HYDRONICS AND PLUMBING DESIGN RECOMMENDATIONS

INTRODUCTION

The hydronics loops used to extract heat from the A3 fixtures are similar to other common hydronics applications, and can utilize standard components and design techniques. Re-use and rejection of the captured heat can further utilize common dry coolers, cooling towers or adiabatic coolers found in other systems. The sizing of these systems can be performed using the same techniques used for other applications. These recommendations are intended to be used by design professionals to aid in this process.

A3 REQUIREMENTS

These requirements are drawn from the A3 Specifications, as well as basic system needs.

Always consult the A3 Specifications, Brochure, Data Sheet for the latest information.

FLOWING COOLING WATER IS REQUIRED

The A3 REQUIRES flowing water to achieve full power. Lack of flowing water at the appropriate temperatures and flow rates will result in the housing temperature reaching its thermal limit, at which point the internal controls will reduce power to maintain approximately 65C-70C at the LED baseplate.

In still air, this is only about 15% of full power, hence the A3 cannot be effectively used without water cooling.

While operation at thermal limits is not immediately destructive, long term operation at elevated temperatures will reduce the service life of the components.

GENERAL SYSTEM CONSIDERATIONS AND ASSUMPTIONS

The A3 contains TWO copper cooling tubes. The water may flow in either direction in either tube, and both parallel flow and end return (U-configuration) are acceptable.

[ADD PICTURE OF A3 as with water flow in each of the two directions]

An approximate rule of thumb is that the U-return configuration can support up to 6 lights per single supply/return connection, and the and the parallel flow configuration can support up to 12 with two supply and two return connections. See below for flow rates and temperature rise calculations. [3 gpm/tube @ 8F rise assumed here].

Fittings:

DO NOT SOLDER THE COPPER TUBES

Connection of the A3 to the water loop system should use push fittings with PEX or Copper intermediate tubes, or flexible hose with constant tension (Oeiteker full round crimp) clamps. It is perfectly acceptable to use multiple methods in the same installation for convenience. All have been successfully used in many installs.

PEX or COPPERCopper Sharkbite or similar fitting

PEX or COPPERPlastic Push Fit

John Guest or similar

Heater HoseTyp SAE J20R3

Oeiteker or similar full round clamp

DO NOT USE SCREWDRIVER DRIVEN CLAMPS, or crimp clamps with gaps. They will deform the copper tubes and leak. Flare fittings while technically feasible are the most complex to install and are not recommended.

Correct Clamp

These clamps have a continuous flat band. Commonly known as Oeiteker

Clamps.

DO NOT USEThese clamps have a flat spot, or pinch the hose.

They will unevenly compress the hose, and may even deform the cooling tube.

Should a light need to be replaced, it is recommended to replace any pex or hose used on either end. When lights are mounted at center to center spacings of 4.5 feet or less, it may be easier to use hose as it is more flexible during the install process with short lengths. For long lengths, a support or copper tubing may be helpful to prevent the sag of the tube. Copper tubing can be used with push fit slip fittings to allow lights to be conveniently removed.

Agnetix supplied U return and Y hose, made from [Jxxx rated silicone materials commonly used in industrial and automotive are available to further simplify the installation.

Agnetix offers pre-formed silicone hose in the U and Y configurations to ease installation. These eliminate fittings in the end return configuration, and allow a single ¾” manifold outlet to feed both tubes in the parallel flow configuration, reducing the number of components, system cost and installation effort. In addition Agnetix offers UV stable industry standard 5/8” ID white silicone heater hose in bulk lengths as a service to our customers.

[Add screenshot of U and Y components drawings] Pictures,

Manifolds:

Both pre-manufactured hydronic manifolds and custom built manifolds are acceptable. Pre-manufactured devices can be ordered with pre-installed shutoff valves and flow meters. These tend to be lower flow devices, and may require switching to the parallel flow configuration utilizing more outlets. Site specific manifold layouts in either Copper or PVC are suitable as well, and tend to result in a cleaner looking application, especially when more than 2 or 3 runs of lights are deployed in a room.

To maximize serviceability, each supply and return line should be fitted with a valve. The return end may utilize a check valve for this if desired, but it is more helpful to have a drainable shutoff valve. It is also helpful for verification of system performance to install flowmeters either in individual lines, or on the manifold inlet.

The [name of valve] brass valve shown below can be conveniently attached to a PVCxFIP Tee, allowing a simple installation which provides for drain/fill ports at both ends as well as shutoff 3 way valves to make this process easier.

Care should be taken to balance the flow through the manifold system’s various branches. The backpressure from valves and the various fittings is often sufficient to do so long as the manifolds themselves are not undersized.

Pressure gauges on the manifolds can be helpful in diagnosing system issues.

The lights include temperature sensors inside each unit, so additional such sensors on each manifold are not required.

