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Misc Information


Letter to our Customers
BTU Capacity of Pumps
Paper About Remote CHILLKING® Chiller Going to Canada
CHILLKING® Study Guides
Reducing Humidity in Greenhouses
Information Natural Gas Engine Driven Chiller
More Information about Dehumidifiers
How Dehumidifiers Work
Humidity Control for Pathogen Prevention in a Greenhouse or Indoor Garden
About Latent Heat
Nutrient Diagram for Chiller Setup
Inside our 6 ton Dehumidifier Air Handler
Temperature and DehuKing Dehumidifiers

CHILLKING® letter to our customers.

I came across your website while investigating new sources for marketing our products. Before I start I do understand the difference in hydroponics and aquaponics as I have designed the cooling and heating systems for many of the new greenhouses wanting to have better yielding crops and to get more from small spaces. It does seem as if our companies have crossed paths sometime in the past. We have extremes in temperature in Austin, Texas but not as cold as Tulsa. These extremes make our systems very much in need.

I've run across many reasons for farmer's decision to invest in aquaponics as I'm sure you have also. It seems as if all share a common interest in preserving Mother Earth and using what she has given us to the best of their abilities. That is where CHILLKING® stands out in our industry. Most that have experience in indoor gardening know our name as the leading name in cooling systems for hydroponics.

We have been building chillers for over twenty years. Our goal is to produce the most economical, environmentally friendly, dependable chiller in the industries we serve. Only CHILLKING® guarantees that our chiller will produce 110% at minimum of the chiller's nominal tons listing. A ten ton must produce eleven tons at 90F ambient conditions. Many companies boast 100% ratings however they are at 70F ambient or a 90F condenser, not the same thing. Nonetheless CHILLKING®'s chillers exceed their nominal tons rating by a minimum of 10% when tested at 90F ambient. CHILLKING® tests every chiller under load, each chiller is fine tuned to use as little energy as possible. No CHILLKING® chiller is allowed to leave our factory unless it exceeds it's rating by 10%. In addition to producing 10% more than nominal tons listing we use much less energy while under load. We normally use 15% to 25% less electricity than most of our competitors. When a chiller produces 10% more BTU it is satisfied 10% sooner. Quite often our chillers produce 25% more than their rating.

I've gone into depth because we are not the ordinary chiller company. We hold the only patent to yield 100% tank capacity when refueling with hydrocarbons such as methane or compressed natural gas. We are the only authorized Chiller company for International Dairy Queen and Sonic Drive Ins, some of our other customers are Dell, Disney World, International Paper, Rockwell, GE MRI, Hitachi MRI. Airbus is purchasing a 200 ton system from one of our distributors that we will design especially for that application. We have partnered with hydroponic companies building modules for the new MMJ industry in legal states. We worked with the University of Arizona many years ago in designing a system for their agriculture laboratories. In addition we have worked with many other industries.

We are building prototypes that run from solar panels with lower voltage compressors. Our goal is a grid free self-sufficient, stand alone cooling system. We were the first chiller company to recover waste heat from the chiller and repurpose it by storing it for a future need. We have tied our heat recovery system into solar collectors as well. In addition CHILLKING® builds cooling towers and dry coolers however our new chillers have proven more energy efficient than cooling towers so we seldom recommend those. We do have hybrid systems also. The possibilities are endless.

I've gone into more depth on this email than I normally would while introducing CHILLKING®. I've done so because I feel there is more opportunity for growth as well as being an excellent industry for health and our planet. All companies have an obligation to our planet and consumers. If you feel there are opportunities for your company and CHILLKING® to work hand in hand on projects please contact me. Your company is one of the few companies I am reaching out to in the industry. We would be most happy to design a system especially for your company or offer support.

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Information Regarding BTU Capacity of Pumps

Everyone in the chiller business knows that the law of thermal dynamics is what governs sizing of BTU.

1 BTU to change 1 pound of water 1F in 1 hour

All calculations are based on that. We first convert GPM to per hour, then get the weight and multiply times the Delta "T" of 20F. The temperature differential of most heat exchangers(HEX or HX) is 20F, meaning in at one temperature and out 20F cooler.

This exercise is to demonstrate the tremendous BTU than be carried by pipe size. The below numbers are based on minimum flow capacity of different sizes of PVC water lines.

The first calculation is for 1.5" pipe. I use a low GPM in all my calculations such as 1.5" pipe will easily carry 80 GPM at 40 psi. Each line size below is capable of 50% more given more pressure and clean smooth lines.

