ThermoKing TriPac APU

Thermo King TriPac Auxiliary Power Unit (APU) Review

Adding an APU to your truck can end up saving you thousands of fuel expenses, wear and tear maintenance repairs, and potential fines or tickets due to idling. While the benefits can be quite large there are also all different brands and manufacturers of auxiliary power units out there as well. Each one has its own specific set of pros and cons.

So, how do you know which one is the right one to buy for your needs and your budget? In this article we are going take an in-depth look at one of these auxiliary power units on the market today. We will review cost, quality, dependability, serviceability, and the overall effectiveness and power that TriPac APU from Thermoking can provide for your truck.

Diesel Vs Electric

Before we get into the actual review I first want to illustrate to you the differences between an electric and a diesel APU. As I write this article the diesel APU is by far the most popular but in recent years the electric has been making inroads with various city fleets and other applications. What type of APU you need directly depends on what and how you drive. Are you a long-haul driver who is on the road for many nights out of the week? Then chances are a diesel APU will be the best for you. However, if you are smaller distance driver and could use the APU while waiting at a dock or port then the electric model would be best for you.

The electric APU offers you an almost maintenance free APU experience. The downside of these systems though is that they have a limited power supply and when the batteries are depleted you will need to run your truck for another four to eight hours to charge them back to full capacity. A diesel APU on the other hand will run as long as there is fuel in your truck’s fuel tank. Diesel can also provide overall more power when needed then an electric APU. The big downside with diesel is that there are maintenance requirements that take time and money. Keep these facts in mind when reading the review.

Thermoking TriPac Diesel APU

I’ll start this off by stating that Thermoking is seen within the industry as the king of APUs. They are the premium model. If you are driving for a fleet and your truck has a Thermoking APU in it then you know your company takes care of its drivers. However, It should be known that there is some debate on who takes the gold medal for APUs. Some truckers and companies prefer the Carrier Comfort Pro over the Thermoking, but I still believe the majority of truckers that state Thermoking is number one and Carrier is a close second.

Features & Components

When purchased and installed the TriPac comes with a few major components. The first and obviously most important is the APU engine itself. This engine, along with the alternator, and air conditioner compressor are typically mounted on the side of the truck a bit behind the cab and to the left of the fuel tank. Now, obviously each truck is different so the ideal location on your truck may be in a separate area. It comes with a standard sixty-five amp alternator but can be upgraded to one-hundred and twenty amp if you want faster charging or need more power.

The seventy-five hundred BTU heater is typically mounted inside the cargo compartment of your sleeper. Again though, this can be upgraded to a thirteen-thousand BTU heater if you need the extra heat. You also receive a thirteen-thousand BTU air conditioner. The condenser is mounted on the outside back of your truck so that it is protected from salt and other debris. The evaporator is installed under the bed inside the sleeper. The whole unit installed comes in at four-hundred and fifteen pounds. Three-hundred and forty-five of that is the APU itself and the other seventy is the air conditioner.

On the inside of the cab in the sleeper is the human machine interface, or HMI. The HMI has three easy to use knobs that allow you to adjust the heating and cooling as needed. You will also see various alarm codes on this panel in case something goes wrong with your APU. This same panel also allows you to customize the APU using the control system. This will allow you to program the APU to have it geared towards fuel savings, battery life, or driver comfort. The controller can also be programmed so that heating and cooling does NOT occur during days when the truck is not in use. Instead, the APU will simply monitor battery life and engine temperatures so that your truck can start reliably the next time you are ready for the road.

There are also some options that you can add to your APU before purchasing such as an eighteen-hundred watt power inverter or a diesel particulate filter onto the APU. (This is necessary in California.) Other options exist, but they are not as sexy as the ones I’ve mentioned already.

Cost 7/10:

We have established that this TriPac from Thermoking is the premium APU, but now for the bad news. Because this is seen as the premium model you will also see a premium cost associated with it. I have rated the cost for this product as a seven out of ten only because of how expensive it is. These prices can change at any time but as I write this article the average cost for a new Thermoking TriPac system is between ten to twelve-thousand dollars with installation.

While this is a quite an investment many dealers may offer financing options for your purchase. Thermoking also offers a payback calculator which can be found by clicking here. This calculator allows you to put in all of the data for you and your truck and then at the end will provide you with estimated savings as well as an estimated time on when the savings would pay for the APU itself.