There are no internal joints and hence the maximum allowed pressure will be determined by the other components and fittings used.

Pumps:

Various pumps may be used in these hydronic systems. Configurations vary from one small pump per loop, to one per room, to a single pump for the entire facility. Site conditions vary, and it may be effective to split up the task. Redundant pumps are suggested. Variable speed pumps can be helpful. It is generally not necessary to switch off the water flow to rooms which are not lit.

REQUIRED TEMPERATURES

The A3 has a wide temperature allowance. However, the point of the water cooling is to both:

Prevent heat from directly entering the grow chamber from the A3 Keep the A3 at reasonable temperatures for its operation.

As such, it is our recommendation to keep the cooling loop temperatures:

ABOVE the dew point within the grow chamber to prevent condensation on the A3 BELOW 120°F or 48°C at the last fixture in a loop

This range is generally wide enough to allow simple controls and easy operation of the system. When designing the cooling loop, please bear in mind that:

A chiller is not recommended

Recommended Water Temperature Range

Dimming OFFRoom Dewpoint

The LEDS will run approximately 15°F or 7°C higher than the water The case temperature is important even when the light is OFF due to dewpoint and condensation. Allowance needs to be made for the temperature rise of previous lights in the chain.

o A suggested design temperature of approximately 100-110

FLOW RATES

The A3 contains TWO copper cooling tubes. The water may flow in either direction, and both parallel and U- shaped end return configurations are acceptable.

In the standard situation where multiple lights are connected in series the minimum TOTAL flow rate should be designed to provide between 0.33 to 0.5 GPM per light with at least 0.5GPM per tube to ensure turbulence. Higher flow rates allow for smaller dry coolers and cooling towers.

The maximum flow rate per tube is set by the tubing wear limit. The Copper Development Association’s Copper Tube Handbook recommends maximum water velocities of between 5 and 8 feet per second for “Hot” and “Cold” water, respectively. For the ½” copper tubing used in the A3, the flow velocity is 1.37 ft/s per gpm. Hence the recommended range of maximum flow rates is between 3.6 and 5.8 GPM per tube. It is the responsibility of the design professional to ensure flow rates are appropriate.

TEMPERATURE RISE VS FLOW RATE

The temperature rise in the cooling loop can be easily estimated from the heat produced per light by the A3 (600W), the flow rate, and N the number of lights:

∆T℉= 600W147∗GPM

∙N

or

∆T℃= 600W70∗LPM

∙ N

There is virtually no change in the amount of heat captured in the cooling loop as the A3 temperature changes. The internal temperatures increase proportionally to the cooling loop temperature.

When choosing between a U-Return configuration, and a parallel flow design, it must be noted that the parallel flow setup is required over approximately 4 gpm total flow, since higher flow rates will cause tubing degradation, as all of the flow is confined to the one tube.

BASIC SYSTEM DESIGN

While a complete guide to the possibilities of the hydronic system is beyond the scope of this guide, some basic guidance and a few examples can illustrate the concepts and their operation in a simplified manner. The basic purpose of the hydronic loop is to:

Extract waste heat from the A3 Reject heat to the outside efficiently (Optionally) Allow re-use of the heat as desired

Hence we can imagine the most basic configuration: piping the water from a small reservoir to a pump to a set of piping connecting the lights to make it flow through all of the copper tubes to a radiator placed outside of the grow chamber and finally back to the small reservoir.

Indeed this system is used in small setups for both temporary demonstration purposes, and for commercial use, where re-use of the heat is not desired, impractical, etc.

The systems design in this case involves mostly selecting the dry cooler, and then choosing a suitable pump to achieve the water flow needed.

For example:

We know that for a 6 light system, if we choose a reasonable 3 GPM flow rate, i.e 0.5GPM/Lgt, we will have about 8 F of temperature rise across the series of lights.

We can select the U return configuration in this case as 3GPM is below the wear limit which begins above 4GPM.

The minimum dry cooler must then be capable of a capacity of 3600W of rejection at the maximum expected outside temperature, the maximum recommended water inlet temperature (120F), and 3GPM.

Once a suitable dry cooler is selected, its known water flow characteristics as well as those of the plumbing can be used to properly size the pump top achieve 3GPM.

Additional components such as air separators, an expansion tank, and provisions for filling and draining the system are also needed, as with any hydronics system. (In many cases this is referred to as a boiler support package.)

A thermostat on the dry cooler inlet can operate the fan. Setting this at approximately 100F to 120F will generally achieve good thermal regulation. Multiple dry coolers can be placed in various configurations to expand capacity as is common. If the fans cycle too often, then either use staging of multiple units or add a buffer tank.

It is important not to crash the water temperature below the dewpoint in the room, to prevent condensation. In very cold climates It may be necessary to install a temperature controlled bypass valve to skip the radiator completely to achieve this. Glycol may also be needed.