80 X 60 minutes = 4800 GPH X 8.34 lbs weight of one gallon = 40,032 X Delta "T" equals 800,640 BTU / 12,000 = 66 tons

1.5" flows 80 GPM and carries 66 tons
2" flows 127 GPM and carries 105 tons
2.5" flows 190 GPM and carries 158 tons
3" flows 273 GPM and carries 273 tons
These are minimum flow for these sizes, they will easily flow 40% to 50% more

So, depending on length of run and number of turns you have to make a decision.

Usually you don't have to worry about a couple of hundred feet unless there's a lot of variables. If you run too large of line it creates a pressure issue so balance is important. Instead of using a large pump our suggestion would be two or three pumps. Three pumps use lower HP. Most 1 HP pumps are 40/40 easily. 40 psi and 40 GPM on 1" copper lines.

This example was written for a 10 ton chiller

You have more than enough water per BTU however you have to hold enough pressure or GPM to satisfy the equipment although the BTU load isn't that much compared to volume of water.

A critical factor. Only return used water back to the chiller, use a small bypass to keep water in lines at set point.

If you do not flow unused water back to the chiller then you have more useable GPM and pressure to distribute the flow. Unless the pressure in the line is high enough to force water down each chamber something is going to starve. Most owners are flowing 75% of their water back to the chiller and using 25% or less of it for cooling. This artificially creates a need for GPM. When we do an install we do not attach the supply line to the return line. We use a small bypass to flow some water back to the return line to give a good temperature reading and to keep water flowing in the winter.

Most jacketed vessels are limited to around 15 PSI. Many manufacturers limit the psi to 12 psi. I have toured many of the factories building jacketed vessels.

The below is in reference to an existing brewery wanting to plan for the future when they purchase their new chiller.

If it were me and I was plumbing his system I would use 2" supply with 2.5" return. At the largest I would use 2.5" with 3" return. If you use 2" I'd use two 2 HP pumps and on 2.5" I would use 2 @ 2.5 HP. The sweetest would be 3 @ 1.5 HP, staged based on pressure. Have the second pump kick on if the pressure drops below a certain point. Then the third pump. The pressure switches are field adjustable. If you stop flowing most of the water back to the chiller you will most likely never have the second pump come on or the third pump. It would give excellent redundancy and flow. On either pipe size the three pump alignment would beat VFD. The staging I would use is based on the restriction of chilled water bypassing to the chiller. If your standing pressure without demand from equipment was 40 psi I would stage pump two at 30 psi and three at 15 psi. If you put the range too close your pumps will short cycle.

Important factor,
We build our chillers with a built in bypass from the pump head to the chiller. We use 3/8" copper and insulate it. This water flowing over our evaporator raises our BTU rating. It also allows the pumps(main supply line from chiller) to be totally closed and run indefinitely without harm.

If you could evenly distribute the flow a 1 HP could supply 33 tons of water. The problem is you would have to have a flow regulator or pressure control on each vessel to make sure non starve. I'm not saying use a 1 HP but it's easy to see how one could be used. It's easier to buy a larger pump that can supply the needed pressure for even distribution.

Regarding VFD
Most customers don't realize how frequency drives work. It either uses a pulse or it changes power to the pump. Either method uses more energy and drastically shortens pump life. The next two paragraphs are taken from a company that are experts in pressure regulating and flow. From Cycle Stop Valves Inc.'s website. They are based in Lubbock, Texas. They have much more information on their website.

These Variable Speed type pumps do not save energy, and do not make pumps last longer. To the contrary, varying the speed of these type pumps can increase the energy used by as much as 500% per gallon produced. Likewise, varying the speed increases the heat in motors, causes excessive vibration, and shortens the life of motors from other undue stresses.

So how do these people get away with lying? As they say, the Devil is in the details. Read the fine print carefully. Comparing a VFD to the most inefficient pump system possible is the usual way to show it saves energy. Many articles will barely mention discontinuing the use of a dump valve, lowering the pressure required, or even installing a smaller pump in the system. Although these are the real reasons for the documented energy savings, the VFD added to the big pump wrongfully gets all the credit.

Flow is reduced 5 times faster than the amp draw.

If you are considering VFD you should visit www.cyclestopvalves.com

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1. Are all chillers made the same?
No, there are numerous ways to build a chiller using numerous materials. Some have no reservoir while others have plastic or stainless steel reservoirs. There are probably as many features as there are on new cars.

2. I was told by a chiller company that doesn't manufacture a low temp chiller especially for breweries that you can use any chiller for breweries. Is that correct?
While there is some truth to what he says it isn't practical truth. If you use a chiller that isn't designed for low temp it may reach set point, however normally this is achieved by oversizing to make up for the inadequacies of the standard temp chiller. The cost per BTU purchased and the cost to produce BTU will be much higher. A low temp chiller has a refrigerant charge for low temps, a water pump that operates efficiently at low temps and the chiller plus plumbing is well insulated to different degrees by different manufacturers, some more than others.

