ColdLogik Rear Door Coolers – RDHx

The Logical Data Center​

Yesterday’s Thinking for Todays Data Centers

Nobody invites change, especially when their existing business model works and is profitable, so for change to occur, there are normally key drivers. The data center industry is no different and the need for change is beginning to accelerate.

Data center owners are being made accountable for their environmental impact, poorly designed data centers simply create massive carbon emissions, waste vast amounts of valuable potable water and continue to use ozone depleting refrigerants. Because emotion alone doesn’t always create change, enforcement via legislation by governments, alongside demands from customers and stakeholders, is starting to be introduced to help combat high carbon emissions and encourage sustainability.

Technology changes are also a key driver in data center utilization, and the introduction of new chip sets, with their leap in compute power and the resulting increase in heat load, will leave many air moving data center designs, even with bolt on improvements simply unable to cope.

But, it will be the customers who will chose to use eco-friendly data centers, that will prove to be the tipping point – The good news is, change is a coming!


The Modern Data Center Approach

A modern data center design should be able to meet each one of these drivers, and at the same time offer more. A ColdLogik data center does exactly that. A data center that is robust, adaptable and ready to control the whole room temperature from this one single solution in a sustainable and more profitable way.

Capable of low, medium and high duty using the same technology and control philosophy – it’s not genius, it’s simply ColdLogik!

Sustainability and Profitability


Up To 93% Energy Savings
  • Energy Efficiency Ratio (EER) of over 100 at maximum capacity
  • Average 15% reclaimed power for Compute by comparison to traditional cooling
  • Potential Cooling PUE available of 1.035
  • 3.5% ColdLogik Power to Cool 100% Heat Load vs 38% traditional methods


Reduction of CO2e up to 99%
  • Isolating Global Warming Potential (GWP) gasses to one centralised area
  • Reducing the volume of GWP gas significantly
  • Over 50,000 trees worth of carbon saved per 1mW ColdLogik deployment.

Real Estate

95% space saving of cooling white space for an equivalent deployment
  • No need for supplementary Cooling.
  • No area taken in the white space for coolant distribution


Up to 100% water saving
  • Higher water temperatures reduce the need for mechanical cooling, whilst maintaining ASHRAE A1 temperatures

Savings and Benefits

Operational Efficiencies

  • Increase hardware lifespan by removing hot spots
  • Operates above dew point, no condensation management required with maintained humidity levels
  • Rapid ROI and lower cost of ownership
  • Vast reduction on Smart Hands Requests (service tickets)
  • Increase computing capacity
  • Save CapEx on building costs

Simplicity by Design

  • Plug and Play
  • Versatile deployment
  • No Supplementary cooling
  • Adaptive intelligence
  • No specialist hardware or infrastructure
  • Controls the whole room temperature
  • Fast-track Data Center Planning and
  • Deployment Strategy

Modular & Retrofittable

  • Scalable
  • Rapid Deployment
  • Suitable for both legacy or new build environments
  • Future-proofing
  • Removal of raised floors and aisle containment
  • Compatible with both warm and cold water supply

The Range

CL21 Smart Passive

CL21 Passive 47u 600 x 1200 5210 LIGHT GREY ISO cropped
CL21 Passive 47u 600 x 1200 5210 LIGHT GREY Face On copped

Up to 29kW sensible cooling 42U, 47U, 52U
600w, 750w, 800w


CL21 ProActive

CL21 47u 600 x 1200 5210 ISO LIGHT GREY cropped 1
CL21 47u Top Fed Active Front View cropped 1

Up to 30kW sensible cooling 42U, 47U, 52U
600w, 750w, 800w


CL20 ProActive

CL20 42u 600 x 1200 LIGHT GREY cropped
CL20 RDC RC 42u 600w Front View cropped

Up to 92kW sensible cooling 42U, 48U, 52U
600w, 750w, 800w


CL23 HPC ProActive

CL23 HPC CL23 48u 800 x 1200 5210 ISO LIGHT GREY1 cropped 1
CL23 HPC 48u 800w HPC 200 Door and Cab FRONT.37 with logo cropped 1

Up to 200kW (Actual headroom 220kW+) sensible cooling
48U, 52U


ColdLogik RDC’s- One Solution

Rear Door Coolers (RDC), commonly known as RDHx, are often misrepresented especially by competing product manufacturers.

Most discussions centre around the argument between Air Cooling and Liquid Cooling, whereas RDC’s are in a league of their own and are ‘Air Assisted Liquid Cooling’, which means they provide comparable energy savings and high performance capabilities as liquid cooling products, but without specialist hardware or the requirement of supplementary cooling products in order to cool the rest of the data center. Furthermore they provide the same low CapEx and duty capabilities of ‘Air Cooling’, but unlike ‘Air Cooling’ technology RDC’s provide a rapid return on investment ‘ROI’, at the same time as future proofing the data center.

