How much does silicone oil expand by when heated?

The general ‘rule of thumb’ for silicone oil is that it expands (or contracts) by approximately 10% per 100°C (1% per 10°C).  Note that this relationship can vary depending on the temperature and the particular thermal fluid used.  (The datasheet of your thermal fluid might contain some relevant information.) When estimating the expansion of oil with heating, you need to be consider the oil in the Huber unit, in the hoses and in the application (e.g. vessel jacket).

Can a Huber unit with Pilot ONE controller be controlled by a PLC via Ethernet, and if so, how?

It is possible to control a new Huber unit with Pilot ONE controller via a PLC/DCS etc. Pilot ONE controllers have an Ethernet interface included as standard. Setting up and using the Ethernet connection:
  • To activate the connection: in the Pilot ONE control panel navigate to Menu > Interfaces > Ethernet > Remote Access > Always On.
  • Set the Huber unit’s IP address as desired.  This setting can be accessed at Menu > Interfaces > Ethernet > IP Address
  • Establish a TCP (Transmission Control Protocol) connection to the Huber unit’s IP address and use the TCP port 8101.
  • Use the Huber commands: PB commands (recommended) PP/LAI commands
  • You cannot use the Modbus TCP protocol.
For information on the RS232 and AIF (4-20 mA) options for new Huber units with Pilot ONE, please refer to the separate FAQ entries.

Can I have a CE declaration for a Huber unit?

Yes, but we need to know the serial number of the unit first please.  If you don’t have it yet, we can send you an example CE declaration for the model.

What is a simple way to record/view data from a Huber unit?

You could use the USB port on a Pilot ONE controller to record temperature data onto a USB stick, which you could then edit/view in Microsoft Excel.  The E-grade ‘Exclusive’ (or ‘Professional’) is required for this function.  (You can refer to the separate FAQ entries for more information on E-grades.) Alternatively, SpyLight is basic Huber computer software that can be used for viewing/monitoring data.  You can download it onto your PC for free (at  You would need an appropriate cable to connect the computer with SpyLight to the Huber unit. There are also other methods of communication to connect a Huber unit to a computer system, e.g. to send the Huber set points from a PLC.  Please see other FAQ entries for further details.

Can I use the Pilot ONE controller away from the Huber unit?

It is not possible to take the Pilot ONE control panel off the Huber unit, take it away separately to program or test it, and then put it back on the Huber unit.  The Pilot ONE controller needs to be connected to the Huber unit to use it. Nonetheless, the Pilot ONE controller can be positioned some distance away from the Huber unit but still with the two connected.  We refer to this as using the Pilot ONE as a remote control. The Pilot ONE controller lifts out, and then you can access the connection ports on the Pilot ONE and the Huber unit to connect up with a (specific) cable.  The standard length is 3 m (part number HB16160), but longer, custom lengths can be supplied if required (recommended maximum 25 m).  We also offer a wall bracket (part number HB9493) and a table stand (part number HB9494), which you can use to fix the control panel in a convenient location.

When do I need a size adapter when connecting a circulator to my jacketed lab reactor?

Our standard jacketed lab reactors have the following connections for Huber (or other circulator) hoses:
  • Reactor-Ready and Reactor-Ready Duo: M24 male
  • Reactor-Ready Pilot: M30 male
  • Lara (current model): M24 male
  • Lara (older version): M16 male
Huber units (or other circulators) have fittings for connecting to the hoses (referred to as pump connections) of a particular size for that Huber model, as stated in its technical data, e.g. M24, M30 or M16. These are always male. If your jacketed lab reactor has the same size fittings as your Huber unit (e.g. they are both M24), you can use a hose of that size (M24 in this case), and no size adapters are required. (Huber hoses are always female at both ends.) If your jacketed lab reactor has different size connections to your Huber (e.g. Reactor-Ready is M24 and your Huber is a Petite Fleur, which is M16), you could potentially use a hose of either size (e.g. M16), but you will need a size adapter where the size changes (in this example, between the M24 Reactor-Ready and the M16 hose). The descriptions of size adapters match the adapters themselves, not what they connect to. You always need male joining to female. For example, to connect M24 male Reactor-Ready to a M16 female hose, you need an M24 female to an M16 male adapter, part number HB6724. There are a range of size adapters listed in the Huber catalogue. Please contact us if you require further assistance. N.B. The full names of these M fittings are:
  • M16x1 or M16/1
  • M24x1.5 or M24/1.5
  • M30x1.5 or M30/1.5
They have been abbreviated in this post for clarity. The short names are commonly used.

