Although you might consider a propane heater, you should only do so if you have a way to attach a DOT approved propane tank on the outside of your truck. Beyond this, your choices are limited to one of three choices: all-electric, gas- or diesel-fired, and those that use the hot coolant in your vehicle’s radiator much like the heater core that keeps your cab warm. For the most part however, propane is not recommended due to safety issues, and electric heaters are only good when you can plug them in. Let’s look at some truck heaters before talking about what to look for when buying one.
These are our recommendations for the 4 best heaters for box trucks on the market:
Happybuy 5KW Diesel Air Heater
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The Happybuy 5KW Diesel Air Heater (see full specs) sits at the top of the list as one of the most popular truck and truck box heaters available. It runs on diesel drawn straight from your fuel tank if your vehicle runs on diesel or an auxiliary tank if it doesn’t. The kit comes with everything you need to install it, including two mufflers. Most importantly, this heater sips fuel and won’t drain your battery overnight.
Flex-a-lite Mojave Heater
The Mojave may be one of the simplest heaters for your box truck in that it is designed to use the same coolant flowing through your truck’s engine and cab heater core to provide heat. The maximum heat output is 12,000 BTU and the 12V electric fan has three settings.
Don’t be fooled by its small size (see full specs), this heater will provide plenty of heat for the box and its smaller stature makes it easy to mount virtually anywhere you can run water hoses and wiring to.
Maxpeedingrods 5KW 12V Diesel Air Heater
This is another relatively complete heater and installation kit designed to draw fuel from your vehicle’s tank or a separate tank for those who have gasoline-powered trucks. Made to be used when your vehicle is going down the road or parked at night, it offers super quiet operation, overheat protection, and a remote control that lets you adjust heat and fan settings on the fly.
For those who need overnight heat in their box, this unit is very fuel and power efficient. Depending on ambient temperature and where you have it set, it uses approximately 1 gallon of fuel per 24 hours. Hands down, this is one of the best heaters for box trucks around.
JEGS 70602 Auxiliary Heater
The JEGs 70602 is another heater designed to use the heat generated by the engine via the coolant. It works in the exact same manner as your truck’s heater core. Hot coolant flows through it and warm air is forced out through three vents by a three-speed electric fan.
Installation is simple. You need enough heater hose to run from the intake heater hose to the unit and back to the return line and a 12V power source. This unit will only provide heat if the engine is running so it is more suited to providing heat when you are using the truck unless you let it idle overnight. However, it will do a fantastic job of preheating the box and keeping it warm for a long time at night.
How to Buy the Best Heaters for Box Trucks
Buying a heater for your box truck needn’t be complicated unless you let it be. Think of the box as a portable room that needs to be heated. There are several different styles on the market, including diesel fired, electric, propane, and hot water. However, both propane and electric heaters are not suited for use while driving since one involves an open flame and the other requires 110V to operate.
The most common choices are diesel-fired and hot water heaters. Both are designed to be operated safely while the vehicle is being driven. The big difference between the two is that only the diesel-fired heater can provide heat once the vehicle has been turned off. There are several important things you should consider in your search for the best heater for a box truck.
The Size of the Box That Needs to Be Heated
This should be one of your first considerations as just like the rooms in your home. The bigger the room or in this case box is, the harder it is to heat. According to experts, it takes a heater rated at a minimum of 5,100 BTUs to heat 144 sq. feet. This figure is calculated based on a home with insulated walls and thermal pane windows.
You can do the same to the box on your truck by covering the inside of the walls with Styrofoam insulation. Base the output of the heater you choose on this calculation. Thus, if your room measures 288 sq. ft. it should require 10,200 BTUs if this holds true.
However, even if you insulate the walls and roof of the box, you still have air leaks around the door and cold floor to consider. With this in mind, it is better to err on the side of caution and choose a heater that is rated higher than your calculations show you need.
