Across many different industries in a variety of applications, precise temperature control is paramount.

In chemistry, temperature is a deciding factor in the selectivity and yields of many reactions. In research laboratories, pilot plants and kilo laboratories, temperature control systems ensure exact temperatures and stable process conditions. Radleys are the longest serving distributor of Huber temperature control systems in the UK – we are serious about temperature control! We’ve compiled a list of the top tips for maximising the efficiency of your temperature control units (also called circulators or thermoregulators), so that you can get the most out of your equipment and focus on doing great science!

Choose insulated hoses

A well-insulated hose reduces thermal losses to the environment and ensures you have efficient heat transfer from the temperature control unit (TCU) to your application.

Check the diameter and length of your hoses

Choose hoses that match the inlet and outlet diameters on your TCU or application. By ensuring there are no flow restrictions, you will get the highest flow possible and the best temperature control.

Avoid quick release self-sealing couplings, as unless they are the specially designed Huber ones shown below they nearly all increase back pressure and reduce flow.


huber temperature control
huber temp control
huber temp control
huber temp control

Keep your hoses as short as practicable. Long hoses create more back pressure and reduce flow. Make sure your hoses are not kinked or bent too tightly, as this can create flow restrictions.


Swap from water/glycol to silicone oil for your heat transfer fluid

Water has a very high specific heat capacity (4.18 joule/gram °C), which means that it takes a lot of energy to heat up. When you translate this to the real world, it means it could take twice as long to get to the desired temperature compared to silicone oil!

Water boils at 100 °C and freezes and 0 °C, so it cannot be used for applications outside of this temperature range (a fact that is often overlooked…).

The caveat to choosing silicone thermal fluid is that you can’t use silicone hoses as they will dissolve over time; instead choose insulated hoses with PTFE or metal inners.

Make sure your thermal fluid is in good condition

​Never mix thermal fluids, as this can result in polymerisation during heating, which will block the inner pipework of your TCU.

Keep an eye on the colour of your thermal fluid, as when oils degrade or crack they often turn a darker colour. When an oil has degraded, its safe working temperature range will be reduced and it should be replaced.

Choose a thermal fluid that has a low viscosity as thick, viscous oils will increase back pressure and reduce flow, impairing the temperature performance.

Plumb in through the bottom and out through the top​

Ensuring the flow from your TCU goes into the lowest point of your application reduces the risk of air pockets forming, which can restrict flow around the system and also damage the pump.

Avoid open bath circulators for very high and very low temperatures​

With an open bath unit, the thermal fluid is exposed to air. This can lead to oxidation of the fluid at higher temperatures of operation, which reduces its ability to transfer heat and can also lower its flash point!

At lower temperatures (<0 °C) ice can form around the cooling coil of an open bath system due to the moisture in the air. The ice acts as an insulator and hinders heat transfer to the thermal fluid.

Take care of your temperature control unit

​Over time dust and dirt can obstruct airflow over the refrigeration condenser, particularly in air-cooled TCUs, so be sure to keep it clean and clear of debris with a hoover or brush.

Make sure your TCU has enough clear space around it to dissipate the heat generated by the refrigeration system. We often see problems with machines that are squeezed into tight spaces and overheat.

Prevent problems before they occur – ask us to service your unit

​We have a factory-trained service team who will be happy to arrange a service visit where we can check refrigerant levels and offer expert advice. Call us on 01799 513320, email or speak to Technical Support or Customer Service on Live Chat.