Can a Huber unit with Pilot ONE controller be controlled by a PLC via RS232, and if so, how?

You can control a new Huber unit with Pilot ONE controller via a PLC/DCS etc. It is possible to send setpoint commands and receive temperature readings, and also stop the Huber if a particular temperature is exceeded. There are different methods of communication available, but RS232 is commonly used. You can refer to the Huber data communications manuals – PB commands (recommended) or PP and LAI commands (older). The RS232 cable for new Unistats with Pilot ONE is HB55018 (with a 15-pin end for connecting to the Huber).  For other units, a 9-pin RS232 cable is offered, part number HB6146.  Please feel free to ask if you have any queries. For information on the Ethernet and AIF (4-20 mA) options for new Huber units with Pilot ONE, please refer to the separate FAQ entries. For older Huber models, please contact us with the serial number of your unit, and we can advise on your options.

Can a Huber unit with Pilot ONE controller be controlled by a PLC via an AIF (analogue interface), and if so, how?

You can control a new Huber unit with Pilot ONE controller via a PLC/DCS etc. There are different methods of communication possible, including 4-20 mA using an analogue interface (AIF).  The 4-20 mA communication can be used to send signals to the Huber unit (control it) in addition to receive signals (monitor it). The analogue interface has one programmable input channel (e.g. for setpoint), and three output channels (setpoint, external temperature, and programmable).  If you want to control multiple parameters, we would advise you consider another method of communication. You would need to purchase an [email protected] (optional accessory) to have an analogue interface.  Please search the FAQs for further details of the [email protected] We can supply a cable for connecting to the analogue interface on the [email protected], part number HB9353.  This has an open end, for wiring into your application.
For information on the RS232 and Ethernet options for new Huber units with Pilot ONE, please refer to the separate FAQ entries. For older Huber models, please contact us with the serial number of your unit, and we can advise on your options.

Can a new Huber with Pilot ONE or MPC plus be controlled/monitored by LabVIEW or MATLAB?

Yes, your new Huber is compatible with LabVIEW and with MATLAB, via RS232 communication (serial interface). You can connect the Huber to a computer using the appropriate RS232 cable (either HB55018, with a 15-pin end for the Huber, or HB6146, with a 9-pin end for the Huber – let us know if you need help determining which would be suitable). Huber RS232 commands are detailed here for PB commands (recommended), or here for PP and LAI commands.

What is a Huber Pilot ONE E-grade? How do I upgrade it?

Huber Pilot ONE controllers come with 3 possible levels of software, which are referred to as E-grades. Unistats, as the most advanced type of Huber units, come with the highest level of Pilot ONE software as standard, which is the ‘Professional’ E-grade. Open bath units, such as Ministats, are more basic models.  Those with Pilot ONE controllers only come with the lowest level of software, which is the ‘Basic’ E-grade.
Higher E-grades have more features available.  You can purchase an upgrade code if you want to move up to a higher E-grade to gain additional features.  For example, please see the separate FAQ entry ‘Why would I need HB9495 Basic to Exclusive Upgrade?’ for more information on the most common upgrade. The part numbers for the upgrades are:
  • HB9495: Upgrade to Exclusive
  • HB9496: Upgrade to Professional
If you would like to upgrade an existing Huber unit, please let us know the serial number of your Huber unit, and we can issue a code. To apply an E-grade, in the Pilot ONE controller, you should navigate: Menu > System Settings > E-Grade > Activate Packages > select the package number (e.g. 2 Exclusive), and then enter the activation code supplied. To check your current E-grade, in the Pilot ONE controller, go to Menu > System Settings > E-Grade > Activated Packages.

What is a [email protected]?

A [email protected] is an optional accessory for Huber units with Pilot ONE. Depending on the model of your Huber unit, you would use either external [email protected] (part number HB6915) or the the internal [email protected] (part number HB31217).

huber com g@tes

The [email protected] provide the following interfaces:
  • Analogue interface (AIF) for 4-20 mA communication
  • POKO (volt-free contact / floating contact)
  • ECS (external control signal)
  • RS232/RS485 (serial)
  • The external [email protected] also has a level interface (to connect an external float switch, for monitoring the level of an externally closed application).
These are in addition to any interfaces already on the Huber unit.  A [email protected] is always required if you need an analogue interface.

