"Do I need a temperature control unit or a chiller?" It is one of the questions we are asked most often, and it almost always starts from a confusion: both units move water through the mould, but they do not do the same job. One keeps a temperature stable. The other produces cold. Understanding the difference avoids buying the wrong unit or, worse, buying only one when the process needs both.
What a temperature control unit does
A temperature control unit (TCU), also called a thermoregulator, keeps the mould or reactor at a constant set temperature. To do so it can heat with electric heaters and cool with a heat exchanger or by direct injection of mains water. Its job is stability: the cavity should be at 80 °C for the first part and for the ten-thousandth.
Depending on the fluid, it works in different ranges. With water and an open tank, up to about 90 °C. With pressurised water, up to 140–180 °C depending on the unit. With thermal oil, up to 300 °C. If you are unsure which fluid to choose, we explain it in water or oil temperature control unit.
Its limit is at the bottom end: a TCU cools with the water it receives. If the mains or tower water comes in at 25 °C, it cannot bring the mould down to 15 °C.
What a chiller does
A chiller, water chiller or process cooler is a refrigeration machine. It has a compressor, condenser and evaporator, and its job is to produce chilled water at a temperature below ambient or mains water, normally between 5 and 20 °C. With glycol it can go below 0 °C. Its goal is cooling capacity: removing kilowatts of heat from the process.
A chiller is not designed to heat or to fine-tune the temperature of a hot mould. If you connect it directly to a mould that must run at 60 °C, it will not work.
Comparison table
| Criterion | Temperature control unit (TCU) | Chiller |
|---|---|---|
| Function | Keep the mould stable at a set point | Produce chilled water |
| Typical range | From the cooling water temperature up to 90 °C (open water), 140–180 °C (pressurised water) or 300 °C (oil) | Approx. 5–20 °C; below 0 °C with glycol |
| Heats | Yes, with electric heaters | No |
| Cools | Yes, with the water it receives | Yes, with a refrigeration cycle |
| Key figure | Accuracy and stability (°C) | Cooling capacity (kW) |
| Installation | Next to the mould or reactor | Next to the machine or centralised |
When a TCU is enough
When the mould temperature is clearly above the available cooling water. As a rule of thumb, if the set point is at least 10–15 °C above the mains or tower water, the TCU controls without problems. This is the case for most engineering plastics: ABS, PC, PA or POM with moulds between 60 and 120 °C, and for almost all oil-based moulding. See typical values in the mould temperature table by polymer.
When a chiller is enough
When the mould has to run cold, below the mains water temperature, and high accuracy is not needed. This is common for thin-wall PP or PE packaging, preforms or parts with very short cycles, with moulds at 10–20 °C. The chiller delivers water at a fixed temperature and the mould settles wherever it settles.
When you need both
This is the most common set-up in plants with several machines:
- The chiller provides the cold to a water circuit at a low, constant temperature, for example 12–15 °C.
- The TCU uses that water as its cooling source and sets the exact temperature of each mould.
This way each mould has its own set point and accuracy, and the TCU no longer depends on the mains water being at 18 °C in winter and 28 °C in August. The opposite case also occurs: a mould with a hot zone and a cold zone, with a TCU on each side and the chiller feeding both.
There is a clear sign that a chiller is missing: the TCU is in cooling mode all the time and the mould still does not reach the set point. It is not a lack of TCU capacity; the water it receives is simply too warm.
Terms by country
- In Spain the usual term is "atemperador". In Latin America "termorregulador" is widely used and, in technical settings, the abbreviation TCU. You will also hear "mould temperature control".
- "Chiller" is used everywhere. In Spain people also say "enfriadora" or "refrigerador"; in Mexico, "equipo de agua helada" (chilled-water unit).
Typical mistakes
- Buying a more powerful TCU to cool more, when the problem is the inlet water temperature.
- Connecting a chiller directly to a mould that needs 50–60 °C.
- Lowering the chiller water below the dew point and causing condensation on the mould.
- Sizing the chiller without counting the loads of the TCUs it feeds.
Frequently asked questions
Can a temperature control unit cool?
Yes, but only down to a few degrees above the temperature of the water it receives. It does not generate cold by itself.
Can a chiller replace a temperature control unit?
Only if the mould runs cold and you do not need to accurately control a temperature above ambient.
What is a TCU?
It stands for temperature control unit: the same unit that in Spain we call atemperador and in Latin America termorregulador.
How do I know what chiller capacity I need?
With the formula Q = m · cp · ΔT and the kg/h of your process. We explain it step by step in how to size an industrial chiller.
TCU, chiller or both?
Tell us the mould temperature, the material and the temperature of your cooling water, and we will tell you which set-up makes sense. See our industrial temperature control units and industrial chillers, use the equipment selector or talk to a technician.