How to install in row cooling units

Let’s cut to the chase: you’re buying in-row cooling units, or you’re a dealer who needs to show your customers how to install them properly. In-row cooling isn’t just for hyperscale data centers anymore. It’s showing up in mid‑size server rooms, pharmaceutical cleanrooms, and even some manufacturing plants where heat density is climbing. If you get the installation wrong, you’ll face hot spots, compressor failures, and unhappy clients. So here’s the real deal—step by step, no fluff.

Before you start: what you need to know about in‑row cooling units

In-row cooling units sit directly between server racks or equipment rows. They pull hot exhaust air from the back of the racks, cool it, and discharge cold air into the cold aisle or directly to the front of the equipment. This is fundamentally different from traditional perimeter CRAC units that cool the whole room. In-row units are closer to the heat source, which gives them better efficiency and allows you to handle densities up to 50 kW per rack or higher, depending on the model.

But you cannot just drop a unit on the floor and plug it in. Here are the key factors that affect every installation:

1. Floor loading and subfloor clearance
Most in-row units weigh between 200 kg and 600 kg when fully charged. If you’re installing on a raised floor, verify the floor panels and pedestals can handle the point load. For example, a typical 25 kW in-row unit like the Vertiv Liebert XDC weighs about 350 kg. Standard raised floor tiles with a static load rating of 680 kg are fine, but older tiles rated at 450 kg may crack. Also, check if the unit needs a seismic base if you’re in an earthquake zone—many customers skip this and regret it.

2. Cooling capacity and air flow requirements
Every unit has a rated cooling capacity at a certain supply air temperature. For instance, a 35 kW unit at 18 °C supply air can handle roughly 10 to 12 server racks with 3 kW each. But that assumes the airflow path is clear. You need to calculate the total heat load of the row and select a unit with at least 20% safety margin. Don’t forget that the unit itself consumes power—typically 3 kW to 5 kW for the fans and compressor.

3. Piping and electrical requirements
In-row units can be air‑cooled, water‑cooled, or chilled‑water. The most common for small/medium sites is chilled‑water or glycol‑cooled systems because they are simpler to install. But if you’re using a direct expansion (DX) system, you need a remote condenser located outside, and the refrigerant lines must be sized correctly. For chilled water, you need supply and return pipes with proper insulation, usually 1‑inch or 1.5‑inch diameter depending on flow rate. Electrical requirements: most units require 208V or 480V three‑phase power. Single‑phase models exist for small capacities but are rare for over 20 kW.

4. Environmental conditions
The unit’s operating range matters. Typical in-row units can handle ambient temperatures from 18 °C to 32 °C at the air intake, but if your customer’s server room is poorly insulated or has high humidity, you may need to add a pre‑cooling coil or dehumidifier. Also, keep the unit away from direct sunlight or hot walls.

5. Manufacturer documentation
Always read the installation manual. I know it sounds boring, but every brand has specific requirements for clearance, airflow direction, and control wiring. For example, some units require 600 mm clearance on the front for service access, others need 800 mm. Ignore that and you’ll end up cutting drywall later.

Step‑by‑step installation process for in‑row cooling units

I’ll walk you through a general procedure that applies to most brands like Vertiv, Schneider, Rittal, or your own Chinese‑manufactured units. Adjust according to your specific product.

Step 1: Site preparation

Deliver the unit to the installation area as close as possible to its final position. Unpack it on a flat, clean surface. Check for any shipping damage—dents, broken pipes, or loose screws. Document with photos for insurance. Then:

• Level the area. Use a laser level or a long spirit level. The floor must be flat within 3 mm per meter. If it’s not, you’ll get vibration noise and premature bearing wear.
• Mark the positions for electrical conduits, pipe openings, and drain lines. If you have a raised floor, cut the tiles carefully. Use floor grommets to protect pipes.
• Install any seismic bracing or floor anchors if required by local code.

Step 2: Position the unit

Roll or lift the unit into its final location. Most units have casters or feet. If using casters, lock them after positioning. If using adjustable feet, screw them down until the unit is stable and level. Do not skip the anti‑vibration pads—they reduce noise transmission and keep the neighbors happy.

