Overview
Thermal relief valve, 165 °F. Sapphire part number 23-033, listed in the parts schedule as Vlv, 165 Deg Thermal.
A thermal relief valve protects a pump. When solution is recirculating rather than flowing — the machine running with the trigger closed — the pump's own work heats the water it is holding. The thermal valve opens at its set temperature and dumps that heat before it damages the pump seals.
Important — this part has been superseded
Sapphire now supply a retrofit kit that replaces the original 165 degree thermal relief valve:
48-168 — Thermal Valve Retrofit Kit
If you are replacing a failed 23-033, order the retrofit kit rather than the original valve. A supplier issuing a retrofit kit for a specific valve is telling you something about how that valve performed in service, and the kit is the answer they arrived at.
Ask us before ordering this part on its own — in most cases the kit is what you actually want.
What a failed thermal valve looks like
- Stuck closed — the pump has no thermal protection. Nothing appears wrong until the pump seals fail, and by then the damage is done. This is the dangerous failure.
- Stuck open or weeping — a constant dribble to waste, pressure that will not hold at the set point, and a machine that appears to be losing solution for no reason. Annoying, but it fails safe.
Because the dangerous failure is silent, a thermal valve is worth replacing on condition rather than on symptom.
Operating advice
The habit that saves pumps is not leaving a machine running against a closed trigger for long periods. A thermal valve is a backstop, not an operating strategy — every time it opens, the pump has already been doing work it did not need to do.
Frequently asked questions
Should I order this or the retrofit kit?
The retrofit kit (48-168) in most cases. Ask us with your machine details.
What temperature does it open at?
165 °F (approximately 74 °C), per Sapphire's parts schedule.
How do I know if mine has failed closed?
You generally cannot tell from the outside, which is the argument for replacing it as scheduled maintenance rather than waiting.
Which machines is it fitted to?
Sapphire truckmounts. Send us your model and serial number and we will confirm before you order.
Tell us your machine model and we will confirm whether the original valve or the retrofit kit is the right part.