3. What is the difference between a brewery chiller and a standard chiller?
There are only a few companies that design true brewery chillers, those companies such as Pro Chillers, GD Chillers, and CHILLKING® Chillers will tell you there is a big difference between standard chillers and low temperature chillers designed for breweries. At times a different coolant pump is required because low temps make lubricants sluggish. All three manufacturers have their preferred method of removing heat. The reservoirs are also well insulated. Some use stainless steel reservoirs while others use plastics. In the opinion of CHILLKING® the most important component is the evaporator. This is where the heat is removed from the coolant. Study the brands and find the one that best suits your needs.

4. Are all brewery chillers of the same basic footprint?
Again it depends upon design, some companies build a horizontal version and a vertical version of a chiller model that has the same performance. Normally they use the same components in a vertical as they do a horizontal, they just build upwards.

5. Do all chiller companies use a standard industry design?
No, although some may appear the same this is because the laws of thermal dynamics never change. You may notice a difference in line size within the condenser or different tanks. But the base is always the same, condenser, evaporator, compressor. The compressor moves the refrigerant, the evaporator removes heat from the environment it's in, and the condenser discharges the heat absorbed by the evaporator. There is more to it but all follow this basic design.

6. Are the warranties the same throughout the industry?
Each company has a standard warranty for their product. Most companies use Copeland Compressors. Copeland gives a 1 year warranty, anything beyond this is by the chiller manufacturer and their belief in the life of their compressors based on the design of their chiller. The most important part of the warranty in the opinion of CHILLKING® is the compressor portion. If a company has no compressor issues it is very easy to offer a long term warranty.

7. I have a fast food restaurant with several pieces of equipment. Why does a six ton CHILLKING® provide enough cooling for more than six tons of equipment?
CHILLKING® has been designing, building, and installing chillers for fast food and yogurt for over twenty years. We understand the business better than any chiller company. We use a very large reservoir in our chillers, this gives you reserve capacity for starting several pieces of equipment. When we first got into the fast food business we bought very expensive equipment for long term testing of ice cream, ice, and slush machines. We know the cycle and run times of each piece of equipment by manufacturer. If we size a system, we guarantee our sizing. Be it restaurant, yogurt, store, or brewery, we stand behind our sizing. Our guarantee is based on the information given to us by the customer at the time of sizing the equipment.

8. How many amps does a chiller circuit require? Do you build single phase and three phase chillers? If so what voltages do you build chillers for?
CHILLKING® builds chillers in single phase and three phase. We build in most any voltage there is. We build low voltage chillers in 24v and 48V, then more traditional 1 Phase in 120v to 208v and 240v. In 3 phase we build 208v, 220v, 230v, 240v, 460v-480v, and 575v-600v. Ask for other voltages. The amp draw of a chiller depends on the size of chiller and voltage. Check our specs page for amp draws of models.

9. Are your chillers built for indoors or outdoors?
All CHILLKING® Chillers and CHILLKING® Coolers are built to be used outdoors or indoors. Any of our outdoor chillers can be used inside also however check with your sales associate at your dealer, there must be adequate space to discharge the heat into.

10. Where does the chiller need to be located?
Many are located on rooftops. If location on a roof is planned it is important to check with the structural engineer for weight loads. Your chiller can be located at ground level if you prefer. Be sure to check with CHILLKING® for proper concrete pad thickness or rooftop robber vibration pads. If located at ground level and your equipment is higher than the chiller you must have valves on the main supply and return lines to prevent back flush and overflow.

11. How much glycol do I use? What type?
CHILLKING® only recommends and sells a high quality food safe Propylene glycol(PG). It has all the additives and ingredients to keep your system clean and operating for years. We sell PG in 55 gallon drums of 95% pure PG, the other 5% is the additives and cleansers to keep you operating. We do not recommend ethylene glycol unless industrial applications. The amount to add is based on your operating temperature and upon the ambient conditions during winter. Whatever is the lowest temperature is the determining factor.

12. Does the pump need to run 100% of the time?
No it doesn't, however in most cases you use more energy by starting and stopping your pump. Also, we use a bypass in the pump to increase BTU capacity. I can't give away secrets however only CHILLKING® guarantees 110% of the rated tonnage of the chiller at 90F ambient and 50F LWT. This drastic increase in BTU is assisted by pump boost. In some cases it is better to cycle the pump. Ask your CHILLKING® Pro.


