My truck did not have a heater previously. I bought and refurbished one that did not have the control valve. I installed it without a control valve except a manual shut off valve that I can close in the summer months to minimize the extra heat in the cab. I have not run it yet but plan to control the heat delivered by fan speed. Given the limited number of times I anticipate that I will drive the truck when heat is needed I am hoping not to need to add the complexity of a control to the system.
