Natural gas generator sets used for prime power or peaker operation depend on stable engine temperatures to deliver reliable performance and consistent operation—especially when loads change or ambient conditions swing.
The three common fluid circuits on this engine that require temperature regulation are:
- Jacket Water Coolant
- Lubrication Oil
- Charge Air Cooler Coolant
This article compares two proven AMOT approaches used on gas genset cooling loops:
- Wax thermostatic (self-actuated) temperature control valves
- Electric actuated control valves (dynamic temperature control)
(Trademark note: Caterpillar, Cat, and CAT are trademarks of Caterpillar Inc. AMOT is not affiliated with or endorsed by Caterpillar Inc.)
Why Coolant Temperature Control Matters on Gas Gensets
A 3-way temperature control valve continuously blends the cold water from the radiator with the hot engine fluid, so coolant returning to the engine stays near the target temperature. When it’s thermally stable, you typically get:
- Predictable warm-up and steadier operating temperatures
- Better control through load steps and cycling (common for peaker duty)
- Reduced risk of overcooling at light load or cold ambient starts
Option A: Electric Actuated Temperature Control Valves (ACV)
How it works?
An actuated control valve provides the same blending function, but valve position is driven by an external control signal (often from a genset controller or PLC). Electric actuation enables tighter control, faster response, and adjustable setpoints when operating conditions change.
Best-fit Use Cases
- You need adjustable temperature targets (seasonal, different duty cycles, load following)
- You want tighter stability during cycling and step loads
- You want control integration (temperature targets based on load, ambient, or other plant conditions)
Pros
- Adjustable setpoint for prime/peaker modes
- Better transient control during fast load changes
- Enables advanced strategies (closed-loop control and optimization)
Trade-offs
- More components (actuator + wiring + control integration)
- Requires power and clear ownership for tuning and troubleshooting
Option B: Wax Thermostatic Temperature Control Valves (TCV)
How it works?
A thermostatic valve uses a wax element that expands/contracts with temperature. As coolant warms, the element shifts internal valve position to send more flow through the cooler; as coolant cools, it shifts back toward bypass.
Best-fit Use Cases (Common in Gas Power)
- You want simple, self-contained control (no external power or signal)
- You want a rugged, proven approach that maintenance teams understand
- Your target temperature is fixed and does not need to change by operating mode
Pros
- No wiring, no controller required
- Straightforward commissioning
- Service-friendly element-based maintenance
Trade-offs
- Regulation temperature is typically fixed at a calibrated setpoint
- Less ability to optimize temperature targets across changing modes (prime vs peaker, varying ambient, heat recovery on/off)
Quick Selection Guide (Prime vs Peaker)
Consider Wax (TCV) When:
- You want “install it and run” simplicity
- Your operating profile is consistent
- You prefer minimal controls integration
Consider Electric (ACV) When:
- You run mixed duty cycles (frequent starts/stops, load following, peaker cycling)
- You want tighter control or a tunable temperature strategy (mobile packages)
- You require advanced integration with your plant or genset controller
What AMOT Needs to Size the Right Solution
To recommend the right valve/element/actuator configuration, gather:
- Cooling circuit details (jacket water / aftercooler / mixed loop)
- Flow rate and target regulation temperature(s)
- Flange connection sizes
- Available power and preferred control signal (if actuated)
FAQ
Where is the thermostat on a Cat® 3520 gas genset?
Many packages use a temperature control valve in the coolant circuit (often a 3-way blending valve) to regulate jacket water temperature—not only a small inline thermostat.
Can I upgrade from wax thermostatic control to electric control?
Yes, electric actuation can add flexibility and tighter control.
Is electric control worth it for peaker cycling?
Often yes—cycling and step loads benefit from faster response and adjustable control strategies.
Contact AMOT so we can help you select a wax thermostatic or electric-actuated temperature control approach based on duty cycle and package design.
