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1. Greenhouse size:

• Measure the total exterior surface area of your greenhouse in square feet. This includes walls, roof, and doors, but not the floor.

2. Heat loss factors:

• Identify the heat loss factor (U-factor) of your greenhouse materials. This value represents how readily heat escapes through the materials. Lower U-factors indicate better insulation.
• Common U-factors for greenhouse materials:                                                                                        –  Single-layer plastic: 1.5-2.0 BTU/(hrft²°F)                                                                                           –  Double-layer plastic: 0.75-1.0 BTU/(hrft²°F)                                                                                     –  Glass: 1.0-1.5 BTU/(hrft²°F)

3. Temperature difference:

• Calculate the desired temperature difference (ΔT) between the inside and outside of your greenhouse. This is typically the minimum temperature you want to maintain inside minus the average outdoor temperature during the coldest period.

4. Heater output:

• BTU (British Thermal Units) measure the heating capacity of a heater. Use the following formula to calculate the required heater output (BTUH):                                                            BTUH = Surface Area (sq ft) * U-factor (BTU/(hrft²°F)) * ΔT (°F)

5. Safety margin:

• Add a safety margin of 10-20% to the calculated BTUH to account for heat loss through ventilation, infiltration, and other factors.

• Allow enough free space to the left and right of the air heater to enable maintenance and repair works to be carried out.
• The air heater must be connected to a reliably earthed and watertight wall socket at all times. 
• The air heater must never be connected to a duct system.
• Inspect the air heater prior to use and check for damages.
• Avoid exposing the air heater to water and moisture for long periods of time.
• Keep the control instruments free from dirt and grease.
• Bear in mind that some parts of the air heater become hot during use.
• When the air heater is not used for long periods of time, remove the plug from the wall socked and shut off the gas supply.

Heating Power: 

• Warehouse: 80-110 W/sqm
• Factory: 120-180 W/sqm

Burner: Two-stage BP burner or modulating BS burner

Radiant strips module (pipe&reflector): Double pipe or single pipe

Controls: Local control or remote control

• Minimum distances to combustibles must be met, according to the manual.
• Installation is not recommended in places where there are chlorine products, solvents or explosives, but certain models are suitable for that type of environment.
• Enough expansion joints should be designed and installed.

Here are the criteria to consider in selecting the units:

• Vertical or horizontal units;
• Indoor or outdoor applications
• Fuel types, such as natural gas, propane, diesel and etc.
• Max. static pressure of centrifugal blower(s)
• Heating power
• Air flow rate

To start with the installation, it’s best to begin with a pre-installation checklist (a list of items to check before installation). The following is a basic checklist, intended as an example:

• Choose a suitable location for installing the heater.
• Ensure that ventilation requirements can be met.
• Examine any issues that may affect the installation of HVAC, plumbing, and electrical systems.
• Design and plan the correct fuel supply pipeline.
• Design and plan the correct supply and return air ducts (if necessary).
• Check the minimum distance from combustible materials in accordance with manufacturer recommendations and local regulations.
• Ensure equipment is easily accessible for maintenance.

     Patio heaters are selected based on two major factors:

• Infrared heating comfort: consider heater installation height, outside temperature and wind speed
• Infrared heating coverage: The heating coverage is proximately two times the width of the height of the heater and 1.2 times the length of the heater.

• Safe placement: minimum clearance to combustibles to be complied with, according to each manufacturer.
• Safe Surroundings: Never place anything above or below your patio heater or check the manufacturer’s recommended inches of clearance, which varies according to the number of BTUs the heater radiates.
• Fuel Safety: Patio heaters that use natural gas offer a more cost-effective alternative to heaters that use propane tanks. However, it is essential that you have the heater connected to the natural gas line by a professional. 
• Weather Protection: There is nothing more dangerous to a patio heater than wind. You can protect your patio heater from the wind by placing it in a location that has less exposure. Chain installation is prohibited in windy conditions.

• Luminous Gas Patio Heater

     Patio heaters are selected based on two major factors:

• Infrared heating comfort: consider heater installation height, outside temperature and wind speed
• Infrared heating coverage: The heating coverage is proximately two times width of the height of heater and 1.2 times length of the heater(see brochure for details).

• Safe placement: minimum clearance to combustibles to be complied with, according to each manufacturer.
• Safe Surroundings: Never place anything above or below your patio heater or check the manufacturer’s recommended inches of clearance, which varies according to the number of BTUs the heater radiates.
• Weather Protection: There is nothing more dangerous to a patio heater than wind. You can protect your patio heater from the wind by placing it in a location that has less exposure. Chain installation is prohibited in windy conditions.

• Electric Patio Heater

Case example:

1. Design conditions:

The length, width and height of the drying room are 16m, 6m, and 4.6m respectively; the surrounding of the drying room is made of rock wool sandwich panels, and the roof is made of rock wool board ceiling; the minimum outdoor temperature in winter is 0°C.

2. Design requirements

The overall time for high-temperature disinfection of vehicles is 40 minutes, the time required to heat up to 70 °C is controlled within 10 minutes, and the temperature above 70 °C is maintained for 30 minutes.

