Unlocking the Power of Reheat Coil: From Basics to Troubleshooting

Updated: Dec. 5 ,2025 · 20 min read

Hi and welcome to the bright world of reheat coils in HVAC systems. This extensive guide takes you through its basic functions, various types and uses, how to choose the best one for your needs, installation process, cost-effective use tips and maintenance guidelines as well as troubleshooting preparations.

This guide gives you a clear understanding of reheat coils so that reheat will not be a mystery to you but something you can command. So now let's continue with the reheat coil, and how it affects your comfort and efficiency.

Understanding Reheat Coil

A reheat coil is an element of an HVAC system to warm up air which has been cooled. This is especially important in multi-zone buildings where different sections of the structures may require differing temperature conditions. The reheat coil allows for more appropriate temperature control throughout these diverse regions, in turn providing a greater level of comfort and reduced energy consumption.

Reheat coil operation is based upon temperature sensing and a centrally located control system. These temperature sensors are situated in predetermined places (zones) throughout a structure and continually measure the environment. This information, when received by a central controller from these sensors indicates that the condition of some thereof is such that the incoming air temperature in a particular zone needs adjustment. This control device subsequently energizes the reheat coil which is supplied with high temperature water or steam from a central boiler, or equivalent heat producing station.

While the air passes over the reheat coil, it absorbs heat from the water, effectively increasing its temperature before being released (reintroduced) into a zone requiring added heat. While it may seem inefficient to cool and then heat air, this is actually not the case as it helps in maintaining a controlled temperature for better energy efficiency.

Diverse Varieties of Reheat Coil

Now that we’ve covered the basics of how reheat coils work—and why the whole mechanism matters—let’s take a look at the different types you can actually choose from. Just like picking any major piece of equipment, the “right” reheat coil really depends on what your grow room needs. Each type has its own strengths, quirks, and a few drawbacks. So let’s break them down a bit and see what each one brings to the table.

Hydronic Reheat Coils: The “Go-To” Choice for Many Commercial Jobs…

The hydronic reheat coil utilizes water for the process of conveying heat and is an efficient means to ensure consistent temperatures within your growing rooms. The water is pumped through tubes evenly distributing heat. This latter type of coil is very useful in cannabis farming because it controls the heat and moisture which is a requirement for healthy plants.

Electric Reheat Coil: An Energy Efficient And Environmentally Friendly Option For Growers

If you need fast response and minimal environmental impact, electric reheat coil is the choice. They heat up quickly, enabling fast responses to changes in temperature — important when finely tuning the environment for cannabis plants. And with low-effective installation and maintenance criteria, this type of grass is definitely the favourite of cultivators who want a simple yet green solution.

Steam Reheat Coil: Bringing Natural Energy Into the Grow Room

Steam, especially when paired with gas-fired reheating coils, taps into natural energy in a surprisingly efficient way. These coils use natural gas to generate strong, steady heat, which is why they’re so popular in larger cultivation facilities. Yes, you’ll need proper ventilation and some safety measures in place, but the payoff is big: powerful thermal output and a heating method that feels both efficient and naturally aligned with how growers want their systems to run. For operations looking for a reliable, energy-smart option, steam reheat is often a solid fit.

Gas Reheat Coil: Harnessing Natural Energy in Indoor Grow Facilities

Gas reheat coils are an efficient means for providing air heat by natural gas and as such are competitive in larger size grows. The heated environment requires ventilation and safety protocols, but their heat output makes them an ideal option for growers who seek powerful natural remedies.

Hydronic coils offer reliable power, with electrics being the most efficient, steam boasting classic dependability and gas-fired providing an eco-friendly alternative – reheat coils lean towards the preference of grow ops thanks in large part to its customizability.

Unlocking the Many Functions of Reheat Coils Grow Room HVAC Design

Getting a bit granular let’s take a closer look at the types of reheat coils — and how they play an instrumental role in your cannabis grow facility’s climate control. Let’s break down how to use them, and when you should lean on each for reaching specific sets of climate-control goals on behalf of pot plants.

Dehumidification

Exact control over humidity is no luxury in cannabis farming; it’s an absolute necessity. Too much humidity can lead to mold, mildew and a range of diseases that can destroy crops.

When an HVAC system cools interior air, that air becomes too humid. And this, of course is where the reheat coil comes in to warm the cool, damp air. Hotter air can hold more moisture, and if the air temperature increases, it can accept additional moisture, lowering its relative humidity. This is especially important when the lights are off and cannabis plants respire more (they will be expelling humidity into your room atmosphere).

And with humidity in check, the chances for moisture-related hazards — like mold — drop significantly. Also, having the right humidity levels can increase the amounts of resins that are produced by your plant leading to higher quality yield.