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Paper About Remote CHILLKING® Chiller Going to Canada

We have a large reservoir of Propylene Glycol that is good to a minimum of -35F that we use for testing our chillers. When we drain the PG from the chiller we leave a residual amount in the pump after testing. The main reason is to keep the seals moist in case someone takes quite some time installing. We have many customers anxious to get their chiller to only get delayed by the building department or some snag so we do our best to think ahead. The chiller has the proper charge of refrigerant for 20' of line sets. If the runs are much longer than 25' it is standard practice to increase the line size. There is a chart inside the cover that has this information. A licensed installer will already know these sizes. An increase in line size will require additional refrigerant, we can give you the amount to add after we know length and size. The refrigerant charge has been pumped down into the condensers. Since we run all chillers and do a BTU test we have to weld lines in place. When we cut the lines we prep for the installer.

This part is very important. The CHILLKING® chiller cabinet with the components that stay at ground level is dry charged with nitrogen. We weld the lines shut, draw another vacuum and add nitrogen. This ensures a dry system upon arrival. They just need to cut the stub outs and weld in their lines. Pay close attention to keep the lines separate, they are marked as 1 and 2 for condenser 1 and 2. When they make the cut the dry nitrogen charge will leak out. It is not refrigerant. Only the condensers have refrigerant in them. They have the critical charge for the chiller. Then they draw a vacuum on the line sets and evaporator. After the standard 3 on 3 off vacuum they open the king valves on the condensers. The condensers have a pressure valve for low ambient. It does not allow the fan to come on until adequate pressure is attained.

When the installer is ready we can send all pressure settings to just double check everything. A manual is included in the electrical panel. There will be an ETL sticker that has critical charge in ounces and the pressures. The access is marked on the chiller.

The most overlooked thing in the manual is the drawing showing how to put a T in line to use for glycol access. Just as the return line enters the chiller install a "T" with the leg facing up. Install a threaded slip fitting into the upright leg and a cap or plug to seal the line. Use the same size plug or cap as the glycol return line, do not reduce it. This is used to fill the system and add propylene glycol. It is also for testing the strength of your glycol during your late summer checkup.

Very important! If it is very cold upon start up please allow time for the compressor heaters to warm the compressors before start up. We advise 15 to 30 minutes, this is to heat the oil in the compressor to give adequate oiling upon start up. These are very rugged Copeland scroll compressors however every step to extend compressor life will give you at least 15 years of dependable compressor life. Most of our original chillers using Copeland compressors from 20 years ago are running the same compressor.

If the chiller cabinet is lower than the equipment being cooled and you happen to have a power failure the liquid coolant will flow back to the chiller. It is a vented system so the tank could overflow. It is best to install two electrically activated valves at the discharge port and the return port of the glycol chiller lines. These valves open on power applied to the pump. They should be wired into the water pump circuit. This ensures that if the pump is running the valves are open. You can use a check valve on the discharge line however the return line requires a solenoid or motor driven valve. Valves can be purchased in various voltages, we advise using the low voltage for controls coming from the transformer. Our office can assist the installer with drawings depending upon the method used.

CHILLKING® installs a low level float switch as standard practice on every chiller. This switch can be used to turn on a led, an alarm, auto fill, or all three. We feel the float switch is much more dependable than a side mounted sight glass plus we don't charge for it. Our experience has been that the sight glass will turn opaque and age to the point that you cannot read it. They also get broken easily and leak. When it is on a chiller on the roof it is very difficult to check the level. An alarm or light wired in has proven to be the most dependable. Most customers prefer a buzzer or alarm. I feel this is best because with time the employees stop checking fluid level and a sudden buzz or ring will awaken them. When it sounds the chiller is not desperately low. It is 2" to 3" below the full mark.

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CHILLKING® study guides

Basic refrigeration used in chillers.

Many of our new employees will be surprised at how many different methods, refrigerants, designs, solders, and construction methods go into designing or building a chiller. CHILLKING® employees are exposed to a much larger "palette of color" than would be an average HVAC technician. What I mean is that some artist will use many colors to create a work of art while others may limit themselves to black and white.

CHILLKING® employees will work most of the time with a refrigerant commonly known as Puron, Suva or Forane with a refrigerant code of 410A. This refrigerant was designed and engineered by Allied Signal in 1991. They are now a division of Honeywell. It was commercialized by Carrier Company because they were one of the first large equipment manufacturers that recognized its ability to produce higher BTU with less energy.

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Reducing Humidity in Greenhouses

Source: The Center for Agriculture, Food and the Environment/UMass Amherst

Contact Biotherm Solutions, DehuKing's exclusive distributor, for additional information or to purchase.

Click here to learn more about reducing himidity in greenhouses from The Center for Agriculture, Food and the Environment/UMass Amherst.

