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What is chilled-water climate control, and how does it work?

First things first: cooling of any kind, chilled-water or HVAC, does not mean adding cold, it means removing heat.

On a very basic level, chilled-water climate control works similarly to traditional HVAC: compressors are used to circulate a cooling medium to the air handlers located inside a room.

With HVAC, each compressor is connected to a specific air handler(s); when one turns on, so does the other. However, with a chilled-water system,  compressors are not tied to specific air handlers. Instead, all compressors located outside the facility are tied to a single cooling reservoir located inside the building. The compressors work together to cool the reservoir, which acts a battery for stored cooling energy.

A chilled glycol-water mix is then pumped from the reservoir around the building to air handlers within the grow rooms. The air handlers are controlled by a simple wall thermostat mounted inside the room. The result is that cooling in the room can be achieved without even engaging a compressor outside because the compressors are keeping the reservoir cold and operate independently of the room temperature. Further, a single compressor can operate multiple air handlers (and vice versa), resulting in far more flexibility in installation, simple and affordable redundancy (backup system), and reduced costs.

Because of the increased heat capacity of water to air (see more on this in FAQ #2), Surna’s chilled-water systems can provide consistent 24-hour dehumidification to your room. Our system dehumidifies even when the compressors aren’t running, so humidity spikes can be eliminated.

As your cooling needs expand, more cooling compressors can easily be added to the same reservoir and water lines can be plumbed to new areas of the building without redesigning the entire cooling system.

Because chilled-water climate control moves water (through pipes) instead of air (through ducts) around the building, we are able to harness the heat retention of water to provide more efficient cooling. Additionally, the closed-loop system prevents evaporation, ensuring that no extra moisture is added to the rooms.

What benefits will I get from water-cooling?

Energy Efficient Heat Removal

The thermal conductivity of water is 0.6 W/(m*K) while the thermal conductivity of air is 0.03W/(m*K). Further, the heat capacity of water is 4 times the heat capacity of air, meaning that water will increase in temperature at ¼ the rate of air when the same amount of BTU’s are absorbed. What this means is that water can remove 4 times as many BTU’s as air, 20 times faster than air, leading to drastic reductions in electricity usage while providing a more accurately controllable environment. Superior heat capacity allows Surna’s system to provide cooling even when the compressor is not in use.

Completely Seal Your Garden

Our cooling system allows you to completely seal your garden providing a reduced threat from pest invasion while allowing for more accurately controlled environmental conditions such as CO2 and humidity levels. By removing these variables, gardeners are freed up to focus more of their attention on providing consistent results and optimizing production yields for their facility.

Increased Control

Because the heat transfer properties of water are so much greater than that of air, you can count on a much faster response time and more accurate control of your garden’s environment. The ability to maintain tighter control of your garden’s temperature, humidity and CO2 provides an environment where high-quality results are more consistently achievable.

Built-in Redundancy

Our systems are designed to provide the ability to use redundant compressors on a central cooling storage tank, allowing you to take compressors out of the loop for service without losing cooling to any one area of the facility.

Additionally, an “extra” chiller can be plumbed into the system, thus providing complete system redundancy at minimal cost. Then, if there is a short-term failure, the idle chiller automatically turns on, resulting in no loss of cooling inside the building.

Superior Dehumidification

Surna’s system provides dehumidification as a byproduct of cooling, similarly to traditional HVAC. However, the volume of dehumidification that Surna’s system can achieve is substantially higher than that of traditional HVAC because we maintain a more consistent evaporator temperature along with a larger surface area on the evaporator for dehumidification.

Further, when cooling isn’t needed in a traditional HVAC system, there is also no dehumidification happening, resulting in humidity spikes. Traditionally, you would have to then supplement that with additional dehumidification, which uses additional power. Surna’s system offers a 24-hour dehumidification option where the only energy used comes from the use of a fan and reheat coil. This system helps maintain consistent humidity and avoid detrimental spikes.

