Alright, let’s get straight into it. You’re a distributor, a contractor, or maybe a facility manager who needs to know exactly how to put an inrow cooling unit into service. I’m not going to waste time with fluff. Inrow units are becoming the go‑to solution for high‑density server racks, especially when you’re dealing with 20kW to 60kW per rack in modern AI and HPC clusters. The global inrow cooling market hit about 1.8 billion USD in 2023 and is projected to grow at 12% CAGR through 2030, according to a report by MarketsandMarkets. So if you’re in the business of supplying these units, you need to master the installation process. Here’s a step‑by‑step breakdown that’s practical, not theoretical.
Site prep and what you need before you touch the unit
You don’t want to start unpacking a 500‑pound cooling unit only to realize the floor can’t handle it or the pipes don’t fit. First thing: check the load capacity of your raised floor. Most inrow units weigh between 400 and 700 kg (880 to 1540 lbs). The floor tiles and support structure should be rated for at least 1500 kg/m². If you have a concrete slab floor, you’re fine, but still verify that the unit’s footprint doesn’t exceed the floor load rating. Use a load‑bearing plate if needed.
Next, measure the physical space. Inrow units are designed to fit between server racks, usually in a row of 600mm or 700mm wide racks. The unit itself is typically 600mm wide, 1100mm deep, and around 2000mm tall. Leave at least 200mm clearance at the back for airflow and service access. Also account for front access – you need about 800mm in front of the unit to open the door and reach the controls.
Power requirements vary. For a 50kW unit, you’re looking at a 3‑phase 380–480V AC input, 60A to 80A per phase. Make sure your PDUs and breakers are sized correctly. Most modern inrow units come with dual power feeds for redundancy. Each power cord needs its own breaker. Don’t forget to check the Earth leakage – some units have built‑in RCDs, but local codes may require additional protection.
Now the cooling medium. Inrow units can be chilled water, direct expansion (DX), or pumped refrigerant. Each has different connection requirements. For chilled water units, you need water supply and return lines with proper insulation. Typical supply water temperature is 12–18°C, return 18–25°C. Flow rate for a 50kW unit is about 8‑10 m³/h at a 5°C delta T. For DX units, you need refrigerant lines (usually R410A or R454B, now trending toward low‑GWP refrigerants like R32). The lines must be sized according to the manufacturer’s table, with proper oil traps if the vertical lift exceeds 5 meters.
A quick real‑world reference: In 2024, ASHRAE updated its thermal guidelines for data centers, allowing supply air temperatures up to 27°C for class A1–A4 equipment. That means you can raise the chilled water temperature to 18°C, improving chiller efficiency. But your inrow unit’s controls must support that setpoint range.
Essential tool and component checklist
| Tool / Component | Purpose | Notes |
|---|---|---|
| Forklift or pallet jack (load capacity ≥ 1000 kg) | Moving the unit from truck to installation spot | Use soft slings, never lift by the refrigerant lines |
| Torque wrench (20–100 Nm) | Tightening flange bolts and electrical terminals | Follow manufacturer’s torque specs |
| Refrigerant manifold gauges | DX units: checking pressures, charging | Use for R32 with proper adapters |
| Water flow meter and thermometer | Chilled water units: balancing flow | Measure flow in L/min, temp in °C |
| Network cable (Cat6a) and RS485/USB converter | Connecting the unit to BMS or controller | Pinout varies by brand |
| Bubble level (2‑foot) | Leveling the unit | Inrow units must be level within 2mm per meter |
| Pipe insulation (closed‑cell, 10–20mm thick) | Chilled water lines: prevent condensation | For supply temp below 18°C, thickness ≥ 15mm |
| Vacuum pump (≥ 5 CFM) | DX units: pulling vacuum before charging | Target < 500 microns |
Don’t skip these. I’ve seen installations fail because the crew used a cheap tool that slipped and damaged a pipe. One more thing: check the ambient conditions of the room. The unit’s condenser (if it’s a self‑contained DX model) needs outdoor or conditioned space air intake. Or you may have a remote condenser – then you need to run interconnecting piping to the outside.
Physical installation: lifting, positioning, and leveling
Let’s talk about getting the unit in place. First, remove the unit from its crate. Inspect for any shipping damage. Report any dents or bent fins immediately – don’t proceed. Use a forklift with a long enough fork to reach under the unit’s base. Most inrow units have forklift slots at the bottom. Insert forks from the front or back, not the sides, to avoid hitting the control box.
If you’re moving it into a tight aisle, use a pallet jack instead. But note: the unit’s weight distribution might make it tip forward if the jack is too short. Secure the unit to the jack with straps. Move slowly, especially over raised floor tiles. One wrong bump and the unit could tilt.