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Zoomable Image

Source: USGS

Learn more about Evapotranspiration and The Water Cycle from the USGS by clicking here.

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Information Natural Gas Engine Driven Chiller

Source: HPAC Engineering

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More Information about Dehumidifiers

Self-contained, free-standing dehumidification units

DehuKing came to be because of demand. Our founding company has been building dehumidification for twenty years but as a part of their chiller operations. In recent years there is demand for independent freestanding dehumidification machines. DehuKing is introducing a full line of dehumidifiers made of stainless steel and upgraded heat exchangers. Even the footprint is smaller than competing machines.

DehuKing coils are inside the cabinet, this protects the coils from damage. DehuKing coils are angled in order to get more coverage as the air is drawn across the coil. The cooled dry air is drawn across the condenser and discharged at close to the environment temperature. Condensed water is collected in a stainless steel pan and directed to remote tanks or plants.

CopelandTM compressors* are used in DehuKing dehumidifiers, we use parts that are readily available locally. We use U.S. made parts when possible in our DehuKing dehumidifiers. GE motors, CopelandTM compressors, Emerson parts, A.O. Smith, Johnson controls, and many other fine American brands. DehuKing only buys an imported part when a U.S. built part is not available. Even then we make every effort to buy from an American company.

*At times it’s not possible to purchase a CopelandTM compressor, if so another brand of comparable value and performance will be substituted.

DehuKing builds dehumidifiers from 272 pints per day to 864 gallons per day. It is important to you that DehuKing does this as economically as possible. Power to condensation is listed on the spec’s page, watts used to a gallon condensed. You will find that we are very competitive in power used. Our parent company CHILLKING has manufactured chillers that use less power for twenty years. DehuKing dehumidifiers are engineered to save energy, outperform the competition, and be superior in construction and quality. For more information on operating costs compared to desiccant dehumidifiers and competitors refrigerant dehumidifiers click here.

In addition to these powerful dehumidifiers DehuKing manufactures chillers. When using a DehuKing Chiller an air handler that is set up for dehumidification is used. It has a chilled water coil and a hot water coil. These can have a very small footprint based on the type fan used. The DehuKing dehumidifying air handler is installed inside and the DehuKing Chiller is installed outside to make a very solid DehuKing dehumidifier. These perform at the same rate as our DehuKing package units.

Every DehuKing has filtration. In addition DehuKing offers ionizers for the machines, ionized air increases plant growth and makes for stronger crops. Each machine can be ordered with charcoal filtration as well. It is important to us that your DehuKing machine does extras besides dehumidification. We at DehuKing want to increase air quality.

Some have used our machines to collect bathing water and even drinking water. TO BE USED AS DRINKING WATER REQUIRES NUTRIENTS ADDED. Disaster areas without power and working wells have ordered the DehuKing chiller dehumidifier combination and produced water. This is enough water for 86 people if they use 10 gallons per day each, very conservative use would allow for 160 people.

*Based on maximum relative humidity.

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How Dehumidifiers Work

Dehumidifiers operate by absorbing heat from the air, in doing so they dehumidify as the air moves across the refrigerant chilled HEX evaporator. This cold air will be at the BTU rating of the unit. A 24,000 BTU unit will have 24,000 BTU of cold air discharged. When absorbing heat into the refrigerant it absorbs until the refrigerant evaporates inside the HEX and moves on. More refrigerant takes its place to absorb more heat.

The chilled evaporator HEX is at such a temperature it will collect moisture from the air moving across the evaporator. Although the refrigerant is evaporating the humidity is condensing to become water.

Now we have 24,000 BTU of heat in the refrigerant and it must be discharged. The refrigerant has moved into the condenser HEX while under pressure created by the compressor. The heat is removed is when the dry cold air moves across the condenser HEX. Remember that there is 24,000 BTU of cold air to remove 24,000 BTU of heat from the under pressure hot refrigerant. These would counter each other if perfectly equal.

There is a misconception that all of the heat from the compressor is absorbed into the refrigerant to help cool the compressor. Unfortunately it’s not. The electrical energy used to spin the compressor motor creates heat. The condenser fan motor creates heat also. There’s about 1,000 BTU of heat or more that doesn’t have a home so it migrates into the environment. If you insulate the compressor it will overheat and lock up.
The laws of thermal dynamics cannot be beaten but we can work around them.


The DehuKing brand has a solution. No matter whose unit you own, be it our brand or a competitor’s brand, it will generate some heat as it dehumidifies. We have two solutions.