How do I add a [email protected] to my existing Huber unit?

External [email protected] (part number HB6915)
You could either connect it with a 3 m cable (part number HB16160), or alternatively use a shorter cable and a bracket to mount it on the unit (different part numbers for different Huber models).
huber external com g@te hb6915
Internal [email protected] (part number HB31217)
Remove the RS232 plate from the Huber unit (4 screws), and disconnect the cable on the back.  There is another cable inside (which may be slightly hidden; it’s labelled -WVL3) that connects to the back of the internal [email protected] plate.
huber internal com g@te hb31217

How/where do I add a Pt100 temperature probe in my AVA system?

There are a number of ways you can add a Pt100 temperature probe, normally used with AVA to automate a circulator (thermoregulator, e.g. Huber).
Connection to circulator and PID control via circulator – recommended
Physically connect the Pt100 probe to the circulator. In the AVA Apparatus window, add a circulator, and in its settings, for ‘External temperature probe connected to circulator?’, select ‘Yes’; the temperature probe will now be shown in AVA.  Tr (controlling the temperature of the reactor via the external probe) is now possible.  The circulator itself will be responsible for the PID control.
Connection to Data Hub and PID control via AVA
You can use this option if your circulator does not have a socket for a temperature probe. Physically connect the Pt100 to the Data Hub.  In the AVA Apparatus window, add a circulator, and in its settings, for ‘External temperature probe connected to circulator?’, select ‘No’; then click on the pale grey outline of a temperature probe in the reactor and add a temperature probe.  Tr (controlling the temperature of the reactor via the external probe) is now possible.  However, rather than the circulator being responsible for its own PID, the AVA software will control it.
Additional temperature probe just for monitoring
You could do this if you want to monitor another temperature probe (not related to control of the circulator), such as one for a reflux divider; you can use its reading for a step override, for example. Physically connect the Pt100 to the Data Hub. In the AVA Apparatus window, use the top left zone (pale grey box) to add one temperature probe. (It is also possible to use the top right zone to add further additional temperature probes like this, if you have AVA level 4.)

What precautions should I take when working at extreme temperatures in my jacketed lab reactor?

All our jacketed lab reactors (including Reactor-Ready, Reactor-Ready Duo, Reactor-Ready Pilot and Lara) have an advised temperature range of -70°C to +230°C (thermal fluid temperature, i.e. circulator internal temperature). When working at low temperatures, vacuum jacketed vessels are recommended – please see the separate FAQ entry on vacuum jacketed vessels for further details. In addition, for extreme low temperatures (below -50°C), we suggest that piston O-rings are replaced between every run, because these conditions can cause the O-rings to harden and become brittle, potentially reducing the effectiveness of the seal. For temperatures above +150˚C, for Reactor-Ready Pilot, we recommend the use of high performance Chemraz piston O-rings to minimise the risk of weeping.  The O-rings should be inspected between runs and replaced regularly. We also offer a secondary valve for the run-off (outlet) of the bottom outlet valve (part number RR139098 for Reactor-Ready, Reactor-Ready Duo or Lara; RR139137 for Reactor-Ready Pilot) to catch any liquid that may weep around the piston at temperature extremes.

Run off secondary valve B24 to stopcock

Additional considerations when working at high or low temperatures are the temperature limits of your circulator (remembering that the temperature range of the process will be narrower than this) and thermal fluid (especially regarding high viscosity at low temperatures and inert gas blanketing at high temperatures). If you chose to work beyond our recommended temperature guidelines, this would be at your own risk.  One potential issue is that PTFE (used for many Reactor-Ready parts) can soften when used at very high temperatures.

Do I dilute ethylene glycol for use in a circulator? By how much?

Water-glycol can be used as a thermal fluid in open bath units and chillers (although it must not be used in Unistats).  Glycol is commonly used to reduce the freezing point of water, so you can work at low temperatures. You do not use ethylene glycol neat, because it is so viscous. You dilute it with water to reduce the viscosity and so improve the flow (and also make it more cost effective). The exact proportion of water-glycol to use depends on what temperature you want to work at, as the proportion determines the freezing point of the mixture – and you want to make sure that the freezing point is below the temperature that the water-glycol mixture will be cooled down to in your system.  There are tables and graphs available online that show the percentage / freezing point ratio. A mixture of about 2:1 water:glycol (around 33% glycol) is often recommended, as this has quite a low freezing point without being too viscous. (Changing the proportion also affects the boiling point of the mixture.)