So, to dispel the disinformation, we challenge to prove that RDC’s are the ideal cooling technology for both legacy and new build data centers. Whether the rack density is below 10kW, for typical applications, through to 200kW for high performance compute, ColdLogik RDC’s offer the most cost effect and energy efficient cooling solution on the market.

Legacy Data Centers

There are many reasons to want to get more from an existing data center, such as increasing revenue stream, removing hot spots, offering customers greater flexibility, or simply increasing the life cycle of the data center; the ColdLogik RDC solution provides exactly that, and is the only truly retrofittable solution capable of achieving and overcoming restrictive issues within legacy data centers

  • ColdLogik RDC’s are fully retrofittable onto any OEM Rack
  • RDC’s can use the return water from the existing perimeter room cooling and chiller system
  • RDC’s can be top and bottom fed as standard
  • RDC’s do not affect baying racks on either side
  • Full rear access to rack
  • Can be retrofitted to Hot Aisle Containment System, without need to change floor layout
  • RDC’s are the only retrofittable solution capable of achieving all the restrictive issues within legacy data centers

ColdLogik RDC performance vs other competitive technologies

Screenshot 2021 08 09 at 11.25.24

How It Works

The ProActive and Passive

Ambient air is drawn into the rack via the IT equipment fans. The hot exhaust air is expelled from the equipment and pulled over the heat exchanger assisted by EC fans mounted in the RDC chassis. The exhaust air transfers heat into the coolant within the heat exchanger, and the newly chilled air is expelled into the room at, or just below, the predetermined room ambient temperature designed around sensible cooling.

Both processes are managed by the ColdLogik adaptive intelligence present in every proactive RDC, in this way the Rear Door Cooler uses air assisted liquid-cooling to control the whole room temperature automatically at its most efficient point

The passive RDC operates in the same way, but because it has no controller or fans, it relies purely on the IT equipment fans producing enough static air pressure to self cool. In the correct deployment, the passive RDC is truly the most efficient cooling method available today. If the active equipment is unable to produce sufficient air, the CL21 passive also provides an upgrade path without needing to replace the entire unit as with others. This means the airflow representated in the CL21 RDC below is applicable to both active and passive models.

Screenshot 2021 07 27 at 09.17.47

Room Management

Each ColdLogik Cooler is able to operate without requiring active supervision and can be remotely monitored through the Building Management System, or through the ColdLogik Room Management System (RMS) for a ‘hands-off’ approach to cooling and a significant reduction in service tickets being raised.

Screenshot 2021 07 27 at 09.18.02

Resiliency Features

  • Up to N+4 on fans
  • A and B power feeds (ATS) as standard
  • Specifically designed PCB’s for enhanced functionality in the event of failure
  • Hot swappable fans
  • Universal fans reducing the need for localized resiliency stock
  • Leak prevention system available for deployment if requested

A ColdLogik RDC Data Center

Screenshot 2021 07 27 at 08.51.07
Screenshot 2021 07 27 at 08.53.49
Top and Bottom Hose entry points as standard

External Plants

Dry-Air Coolers ONLY
NB. Climate Dependant
Cooling Tower/Adiabatic Cooler1.06
ColdLogik Standard Chiller (20 – 30)1.18
Standard Chiller (14-20)
NB. Industry standard
Standard Chiller (7-14)
NB. Industry standard

Deployment Strategies

cl20 portrait scaled

Deployment strategies – a general understanding

There is a myth that rear of cabinet cooling systems are only suitable for medium to high density cooling, dedicating one RDC to each cabinet. We can dispel that myth as we have deployed many low-density installations, which dissipate up to and around 3kW per cabinet. Just like with CRAC and In-row cooling you would not dream of deploying a unit per cabinet – so is the case with rear of cabinet cooling. By deploying CL20’s in a logical manner, it is possible to design a low, medium or high duty room or a mix of all three requirements in one space all of which can be achieved with one elegant solution - The ColdLogik CL20 ‘RDC’.

How is this achieved?

Clearly every data center is different and requires a flexible solution for its specific cooling requirements.  There are various standard CL20 coolers within the range, offering a broad range of different duties and airflows.

Where less than one door is utilized per cabinet, air from the cooler mixes with the warm air leaving the adjacent cabinets, the result is air at the predetermined room temperature. Each ‘RDC’ is intelligently managed via the ColdLogik Management System 'CMS' for optimum efficiency with embedded computers which continually adjust the operational parameters in response to the heat removal demands placed on the system. By making these continual load adjustments, the ‘CMS’ controllers maintain the room ambient temperature.

Low to high density cooling
with one solution in one space

Deploying ColdLogik RDC in MTDC

How a ColdLogik Rear Door compare to traditional air-conditioning in Multi-tenant Data Centers.

ColdLogik Deployment in Data Centers

How to deploy ColdLogik Rear Door Coolers in a Data Center with existing or new cooling plants.

How it Works

How the ColdLogik Rear Door Cooler cools a Data Center.

Shared Rear Door Cooling

How does the ColdLogik Rear Door Cooling manage data center rack heats when deployed every 2 or 3 racks.

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