For a row installation, the unit should sit in line with the server racks. The hot aisle side (usually the back of the unit) should face the hot aisle, and the cold aisle side (front) should face the cold aisle. Some units can be reversed in the field. Double‑check the airflow arrows on the unit.

Step 3: Connect chilled water or refrigerant piping

For chilled‑water systems:

• Shut off the main water supply. Purge the pipes with compressed air to remove debris.
• Connect the supply and return lines using flexible hoses or rigid copper pipes. Flexible hoses are easier for alignment but must be rated for 10 bar and 90 °C minimum.
• Install a strainer in the supply line before the unit to catch any particles. A missing strainer is the number one cause of clogged heat exchangers.
• Use a pressure gauge and flow meter to verify the design flow rate. For example, a 35 kW unit with a ∆T of 5 °C needs about 6 m³/h of water.
• Insulate the piping completely to prevent condensation. Use closed‑cell insulation with a thickness of at least 13 mm for chilled water at 7 °C supply.

For DX systems:

• Run the refrigerant lines from the outdoor condenser to the unit. The lines must be clean, dry, and free of leaks. Use brazed joints with nitrogen purge to prevent oxidation.
• Calculate the line length and elevation difference. Most compressors can handle up to 30 m vertical lift and 50 m total equivalent length. Exceed that and you’ll need an oil trap.
• Evacuate the system to below 200 microns before charging. Charge the refrigerant according to the nameplate (usually R‑410A or R‑134a).

Step 4: Electrical connections

Always lock out/tag out the circuit breaker. Use a licensed electrician if you’re not one.

• Connect the main power cable to the unit’s terminal block. Follow the wiring diagram. Most units need a ground wire and a neutral (for 3‑phase wye systems).
• Install a dedicated circuit breaker sized per the unit’s maximum fuse rating. Example: a 35 kW unit at 480V draws about 45 A, so you need a 60 A breaker.
• Connect the control wiring for the thermostat, BMS interface (BACnet or Modbus), and any external sensors. Some units require a remote temperature sensor placed in the cold aisle to modulate cooling.

Step 5: Drain connection

In‑row units produce condensate if the supply air temperature is below the dew point. Even chilled‑water units can sweat in humid climates. Connect the drain line to a floor drain or a condensate pump. The drain must have a P‑trap to prevent air from flowing backward. Test by pouring a bucket of water into the drain pan—no leaks.

Step 6: Commissioning and testing

Power up the unit. Set the controller to the desired supply air temperature (typically 20 °C to 22 °C for data centers). Let the unit run for at least 30 minutes.

• Check for error codes on the display.
• Measure the supply and return air temperatures with a handheld thermometer. The delta should be within the unit’s specs (usually 10 °C to 15 °C for DX, 5 °C to 8 °C for chilled water).
• Check the air flow using a vane anemometer. Many units have a built‑in speed sensor; verify it matches.
• Listen for abnormal noises like grinding or hissing. If you hear gurgling, you probably have air in the water pipes. Purge the air using vent valves.

Common mistakes to avoid when installing in‑row cooling

I’ve seen these errors hundreds of times, both in China and abroad. They cost time and money.

Mistake 1: Ignoring the hot‑aisle/cold‑aisle containment
An in‑row unit only works well if the hot and cold air are separated. If the server room has open racks with no containment, the unit will recirculate hot air and never reach its rated capacity. Always install blanking panels, brush strips, and a physical barrier between the hot and cold aisles. Without containment, you’re wasting the unit.

Mistake 2: Undersizing the piping
Customers often use the same pipe size as for perimeter units. But in‑row units have higher flow rates. A 3/4‑inch pipe may be fine for 10 kW but will cause high pressure drop and reduced cooling for 35 kW. Use the manufacturer’s pipe sizing chart. Here’s a quick reference table:

Mistake 3: Placing the unit too close to a wall or rack
Every unit needs clearance for both airflow and service. The manufacturer usually specifies minimum distances. For example, a common requirement is 600 mm in front and 300 mm in the back. If you squeeze it, the fans will struggle and the compressor may overheat. Also think about future maintenance—you need room to pull out a filter or replace a fan motor.