What is delta T?

Delta T (ΔT) is the difference between two temperatures.  We use this term to refer to the difference between:
  • The temperature of the oil in a vessel’s jacket (also called internal temperature) and
  • The temperature of the vessel contents (also known as process temperature or reaction temperature).
We usually consider the delta T when a jacketed vessel is being heated or cooled.  The temperature of the vessel contents will lag behind the temperature of the oil in the jacket.  If the delta T is too large, it could stress the glass and lead to breakage. We therefore recommend that the delta T limit is set to 50°C (50K).  With current Huber thermoregulators with Pilot ONE controllers, you can adjust this by Menu → Protection Options → Delta T Limiter → type 50 in ‘New value’ field → tap ‘Ok’ to confirm. In the previous Nuevo controllers the delta T limiter can be found in the ‘Limits’ menu, and in older Unistat controllers it is program 18. Please note, this control can only be achieved if the contents temperature is being monitored. If it is not being monitored (if the vessel is empty, for instance) then great care should be taken to heat or cool the vessel in a controlled, gradual way to prevent thermal shock (e.g. by use of a ramp function).  When using a temperature probe in the vessel (external Pt100), please ensure the end of the Pt100 is always immersed in the vessel contents. Please also be aware that even if a delta T limit is set, it is possible for this limit to be exceeded slightly in practice.  If this poses a problem for you, we recommend you reduce the delta T limit setting to below your desired limit.

Do I set the delta T in AVA?

Note: for an introduction to delta T, please see the separate FAQ entry ‘What is delta T?’.
Under normal circumstances, you cannot set delta T in AVA – it is not applicable.
  • If, as we recommend, you plug the Pt100 temperature probe directly into the circulator (e.g. Huber)
  • and have it configured like this in AVA (in the circulator properties box, for ‘External temperature probe connected to circulator?’, ‘Yes’ is selected)
  • then the circulator is responsible for the temperature control.  If you implement a Tr (reaction temperature) setpoint/ramp, AVA will send Tr instructions to the circulator, and the circulator will calculate the required Tj (jacket temperature).
  • In these circumstances, you should set the delta T limit in the circulator controller itself (not in AVA).  The circulator is responsible for measuring and responding to the delta T.
If the reactor Pt100 is separate from the circulator, you do set delta T in AVA.
  • It is possible (e.g. if the circulator does not have a Pt100 socket) to plug the Pt100 for the reactor into the Data Hub instead
  • and set up the Apparatus like this in AVA (in the circulator properties box, for ‘External temperature probe connected to circulator?’, select ‘No’, then click on the outline of a temperature probe in the reactor to add a Pt100 there)
  • and then when you click on the circulator properties box, you will see that the field ‘Maximum temperature difference Tr – Tj’ has appeared.
  • In this case, when you set Tr, AVA calculates the Tj and sends the Tj instructions to the circulator, considering the delta T limit set in AVA.

How can I improve the performance of my jacketed lab reactor condenser?

If your condenser is struggling to contain all the vapour generated in your jacketed reaction vessel, there are a number of steps you can take.
Ensure your condenser is large enough
It’s important to use a condenser that is an appropriate size for your equipment and application, e.g. vessel size.  Here at Radleys we offer a wide range of condensers with different surface areas, and we can also make custom condensers if required. Please contact us and we’ll be happy to advise.
Use appropriate cooling water, e.g. use a suitable chiller set correctly
Ensure you have sufficient cooling water for the condenser.  It may be helpful to use a chiller, if you do not have a suitable chilled water supply (e.g. tap water is too warm).  If you do use a chiller, make sure it has enough cooling power to effectively condense the chemical vapours.  Note that cooling power decreases with set temperature, so it may actually help to increase the temperature the chiller is set to to obtain more cooling power whilst maintaining a large enough temperature difference.  We often recommend +15⁰C; at -20⁰C the chiller will have little cooling power!
Minimise the amount of chemical vapour generated
Do not apply excessive heat to the reaction vessel.  There is no benefit to overheating, as the temperature cannot exceed the solvent boiling point – you simply generate more chemical vapour to be condensed.  If you are refluxing, make sure you aren’t using reactor control (setting temperature via a Pt100 probe in the vessel) and setting the temperature higher than the boiling point, or the jacket temperature could keep increasing in an attempt to raise the reactor temperature, producing too much vapour.  Furthermore, ensure any exothermic reactions are controlled, e.g. by using AVA software.