Cold Air Distribution

Cooler night temperatures are important for the flowering cannabis plant. But, cooling without judgement can be harmful.

These coils help in adjusting the temperature of cooled air post its first cycle of cooling. This helps ensure the air entering the growing space doesn't come in too cold and shock the plants.

Uniform distribution of cold air all over the plants to have similar ambient conditions. It is such uniformity that helps to prevent some plants from growing faster than others when they are exposed to different temperatures.

Temperature Zoning

Various types of cannabis can have different temperature requirements. Indicas might prefer different conditions than sativas, and hybrids might be somewhere in between.

By reheating air in specific areas, these coils can be used to create microclimates within a large grow atmosphere. This zoning allows for an optimum temperature regulation of the development of each strain.

Recognizing and accounting for the unique temperature requirements of individual strains will enable growers to maximize the genetic potential inherent in each, avoiding undue lag in growth, underproduction of cannibanoids or loss.

Improving Comfort

Beyond the cannabis plants themselves, an optimal environment also includes the best growing conditions for a labor force of cultivators.

Reheat coils assist in the maintenance of uniform air temperatures and humidity. Those coils stop wild temperature swings in the space - enough to ensure that plants and humans are equally comfortable in their surroundings.

For the plants, a stable environment with no sudden shocks is less stressful and that translates into better growth and higher yields. For the growers a stable working environment is beneficial for higher productivity and to minimize potential errors that can influence crop quality.

Reheat cores, due to the multiple roles they play within HVAC systems, prove to be valuable companions in pursuit of flawless cannabis cultivation.

Their kingpin positions, whether it be thoughtful humidity output management, accurate cold-air distribution, consistent temperature control or simply allowing cannabis plants to grow comfortably in peace all highlight the importance they have when providing a thriving cultivation environment.

Factors to Consider When Choosing a Reheat Coil

If you’re thinking about adding a reheat coil to your current HVAC setup—especially after seeing how widely they’re used—you’ll want to look at a few important details before actually buying one.

Check What Your Existing System Can Handle

Your HVAC system’s capacity plays a huge role in determining the kind of reheat coil you can use. A small residential system, for example, simply won’t keep up with the demands of a large cannabis grow. In situations like that, the system’s BTU rating becomes your main reference point for figuring out what size or type of coil is appropriate.

Most of this information is in the manufacturer’s manual, but if anything feels unclear—or the specs seem confusing—it’s always safer to check with a professional. Making sure your system is actually compatible will save you from a lot of headaches later.

Material and Durability

As far as reheat coils, it’s not just price, but material performance. However, copper's coils offer a high thermal conductivity and may corrode in specific settings. Springs made of stainless steel are hard-wearing, but may be more costly. And for the record, long-term payback vs. lay out. The least expensive coil might end up costing more in repairs and replacements.

Energy Efficiency

And a high efficiency reheat coil will save you some money and it’s also better for the environment as well. Look for high SEER (Seasonal Energy Efficiency Ratio) coils. Most of these have become energy efficient over the years, and although this can mean a higher initial price tag, it can also save money down the road in lower energy bills.

Size and Installation

You’ll also want to consider what amount of air volume your grow space demands (in CFM, or cubic feet per minute). When it comes to growing cannabis, a properly sized reheat coil is about temperature and humidity…and so much more. Coil may not be sized to match air flow requirements and result in reduction if air speed and then bad room air. Mold and pests can result from stagnant air. But a high-powered one can move air through too fast — and dry out your plants. And think of the simplicity of installation. And some might require special tools, or professional installation to put these in place, which would increase the overall cost.

Maintenance and Cleaning

The best reheat coil ever is still going to require service from time to time if you want the most bang for your buck. Over time, use coils can accumulate sufficient amount of dirt or mold which may decrease its effectiveness and harm plants. Look for a design that is easy to reach and clean. One of the great benefits to getting this aspect dialed in properly is twofold: not only does it reduce the amount of labor intensive tasks, but also keeps your marijuana plants thriving.

Selecting the correct reheat coil is a complex decision based on system needs, material used, preferences for energy efficiency, size considerations and ongoing maintenance. Do your homework and ensure the successful success of your cannabis grow.

How to Install Reheat Coils Step by Step

Once you’ve chosen the best reheat coil for your marijuana grow room or cultivation facility, what comes next is just as vital – installation. A proper install is the secret to ensure the money you spend in your HVAV will be reflected in your crop yield. Here's how to proceed.

Gathering Essential Equipment and Tools

Get all the tools you need for the job. And the procedure goes faster when you know what each one does.