SUMMARY

TOTAL flow rate should be designed to provide between 0.33 to 0.5 GPM per light with at least 0.5GPM per tube.

Keep the cooling loop temperatures:

ABOVE the dew point within the grow chamber to prevent condensation on the A3 BELOW 120°F or 48°C at the last fixture in a loop

INDOOR HVAC CALCULATIONS

One of the primary reasons for using a water cooled lighting system is the reduction in necessary HVAC capacity required. Proper sizing and selection of equipment cannot be explained in this general document, and requires calculations and equipment performance data which varies significantly.. However, target heat and moisture removal rates can be estimated, and provide a useful starting point for this analysis.

The total energy added to a room can be readily calculated for HPS, LED, and water cooled LED sources. Because an indoor grow can be modeled as a closed system, this is a good estimate of the required energy removal rate needed. This can be further divided into three types of energy:

1. (Heat) transferred to the air (or working fluid for a water cooled unit) from fixture, and power supply.2. Visible (PAR) light directed towards the surface of the plants.3. Invisible (IR) energy, i.e. radiant heat, also directed towards the plants.

A typical HPS lamp will split its 1050W energy consumption into these three components in approximately a ratio of 10% Heat, 38% PAR, and the remaining 52% as IR. An air cooled LED fixture will not produce IR energy, but instead will produce much more heat transfer directly to the air, generally about a 50%/50% split between Heat and PAR. A water cooled LED fixture will generally not have a significant transfer of heat to the air, but rather the heat which would have been transferred to the air will go instead to the water cooling fluid.

Photosynthesis utilizes very little of the PAR light, and thus it is a fairly simple matter to calculate the total energy delivered to the room, and use it as a good proxy for total equipment size, the so called “Sensible load.” A more complex task is to determine the plant’s Evapo-Transpiration (ET) rate, in order to predict the required moisture removal rate, or so called “Latent load.”

Growers have tried to estimate ET from known watering rates, but this is a useless exercise. Most of the water delivered to plants does not transpire. Instead, more than 90% goes down the drain, or seeps deep into the soil. It is extremely difficult to accurately measure the water lost, and any estimate of ET based on the difference will be very inaccurate or useless.

In addition, if we wish to predict the ET for new lighting conditions or to predict the required watering rate, this strategy obviously does not help.

Virtually all outdoor horticultural moisture and watering analysis today is based on the Penman-Montieth equation, or its derivatives. This equation was developed from the first principles of physics for the purpose of determining the transpiration and hence necessary watering rates for outdoor crops, and is now extensively used in climate change studies. The calculation process requires careful measurement or estimates of several hard to measure parameters, which are important for extreme conditions and outdoor settings.

In order to avoid this type of effort, a simplification was performed by Priestly-Taylor, eliminating much of the observation, and condensing the more difficult parameters to a single “fudge factor” which is applicable for situations where the plants are properly watered. This is useful for agriculture where proper watering is the aim in the first place.

In effect Priestly-Taylor takes the total energy provided by the sun, adjusts for canopy coverage, and estimates the fraction used to warm the plant vs that which will boil away the moisture. In a proper indoor facility, canopy coverage is high, the temperature is high and stable, the light level is high, and there are no wet surfaces.

Under these conditions ET, or rather total Latent can be predicted simply as a percentage of the sum of items 2 and 3, typically between 25% and 50% based on cultivation practice, and the left over area of wet surfaces.

NEW CONTENT:

Here are some useful plumbing parts which can make your install easier.  This is intended for systems of ALL SIZES, so its a bit lengthy.

Agnetix Parts which are available:WHITE 5/8 Id Heater hose < (for between lights) $5 per meter (Bulk 50M rolls available)Agnetix - WHITE “Y” Fitting for straight through loops $8 perAgnetix - WHITE “U” Fitting for up and back loops $5 per 

Other Parts:Oetiker Clamps for between lamp hose: -- Correct size is either (depending on thickness of hose wall, buy both and pick the right one):-------16700031 Stepless Ear Clamp, One Ear, 7 mm Band Width, Clamp ID Range 22.4 mm (Closed) - 25.6 mm (Open) ------16700033 Stepless Ear Clamp, One Ear, 7 mm Band Width, Clamp ID Range 23.9 mm (Closed) - 27.1 mm (Open)Oetiker Clamps for Y & U Fittings:For the U and the thin part of the Y: ------16700035 Stepless Ear Clamp, One Ear, 7 mm Band Width, Clamp ID Range 25.4 mm (Closed) - 28.6 mm (Open)For the Thick part of the Y:  ------16700040 Stepless Ear Clamp, One Ear, 7 mm Band Width, Clamp ID Range 28.4 mm (Closed) - 31.6 mm (Open)