How can I choose between Unistats and open bath circulators?

Unistats are technologically advanced circulators from Huber.  Open bath units are a more traditional design. Generally, Unistats are recommended for more demanding reactor applications (e.g. rapid cooling/heating required, large exothermic reaction to control, large vessel volume, or very low/high temperatures required), while bath units are a lower cost alternative for less demanding reactor applications.  (Of course, if you want to put objects into a bath rather than temperature control a jacketed reactor, you will need a bath unit!) Some key differences between the Unistats and baths are as follows:
Huber Unistats
  • Small internal volume – faster temperature change possible, as less oil in the circulator to heat/cool.
  • Plate heat exchangers compared to coil heat exchangers – more efficient heat transfer, so again, faster heating/cooling.
  • Thermal fluid (oil) isn’t exposed to air at very high or low temperatures – longer lifetime of oil, and can use it at a wider temperature range than in open baths.
  • Integrated expansion tank to allow for oil expansion under heating and contraction under cooling.  Additional expansion tank can be added for further space for drain-down of a reactor.
  • Have Pilot ONE controllers with the highest level (E-grade) of software – ‘Professional’.
  • Cannot use water-glycol as thermal fluid (only oil).
  • Higher cost.
Open baths
  • Slower heating/cooling per kW as larger internal volume so more oil to be heated/cooled (the temperature change you want in the vessel’s jacket must take place for the oil in the bath too) and coil heat exchanger used rather than plate heat exchanger.
  • The bath is open to atmosphere (oxygen and water vapour).  At high temperatures, oil (if used as thermal fluid) can be degraded through its reaction with the air, and vapours are given off (which smell).  At low temperatures, moisture absorbed into the thermal fluid means ice can form on the refrigerator coil and ice crystals can form in the fluid.
  • Lower maximum temperature of oils – should not be used above flash point.
  • No expansion tank; take care not to overflow bath.
  • Huber open baths may have only a basic controller.  Huber bath units with a Pilot ONE controller have the lowest level (E-grade) of software as standard – ‘Basic’.
  • Can use water-glycol as thermal fluid, as an alternative to oil.
  • Lower cost.
  • N.B. Some issues can be minimised and performance improved by purchasing a displacement insert and/or a software upgrade – please see separate FAQ entries for more information.  Please note, these options are not available for all models.

How do I decide between air-cooled and water-cooled Huber circulators?

Most Huber units are available in either air-cooled or water-cooled versions. Water cooling and air cooling is referring to heat removed from the Huber unit itself (cooling of the condenser in its refrigeration system, after it has removed heat from your application).  It does not refer to how the Huber unit cools your application – e.g. a water-cooled Unistat would still circulate oil, not water, around a vessel’s jacket.
For relatively small (low to moderate cooling power) models, the air-cooled versions are recommended.  For some large units (very high cooling power), only water cooling is available.  If you are using a chiller to recirculate cooling water to minimise water consumption, you certainly should use an air-cooled rather than a water-cooled unit.
Air-cooled circulators
  • Use internal fans to pull cool air in for cooling.
  • Warm air is ejected into the lab.
  • This warm exhaust air must be able to rise without hindrance. Fresh air must also be able to enter the machine.  You must ensure there is sufficient space around the unit – more clearance is needed than for water-cooled units.
  • If grills get dusty or blocked, your efficiency will drop off and the system may cut out.
  • Large units can be noisy.
  • For high cooling power units where there is still a choice available between air-cooled and water-cooled, the air-cooled units can be larger (have bigger dimensions).
Water-cooled circulators
  • Water-cooled Hubers are denoted by a ‘w’ at the end of their model name, e.g. Unistat 405w.
  • Water circulates past the circulator’s condenser to remove the heat.
  • The water supply must be of a suitable pressure, temperature and purity.
  • The circulator must have access to a drain for waste hot water to be disposed of (unless you are using your own looped chilled water supply).
  • Water-cooled models are quieter than air-cooled.

What do Huber oil names mean, e.g. SilOil M40.165/220.10?