Once at the location, position the unit exactly between the racks. It should align with the front of the racks – the front door of the unit should be flush with the rack front doors. That ensures proper air containment. If you’re using a hot‑aisle containment system, the unit’s rear must discharge into the hot aisle. Typically the unit blows cold air out the front and draws hot air from the rear. So the hot‑aisle side is the intake side (rear), and the cold aisle is the supply side (front). Double‑check the airflow direction with the unit’s manual – some models have reversible fans, but by default they are set for forward flow.
Now leveling. Place a bubble level on top of the unit, both front‑to‑back and side‑to‑side. Adjust the four leveling feet by turning them. Most units have adjustment screws on the bottom. Turn clockwise to raise, counter‑clockwise to lower. Aim for zero tilt. A tilted unit will cause uneven water distribution in coils and may lead to air pockets.
Anchor the unit to the floor if required by seismic codes. Most inrow units have mounting brackets that bolt to the floor. Use M10 or M12 expansion bolts. For raised floors, you might need to fix the unit to the pedestals. Check local regulations.
After leveling and anchoring, connect the chilled water pipes or refrigerant lines. For chilled water, install flexible hose connections between the unit and the building piping. These hoses absorb vibration and allow for slight misalignment. Use ball valves on both supply and return so you can isolate the unit for maintenance. Torque the flange bolts to the spec – usually 35–50 Nm for DN25 flanges. Then wrap the pipes with closed‑cell insulation. Pay extra attention to the valves and fittings – they are often left uninsulated, which causes condensation.
For DX units, the refrigerant lines must be brazed with nitrogen flowing through the pipe to prevent oxidation. Use a refrigerant grade copper pipe. After brazing, pressurize the system with nitrogen to 150–200 psi and let it sit for 24 hours to check for leaks. Then pull a deep vacuum below 500 microns. Break the vacuum with refrigerant vapor. Then slowly open the service valves to charge the system. You don’t need to weigh in the full charge – most units have a sight glass and subcooling specification. Use the manufacturer’s charging chart.
Electrical hookup and control system configuration
Time to wire it up. First, turn off all power sources. Verify that the main breaker is locked out. The inrow unit typically has a main disconnect switch inside the control panel. Connect the incoming 3‑phase power to the terminals. Use wire sizes based on the unit’s full‑load amperage (FLA). For a 50kW unit, that’s about 80A per phase at 400V. Use 95mm² copper wire or as per local code. Install a properly rated circuit breaker in the main board – don’t rely on the unit’s internal fuses as your primary protection.
Ground the unit correctly. Use a dedicated ground wire, sized per NEC or IEC. Connect it to the ground lug inside the panel. Don’t share ground with other equipment.
Now the control wiring. Most inrow units come with a local touchscreen controller. You also need to connect it to your building management system (BMS). Typically you use Modbus RTU (RS485) or BACnet MS/TP. The default baud rate is usually 19200. Set the unit’s Modbus address to a unique number. For a row of 10 units, assign addresses 1 through 10. Do not duplicate addresses.
Connect a network cable from the controller to the local area network if you want remote monitoring. Many manufacturers now offer cloud‑based dashboards via an Ethernet port. Use a static IP or DHCP reservation. Check that the firmware is up to date – some shipping units have outdated versions that cause communication errors.
Next, program the unit’s internal parameters. At minimum, set the target supply air temperature. For a typical 22°C cold aisle, set the unit to deliver 20°C air. If you have a chilled water system, also set the water temperature setpoint (e.g., 16°C for the supply water). The unit’s controller will modulate the chilled water valve to maintain that air temperature.
Don’t forget the fan speed control. Most modern inrow units use EC fans with PWM control. Set the fan curve based on your heat load. If the unit has a pressure sensor inside the cold aisle, you can set it to maintain a specific static pressure – usually 10–20 Pa. That ensures consistent airflow even when doors open.
One common mistake: setting the temperature setpoint too low. This wastes energy and causes condensation on pipes. According to the 2024 ASHRAE guidelines, you can run a 20°C cold aisle without issues. So set the unit to 22°C supply and let the server fans do the rest.
Commissioning and performance verification
After everything is wired and connected, it’s time to fire it up. Do not just flip the switch. Follow this sequence:
- Open the chilled water valves (or refrigerant service valves). For water units, check that water is flowing – you should hear a steady sound and see the flow indicator move.
- Turn on the main disconnect. The controller should boot up. Wait two minutes for the display to initialize.
- Set the controller to manual mode and start the fans individually. Listen for unusual noise – bearing whine or rubbing means a defective fan. Replace before proceeding.