USE PROPER TOOLS with the Oeiteker clamps.  Make life much easier.Crimper: https://www.amazon.com/dp/B01IBA4SS0/ref=dp_cerb_2Cutter for removing a clamp: https://www.amazon.com/Oetiker-14100502-Hand-Clamp-Cutter/dp/B07S2V8R15/ref=dp_ob_title_def

Manifold Tee:PVC Tee which you can use to build the manifolds on either the pump side or the light side.  This one is in 1 1/2" but both 1 1/4" and 2" are available easily.  These are easily available.https://www.supplyhouse.com/Spears-402-210-1-1-2-x-1-1-2-x-3-4-PVC-Sch-40-Threaded-Tee-Socket-x-FIPT 

The rules for PVC are that you need approx:1" -- 8 GPM -- 16 lights1.25" -- 12 GPM -- 25 lights1.5" -- 17 GPM -- 35 lights2" -- 27 GPM -- 55 lights

These are the guaranteed easy flow.  You can usually go twice that rate if you take care not to have too many elbows and match the number between rooms, etc.

Manifold Valve:This is the ball valve with hose bib drain....  in 3/4, for the Y configuration and 1/2 or 3/4" for the U.  https://www.supplyhouse.com/Webstone-40613-3-4-Pro-Pal-Full-Port-Forged-Brass-Ball-Valve-w-Hi-Flow-Hose-Drain-Reversible-Handle  

This one is threaded on both sides, so you would need a short stub on the output and a nipple on the input.   These are great because they allow you to get the glycol out before removing a light or adding to the system, should it be necessary.  If you don't want to use individual line valves, then you will have to drain a lot of the system. which is annoying.

Nipple:https://www.supplyhouse.com/Bluefin-BRN075-3-4-x-Close-Brass-Nipple  

Stub on the output:There's a couple of ways to get to copper pipe, to then attach the Y....  

Normally, we could use a hose barb fitting, but they don't make them as a standard part in 3/4NPT- 7/8 hose, which is what would be required to match copper tube sizes....  I picked this because its always possible to get to 3/4 copper tube somehow....  However, it IS a standard ID for PEX, so this is the easiest optionhttps://www.supplyhouse.com/Bluefin-PXM100-075-1-PEX-x-3-4-NPT-Brass-Male-Adapter-Lead-Free  

2nd easiest way is sharkbite Male NPT adapter + a little piece of 3/4 Copper tubehttps://www.supplyhouse.com/SharkBite-U134LF-3-4-Sharkbite-x-Male-Adapter-Lead-Free 

3rd easiest is Solder Male NPT Adapter adapter to short piece of Copper Tubehttps://www.supplyhouse.com/Elkhart-30330-3-4-Copper-x-Male-Adapter  

Pumps:

Calculate and use the correct pumps.  Use more than 1 for redundancy.

When making manifolds for pumps, if the pump does not come with union connectors, or a check valve, then you can use these:https://www.supplyhouse.com/Brass-Fittings-164000  https://www.supplyhouse.com/Bluefin-SCT075-3-4-Threaded-Swing-Check-Valve-Lead-Free  

The pump must be removable, and have valves on both sides.  The check valve is sufficient on the OUTPUT side.  A ball Valve is needed on the input side.  No drain is needed here.https://www.supplyhouse.com/Webstone-40533W-3-4-MIP-x-FIP-Full-Port-Forged-Brass-Ball-Valve-Lead-Free This one is MxF so you need one less nipple....  Make it slightly smaller for the whole assembly. These are generally available.

Fill/Drain:Filling and draining these systems should not be much of an issue once things are up and running, but can be annoying initially.  We suggest something like this for the filling part:https://www.supplyhouse.com/Watts-0386466-RBFF-1-2-Residential-Boiler-Fill-Fitting These are commonly available.

Drains:An additional drain port should be added, along with a blocking valve, so that the entire system can be easily drained.  This is required to happen every time any changes are made to the system to purge debris.  The use of compressed air and well located ports can make this easy. 

Glycol:When using glycol, codes usually require that the systems be fully isolated, but you will need a place where you can bring in a vat of glycol mix, and pump it in.

Expansion:  CALCULATE and choose an appropriate expansion tank.  Water and various glycol mixes can expand a lot between super cold and warm temps.  These can get big.

Air removal:You will need an air separator to get the air out of the system when filling.  Install this after purging, or prepare to clean it later (painful).  Use the correct size or next size up, or flow will be restricted.  This is just one option.https://www.supplyhouse.com/Watts-0858546-3-4-AS-MB-75-Microbubble-Air-Separator  

It is often helpful to use the drain ports together to initially fill the system from a vat of glycol mix, but there will always be a LOT of air left over after doing that.  Adding additional little air separators at various high parts of the system can help a lot.