Quality & Savings 9/10:

As I stated before, the TriPac is seen as the best of the best. Besides the reputation let us also take a look as to why this is. The first point I want to make is the overall fuel savings you receive when running the APU versus when idling. When a truck idles it typically burns about one gallon of fuel per hour of idling. As you can imagine this can add up quite fast if you are idling for multiple hours at a time multiple days a week. With the TriPac system the diesel fuel burn rate is shrunk to .185 gallons per hour. That is OVER an eighty percent reduction in fuel cost! This feature alone will help pay for the APU after only about a year of having it installed.

The other big point to look at is the two-thousand hour maintenance needs. There are various APUs on the market today and their maintenances needs are all different. Some of them require maintenance every one-hundred hours, five-hundred hours, or even one-thousand hours. There are very few out there that offer such a large service window of two-thousand hours. The only other APU on the market that can compete with this is Carrier’s Comfort Pro. This large window works out to only needing to service the APU about once a year.

The last point worth mentioning here is the overall sound level of the APU. Many of the cheaper APUs on the market today have complaints on how loud they are. The TriPac from Thermoking comes in at only sixty-eight decibels. That is little less then the sound of a hair dryer or vacuum running nearby. Compare this to some of the louder APUs on the market place that sound like a lawn mower running and you can physically hear the quality difference coming from the TriPac APU.

Serviceability 8/10

I know I mentioned this earlier folks but I have to say it again – A two-thousand hour service window. It is a remarkable time that allows you to time your APU maintenance with that of your annual truck maintenance. Having this gives peace of mind and truly makes the APU part of your truck instead of a ride along. Other APUs out there with service windows of only one-hundred or five-hundred hours are a pain in the ass as maintenance is required every month or every other month. If something does go wrong with this TriPac APU it comes with twenty-two different service alarm codes that makes diagnosing the problem much easier for trained technicians.

Thermoking has nearly two-hundred authorized service centers across the United States with many of them offering twenty-four hour service. This puts most of these locations within an hour or two drive from you. It is recommended that any service be done by these authorized service centers. These technicians have been trained on the Thermoking models and know how to diagnose and repair. They also have access to the right replacement parts. If repairs are done at a non-authorized service shop then you may run into difficulty such as not able to find replacement parts or the mechanic simply doesn’t know how to solve the issue.

Dependability 7/10:

Warranty policy and terms can change but as I write this article I found that Thermoking offers a one year warranty on the TriPac unit and a two year warranty on major components. There was also talk of an extended warranty option that you could be offered at time of purchase. Typically extended warranties are usually a waste of money, but it may not be the case here on this unit. The reason I say that is during my research I found quite a few drivers or fleet owners stating that their TriPac units would tend to breakdown after a couple years of use. This would result in downtime and finding an appropriate dealer to work on the unit.

If you are not nearby an authorized service center and it is an emergency then you can take it into a mechanic’s shop but they may not know how to work on the Thermoking APU.  That is one thing that can be said about the less expensive APU models. A mechanic can typically figure them out and know how to repair them… but with a Thermoking model if you are unable to find a service center then you may have difficulty finding someone who can repair the unit.

Effectiveness/Power 9/10

You will not be wanting for power, air conditioning, or heating if you have a TriPac unit installed. They are known for their power and can provide you with a cool cab all the while running multiple appliances as well. This is another reason why there is so much fanfare for these units within the industry. However, there are other competing APUs out there have larger air conditioners and heaters.

One such example is the APU from Rigmaster. Their air conditioner comes in at twenty-four-thousand BTUs and their heater at thirteen-thousand. Personally though, I think that twenty-four thousand air conditioner is overkill and actually sucks power away from other needs such as appliances or electronics. For another comparison, the Carrier Comfort Pro has an air conditioner of only twelve-thousand BTUs. If you have a very larger sleeper and are driving in hot climates then the Rigmaster may make sense for you… just note that it may be overkill in most situations.


When it is all said and done folks I give the Thermoking TriPac APU a rating of eighty percent. While this scored lower than I had anticipated a big part of the lower score was due to the cost and the reports of downtime after a couple years of service. Do not get me wrong though this is a high quality APU that provides you with a long service window and fuel savings. I do want to state before I close this article that I do NOT own a Thermoking unit.

Instead, this review was written off of my research by talking to those within the industry, reading product information, other reviews, and comparing that information to competitors data. I also want to point out that some of the finer details in this post may change as new models and revisions are released by Thermoking. I hope this article was helpful and provided you some insight before making your APU purchase.

Thanks for reading,

Alec Johnson

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