3. Equipment selection
3.1 Heater selection: the minimum outdoor temperature is 0°C, and the indoor temperature is required to be 70°C, then the overall temperature rise is 70°C; the room space volume is 16*6*4.6=441.6m³, and the thermal insulation coefficient is 2.7 (this coefficient is conservative considering the heating and heat absorption of the wet vehicle itself), the required heat load = 441.6*70*2.7=83kW, that is, the heating space needs 83kW of heat per hour, and the designed heating time is 10 minutes, then the required heat load is 83*60÷ 10=498kW, the heat load of each equipment is 80kW, then 498÷80=6.225, it is recommended to choose 6 sets of 80kW equipment.
3.2 Heat recovery Ventilator selection: In order to shorten the drying time, it is necessary to discharge the air with high temperature and high humidity to the outside; considering the large temperature difference between indoor and outdoor, heat recovery ventilators needs to be added to solve the contradiction between dehumidification and energy consumption. After calculation, two 2,500m³/h heat recovery devices and six 80kW heaters were selected to match.
3.3 Rear exhaust fan selection: In order to dry the inside of a closed vehicle, four 36″ high-temperature explosion-proof fans are specially selected and installed at the rear of the vehicle to blow air into the vehicle for heating and drying.

Typical Layout of ASF Disinfection Drying Station

To select an air curtain the following factors should be kept in mind:

• The height of the installation measured from the discharge diffuser to the floor
• The width of the door
• The location of the building to determine the level of protection needed against weather conditions (temperature, humidity and wind)
• If the building has several doors in the same area, different or opposite façade
• If the building has several storeys connected by escalators/stairs
• Pressure differences between the inside and outside of the building
• Door compatibility: Always open, automatic open, manual open, revolving door, etc.
• Characteristics of the ventilation and air conditioning installation
• Voltage and electrical power availability
• Type of business, style and decoration of the premises
• Free hanging or recessed, horizontal or vertical installation, heated or unheated, etc.

The information within this section has been designed as a ‘quick check’ for non-technical
stakeholders to confirm that their air curtains have been installed in an appropriate and functional
way. These checks are not comprehensive and should not replace the manufacturer’s installation
instructions.

HOW FAR IS THE AIR CURTAIN FROM THE DOOR HORIZONTALLY?

An air curtain should be installed close enough to the opening to prevent heat loss from cold air entering the space or vice versa for cold room applications. As shown in the diagram below, in an ideal installation, there would be no separation horizontally between the opening and the air curtain. However, the air curtain can still be effective provided the separation is within 50 cm.

HOW FAR AWAY IS THE AIR CURTAIN FROM THE DOOR VERTICALLY?

Ideally, the outlet of an air curtain is installed directly above the opening it is designed to protect.
If an air curtain is installed too far above the opening, the result will be one of the following
two outcomes: the air curtain may not be fully effective or a larger more powerful unit may be
required. Both these outcomes are a consequence of the energy required to create and maintain
the jet of air across the opening. As a general check, unless the additional height has been taken
into consideration, a vertical separation of up to 50 cm is acceptable

DOES THE AIR CURTAIN COVER THE ENTIRE WIDTH OF THE DOOR OPENING?

In an appropriate installation, the stream of air generated by the air curtain should cover the entire
opening it has been installed to protect. If the air curtain is oversized, it will use additional energy
without providing any additional benefit to the consumer. If the air curtain is undersized, it cannot
create an air stream large enough to fully protect the opening it has been installed above, leading
to increase space heating or cooling costs as a result of infiltration.

Heating Power (Recommendation only): 

Minimum heating power(kW)=Poultry house volume(m³)*0.07kW/m³

Considering small temperature difference in a poultry house, a typical 100m*12m broiler house needs 400kW thermal input or 4 sets of KWIH100 heaters while 120m*12m broiler house needs 6 sets of KWIH100 heaters.

Here are some criteria to consider in installing the units:

• Installation height;
• Positioning;
• Warm air circulation;
• Venting: combustion products are usually vented outdoors.

                                       Typical layout of KWIH heaters in a broiler house

Heating Power: 

• Warehouse: 80-110 W/㎡
• Factory: 120-180 W/㎡

• Pig House: Volume(m³)*0.04(kW/m³)

• Poultry House: Volume(m³)*0.07(kW/m³)

Combustion: Sealed combustion (the combustion air is taken directly from the space to be heated or from outside).

Venting: The combustion products can be vented indoors or outside.

• Minimum height to be respected, according to each manufacturer.
• Installation is not recommended in places where there are chlorine products, solvents or explosives, but certain models are suitable for that type of environment.
• The combustion products are vented indoors with additional ventilation. Usually, this calls for an interlock between the appliance and a mechanical extractor fan. A fresh air supply unit needs to be installed in order to maintain an acceptable level of CO2 (5,000 ppm). For more details, consult the manufacturer’s Installation Guide.
• The ventilation rate stipulated in Code B 149.2 is 300 ft3 of air per minute per 100,000 Btu/hr or each kW per 22m³/h fresh air of low intensity infrared installed.

Heating Power: 

• Warehouse: 80-110 W/sqm
• Factory: 120-180 W/sqm

Combustion: Sealed combustion (the combustion air is taken directly from outside but mostly from the space to be heated)

Venting: The combustion products can be vented indoors or outside but mostly outside for multiple burner system.

• Minimum height to be respected, according to each manufacturer.
• Installation is not recommended in places where there are chlorine products, solvents or explosives, but certain models are suitable for that type of environment.
• The combustion products are vented indoors with additional ventilation. Usually, this calls for an interlock between the appliance and a mechanical extractor fan. A fresh air supply unit needs to be installed in order to maintain an acceptable level of CO2 (5,000 ppm). For more details, consult the manufacturer’s Installation Guide.
• The ventilation rate stipulated in Code B 149.2 is 300 ft3 of air per minute per 100,000 Btu/hr or each kW per 22m³/h fresh air of high intensity infrared installed.