All pressure washer plunger and piston pumps have a water temperature limitation of 160° F. A few selected pump models can be equipped with high temperature seals and valves at extra cost to boost the temperature tolerance to 180° F. Consult Spartan Engineering Department regarding compatibility of high temperature equipped pumps with standard pressure washer models.

All pressure washers that are trigger gun equipped use an unloader valve to bypass the water flow from the pump outlet back around to the pump inlet when the trigger gun is off (no flow through the gun). As the water is re-circulated, the water rapidly heats up from the pump friction heat dissipation. It is not uncommon for bypass water to heat up from 60° F to 160° F in 2 to 3 minutes of no flow through the gun. Pump heat damage has been one of the most common causes of frequent pump faulure in pressure washers (all makes and models) for many years. To prevent this problem, all Spartan standard trigger gun models are equipped with a thermal relief valve in the bypass loop that opens up and bleeds off some water when the temperature reaches 140° F. This allows cool make up water to come into the system and keep the pump from overheating.

In some cases, customers have the need to feed hot water into a pressure washer already heated, 100 to 160° F. This leaves very little margin for bypass mode heat build up. This will almost certainly result in pump damage as the heat build up overwhelms the thermal relief valve. Therefore, when using hot water feed, it is imperative that the machine be equipped with our optional motor control system. This sophisticated control times out and shuts down the pump and motor when the trigger gun is off and instantaneously restarts when the gun is reactivated. The shutdown time delay (usually 30 to 45 seconds) is to prevent motor damage from the trigger gun abuse (rapid repeated on/off of the trigger gun). This system is fully automatic and requires no operator attention.

The automatic motor control system is not to be confused with standard burner combustion controls on hot high pressure units which instantaneously stop and start the burners in response to water flow to prevent heating coil burnout.