SilOil is short for silicone oil. The first part of the code is the lower temperature limit (°C) of the oil.  This is the temperature of the fluid where the viscosity has reached 50 centistokes (cSt; equivalent to mm2/s); cooler than this and the oil would be too viscous to pump.  The ‘M’ or ‘P’ before the number refer to minus or plus respectively. The second part of the code (in between two full stops) is the higher temperature limit (°C) of the oil. If there are two figures separated by a ‘/’, the first corresponds to the maximum in an open bath unit (e.g. Ministat) and the second is the maximum in a Unistat. The maximum recommended temperature for a bath unit is below the oil’s flash point, to ensure safety. Unistats are hermetically sealed, so can be used at slightly higher temperatures. The final part of the code is the viscosity at 25°C (around room temperature) in centistokes, cSt (i.e. mm2/s).  The higher the number, the higher the viscosity.

What are 90° bends? Why are they beneficial?

90° bends (90 degree bends) are also known as right angle adapters or elbow adapters.

Huber 90 degree bend

We recommend them for use with circulators (typically Huber units), one for each hose.  They are inserted between the hose and its respective hose connection on the circulator. Highly insulated circulator hoses are not very flexible, and Huber hose connections point straight out of the side or back of the unit.  Depending on where you want to locate the circulator relative to your reaction system, including the 90° bends can make it easier to position the hoses in the appropriate direction. Choose 90° bends that are the same size as your circulator hose (pump) connections. The part numbers are:
  • HB6195: M16/1 90deg Adapter
  • HB9256: M24/1.5 90deg Adapter
  • HB6461: M30/1.5 90deg Adapter
  • HB6699: M38/1.5 90deg Adapter
On Reactor-Ready, Reactor-Ready Duo and Reactor-Ready Pilot, the manifolds you connect the circulator hoses to already have 90° bends as standard, so you do not need to purchase them for the reactor end.

When should I use an inert gas (nitrogen) blanket with a Huber bath unit?

In open bath circulators, oil (thermal fluid) is exposed to the atmosphere. At high temperatures, the oil can be degraded, and there is also a small risk it can become gel like. For the common Huber silicone oils, we recommend the use of inert gas (a nitrogen blanket), particularly if you will be working at temperatures over 150°C, to prolong the lifetime of the oil. We can supply bath covers with fittings (an inlet and an outlet) for inert gas as custom; please contact us for further details.

How much space (clearance) do I need around a Huber unit?

It is best to have as much space around the Huber unit as possible. However, if you need to position it a small space, please ensure there is sufficient clearance to the ceiling and walls where the machine is sited; the guidelines are as follows:
Air-cooled models
These transfer all the heat energy taken from the temperature-controlled application into the environment.  This warm exhaust air must be able to rise without hindrance.  Fresh cool air must also be able to enter the unit. You should leave at least 20 cm space around the air-cooled Huber unit, and at least 70 cm between the back of the unit and any obstruction.
Water-cooled models
There should be at least 10 cm space around the unit.

What is ‘flashing’? How do I ‘flash’ a Pilot ONE controller? How do I update Pilot ONE firmware?

The process to update the firmware of a Huber Pilot ONE controller is called flashing. To do this, download the Huber Pilot ONE Flasher software from the Huber website The download will contain the manual with instructions on how to download the latest firmware from the internet and transfer it to the Pilot ONE controller; this can also be viewed online.

How can I calibrate my Huber unit?

You can check the accuracy of a temperature sensor by placing a calibrated reference temperature sensor (not supplied by Huber/Radleys) close to the sensor in question, and noting the readings at your desired temperatures. If you would like to calibrate an external temperature sensor (a Pt100 you have purchased as an optional accessory, to plug into the Huber (via the LEMO socket) and position in your application (e.g. jacketed lab reactor), you can simply place your calibrated reference temperature sensor next to the external Pt100 in the application. Huber units contain an internal temperature sensor, which is used to measure the temperature of the thermal fluid flowing out of the Huber unit to the external application.  Please note that Huber calibrate the temperature sensors at their factory, and so calibration of new units by customers is not required.  Nonetheless, if you would like to calibrate the internal temperature sensor, to position your reference temperature sensor next to it, you would need to purchase a calibration bend.

