What the valve does
It senses the lubricant temperature and opens the cooler path as the oil warms. At start-up it bypasses the cooler so the machine warms quickly; at working temperature it sends oil to the cooler.
Symptoms of a problem
Signs of a faulty valve:
- High discharge temperature or repeated high-temperature trips
- Oil running too cold, with water in the oil
- Slow warm-up or unstable temperature
- Oil leaks at the valve
Identify the valve
To identify it:
- Compressor make, model and serial number from the nameplate
- The existing part number and any superseded number
- Photographs of the nameplate and of the installed part
- Operating hours and the fault or service interval that triggered the enquiry
Check the cooler and fans first
High temperature can also come from a dirty cooler, low oil level, blocked airflow or a failed fan. We check these so the cause is treated, not only the valve.
Before you order
Confirm the opening temperature rating and the element type for your machine.
Ask for the supply status of the item: whether it is genuine, OEM-approved or an alternative, and whether it is in stock or must be sourced.
Check the lead-time basis and the warranty terms that apply.
Frequently asked questions
Does the valve have a temperature rating?
Yes, valves open at specific temperatures, and the correct rating depends on the machine and fluid. We confirm it before quoting.
Can a faulty thermostatic valve damage the machine?
Prolonged overheating or running too cold can shorten oil and airend life, so it is worth fixing promptly.
Is it a quick replacement?
Often yes, but the oil circuit may need topping up and the system checked afterwards.
Field guide
Thermostatic valves: keeping oil at the right temperature
The thermostatic valve on an oil-injected screw compressor sends oil through the cooler only when it is warm enough. This lets the machine warm up quickly and prevents water condensing in the oil when it runs cool. When it fails, oil either overheats or runs too cold.
| Failure | Symptom | Risk |
|---|---|---|
| Stuck in bypass | High discharge temperature even with a clean cooler | Oil breakdown, high-temperature trips, airend damage |
| Stuck open to cooler | Machine runs cool, especially at light load | Water condensing in oil, emulsion, corrosion |
| Partly working | Temperature swings | Unstable operation, gradual oil damage |
The element is selected for a particular opening temperature to suit the machine and its oil. Replace it with the correct rating, not just the same size. Milky oil, water at the oil drain or rust in the separator tank are signs the machine has been running too cool for some time; replacing the thermostatic element without changing the contaminated oil only solves half the problem.
What to send for a quotation
- Compressor make, model and serial number.
- Photo of the valve housing and element markings.
- Typical discharge temperature readings and oil condition.
Send it through find my part or the spare parts enquiry, or call +91 99590 60718 or +91 92468 88812.