Choosing the Right Installation Spot

Picking where to install a reheat coil isn’t just about finding a place that’s easy to reach or close to the ductwork. There are a few other things you really need to think through:

1. How the airflow inside the room will change once the coil is in place
2. Whether the location allows for easy maintenance later on
3. If power access is reasonable and the setup meets safety and operational standards 

Installation Tips: What to Do—and What to Avoid

Proper installation matters a lot more than people expect. The way a reheat coil is mounted directly affects how well it performs and how long it lasts. Getting the details right upfront helps avoid efficiency losses and prevents long-term issues that can creep up over time.

Do's:

• Using the manufacturer's indicated height and angle information exactly.
• Check the unit for level, and be sure that it’s level, using a level.

Don'ts:

• Pilot holes should never be skipped: They make screwing in screws straight easier and minimize the chance of cracking wood.
• At any rate: You will certainly want to give yourself at least 12 inches of clearance in every direction for routine cleaning in the future.

Seamless Piping Connections

The connections on your pipes can either make or break the efficiency of your equipment. We need to pay attention to:

1. Precise cuts with a pipe cutter
2. Lubricate all screw threads with pipe thread compound
3. Tighten all connections well, to insure that there are no leaks

Navigating Wiring and Controls

The wiring is finally, but not the least, thing in install.

1. 1.Cut power at the circuit breaker before starting.
2. 2.Wire Stripper- for clean and precise stripping of wire ends.
3. 3.And be sure to consult your HVAC system’s owner manual when installing and connecting the wiring.

In conclusion, how well the reheat coil is installed, affects how it operates, what you pay in energy and your cannabis grow season success. From the initial theme of tool-making, to winding up on wire connections — every aspect of any action that connects either reinforcing or undermining your total life-ecosystem as though you were its mixed-up slip too. Make every move count.

Best Practices for Operating Reheat Coils Efficiently

Once you have your reheat coil in place, the most important thing is to make sure it’s working properly. When you use your coil efficiently you can make it last longer and improve upon your cannabis growing environment too! This section is here to help you achieve just that.

Controlling Temperature and Humidity: Striking the Balance

Before you transition into any other optimization methods, the first thing you’ll want to consider is temperature and humidity. This is where the all-in-one grow room HVAC system comes in to play. Picture a system that not only heats or cools the air, but also controls humidity levels so they are perfect for your cannabis grow operation.

Altaqua Grow Room HVAC System is one of the options, which uses reheat coils to give a balanced climate controlled structure. Our Reheat Coils are utilized to heat low-temperature and moist air. The air, after heating, is passed through a condenser where it is cooled and de-moisturised while providing cooling and dehumidification.

Now that you’ve grasped the importance of your grow room reheat coil system when it comes to climate control, we need to figure out what the ideal temperature and relative humidity tends to be for each stage of growth with your cannabis plants.

Ideal Temperatures and Functions:

Vegetative Stage: 71-82°F (ensures rapid vegetative growth)

Flowering Stage: 68-79°F (prevents heat stress during the most sensitive stage)

Ideal humidity levels:

Vegetative stage: 40-70% (promotes nutrient absorption)

Flowering stage: 40-50% (reduces mold risk)

System Integration: Ensuring Coherent Functioning

Once both temperature and humidity levels reach optimal conditions, we must conduct a comprehensive inspection of the coordinated operation of all equipment and components within the grow room, such as the heating coil's operational status.

Compatibility Factors:

• Does the coil size match your ductwork specifications?
• Does the coil's electrical rating match the building's existing electrical system?
• Can your current control system regulate the coil?

Settings That Elevate Efficiency

Once temperature and humidity settle into the right range, the next step is to do a full check of how every piece of equipment in the grow room is working together. That includes making sure the heating coil is actually running the way it should.

Things to Double-Check for Compatibility

• Is the coil properly sized for your ductwork?
• Do the coil’s electrical requirements line up with your building’s electrical system?
• Can your existing control system actually manage the coil?

Once everything checks out and you know the coil fits your system, you can start fine-tuning it for better performance.

Maintenance Mastery: Ensuring Your Reheat Coil's Longevity

Once the heating coil is dialed in, you’ll also want a solid maintenance plan to keep it running reliably. Skip this part, and even the best equipment can turn into a liability.

Cleaning Filters for Pure Airflow

One of the most important maintenance tasks is keeping the filter clean. If the filter gets packed with dust and debris, the system has to work harder—which means higher energy bills right away. On top of that, clogged filters lower air quality and drag down overall system performance. Over time, the extra strain cuts into the coil’s lifespan. That’s why regular filter checks, cleanings, and replacements are absolutely essential.

Monitoring Refrigerant Levels for Optimal Cooling

Low refrigerant can be sneaky; it might not make its effects known right away but can do some serious, stealthy damage over time. If your reheat coil hasn’t been cooling as well as it should recently, this may not be a simple case of just bad luck. It may be that there’s a refrigerant problem which, if not attended to could develop into bigger issues like compressor failure.

