Plan to shut down for a break
For a break, shut the pressure washer down using its own instructions instead of leaving it running with the trigger closed. Releasing the trigger is not a substitute for shutdown. Do not borrow an idle-time allowance from a different machine.
SIMPSON's general FAQ advises switching the engine or motor off during an extended pause in spraying. Use the current manual for your exact model to establish its operating limits and shutdown procedure.
The pump may still be moving water
Cat Pumps explains that, in the bypass systems it describes, closing the spray gun leaves the pump circulating water. That water can heat up even though nothing is coming out of the nozzle.
A thermal relief valve is designed to discharge some heated water so cooler water can enter. It is a protective device, not evidence that an unattended machine can run indefinitely. Do not assume every discharge or leak has the same cause.
Electric does not automatically mean stopped
The March 2026 manual linked from SIMPSON's CM60976 product page says its electric motor keeps running after the trigger is released. This named example is a reason to check the controls on your own washer, rather than assume all electric machines behave alike.
That manual also separates switching off from releasing retained pressure. Follow your equipment's complete shutdown instructions before handling connections; a closed trigger alone does not establish that the hose is depressurized.
Check the complete setup
Returning bypass water to an external tank changes the arrangement, but does not remove the need to manage heat. Cat Pumps' troubleshooting guidance considers tank capacity and cooling where substantial bypass flow returns to the supply.
Our practical suggestion is to identify the machine, installed pump and applicable manual before the job. If the instructions or return arrangement are unclear, ask the manufacturer or qualified service provider how to pause and shut down that setup. This article does not provide a valve-adjustment or replumbing procedure.
Sources & references
- FAQs — unloader and thermal-valve explanations (undated) — Cat Pumps. Checked November 1, 2026.
- Use and Care Manual, part 7111613, English Rev L — March 2026; operating and shutdown guidance, pages 6–7 — SIMPSON / FNA Group. Checked November 1, 2026.
- Frequently Asked Questions — thermal relief and pauses in spraying (undated) — SIMPSON. Checked November 1, 2026.
- Troubleshooting — excessive heat and bypass circulation (undated) — Cat Pumps. Checked November 1, 2026.