Horticulture Projects

There are many ways to look at horticulture projects from circulating water through grow pipes, to floating pontoons on a water body. Each system though requires water.

Different plants also have different ideal temperature ranges. So, when considering your heating or cooling project please take this into account.

Every Project has its oddities and we can cater for most of these project conditions for heating, cooling or temperature management. We can also cater for space temp control, humidity level control, water reclaim and energy management systems

Client issue

• NFT System
• 6000L in-store and 6000L in circuit
• Tank Volume: 6000 L
• Desired Water Temp: 25^oC
• Water Use – Flow Rate 600 L / m
• Top Up Water Temp: 4^oC
• Water Condition: Fresh
• Top up method: Flow-through

• Solution

  • Installed a TAC300SSD Ti Toyesi Trident Horticulture heater/chiller heat pump with Titanium heat exchanger into the system. Rated at 14kW heating & 10kW chilling.
  • The heat pump was fitted to be able to freely circulate with the sump tank with no issue – problem solved
  • “Plants Happy” = “Client Happy”

Client issue

• Hydroponic Winter Heating System
• 22,500 L in an insulated tank
• Water Temperature 20^oC to 24^oC
• 10,000 L used per day (over a 12-hour period)
• Used in batches each hour or so.
• 835 L per hour flow rate.
• Top up water estimated at around 2^oC in Winter

Solution

• Heat pumps draw heat out of the air and since the unit is for heating in winter, there is less heat available to draw on. We sized the unit based on the reduced heat capacity of winter.  As TAC 1200 provides 0nly ~ 32kW of heating @ 2C ambient compared to ~ 58kW at 20C ambient.
• The heat load includes holding kW like holding a pool at temperature, plus the kW required to ramp the cold top up water back to temperature as quickly as possible.
• Most of the heat load in this project is the temperature of the top-up water being so cold at 2C to 5C and ramping it back up to 20C.  Temperature Ramping kW is always higher than holding kW.
• If the flow rate is less than 835L/hr then the TAC 800 would also be a good choice for this project. The TAC 1200 will allow you more flexibility in flow rates and more capacity in case you also want summer cooling of the water.

One of the biggest expenses on any horticultural venture is the use of water for irrigating crops.

When it comes to outside irrigation very little can be done to save evaporation losses of water to the atmosphere. However, the case is now different for Protect Cropping.

Greenhouse Humidity is one of the big issues when it comes to Protected Cropping Practices. Some plants need relatively high humidity, whilst others need a significantly lower humidity level.

Also as humidity levels increase, so does the risk of fungus, diseases and rot set in, let alone the water build-up on the internal workings of the greenhouse causing rust and corrosion.  Expelling excess humidity is very critical for the health of the crop.

Step 1. – Watering control

Do not apply excessive water to your greenhouse plants. Too much water creates puddles which increase the humidity when the water evaporates. Apply water to the soil rather than directly onto the leaves, flowers and fruits to reduce evaporation. Water your greenhouse plants in the early morning.

Step 2. – Control Condensation and Dripping

Condensation is common in some greenhouse designs. However, unchecked dripping contributes to higher humidity.

Step 3 – Ventilation

Install airflow fans in your greenhouse. These improve the circulation of air and help to expel humid air out. You may also want to install vents around your greenhouse. However, during the winter you need to take measures to control both the humidity and heat. The fans and vents cause temperatures to fall.

Step 4. –  Using Misters

When humidity levels are low, misters are often used. However, they should be used carefully not o overly dampen the foliage of plants and cause other issues like mould or rot to grow. Also, this can cause humidity to increase too rapidly and then having to use airflow and venting to reverse the process, just to then repeat.

Whilst it is necessary to irrigate your crops, and the water that the plants drink is water you will never get back, there is however a large component of water lost to the air.

Plants perspire, water puddles evaporate, and water on the foliage and soil also evaporates into the air within the greenhouse.

This lost water in the form of water vapour (as Humidity) is normally waste vented into the atmosphere away from the greenhouse and unrecoverable.

An Example:

If your greenhouse is 50m by 25m by 10m high, then your building is 12,500 m^3.

If your greenhouse is 25^oC and 70% humidity, then you will have approx. 12g of water vapour per m³ of your greenhouse.

Thus, approximately 150kg or about 150 L of water in the form of water vapour. If this was to raise to 90% humidity, then the amount of water vapour in the air will increase to 225 L of water in the air.

If you do 1 complete fresh air change of your greenhouse per hour, then that is a potential 5,400 L of water vapour lost per day.

Or a massive 1,971,000 L per year in just wasted lost water. Almost a full Olympic pool in avoidable water losses.

Solution

Toyesi PCVER Water Reclaim

Toyesi has developed the PCVER System for Horticulture Projects. This unique system uses an advanced Ventilation system that can reclaim a significant amount of the lost water from water vapour, and return it for reuse. Depending on the system set-up, the projected recaptured of water of up to 90% reclaim can be achieved.

Key Benefits:

By actively drawing air through the system we have several key positive outcomes:

• Actively improve airflow and ventilation rates
• Remove moisture from the air (capture) for reuse
• Reduce humidity to desirable levels.
• Decrease disease, rot of crop and rusting or corrosion of the greenhouse.

Key Options:

• Return dehumidified air back to space
• Capturing excess heat energy normally waste vented.
• Use energy capture to pre-heat return air
• Help control space temperature & reduce the demand for gas space heating, thus decreasing running costs.
• Storage of heat energy for reuse – e.g. Hydroponic root warming.

Client issue

• 4 individual box systems, each covering a 56m x 9.6m x 4m high area or an alternative option to suit the entire area?
• Note that this is for Cannabis and will be in a complete outside air filtered room. The grower has specified 1,400 litres of air exchange per 24 hours per area.
• Attempt to maintain Relative Humidity levels from 50% to 80% pending growing times.

Solution

• Water-cooled dehumidifier
• Single turnover per hour was determined as ineffective at reducing humidity. as a reduction from 80% to low 60% was anticipated.
• A larger system with over 2500 L/s airflow would be required if 50% could be achieved.
• After review and consultation with the client, the increases were approved and the problem handled.

• The client was amazed at just the high volume of condensate water being removed from the air.
• This water can be treated and returned reducing demand on water use and in our current drought conditions that’s got to be a good thing.