Once the space is larger than a room, heaters rental stops being one machine and becomes a set: several units placed where the cold gets in, ducting to carry warm air where a heater cannot stand, thermostats, and a fuel or power supply large enough to feed all of it. A 400,000 BTU indirect fired unit runs about $150 to $250 a day before fuel.
Count the losses, not the floor area
What decides the heat you need is how fast the building loses it: open doorways, missing glazing, an uninsulated roof, and how many air changes an hour the shell is giving away. A sealed office and a bare shell of the same footprint are entirely different problems. Tell the branch the openings and the target temperature, not just the square footage.
Ducting puts the heat where the machine cannot stand
Indirect fired units sit outside and blow through flexible ducting, which is what lets you heat an occupied floor without combustion products inside it. Ducting has a practical run length before the delivered air cools, and every bend costs you. Order the duct, the plenum and the branch fittings with the heater rather than after the first cold morning.
Fuel and power are the half people forget
A large indirect unit burns through fuel steadily and wants a tank on site rather than cans, and the fan and controls still need electricity, which on a bare site means the generator is part of the same order. Electric heaters shift the whole problem onto the supply, and federal rules on using electric equipment apply to those temporary circuits.
Direct fired units put their exhaust in the room
A direct fired heater is cheaper to hire and puts all its combustion products, including moisture, into the space it is warming. That suits an open shell being dried out, and it is wrong for finishing work or an occupied area. Ventilation is a requirement rather than a suggestion, since federal limits on airborne gases apply indoors.
Questions people ask about heaters rental
How many heaters do I need for a warehouse?
It depends on the shell rather than the floor plate, so the branch will ask about door openings, roof insulation and the temperature you want to hold. As a starting point, several smaller units spread along the cold side usually beat one large machine at one end, because distribution is the real difficulty.
What is the difference between direct and indirect fired?
A direct fired heater vents its combustion products into the heated space along with the warm air. An indirect fired unit burns fuel in a sealed chamber, flues the exhaust outside and blows only clean warm air through ducting. Indirect costs more and is what you want for occupied or finishing work.
Is fuel included when you hire a heater?
No. Diesel and propane are supplied and billed separately, either through the branch or through a fuel supplier you arrange, and on a large indirect unit that cost will exceed the hire itself over a week. Ask for the consumption figure at full output when you book.