DehuKing's first solution is to use one remote dehumidifier with every 4 to 5 standard 2 tons 515 pint DehuKing Dehumidifier. This will counter all of the heat generated by the four or five dehumidifiers plus discharge some remaining cold air into the area. The beauty is that the remote dehumidifiers remove the same amount of moisture as the free hanging dehumidifier. It dehumidifies as it cools the environment(2 Ton = 515 pint). Please see the remote spec sheet on our website tech page.

The second DehuKing solution is to use the 4 ton 1,030 pints stand alone dehumidifier. This unit stands on its own four legs just on the other side of the greenhouse exterior wall. The dehumidifier has riser of 3’ that has a small head upon the top of the riser. This riser penetrates into the greenhouse and discharged 4 tons of dry chilled air into the environment. To compliment the machine hang up to 12 @ 2 ton 515 pint dehumidifiers in the environment or use more stand alone 4 ton units. Specs will soon be on the tech page of our Chillking website.

Contact Biotherm Solutions, DehuKing's exclusive distributor, for additional information or to purchase.

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Humidity Control for Pathogen Prevention in a Greenhouse or Indoor Garden

Pathogenic fungi can be very destructive to an indoor garden or greenhouse. Much like pest insects, pathogenic fungi are capable, under the right circumstances, of quickly destroying an otherwise flourishing crop. To effectively defend a garden against such an attack, indoor horticulturists and greenhouse hobbyists should know how to prevent, positively identify, and treat the most common fungi pathogens. As with most garden disturbances, prevention is the most powerful defense. However, chances are good that even the most diligent growers will experience a hiccup or two when cultivating plants indoors or in a greenhouse. The two most common fungi pathogens to plague indoor horticulturists and/or greenhouse hobbyists are powdery mildew and botrytis (fruit or flower rot).

Powdery mildew is a fungal disease that can affect a wide variety of plants. Powdery mildew is a general term for the plant disease caused by multiple pathogenic fungi; all found in the order Erysiphales (a subcategory of the division Ascomycota).

Plants infected with powdery mildew look as if they have been sprinkled with white flour. Powdery mildew usually starts off as small, circular spots on the leaves, but can also be found on the stems or flowers. In some cases, powdery mildew can cause the leaves of a plant to twist, break, or become distorted. The white spots eventually spread and cover the majority of the leaf's surface.

Although systemic fungicides are effective against powdery mildew, they should only be used on ornamental plants. For food crops or other consumables, the best treatment option for powdery mildew is some sort of organic-based fungicide. The most commonly used organic fungicides are sulfur-based fungicides, copper-based fungicides, neem-based fungicides, bicarbonate-based fungicides, botanical-based fungicides, and biological fungicides. Even when using an organic fungicide, it is of the utmost importance to follow the manufacturer's application instructions for safety.

A key to preventing powdery mildew is to make sure the spores never enter a garden in the first place. Perhaps the most common way pathogenic fungi spores enter a garden is through the fresh air intake. By using an intake air filter, a grower can remove many of the spores and pest insects that could otherwise end up in the grow room. A HEPA filter on the ventilation's intake can be a valuable tool to lessen the ability of powdery mildew spores to enter the garden. Fungi spores are microscopic and, even with intake filters, are almost impossible to stop from entering the grow space.

With this in mind, a grower should focus his or her attention on humidity control as another preventative measure. Maintaining proper atmospheric conditions will help prevent the humidity levels conducive for unwanted visitors. In layman's terms, humidify levels are affected by the moisture content and the temperature in the garden area. This is why the temperature variance from the lights on cycle to the lights off cycle is an important factor to consider. Keeping the temperature variance between 10-15 degrees F from the lights on period to the lights off period will reduce the likelihood of condensation and unwanted humidity spikes. By controlling temperature variances, a grower automatically has more control over humidity and, therefore, can more effectively prevent pathogens. A general rule of thumb is to maintain a humidity level of 55% or under in an indoor garden or greenhouse.

Botrytis is a necrotrophic fungus that can affect many different plant species. In horticulture, it is commonly referred to as bud rot, fruit rot, flower rot or gray mold.

Botrytis mainly affects tender tissues, such as flowers, fruits, and seedlings, but can enter the plant's tissue through pruning scars or other distressed or wounded tissue. Lower, shaded sections of a plant are usually the first to show signs of a botrytis infection. The first sign shown by a plant with a botrytis infection is a water-soaked, browned area. The distinctive browning is universal, regardless of the type of plant affected. After the initial browning, a silvery-gray fuzzy mat develops on or around the browned tissue. In extreme cases, or in cases where high humidity is prevalent, a brown, slimy substance can appear; this is actually the decimated plant tissue.