- Start the compressor (for DX units) or open the water valve to 100%. Monitor the suction pressure and discharge pressure. For R410A, typical suction pressure is 130–150 psi at 20°C evaporator temperature; discharge around 350–400 psi. If the system uses R32, suction is higher – around 180–200 psi.
- Check for condensation on the unit’s casing and pipes. If you see water dripping, the insulation is insufficient or the water temperature is too low. Raise the water setpoint to 17°C or add more insulation.
- Measure the supply air temperature at the unit’s front grille. Use a handheld thermometer. It should be within 2°C of the setpoint.
- Measure the air flow using an anemometer at the grille. Most units have a published CFM rating. For a 50kW unit, expect 12,000–15,000 CFM. If flow is low, check for blocked filters – or the fans are not running at full speed.
Now do a full load test. If possible, simulate the actual heat load by installing dummy heaters or turning on servers in nearby racks. Let the unit run for at least 4 hours. Monitor the temperature trend. The unit should maintain the setpoint within ±1°C.
Finally, integrate with your BMS. Verify that the Modbus registers are reporting correct values: supply temperature, return temperature, fan speed, valve position, and any alarms. Test the alarm functionality – tampering with the water flow should trigger a fault.
Performance comparison – typical values for 50kW inrow units (2024 market data)
| Parameter | Chilled water model | DX model (R410A) | DX model (R32) |
|---|---|---|---|
| Cooling capacity | 50 kW | 48 kW | 51 kW |
| Power input (fans + controls) | 2.5 kW | 4.5 kW (including compressor) | 4.1 kW |
| EER (at 20°C supply) | 20 | 10.7 | 12.4 |
| Water flow rate | 8.6 m³/h @ 5°C ΔT | N/A | N/A |
| Refrigerant charge | N/A | 8.5 kg | 7.2 kg |
| GWP (100‑year) | 0 | 2088 | 675 |
| Condenser type | Central chiller | Remote air‑cooled | Remote air‑cooled |
As you can see, R32 units deliver similar capacity with lower GWP and slightly better efficiency. Many OEMs are switching to R32 for new models. If your customers are in Europe, they will need to comply with the F‑gas regulation phase‑down – R32 is a good option.
Frequently asked questions
Q: How long does a typical inrow cooling unit installation take?
A: For a chilled water unit, expect 4 to 8 hours for a two‑person crew, including unpacking, positioning, pipe connection, electrical, and commissioning. DX units take 8 to 12 hours because of refrigerant line brazing and vacuum. Add another 4 hours if you need to run remote condenser piping.
Q: Can I install an inrow unit myself, or do I need a certified technician?
A: You need at least a licensed electrician for the 3‑phase power connections. Refrigerant work (DX units) requires EPA or equivalent certification. Water connections can be done by a general contractor but we recommend using a plumber who knows HVAC. A certified tech is also needed to program the controller if you don’t have the manufacturer’s training.
Q: What are the most common installation mistakes?
A: Uneven leveling leading to air locks in the water coil. Not insulating water pipes properly, causing condensation drip onto servers. Using undersized power cables or wrong breaker rating. Forgetting to set the Modbus address and then spending hours troubleshooting communication. Also, not purging air from the water loop – always use automatic air vents at the highest point of the unit.
Q: How do I know if the inrow unit is the right choice for my client’s data center?
A: Inrow units are ideal when rack power density exceeds 10kW per rack. Below that, traditional CRAC units might be cheaper. For densities 20–60kW per rack, inrow gives better efficiency because you eliminate mixing losses. If the customer has a raised floor, inrow units work well. For slab floors, they’re fine too but you lose the ability to run cables underneath – you’ll need overhead cable trays.
Q: What is the typical lifespan of an inrow cooling unit?
A: With proper maintenance (filter changes every 3 months, coil cleaning annually, fan bearing replacement every 3–5 years), a good quality unit lasts 12–15 years. The control board may fail after 8–10 years – keep a spare or a replacement part contract.
Q: Does the inrow unit need a separate condenser for DX models?
A: Yes, unless you buy a self‑contained version with built‑in air‑cooled condenser. Self‑contained units are less efficient because they discharge hot air into the room, raising ambient temperature. We recommend remote condensers placed outside or in a dedicated mechanical room. The piping length between the indoor unit and remote condenser should not exceed 30 meters for R410A, 25 meters for R32, to avoid pressure drop.
Q: What safety certificates should I look for when purchasing an inrow unit?
A: Look for CE, UL, and ETL marks. For the refrigerant side, the unit should comply with EN 378 or ASHRAE 15. Electrical safety: IEC 60335-2-40 or UL 484. If your market is in North America, also check for cULus listing. Avoid units that don’t have clear certification – importers have had units seized at customs.