There are many steps to properly set the pressure regulator / unloader valve on a pressure washer. We will attempt to cover the proper procedure for a few of the most common unloader valves. Before we begin the step by step procedure, we will go over the basic concept.
There is an ideal spring tension for each unloader valve on a given pressure washer that will result in maximum pressure when the pressure washer trigger gun is engaged, and minimum spike in pressure when the trigger gun is released. Your goal is to find this ideal setting. Some pressure regulators will also let you adjust the pressure to less than this maximum setting to safely wash cars, screens, or wood to name a few things and then return to the maximum setting without going over that point where releasing this gun trigger would result in a dangerous pressure spike.