essex and Cambridgeshire.

Safety and compliance

Gas and LPG: warm air, unit and radiant heaters fired on natural gas or LPG are worked on under the Gas Safety (Installation and Use) Regulations 1998 by Gas Safe registered engineers. All our gas work is carried out under registration 985448.
Oil: oil-fired warm air heaters are handled by our OFTEC trained engineers, with combustion and safety checks suited to oil burners and flues.
Working at height: many warehouse heaters are above forklift reach. Access must be planned; we will not work from unsafe ladders or improvised platforms.
Flue clearances: terminals need clear discharge and combustion air. Blocked, crushed or poorly terminated flues are a carbon monoxide risk and are treated as urgent.
Commercial only: we do not take on domestic warm air or domestic boiler work. Factories, warehouses and commercial workshops are our focus; see also factories and warehouses.

Repair, replace, or put it on a service plan?

Most warm air and radiant heater faults are put right with a repair: cleaning, electrodes, fans, gas valves, burners or controls. Replacement is worth considering when a heat exchanger is cracked or holed, when the cabinet or flue path is badly corroded, when parts for that model are obsolete, or when several heaters of similar age are failing in the same building. In those cases we give you a written comparison of repair against replacement.

An annual service or a PPM visit pays for itself on dusty sites: clean heat exchangers, proved safety devices and working controls mean fewer winter lockouts. For regular servicing see commercial boiler servicing, for planned programmes see planned preventative maintenance, and for how we cover industrial buildings see factories and warehouses.

Questions we get asked

Do you service warm air heaters as well as repair them?

Yes. A service includes cleaning the heat exchanger and burners, combustion and flue checks, testing safety devices such as limit stats and flame failure, and checking fans, filters and controls. Regular servicing cuts down on lockouts in dusty warehouses and workshops.

Can you work on radiant tube heaters at height?

Yes. Radiant tubes and plaque heaters are often mounted high in the roof space, so we bring suitable access equipment or work with your site's access arrangements. Tell us the mounting height and whether a MEWP or scissor lift is already on site when you book.

Do you cover oil-fired warm air heaters?

Yes. We work on oil-fired as well as gas and LPG warm air and unit heaters. Oil plant is handled by our OFTEC trained engineers, and gas or LPG plant under our Gas Safe registration 985448.

Why does our warehouse heater keep locking out on ignition?

Ignition lockout on a warm air or unit heater often means a dirty burner, weak spark, poor combustion air, a flue problem, or a gas valve that is not opening cleanly. Dusty production areas make this worse. We diagnose the cause rather than repeatedly resetting the heater.

Our radiant tube heaters light at one end but not the other. What does that mean?

On multi-burner or longer radiant tubes that can point to a burner that will not light, a blocked injector, a failed ignition electrode, or a flue/combustion-air issue on that section. We check each burner in turn and the common gas and control feed.

Do you repair controls and zone thermostats as well as the heaters?

Yes. Heaters that will not run are often being held off by a time clock, zone thermostat, BMS signal or interlocking safety circuit. We check the call for heat as well as the heater itself so you are not replacing parts that were never the fault.

When should we replace a warm air heater instead of repairing it?

Repair is usually the right first step. Replacement is worth considering when the heat exchanger is cracked or corroded through, when major parts are obsolete, or when several heaters of the same age keep failing. We give you a written comparison. For ongoing care see our commercial boiler servicing and planned preventative maintenance pages.

Are you Gas Safe registered for gas warm air and radiant heaters?

Yes. All gas and LPG work is carried out under Gas Safe registration 985448, in line with the Gas Safety (Installation and Use) Regulations 1998. Oil-fired units are worked on by our OFTEC trained engineers. We are commercial only.

How do I book or get a quote?

Call 0800 0996 007, WhatsApp 07947 578332, or email [email protected] with the site, fuel, make if known, mounting height if the heaters are suspended, and what is happening. A photo of the data plate and any fault code helps. Rates can be negotiated.

Warm air, radiant & unit heater repair