Thermal Immersion Circulators

A thermal immersion circulator is a device that you put into a container of water that will keep the water a uniform temperature. Thermal circulators were originally developed for use in laboratory work where precision heating is needed for many tasks.

Thermal immersion circulators are probably the best piece of equipment you can get for regulating water temperature in sous vide cooking.

Updated Content

This information has recently been updated, you can view the new information in my guides to Sous Vide Machines or my reviews of Inexpensive Immersion Circulators.
This information, as well as over 100 recipes, is available in our book Beginning Sous Vide which you can get at or as a pdf download.

How Thermal Immersion Circulators Work

A standard thermal immersion circulator consists of a heating coil with an attached pump. The heating coil and pump are inserted into a body of water and a temperature is set on the immersion circulator. The heating coil will keep the water at the set temperature while the pump circulates the water eliminating any hot or cold spots.

Each thermal immersion circulator has its own margin of error for holding the temperature. Most low-end circulators will hold the water at a +/- 1 degree Celsius, while some high-end circulators can hold the temperature to within +/- .01 Degrees.

fusionchef pearl circulator

Positives of Thermal Immersion Circulators

Most thermal immersion circulators can be attached to the edge of a normal kitchen pot, making them very convenient to use in sous vide cooking at home.

The biggest benefit of thermal immersion circulators is their precision. Depending on the type of circulator you get, they can regulate the heat from within 1 degree celsius to within .01 degree, both of which are more than acceptable for perfect sous vide cooking.

Negatives of Thermal Immersion Circulators

The biggest issue with thermal immersion circulators is the high cost of purchasing them. They routinely sell new ones for $800 to $1,500, and used ones are $200 to $600 which is pretty expensive for a piece of home kitchen equipment, especially one specific for sous vide cooking.

A minor negative of thermal immersion circulators is the evaporation due to not having a sealed lid. You can use foil or saran wrap to try and seal it better but you will still suffer some evaporation. This normally isn't a big deal unless you are using a 24+ hour sous vide preparation.

Thermal Immersion Circulator Tips

The most well known brands are Polyscience, which was dubbed the best circulator Seattle Food Geek has used and fusionchef by Julabo and Lauda, who makes the Lauda MS immersion heater. Grant also makes a circulator.

You can also look for used thermal immersion circulators on eBay and from scientific lab resell sites.

If you do buy a used thermal immersion circulator, be sure to clean it well since you never know what chemicals were used in it previously.

Jason logsdon headshot This article is by me, Jason Logsdon. I'm an adventurous home cook and professional blogger who loves to try new things, especially when it comes to cooking. I've explored everything from sous vide and whipping siphons to pressure cookers and blow torches; created foams, gels and spheres; made barrel aged cocktails and brewed beer. I have also written 10 cookbooks on modernist cooking and sous vide and I run the website.
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