Huber calibration bend

The calibration bend would be mounted on the Huber outlet, and has a sensor pocket for inserting the reference sensor.  There are different types of calibration bends, for different sized Huber fittings and sensor diameters.  (It is not possible to remove the internal sensor from the Huber unit to calibrate it.) If your Huber unit has a Pilot ONE controller, you can then offset the current temperature reading to match the reference temperature.  Navigate to Menu → System Settings → Sensor Adjustment. With Professional or Exclusive levels (E-grades) of the Pilot ONE software, you can calibrate 5 points (5 different temperatures); with the Basic software, a 2-point calibration is possible.

Can I use water as thermal fluid in my circulator?

If you have a bath unit or a chiller (such as a Minichiller), then you can potentially use water as thermal fluid. Note that usually a mixture of water and ethylene glycol is used rather than just water, to widen the temperature range – adding glycol reduces the freezing point.  (Search these FAQs for ‘glycol’ to find the entry ‘Do I dilute ethylene glycol for use in a circulator? By how much?’ for further details.) Please be advised that if you have a Huber Unistat, you should not use water or water-glycol as thermal fluid – select a suitable silicone oil for the temperature range instead.

How does the Lara drain-down button work?

The Lara drain-down button facilitates the draining of thermal fluid back into the circulator. When the button is depressed, air is allowed to enter the circulator system through a gold-coloured filter situated above the button. This makes the draining process much faster.

Lara drain down button

You would first need to ensure that the circulator has enough space in its expansion tank to accept the oil.  (An additional external expansion tank can be added to a Huber if required.) The circulator would have to be positioned below the Lara, as gravity is used for drain-down. To drain the Lara vessel jacket:
  • Switch off the circulator.
  • Press the ‘drain’ button on the left hand side of the triangular Lara framework.
  • The button must remain depressed to completely drain the jacket.

Which accessories are included with my Huber unit?

Check the technical data sheet for the Huber model. This can be downloaded from the Huber website – search for your model to go to its web page, then click on the ‘Data sheet’ hyperlink. Scroll down to the ‘Accessories and periphery’ section near the bottom.  The parts labelled with a * symbol are included with the unit as standard.

I have a Huber immersion cooler and the display is reading error F1-. How can I fix it?

The immersion cooler models with an MPC control panel (shown below) require an external Pt100 temperature probe to operate. huber immersion cooler mpc controller f1 error and pt100 socket
These models are supplied with a Pt100, so plug this in to the socket (below the display), and the error message should stop.

Where can I find my Huber unit’s serial number?

So we can identify exactly which Huber model you have (e.g. since there have been different versions over the years), we often ask for the unit’s serial number. This should be stated on a silver sticker on the unit, such as the one below: Huber serial number
The number after the ‘/’ indicates the year of manufacture.

How do I communicate with my Huber unit using an RS485 interface?

An RS485 interface is available for Pilot ONE Huber units if you purchase a [email protected], such as the one shown below.  (You can search these FAQs for ‘[email protected]’ for further details.)


We can supply a cable for connecting to RS485 interface on the [email protected] – part number HB6279. This has an open end, for wiring into your application. Further wiring guidance The pinout of the interface is as follows:
  • 6 – A with 120Ω-terminating resistor
  • 7 – A
  • 8 – B
Pins 7 (A) and 8 (B) must be used for connection with the RS485 network. As there are only two wires, they are always connected A to A and B to B, independent of the number of RS485 units. You should typically only use pin 7 and pin 8; pin 6 is not used for normal operation.  If the resistor should be activated for termination, you have to make an additional bridge between 6 and 7 at the corresponding unit.  Please take care that only one termination resistor is connected at each side of the RS485 bus.  This termination resistor is typically required in cases of high baud rates and large distances; please only use the baud rate of 9600 with the RS485 bus.


Huber RS485 only supports half-duplex mode. If a single Huber unit is connected via RS485, the Huber will be able to understand any of the Huber command sets available – LAI, PP or PB commands, detailed here and here. However, if multiple Huber units are connected via RS485, each unit must have its own unique address, and you have to address each unit separately.  This means you need to use the Huber LAI command set, as only LAI enables you to send address information within the command.  If the PLC/DCS etc. sends a command on the RS485 bus, every connected unit is listening, but only the addressed system can answer. If you want to connect multiple Huber units to your PLC/DCS and it has Ethernet functionality, you may find that method of communication easier, as then you have the option of the PB or PP command sets, and furthermore you wouldn’t need to purchase a [email protected] for each Huber unit, as an Ethernet socket is included as standard on Pilot ONE controllers.