Knowledge base
In short
A dry cooler should stand where it can draw fresh outside air freely and where its warm discharge air cannot come back to the inlet. Roofs and open ground both work if there is enough free space around the unit, no walls or screens close in the air, and no exhausts or other hot equipment nearby. The position is best agreed with the maker before the layout is fixed, because a poor position takes cooling away on exactly the hottest days.
The data sheet of a dry cooler assumes one thing that nobody can see on the drawing: that the air reaching the coil is the outside air of the weather report. On site that is often not true. A unit squeezed into a corner of the roof, boxed in by a screen wall or placed downwind of a generator exhaust breathes air that is warmer than the day, and it delivers less than it was bought for. This guide explains in plain words what makes a good position for a dry cooler, on a roof or on the ground, and what to settle with the maker while the layout can still be changed.
The Air It Breathes Is The Air It Works With
A dry cooler hands the heat of the liquid to the air that its fans pull through the coil. The cooler that air is, the more heat the unit can take away. Every bit of extra warmth at the inlet, whatever its source, comes straight off the cooling.
The most common source is the dry cooler itself. Its discharge air leaves warmer than it arrived, and if the layout lets that air drift back to the inlet the unit starts feeding on its own exhaust. This is called recirculation, and it is the reason a unit that was sized correctly can still run short on a hot afternoon. It rarely shows on a mild day, which is why it is often found only in the first summer.
Roof Or Ground
A roof usually gives clean air, distance from people and no risk of the unit being hit by vehicles. It also brings its own questions: the structure has to carry the weight and the vibration, the liquid has to be pumped up and back, service needs a safe way up and a safe place to stand, and roofs tend to collect other equipment such as chillers, extract fans and flues that all compete for the same air.
Ground installation makes delivery, lifting and maintenance easier and keeps the pipework short when the plant room is at ground level. It needs a plot where the air can come in freely from below and from the sides, away from buildings that block the wind or throw it back. Fallen leaves, dust from roads and stored materials and, on some sites, snow piling against the unit are more of an issue at ground level than on a roof.
Neither position is better in general. The site decides, and quite often the space that is left over after everything else has been placed is not the space where the dry cooler works best.
Walls, Screens And The Next Unit
Walls and screens are the usual cause of trouble. A high parapet, an acoustic screen or a decorative enclosure around the units can look tidy, but it limits how the fresh air comes in and holds the warm air in the space where the fans draw from. If a screen is needed for sound or for looks, it should be planned together with the dry cooler, with open area and distance agreed, and not added after the order.
Several units side by side work well when they stand in a line with their discharges all going the same way and enough room between and around them. Placed too close, or with one unit downwind of another, the units at the back of the group see warmer air than the ones at the front. The same applies to other heat sources: generator and boiler exhausts, kitchen and toilet extracts, condensing units and cooling towers should not blow toward the dry cooler inlet, and the dry cooler should not blow toward their intakes either.
Wind, Access And What To Show The Maker
Wind can help or hurt. A steady wind across an open site carries the warm air away, but a wind that pushes the plume back over the unit, or a building that throws a downdraught onto the roof, does the opposite. Knowing the prevailing wind and the heights of the buildings around the unit lets the layout face the right way.
Service is the last point that tends to be forgotten. Fans, motors and coil faces need to be reached and cleaned, and there must be room to lift out a fan or a motor without dismantling the neighbours. A layout drawing with the free space marked around each unit saves a lot of trouble later.
TECS Engineering designs and builds dry coolers and radiators for engine, power plant, data center and industrial cooling. Send a site plan or a roof plan with north, the prevailing wind, the walls and screens, and any exhausts or other equipment nearby, together with the heat load and the liquid data, and the engineering team will check the position along with the unit.
In Short
- A dry cooler only reaches its rating with fresh outside air at the inlet
- Warm discharge air coming back to the inlet (recirculation) is the most common site problem
- Roofs give clean air but need structure, access and a pumped pipe run
- Ground sites ease delivery and service but need free air from all sides
- Screens, parapets and closely spaced units hold warm air at the inlet
- Keep exhausts, extracts and other heat sources away from the inlet
What To Send With An Enquiry
- The heat load and the liquid with its temperatures and flow
- A site or roof plan with north, the prevailing wind and the space available
- Walls, parapets, screens and other buildings around the position, with their heights
- Nearby exhausts, extracts, chillers, cooling towers or other heat sources
- Site climate, altitude and any sound limit with the place it applies to
- How the units will be lifted in and reached for service
Questions We Are Often Asked
Is it better to put a dry cooler on the roof or on the ground?
Either can work. A roof usually gives cleaner air and more distance from people, the ground gives easier access and shorter pipework. The free space around the unit and what stands near it matter more than the level.
What is recirculation in a dry cooler?
It is when the warm air leaving the unit comes back to its inlet. The coil then works with air warmer than the outside air and the dry cooler cools less, mostly on the hottest days.
Can a dry cooler be placed inside a screen or an enclosure?
Yes, if the screen is planned with the unit so that enough fresh air can come in and the warm air can leave freely. A screen added later often costs cooling.
How close can several dry coolers stand to each other?
That depends on the units, their direction and the site. They should stand in a clear line with enough free space so that no unit draws the warm air of another. The maker should check the layout.
What should I send so the maker can check the position?
A site or roof plan with north and the prevailing wind, the walls and screens around the position, any exhausts or heat sources nearby, the heat load and the liquid data.
Contact Us
Send us the heat duty, the fluid temperatures and flow rates, the ambient conditions and the installation limits. We answer with a design proposal - or write to us on WhatsApp.