Proactive Steps in Preventing Corrosion

Corrosion not only looks ugly, but if you work with reheat coil system, then you know that this is something to fight every day. Corrosion can eat away at the vital parts of the system, and once it gains a grip, it advances rapidly. Maintaining anti-rust coating on them and carefully monitoring these bridges is not an option, but a compulsion.

Testing Airflow to Ensure System Health

Airflow is not click and go. Instead, consider it as a “vital sign” for the health of your reheat-coil system. Inspect the airflow with various parts of the system open and note any change, or sudden responses to indicate a blockage or a mechanical failure situation requiring attention.

Regular Maintenance: The Key to Longevity

Regular maintenance phrase is arguably rather boring sounding but in the world of reheat coils it is maintenance key to a long and healthy working life. From the easy stuff like tightening loose bolts to more difficult (like diagnosing problem and changing part).

In order to maintain long and trouble-free life for the reheat coil system, focus needs to be on maintenance. Make the most of your system Whether it’s air quality or mechanical integrity, a tightly-organized schedule for maintenance covers every aspect of your system and can be scheduled on when it suits you so that you don’t have to suffer.

Troubleshooting Reheat Coil Dilemmas: Some Diagnostic Approaches

So you’ve got your reheat coils and they’re doing their job because let’s face it, I’m sure that you guys are doing a good job taking care of them! But sometimes, things go awry. If you meet this, do not get too concerned." In this blog, we will be looking at the solutions to common reheat coil problems.

Tackling Insufficient Heating Challenges

If your reheat coil just isn’t giving you enough heat, you’re probably dealing with an airflow issue or a control valve that’s starting to fail. The first things to check are pretty simple: is your ductwork sized correctly, and are the control valves actually opening and closing the way they should? If everything looks normal but the coil still won’t keep up, it’s time to bring in a technician to run some proper tests.

Fixing Frosting Problems the Right Way

When a reheat coil ices up, its performance drops fast. The most common causes are excess humidity in the room or one or two sensors that aren’t doing their job anymore. Usually, lowering the humidity and re-calibrating those sensors is enough to get everything back to normal.

Spotting and Dealing With Refrigerant Leaks

A refrigerant leak is more than just wasteful—it’s harmful to the environment. If you think there might be a leak, check around for loose fittings and listen for any subtle hissing sounds, which often give away the leak point. But don’t try to fix refrigerant issues yourself; handling it incorrectly can cause serious damage. Always call a professional for this one.

Handling Corrosion and Rust

Reheat coils naturally pick up some rust and corrosion over time. When you start seeing visible spots, it’s usually a sign that the coil is wearing down. If you catch it early, corrosion inhibitors can slow the damage. But once the corrosion gets deep, replacement is usually the only realistic solution.

Other Common Coil Problems—and What to Do About Them

Temperature and humidity are the usual suspects, but airflow issues can get sneaky. If none of the previous problems seem to apply, yet you’re hearing strange noises or the heating feels inconsistent from room to room, it might be something buried deeper in the system. At that point, your best move is to check the owner’s manual for any model-specific quirks—or just have a specialist take a look.

Conclusion

This article has made it clear how reheat coils work by touching upon their countless variations and crucial use in specific HVAC systems, such as Altaqua Grow Room HVAC system. Using the correct type based on energy efficiency, length of lasting and material strength; from an installation and operation standpoint, reheat coils are vital for maintaining temperature and dehumidification.

Performance means more than just installation; it is about continual adjustment and integration into systems. We covered the precise conditions for airflow, temperature and humidity control and how to maintain or troubleshoot your device. All of these factors make for longer life and better performance of your coil – more efficient HVAC system overall.

Whether you are a weather control old-timer or new to the game, this guide is meant to be your all-in-one tool. When you have reheat coils under control, your HVAC system can perform the way it should — meeting specific requirements to better fit specified environments.

FAQ

1. What are the primary uses of reheat coils in cannabis grow rooms?

Reheat coils can do double duty in cannabis cultivation rooms for both dehumidification and cold air distribution. They can achieve comfortable temperature zones and enhance overall air quality, so they are an excellent component of an effective HVAC system.

2. How to pick the right reheat coil for your pot farm?

The selection of a reheat coil is an issue that revolves around system requirements, material life expectancy, overall energy utilization and cost. For instance, electric reheat coils tend to be more energy efficient but at a greater upfront cost. Each kind also has its various pros and cons.

3. What's the frequency of maintenance on reheat coils at a marijuana grow room?

The frequency of reheat coil maintenance varies according to the manufacturer’s recommendation, but inspections should be conducted thoroughly at least every 3-6 months. That can include doing things like cleaning so they don’t corrode or looking for any potential problems, such as dripping refrigerant. Regularly scheduled maintenance is also advised on the system to maintain proper functioning.