English
Français
Flagro more than just heat Leaf logo

Frequently Asked Questions

Answers to common questions to help guide you.

Helpful Information to Guide You

As a rule of thumb, four hundred square feet per 12,000 BTUs (12,000 BTUs equals one ton of air conditioning). However, you must account for other factors, which will affect the total heat load.
General rules of thumb:
  • 100-150 BTUs per square foot for temporary structures, or areas not well sealed and insulated.
  • 30-40 BTUs per square foot for comfort heat in a well-insulated facility/area.
  • 10-15 BTUs per square foot to prevent pipe freezing.
It uses refrigerant and a compressor to transfer heat:
  • In winter: extracts heat from outside air (even when cold) and moves it indoors.
  • In summer: reverses the process, removing indoor heat and releasing it outside.
It passes electricity through a heating element (like metal coils or ceramic). The element resists the flow of electricity, producing heat, which is then spread by convection, radiation, or a fan.
  • To prevent freezing pipes: 10–15 BTUs per sq. ft.
  • Tents/poorly enclosed sites: 100–150 BTUs per sq. ft.
  • Well-insulated, comfort heating: 30–40 BTUs per sq. ft.
Industrial heaters are designed for temporary use and comply with different codes. Residential heaters (like furnaces) are permanent installations and follow separate standards.
  • Rule of thumb: 100–150 BTUs per sq. ft. during construction.
  • Once insulated: 30–40 BTUs per sq. ft. for comfort heating.
For 5,000 sq. ft., multiply the area by the BTUs per sq. ft. to determine requirements.
Go to the Tech Hub/Assistance tab and locate your unit (likely FVO 200 or FVO 400). Check the service bulletin at the bottom for step-by-step instructions. A YouTube video is also available for visual guidance.
Go to the Tech Hub/Assistance tab. Search for the product in question, and you’ll find resources such as operation manuals, tech sheets, data sheets, wiring diagrams, and more. If that doesn’t solve your issue, complete the form at the top of the page. Be sure to include as much detail as possible and upload any pictures or diagrams. Once submitted, one of our tech support specialists will get back to you.
In the Tech Hub/Assistance section, search for your product. At the bottom of the page, you’ll see available resources such as operation manuals, wiring diagrams, and translations in different languages.
In the Tech Hub/Assistance section, search for your product. Troubleshooting information is listed there.
Flagro’s heaters are available in electricity, propane, natural gas, and oil-fired options.
Flagro’s heaters have outputs ranging from 50,000 up to 1.5 million BTUs.
A radiant heater warms objects and people directly (like the sun), instead of heating the air, or being negatively impacted by wind—common examples: infrared heaters, patio heaters.
A heat pump is an all-in-one heating and cooling system. It moves heat rather than creating it, working like an air conditioner in reverse to heat your home.
BTU stands for British Thermal Unit. It is a measure of thermal (heat) energy: the amount needed to raise the temperature of one pound of water by one degree Fahrenheit.
While a term associated with finished facilities, it refers to a system that heats air in a furnace and then blows it through ducts and vents into rooms. This is like the temporary indirect-fired heaters.
Flagro offers SV models (250,000 and 500,000 BTUs) with 100% safety shutoff valves.
Flagro offers liquid propane burners from 300,000–2 million BTUs in two designs:
  • Well type: with gooseneck to fit under large pots.
  • Straight type: direct connection.
Flagro offers vapor and liquid torches ranging from 25,000–2.5 million BTUs. Options include kits with torch, hose, and regulator, or standalone torches. Safety shutoff models are also available.
Radiant heaters are lightweight, easy to move, and fuel-efficient. Smaller indirect-fired heaters (like the 200s on wheels) are also portable, especially with natural gas hookups.
The RC Recirculating Hood Model, which offers better moisture control, equalized pressure, and longer duct runs (up to 150 ft).
It depends on the building’s cubic footage, desired temperature rise, available fuel, air tightness, and local climate. A heat loss calculation is required to determine BTUs and CFMs needed.
