Whether you rent or purchase a refrigerated van is up to you and comes down to your needs and budgetary considerations. If you plan to use the van for years to come purchasing may be a better option, while if you do not need the van for that long, do not want to commit to having the van for longer periods, or are uncertain of the long time you need the van for, renting is likely more suited to you.
Often you may want to purchase the van, but not have the budget to do that from the beginning, luckily there are also rent-to-buy options available, meaning you can easily pay back the vehicle and receive full ownership after the van has been fully paid off. This gives you long term security as well as the long term savings of purchasing a van while allowing you to pay as you go.