Author: keywarm-post

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.