The Flagro F-150 (50,000–150,000 BTUs) or F-375 (220,000–375,000 BTUs) direct-fired units. Radiant heaters (90,000 BTUs) in propane or natural gas are also good options.
Typically, an indirect-fired unit is recommended. Depending on the building’s size, occupancy, and codes, radiant or direct-fired heaters may also be options.
The Flagro Tent Heater THC-85P or the Indirect Fire 200 RC are commonly used for this purpose.
There’s no one-size-fits-all solution. Factors include construction stage, fuel availability, building enclosure, codes, required BTUs/CFMs, and job site conditions. A professional can help identify the best type (direct, indirect, radiant, or electric).
The Flagro F-150, Flagro F-375, and Flagro radiant heaters. These units do not require electricity, making them ideal for new construction sites without utility access.
    • Direct-fired: Flame and heat come directly from the unit.
    • Indirect-fired: Heat exchanger contains combustion products, which are vented outside while heated air is blown inside via ductwork.
    • Radiant: Provides targeted heat directly to objects/surfaces.
  • Soft-start fan regulation at startup and shutdown.
  • Overload motor protection and voltage management.
  • Allows a single fuel line to supply and de-aerate.
  • Improves burner performance.
The Flagro FVO-750 oil or FVNP-750 dual-fuel (propane/natural gas) indirect-fired heater can achieve this.
Flagro offers a wide range of solutions: direct-fired, indirect-fired, radiant, tent heaters, and self-contained heater trailers.
Flagro offers three options:
  • 85,000 BTUs (propane or natural gas)
  • 175,000 BTUs (dual-fuel with selector valve)
  • 330,000 BTUs (dual-fuel, up to 2,600 CFMs)
  1. Increased efficiency.
  2. Ability to extend ductwork up to 150 ft (compared to 50 ft standard).
  3. Improved moisture control.
  4. Better equalization of pressure in the heated area.
Flagro offers recirculating models in two of our main indirect heaters: the 200s and 400s. These are available as both standard and recirculating units.
Flagro offers direct-fired units ranging from 50,000 BTUs up to 1.5 million BTUs.
  • Smaller models (50,000–150,000 BTUs) are variable.
  • Mid-range models go from 220,000–375,000 BTUs (propane, no electricity required).
  • Larger models include 400,000; 1 million; and 1.5 million BTU units.
Options include direct-fired oil, dual-fuel, natural gas, and propane units with a selector valve for changing fuel type.
Flagro offers a wide range of indirect-fired heaters:
  • From 185,000–200,000 BTUs, up to 390,000 and 750,000 BTUs.
  • Soon, we’ll also be offering models up to 1.5 million BTUs.
Flagro supplies both supply-side and return-side ductwork. Each is manufactured differently: supply ducts deliver heat, while return ducts are designed to handle intake air and heat recirculation. They are available in various diameters and lengths.
Flagro offers both direct-fired and indirect-fired models:
  • Direct-fired units release flames and heat directly from the unit.
  • Indirect-fired units use a heat exchanger for safer heating.
Models include the F-400T and FVO-400. We also offer recirculating models for oil and natural gas, such as the FVNP-400 or FVO-400RC.
Flagro offers radiant heaters as well as direct and indirect heaters. Radiant units are available in propane or natural gas and may be equipped with a quick disconnect option.
The Flagro FVO-400LTRC provides all three: heat, lights, and a power source.
Flagro offers two types of self-contained heater trailers:
  • The FVO-1100TR, which includes two FVO-400RC units on the trailer.
  • The FVO-400LTRC, which includes one heater, built-in lights, and 115-amp power service — providing heat, light, and power all in one.
Flagro manufactures a wide array of heaters including Direct-fired, indirect-fired, radiant, and electric models.
Ventilation requirements are provided in the Operations Manuals of the individual products.
All are safe if they are certified by a reputable third party certifier and installed as per the manufacturer’s instructions and applicable national/state/provincial/local codes and bylaws.
By following the manufacturer’s instructions – safety, operating, ventilation, start-up, etc., as well as all required national/state/provincial/local codes and bylaws.