Year Round Use

Our systems are designed to work under extreme temperatures – from 120°F to -20°F. Because they are designed for use in indoor gardens, our systems are also designed to run year-round without turning off. HVAC systems are designed to be used for the hottest months of the year and sit idle for the rest of the year. This means that by the end of 1 year, an HVAC system that has been running for the entire year has already used 3-4 years of its  intended life. When a traditional HVAC system is used for a garden, that system has been repurposed – it was not designed for this type of use. This is not the case with Surna systems, which were designed for year round use and the heavy heat processing a garden environment requires.

Is water cooling complicated?

Water cooling is no more complicated than any of the other systems required to operate an effective indoor garden. Simply put, a water-cooled system consists of a reservoir holding water, a pump that recirculates that water through the chiller and water cooled devices, and a piping system that connects everything together. If you grow hydroponically, you are already familiar with all of this equipment.

Isn’t water cooling more expensive than HVAC?

While traditional chilled water cooling systems are more expensive than HVAC, Surna’s systems have been re-imagined and re-designed to make them comparable in price to HVAC.

Additionally, because water has a higher heat retention than air and can provide cooling even without the compressor, Surna systems also provide cost savings in the form of your month to month electricity bill. When comparing Surna chillers to AC units, we look at tonnage and amperage comparisons. Over time, this results in significant energy savings.

How much chilling capacity is needed to cool my garden?

That depends on your garden. With a little bit of information about your garden’s design and facility layout, we can customize  a cooling system to fit your specific needs. When sizing your cooling system, remember that all heat sources need to be accounted for. This includes lights, humidifiers/dehumidifiers, CO2 generators, and other power-intensive equipment that may be located within the space. Along with this, ambient room conditioning is required to cool any heat transferred through the facility walls. Our systems also provide the capability to cool your nutrient reservoirs so that nutrient temperatures can be optimized for healthy and productive plant growth.

Why are Surna chillers better than other cooling systems available on the market?

Surna chillers are designed with the garden environment in mind allowing them to provide many benefits that other cooling systems can’t, including 24-hour dehumidification, built-in redundancy and ductless cooling. Built with top-of-the-line components, Surna systems have a proven track record for reliability and endurance.

Our straightforward, state-of-the-art design allows for efficient installation of chiller units while making the system easy to operate and maintain for users of any experience level. Additionally, our modular system design allows for quick and painless expansion as your facility grows or your cooling needs increase.

Won’t using a water cooled system add more humidity to my garden?

Our water-cooled environmental control systems will not add additional moisture to your garden. These systems are designed to use a closed fluid loop, meaning there is no way for water to evaporate and escape the system. What’s more, our air handling units provide more efficient dehumidification than HVAC while allowing you to reclaim and reuse the collected condensate.

What about the winter months? Will I still be able to provide water cooling in my garden during cold days?

Surna chiller units are equipped with compressor heaters so that the chiller can remain in operation without incurring damage when you’re experiencing freezing and even sub-zero outdoor temperatures in your area. If you live in an environment that experiences cold or freezing temperatures for most of the year, you might also consider ur compressor-less chillers and dry coolers, which can offer you significant energy saving options by using the outside climate to cool water in the system, giving you the opportunity to capitalize on the free cooling offered by cold outside air without having to introduce that air into your garden.

How long has water cooling technology been used?

Water-chilled cooling and heating is not a new concept. People have been using water to remove heat from machines for more than a century. Currently, chiller and boiler systems are used worldwide for heating and cooling. In the US, they are used primarily in commercial spaces, but overseas, they are increasingly being used for residential climate control. In some areas, chiller systems are actually mandated by local building codes for buildings exceeding certain square footage due to their superior energy efficiency. When it comes to providing consistent, reliable cooling results when it matters. It’s clear that water-cooling is the state-of-the-art technology.

Surna’s water-chilled systems have been installed in commercial gardens all over the world from South Africa and the United Kingdom to Australia and Costa Rica. They provide ultra-high efficiency and are extremely easy to install, offering far more flexibility in installation and use than traditional heating and cooling systems.

What size gardens is this equipment intended for?

Surna systems can be applied to any size garden, however, our systems are designed to handle the cooling needs of large scale commercial production facilities. Our systems are scalable, and modular, making facility expansion and upgrades fast and painless. For smaller, hobby-sized gardens, check out our Hydro Innovations product line.