Botrytis-infected sections of a plant should be removed immediately in order to prevent it from spreading to other areas of the garden. If possible, bag the affected section of plant before cutting it. This should be done to limit the spreading of spores as the infected area is disturbed. After the infected sections of plant tissue have been removed, the rest of the garden should be treated with a biological fungicide. To prevent future outbreaks, it is a good idea for indoor and greenhouse growers to disassemble the grow room after the garden cycle and disinfect everything with a 5-10% bleach solution of a food-grade hydrogen peroxide solution. This will kill any remaining viable spores and reduce the chance of a future outbreak.

Keeping a clean grow room and removing any dying or dead plant material are good first steps for any indoor or greenhouse grower. In a sense, botrytis is an environmental disease. This means it can only develop when the environmental conditions are conducive to its growth. The prevention of botrytis is somewhat easier for indoor horticulturists because they have more control over the environmental conditions. Humidity is the biggest trigger for botrytis in an indoor garden. As long as the humidity is kept below 55%, botrytis is unlikely to develop. The other contributing environmental factor is temperature. Botrytis can only germinate on damp of wet plant tissue in temperatures between 50-70 degrees F. However, once the fungus has developed, it can withstand a wider range of temperature and humidity. Botrytis grows most rapidly in lower temperatures paired with high humidity. The humidity levels in close proximity to the plants are generally much higher due to the plant's transpiration processes. This is why air movement within the grow space is so important for maintaining proper humidity levels. To create good airflow, oscillating fans should be used to mix the humid air that is close to the plants, with the air in the rest of the room; this will help keep the room's humidity uniform.

As previously mentioned, maintaining proper humidity levels in an indoor garden or greenhouse is very important when trying to prevent pathogenic fungi. Put another way, if humidity levels are kept in check, the pathogenic fungi's ability to establish is hampered. The optimal humidity range for indoor gardens and hobby greenhouses is 50-60%. Even when an indoor garden is climate controlled by a mini-split air conditioner, a dehumidifier may have to be used to maintain the optimal humidity level. Again, it is important to remember how the garden's temperature also affects the relative humidity levels. Controlling temperature variances will reduce spikes in humidity. A grower who invests in an atmospheric controller, which can be used to automate fans, air conditioning equipment, and dehumidifiers, will have a much easier time maintaining the optimal temperature and humidity. The controlled, consistent temperature and humidity levels are a strong defense against pathogens.

In addition to atmospheric control devices, which help automate the temperature and humidity in the garden, growers who wish to take pathogen prevention one step further can implement a standalone air purification device. When combined with an air intake filter and an atmospheric control system, a stand-alone air purification device can give even more protection against pathogenic fungi to an indoor garden or greenhouse crop. Essentially, these devices have an internal fan that circulates the air within the grow space; purifying the air in the process. The technology used in these devices can differ, but, most commonly, they either generate negative ions or utilize some sort of UV lighting. Some of the UV lighting systems will actually produce ozone in the purification process. Devices that produce a detectable amount of ozone can cause the ozone levels to build up in the grow space. This can damage essential oil production or, in extreme cases, become harmful to the gardener. Both the size of the grow rom and the amount of detectable ozone should be carefully considered to ensure the air purification unit will be safe for the particular garden application.

Perhaps the biggest draw to indoor and greenhouse gardening is the heightened level of control over the environment. That being said, a grower who fails to control his or her garden's climate properly will likely have a continuous battle with pest insects and/or fungi pathogens. Ideally, a garden's temperature (and temperature variances) would be controlled by an atmospheric controller. When the temperature of an indoor garden or greenhouse is automated, it makes it that much easier to control the relative humidity. However, it must be remembered that, plants are made mostly of water and go through a natural transpiration process as they grow. In other words, the plants themselves naturally increase the humidity level in an enclosed area as they grow.

Without proper air movement in the grow space, the humidity levels close to the plants will be much higher than the ambient air. For atmospheric equipment to operate efficiently and effectively, the humidity of the room must be uniform. This is why an ordinary oscillating fan is such a crucial piece of equipment. If the ventilation system or air conditioning unit cannot, on its own, handle the increased humidity produced by the plants, a dehumidifier should be implemented to keep the humidity levels uniform. When humidity levels are kept in check, pathogenic fungi cannot establish. This is why the ultimate prevention and protection against these pathogens is humidity control. Horticulturists who prioritize uniform humidity levels and automatic control over the garden's temperature and humidity will be better equipped to prevent pathogenic fungi such as powdery mildew and botrytis.

Eric Hopper resides in Michigan's beautiful Upper Peninsula where he enjoys gardening and pursuing sustainability. He is a Garden & Greenhouse senior editor and can be contacted at [email protected]

Source: Eric Hopper; Garden & Greenhouse, July 2019

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About Latent Heat

Some describe latent heat as moisture content in the air however that’s not entirely correct or I should say it is lacking in information. Latent heat is the heat energy used to turn the water into vapor.

