Thermal Bypass

Humanity’s ambitions to reach the farthest stars in the sky and the deepest parts of the oceans have naturally resulted in a gradual increase in the technological complexity of the vehicles designed to carry them there.

These innovative machines for modern times inevitably result in ever-increasing demands on thermal management system capabilities. From the need for almost instantaneous warm-up times to thermal relief to protect delicate components from overheating, thermal management is evolving to keep up with growing system complexity.

To meet the market’s demand for efficient and accurate temperature control, ThermOmegaTech® developed the thermal bypass valve (TBV), which has been implemented in a variety of groundbreaking Aerospace & Defense applications where precise thermal management is critical to project success.

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How It Works

Thermal bypass valves (TBV) are a temperature solution to a temperature problem. Designed with our exclusive Thermoloid® thermostatic actuator technology, the TBV automatically maintains fluid temperature within a narrow and predefined temperature range to ensure optimal system operation, reduce system wear, minimize warm-up times, and extend component life.

The TBV’s thermal actuator continuously monitors the inlet flow’s temperature and directs it accordingly throughout the system. If the fluid temperature is above the valve’s set-point, the TBV automatically self-modulates to divert flow to the system’s cooler or heat exchanger. If the fluid temperature is below the set-point, the flow is bypassed directly to the reservoir and circulates through the system.

Innovatively designed to suit various applications, the 3-way thermal bypass valve can be used to precisely proportion flow in response to fluid temperature variations in both mixing and diverting applications.

Our TBVs can monitor and control any system-critical fluid, including coolant, glycol, oil, hydraulic fluid, water, air, and more.



  • Self-Operating: No need for external power source
  • Dynamic: Used in both mixing and diverting applications
  • Compact and Low Mass: Fits into most designs
  • Thermostatic Element: Responds to temperature changes and is unaffected by pressure variations 
  • Self-Contained: No or minimal maintenance requirements
  • Few Moving Parts: Eliminates component complications or failure
  • Large Temperature Range: Standard valves available in temperatures from 35°F to 210°F (1.7°C to 98.9°C)

Mixing and Diverting Thermal Valves (mouse over images to animate)


Thermal Diverting

Animation of Diverting Valve of Hot Temperature

Animation of Diverting Valve of Cold Temperature

In a 3-way diverting application, the TBV diverts a single inlet flow to one of two outlet ports, depending on fluid temperature. Cooler fluid is shifted to the reservoir while hotter fluid goes through the heat exchanger.

Thermal Bypassing

Thermal Bypass 4 Port Valve Open

Thermal Bypass 4 Port Valve Closed

The TBV cartridge can be integrated into a 4-way manifold to monitor inlet flow and divert the fluid based on temperature. Cooler fluid goes through the valve bypass, while hotter fluid goes through the system’s cooler.

Thermal Mixing

Thermal Bypass Valve Mixing Hot/Cold Full Open

Thermal Bypass Valve Mixing Cold Open

In a 3-way mixing application, the TBV modulates between “hot” and “cold” inlet feeds to mix the fluid to the desired outlet temperature proportionately.


In simple terms, the thermal bypass valve is used in the Aerospace & Defense field to maintain system temperatures within an optimal operating range. However, the systems this applies to are both varied and far-reaching across each corner of the globe, under the sea, and up among the stars.

Typical applications that utilize the TBV include but are certainly not limited to:

  • Electronics system cooling
  • Hydraulic fluid cooling systems
  • Hydraulic thermal bypass
  • Lube oil cooling control
  • Lube oil thermal bypass
  • Fuel/oil cooler
  • Cooling water control for radiators & heat exchangers
  • Direct cooling with water
  • Engine and compressor cooling systems
  • Space vehicle cabin air control
  • Loop-type circulation systems
  • Direct injection water heating
  • Process control
  • Make-up water
  • Mobile oil coolers
  • Battery cooling

Thermal Bypass for Patriot Missile Launcher Radar Set


Thermal Bypass Valve on Generic Aircraft Nitrogen Generator

For additional applications for the TBV in industrial facilities, please visit

Cartridge Integration

We offer thermal bypass valve cartridges to ease integration into pre-existing systems for bypass applications with unique designs and strict space requirements. The TBV cartridge allows for the implementation of the same thermal actuator control element as our standard TBVs without the housing to allow for easier integrations into manifold designs.

Our in-house engineers can work with your team to design a manifold housing for the TBV cartridge to integrate into your system if you don’t have a current design specified. We can also manufacture the manifolds in our state-of-the-art machine shop along with the cartridges if desired. Reach out to our team of product experts to discuss your design if you’re looking for a cartridge-style TBV.


As standard, our thermal bypass valves are offered in ½”, 1″ and 2″ NPT threads, brass or stainless-steel housings, and temperatures ranging from 35°F to 210°F (1.7°C to 98.9°C) depending on your application’s needs.

If one of our standard valve offerings does not meet your individual project’s requirements, our engineers and project managers will work with you to design a solution that solves your thermal control challenge. Changes can be made to a valve’s opening/closing temperatures, flow rates, threads, materials, and the number of ports, their size, and configuration. If you require lower temperatures than our standard offering, please complete our custom actuator or valve form and send it to our team.

To discuss additional customizations and your design needs, we offer personalized Lunch & Learn consultations with ThermOmegaTech’s® Aerospace & Defense product specialists and design engineers.

Contact Our Design Team

Past Projects

Our TBVs have been implemented into dozens of systems throughout the Aerospace & Defense industry. Their precise thermal control is relied on by engineers, scientists, and military personnel to ensure project success, no matter where on earth, sea, or sky it is taking place.

Examples include hydraulic fluid temperature control on the Patriot missile system radar set, thermostatic control for heat exchangers on nitrogen generating carts for on-ground aircraft servicing, FMTV, and other military tactical land vehicles. Our cartridges have been implemented into hydraulic fluid temperature control designs on self-propelled military tactical vehicles, electronics cooling on F-16 Fighting Falcon & SABR AESA radar, environmental temperature control on manned and unmanned spacecraft, and liquid cooling on unmanned UAVs.

Many of these projects required modifications to our standard products, including lower/higher wax melting temperatures, manual overrides, diffusers, and manifold integrations.

Electronics Cooling on F-16 Fighting Falcon Aircraft

Electronics Cooling on F-16 Fighting Falcon Aircraft

Hydraulic Fliuld Temperature Control for Self-Propelled Military Tactical Vehicle

Hydraulic Fluid Temperature Control for Self-Propelled Military Tactical Vehicle

Thermal Bypass on Family of Military Tactical Vehicles for Army

Thermal Bypass on Family of Military Tactical Vehicles for Army

Hydraulic Fluid Temperature Control for Patriot Missile System Radar Set

Hydraulic Fluid Temperature Control for Patriot Missile System Radar Set

Liquid Cooling on Unmanned Aerial Systems

Liquid Cooling on Unmanned Aerial Systems

Thermal Bypass on Generic Aircraft Nitrogen Generator Carts

Thermal Bypass on Generic Aircraft Nitrogen Generator Carts