Rooftop units
in Malaga.

Advantages over VRF and conventional ducted systems

Compared with a VRF system or several ducted units spread around, a rooftop unit wins in buildings with volume. All the plant is on the roof: no false ceilings or plant rooms taken up, no refrigerant pipework running through the building (fewer potential leak points and less gas to declare under F-Gas rules) and all the maintenance concentrated in one accessible place. Installation is quicker than an equivalent VRF because the unit arrives assembled and factory-tested.

It also does, as standard, what other systems need extra kit for: fresh air (mixing outside air with return air according to demand) and free-cooling, which means cooling with outside air alone whenever it's cooler outside than in, without starting the compressors. In Malaga, with mild nights and long shoulder seasons, a well-controlled rooftop unit with free-cooling saves a lot of compressor hours a year in a gym or a supermarket that opens early.

When it isn't the answer

A rooftop unit conditions one large area to one temperature. If the building has lots of rooms with different uses and hours (hotel, cellular offices, clinic), VRF with room-by-room control does the job better. If there is no accessible roof or the structure can't take the weight, there are versions for ground or plant-room installation with a centrifugal fan, but it needs studying. And if your process needs chilled water, the answer is a chiller. We'll tell you on the site visit: we sell the machine that fits, not the heaviest one.

How a rooftop unit is sized

Choosing a rooftop unit isn't choosing kilowatts. It means choosing air flow, cooling and heating capacity, fresh-air rate and available static pressure for the ductwork. We start from the real heat load of the building (floor area, height, insulation, orientation, glazing, occupancy, machinery and lighting), the outdoor air rate Spanish regulations (RITE) require for the use and occupancy, and the hours of operation. From there we select the unit, the number of zones if it runs with dampers, and the type of fan.

Manufacturers' ranges go from units for a medium-sized shop to machines of several hundred kW for sports halls and shopping centres. In our proposal you get the model, its air flow and its capacity with the manufacturer's data sheet, never a round number. Options we consider case by case: inverter compressors, EC variable-speed fans, heat recovery on the fresh air, CO₂ sensor control, active dehumidification (essential in gyms and in supermarkets with open multideck cabinets) and low-GWP refrigerants to stay comfortably within F-Gas rules.

Roof installation: frame, crane, ductwork and electrics

Installing a rooftop unit is a small four-trade project, and we do all of it with our own staff. Roof and structure: we check the load-bearing capacity, fit the base frame or anti-vibration mounts and seal the duct penetrations. Lifting: a crane or lorry-mounted crane, with a road-occupation permit when needed, at a time that doesn't interrupt your business. Ductwork: supply and return ducts calculated by size and velocity, with grilles or long-throw nozzles for high-bay warehouses, and zone dampers if the space calls for them. Electrics: a dedicated supply from the main board, protection and, if your contracted capacity falls short, the upgrade with the distribution company. We finish with commissioning, air flow balancing and a written test protocol.

Replacing old rooftop units

Plenty of supermarkets, gyms and warehouses around Malaga still have a rooftop unit that is fifteen or twenty years old on the roof: it uses far more power than it should, runs on a refrigerant that can no longer be topped up freely, and breaks down in July. Replacing it is simpler than it looks. We reuse the ductwork and the electrical supply when they are in good condition, adapt the base frame to the new unit and do the swap on a closing day or overnight. The refrigerant in the old unit is recovered as the rules require and disposed of as waste. Lower running costs and fewer breakdowns usually pay for the new unit sooner than people expect.

Rooftop unit maintenance

A rooftop unit lives outdoors: sun, salt air on the coast, dust, birds. Without maintenance the coils get dirty, the filters clog, free-cooling stops working because the damper seizes, and consumption climbs without anyone noticing from below. Our contract covers coil and filter cleaning, compressor, fan and belt or EC motor checks, damper and sensor checks, F-Gas leak checks according to the charge, and the log the RITE requires. On a roof, at least twice a year; on the coast, extra attention to the condenser.