To remove the moisture (water vapor) from the air the vapor must be condensed by passing the air across a cold surface that is cold enough to create water formation on the surface. Refrigeration evaporator coils achieve this by the refrigerant passing through tubes with fins that the air travels across. It must reduce the air temperature enough to reach 100% relative humidity(RH). Chillers pump chilled water/glycol through Heat exchangers of the same construction. The HEX must also reduce the temperature to reach 100% RH. This means the air can no longer hold the water vapor, the heat is released, this is latent heat. This is the heat energy that was used to turn the water into a vapor. The “Laws of Thermal Dynamics” state that it takes 1 BTU to change 1 pound of water 1F in 1 hour.

Refrigeration units and chilled water to air HEX units that are below dewpoint have an effect on latent heat and sensible heat. It varies based on time in contact with the passing air to release heat energy and how much the coil drops below dewpoint.

What can occur if not managed properly is that RH increases when the room or environment temperature is satisfied by being reduced too rapidly and not enough vapor has been removed. As an example, the environment dropped from 90F to 70F. The RH started at 80% but it is now 95% RH. The solution is to reheat or preheat the air passing through the air handling unit (AHU). Vapor is still removed and the environment temperature changes very little. With a properly designed AHU the greenhouse can be heated while being dehumidified.

Removing water from the air without a change in air temperature will reduce RH. Or you can raise the environment temperature without removing moisture and your RH is reduced. Plants transpiring will increase RH if the environment temperature remains the same.

It’s important to remember that relative humidity(RH) is a % of vapor in the air at a given temperature. If you reduce the temperature without reducing vapor the RH has increased possibly to dew point. Altitude is also a determining factor in the amount of moisture that air can hold.

By Pat King

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Nutrient Diagram for Chiller Setup

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Inside our 6 ton Dehumidifier Air Handler

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Temperature and DehuKing Dehumidifiers

Here is the deal, when he warms the area he should check the room temperature. His temperature is for the area where the machine is. The dehumidifiers suck a lot of air, about 1200 to 1500 scfm. It will pull from all around the room so the ambient temperature of the air being sucked in is most likely 50F. But let’s pretend the room is 60F. The Evaporator is 25F to 35F colder than the ambient air temperature.

The slower the fan the lower the temperature, that’s because there is less heat across the heat exchanger to raise the refrigerant temperature. Right now I’m just explaining the principal in how it works. So if it’s slower it will dehumidify better. If it’s faster it will remove more heat so we try to use a speed in the middle. The slower the fan the colder the coil.

It appears the evaporator is running 30F colder than ambient. We can add refrigerant but it will not perform well at proper higher temperature. If his room is 60F then his evaporator will be 30F. The refrigerant will have to be colder than 30F to make the evaporator 30F. This explains why all of the metal lines carrying gaseous refrigerant(the coldest) will get frost if the temperature of the room goes to 60F or below. Other companies have in their manual to stop at 58F so they must have a slightly faster fan blade but that’s why we beat them at higher temperatures. (It’s in our manuals now).

If all units are performing like this it is what I’ve explained above, however if only one unit has this problem it may be slightly low on refrigerant, nonetheless he should turn the unit off at 60F. Tomorrow I’m mailing five refrigerant temperature controllers that mount on the largest line coming from the evaporator. It will turn the unit off when refrigerant is 33F and turn it back on when it warms to 58F. We put temp controllers on all future models, they aren’t thermostats. They are freeze temperature controllers. When it starts to build ice the compressor goes off for at least five minutes but the fan continues to run to defrost it.

One thing customers don’t realize is that when it gathers ice it is dehumidifying the room. So it doesn’t stop dehumidifying, it’s actually very close to the same rate when it first starts to ice. But I guarantee if that fellow was to gather the air temperature for the entire area it’s a lot less than the 60F where the heater is. I bet the air coming into the unit is colder than 60F. That heater is a space heater and will heat a small area. Remember if it’s only drawing 1,000 cfm that’s 60,000 cfh in an hour. That’s a 40’ x 100’ x 15’ greenhouse one time turn, but it shows how much air the unit draws, it will pull air from everywhere. Eventually the air from the far end will make there, and it’s not 60F. Even if it was it could ice at 60F.

He needs to read the incoming air temperature with the infrared space heater off because the probe will heat from infrared. Or shield it from the direction of the infrared. Only read the incoming air temperature. It should be above 60F in all of the space.

I hope I wrote this so you can understand it, I’m a little presumptive at times.

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