Mistake 4: Forgetting the condensate pump
If the drain line runs uphill or into a ceiling, you need a condensate pump with a reservoir. Many cheap units don’t include one. Install it inside the unit or nearby. And make sure the pump has an alarm contact that shuts down the cooling if the reservoir overflows. otherwise you get water damage.

Mistake 5: Not balancing the air flow across the row
When you have multiple in‑row units in a long row, the air flow distribution can become uneven. The middle rack might get less cold air because the closest unit takes the path of least resistance. Use directional baffles or variable‑speed fans to balance. Some advanced controllers can do this automatically via pressure sensors.

Maintenance and commissioning after installation

Once the unit is running, write down the baseline readings: supply air temperature, return air temperature, pressure, fan speed, and compressor current. These numbers will help you detect problems later.

Filter replacement – Change the air filters every 3 to 6 months, depending on cleanliness. Dirty filters reduce air flow and increase energy consumption. Use MERV 8 or higher for data centers.

Coil cleaning – Over time, the evaporator coil (or water coil) collects dust. Spray it with a non‑corrosive coil cleaner every year. Never use high‑pressure water directly on fins—they will bend.

Refrigerant leak check – If you have a DX unit, check the refrigerant pressure and superheat every 6 months. A small leak can cause the compressor to cycle more often and wear out faster.

Condensate drain – Pour water down the drain pan quarterly to flush out algae or debris. If you see mold, treat with diluted bleach.

Firmware updates – Many smart controllers now have Wi‑Fi or Ethernet. Update the firmware to get the latest energy‑saving algorithms. Some brands release updates that optimize fan curves for part‑load conditions.

Professional commissioning checklist for dealers
When you hand over the system to the end user, provide a commissioning report that includes:

• Model and serial number
• Design conditions vs. measured conditions
• Power consumption at full load
• Air flow profile (front to back)
• Leak test certificate for refrigerant or water piping
• Photos of the installation

This report builds trust and reduces liability.

Frequently asked questions about in‑row cooling installation

Q: Can I install an in‑row cooling unit on a concrete slab floor without a raised floor?
A: Yes, you can. Many industrial facilities and small server rooms use slab floors. Just make sure the unit’s bottom clearance is enough for airflow. Some units have a plenum that pulls air from under the floor; if there’s no raised floor, you need a ducted inlet or the unit must be designed for front‑to‑rear airflow.

Q: What is the typical lifespan of an in‑row cooling unit?
A: Most units last 10 to 15 years with proper maintenance. The compressor and fans are the main wear items. If you replace them after 8 years, the unit can easily run 20 years. However, obsolescence of control boards often pushes upgrades earlier.

Q: How do I calculate how many in‑row units I need for a row of 20 racks?
A: First, find the total IT load. For example, if each rack averages 5 kW, total is 100 kW. Add a 20% safety margin, so 120 kW cooling needed. If one unit delivers 35 kW, you need 4 units (120/35 = 3.4, round up). But also consider redundancy—usually N+1 configuration, so install 5 units.

Q: Do I need a separate chilled water pump for in‑row units?
A: Yes, unless the existing building chilled water loop has enough pressure. Most in‑row units need a differential pressure of 40 kPa to 100 kPa at the unit’s inlet. If the main loop is far, you’ll need a booster pump. Always check the pressure at the unit’s connection point.

Q: What happens if the in‑row unit loses power – will the servers overheat?
A: Typically, server fans will still pull air through the racks, but the hot air won’t be cooled. If power outage lasts more than a few minutes, the room temperature can rise quickly. Install a UPS for the cooling unit’s control board and pump, or connect the unit to a standby generator. Many modern units have a “free cooling” mode that uses ambient air if the outdoor temperature is low.

Q: Can I mix different brands of in‑row units in the same row?
A: Technically yes, but it’s not recommended. Each brand has different control algorithms, fan curves, and sensor locations. You may get conflicting signals and poor coordination. Stick to one brand per row for best performance.

That’s the straight talk on installing in‑row cooling units. No metaphors, no sales pitch. Just the nuts and bolts. If you’re a dealer, bookmark this guide and share it with your customers when they ask about installation. It’ll save you dozens of tech support calls. And if you manufacture the units, make sure your own installation manual is this detailed—your clients will appreciate it.