All Flagro products are certified by applicable and recognized third-party certifiers such as ETL, CSA, DOT, etc.
Yes, if indirect-fired with ducted heat into the area. Never use direct propane heaters in an enclosed, occupied space.
Industrial heaters are designed for temporary use and comply with different codes. Residential heaters (like furnaces) are permanent installations and follow separate standards.
No. Heaters must be vented according to manufacturer’s instructions and building codes. Combustion products should not be released into an occupied space.
Indirect-fired is always the safer choice for indoor use.
An indirect-fired heater placed outside, with ductwork delivering heat inside. Models are available from 185,000–750,000 BTUs, with new 1.5 million BTU models coming soon. Recirculating options also help with moisture control and pressure equalization.
It depends on several factors: how enclosed or open the site is, whether it’s occupied, fuel availability, and required BTUs/CFMs. Options include direct-fired, indirect-fired, radiant, or electric heaters. A professional can help determine the best fit.
Yes — if installed correctly according to manufacturer’s instructions and local building codes.
If occupied, propane heaters should remain outside with heat ducted indoors. For partially sealed or under-construction sites, follow manufacturer’s instructions and local building codes (venting, clearances, etc.).
Both direct- and indirect-fired units can work. The best option depends on local building codes, occupancy, and how enclosed the facility is.
We do not recommend using diesel heater units indoors. While technically possible (with proper venting and clearances per manufacturer’s instructions and local codes), filling tanks indoors poses risks. It’s best to keep diesel units outside and use ductwork to deliver heat inside.
Call Flagro at (888) 535-8841, email Flagro at at msawchuk@flagro.ca or jculp@flagro.ca, or visit https://flagro.ca/contact-us/ and fill out an online contact form.
Typically, when we receive an order, we confirm it as quickly as possible. If you do not receive a confirmation within 24 hours, that is when you should follow up and ask about your order. Parts are usually shipped the same day or the next business day, while new equipment typically goes out within a couple of days—provided it is in stock.
Anywhere in Canada or the U.S.
Pricing can vary depending on whether you are a distributor, a dealer, or an end user.
We offer a one-year warranty for manufacturing issues on equipment and parts. Regular wear or operator error items are not covered.
There is a 30% restocking fee applied when the product is received, inspected, and deemed appropriate for sale. 
No, we do not offer repair services. Typically, our dealers and distributors either provide repairs themselves or can recommend a local service provider.
Flagro supplies both supply-side and return-side ductwork. Each is manufactured differently: supply ducts deliver heat, while return ducts are designed to handle intake air and heat recirculation. They are available in various diameters and lengths.
Call us at (888) 535-8841, and one of our customer service specialists will assist you.
Flagro equipment is exceptionally durable and engineered to be simple, effective, and provide an excellent ROI. This is contingent upon proper use and compliance with required preventative maintenance, such as changing filters, nozzles, and other components, and cleaning photocells based on usage.
Look beyond upfront cost. Consider long-term dependability, downtime, repair costs, preventative maintenance, and product lifespan. Equipment lasting 15–20 years with minimal annual maintenance offers the strongest ROI.
Typically:
  1. Natural gas (most cost-effective)
  2. Propane
  3. Diesel fuel
Electricity is usually the most expensive per BTU.
  • Direct-fired heaters → best for outdoor/ventilated spaces (construction sites). 
  • Indirect-fired heaters → best for enclosed spaces since they vent exhaust. 
  • Electric heaters → safe indoors, no emissions, but need enough electrical capacity. 
  • Radiant heaters → ideal for spot-heating people or equipment, or where no electricity is available.
Flagro’s website (www.flagro.ca) showcases a wide range of heaters. Flagro has been in business since 1978, providing high-quality products backed by excellent technical support. That reliability leads to a stronger ROI over the lifetime of the equipment.
Important Update: Flagro has launched a new North American Customer Service Center for a streamlined experience to better serve you. For all inquiries, including quotes and shipments, please contact us at 1-888-535-8841.