Where You Plan to Locate the Heater
Next up in deciding what type of box truck heater to buy is where you plan to locate it. Heat rises, but if your loads typically cover the majority of available floor space, you risk damaging your load before effectively heating the entire space. If you use your vehicle as a workspace (think plumbers, carpenters, remodelers, contractors, etc.) with minimal storage, then floor level should work fine providing there will be plenty of open space around the heater.
While it might not be quite as efficient, in most situations you’ll find mounting the heater close to the ceiling is your best option. You need to choose a spot where you can run water/fuel lines and the necessary wiring for the fans that will be out of the way of your cargo.
Your Preferred Source of Heat
In most instances, you’ll find the source of heat is likely to be based on your preference and budget.
Hot Water Heaters
Hot water heaters that use the same hot water for heat that your vehicle’s cab heater core uses are the least expensive and in most cases simplest to install and operate.
These heaters require that you splice into the hose leading in and out of the truck’s heater core with a “T” fitting. Hoses are run into the box and attached to the appropriate connections on the heater. You’ll also need to run 12 volts into the box if it’s not already there for the fans. Depending on the unit you buy, you may have to wire in thermostat, but the instructions for this will be included with the heater as they all differ.
Installing a diesel-fired heater is somewhat more complicated. A pickup line must be installed in your vehicle’s fuel tank or the feed line running to the engine must be tapped into. Keep in mind you are working with fuel; any leaks can lead to fires and serious environmental damage. Be sure all fittings are properly secured and checked frequently.
A fuel pump must be installed to provide fuel to the heater, and you’ll need to install some form of exhaust piping to avoid having a box fuel of diesel fumes. As with the hot water heater, you’ll need a source of 12 volts for the fans, but also to operate the fuel pump and burner injection system.
The biggest benefit of a diesel-fired heater is that you can leave it on even when you are not using the truck. The fans and fuel pump draw little power and can be run for several hours under most conditions without killing your battery. However, if you are concerned about this, you can always install a deep cycle battery that can be charged as needed or connected to your vehicle’s charging system. Unless you are a trained and skilled mechanic, you should have a professional take care of this part of the installation to avoid damaging your truck’s wiring or alternator.
Heater Size Matters
While you do have to consider the output of the heaters you are looking at, you should keep physical in mind just as much as location. You need to have room not only for the heater itself but enough space around to allow for free airflow. Not only will this help heat the box more quickly, but it will also keep the unit from overheating. Bigger heaters typically mean more BTUs, but this is not always the case as overall design plays a role in the amount of heat produced.
Here again, prior planning including where you plan to put the heater will also play a part in the overall dimensions of the heater you choose. Although you might like to have a bigger heater for those super cold days, if you don’t have enough space for the heater and around it, it’s not going to get the job done. You would be better off with a smaller unit that can be mounted where it can be the most effective.
Box Truck Heaters: Final Warm Thoughts
During your search, you will find there are a lot of options when it comes to finding the best heater for box trucks. The models listed above are some of our favorites. Keep in mind that works for one person and situation may not work for another.
Even if you don’t have a diesel-powered truck, you can always have an auxiliary tank mounted to the vehicle’s frame, if there is room for it. While cost is most likely going to play a part in your final decision, it shouldn’t be the only deciding factor. Choose the type of heater you plan to use hot water or diesel, then determine the size and BTU ratings. Add in where you plan to mount it and then assemble a shortlist of options. Now you can look at the prices and determine which fits your budget.
We hope this information helps you buy the best heater for box trucks and put an end to unloading your cargo and storing it in a warm place overnight or having it freeze on the road. One last reminder, no matter which style you buy, there will be a certain amount of retrofitting and installation work involved. When working with fuel lines, pumps, and electrical wiring, if you aren’t 100% sure what you’re doing, take your truck to a professional, it could save your cargo at the least and your life at the most. Good luck!
Founder of Mechanicalcaveman.com, Beau is an unrepentant tool enthusiast and, sporting deadlift-callused hands and incongruously a beer belly, all-around macho guy. When he doesn’t know re tools, he consults with his handyman and car-repairman buds to give you well-reasoned and cutting-edge info. Email him.