Screw compressor heat recovery - free energy from your compressor room
Up to about 90% of the electrical energy a screw compressor draws is converted into heat. Instead of venting it outside, it can heat your production hall, offices or process water and noticeably cut your plant's energy bills.
How much heat does your compressor give off
A 22 kW compressor running 8 hours a day gives off, over a heating season, an amount of heat you would otherwise pay for through your gas or coal bill. The higher the power and the longer the running time, the greater the potential - the best results are seen in plants with machines from about 15 kW upward running continuously.
What recovered heat can be used for
Heating a production hall or warehouse
Blowing warm air from the compressor's cooling circuit - the simplest option.
Domestic hot water
A plate heat exchanger on the oil circuit heats water for washing, staff facilities or processes.
Support for process operations
Drying, preheating, heat curtains.
How the implementation works
Audit
We measure the real running time and temperatures of your compressor.
Choosing the solution
Ducted air recovery or a heat exchanger, depending on the plant's needs.
Installation without stopping production
Most of the work is carried out during a scheduled service visit.
Measuring the effect
We compare energy consumption before and after.
When heat recovery pays off
The fastest payback is achieved by plants where the compressor runs more than 4000 hours a year and the hall or water already need heating. Under these conditions a heat recovery installation can pay for itself in one to two heating seasons. If you are not sure whether your compressor room qualifies, start with an energy audit.
Compressor heat recovery - how it works technically
In an oil-injected screw compressor the heat carrier is the oil. It circulates in a closed loop: it cools the compression stage, lubricates the bearings and seals the gap between the rotors, releasing all the absorbed energy in the oil cooler. Oil temperature leaving the stage is typically 70-90 degrees C, making it the most valuable heat source in the whole compressor room. The second, cooler source is the aftercooler, where compressed air is cooled before entering the dryer.
Compressor heat recovery means tapping a plate oil-to-water heat exchanger into this loop. Hot oil transfers its energy to the plant's water and only then returns to the machine's standard cooler, which acts as a backup and finishes cooling the oil whenever heat demand on the plant side is lower than production. This keeps the system safe: the compressor never loses its own cooling and the oil temperature stays within the window set by the manufacturer. In a well-designed installation, as much as about 94% of the electrical energy drawn by the compressor can be directed to recovery - the remainder is motor losses, casing radiation and heat carried away with the compressed air.
Air recovery or water recovery - the differences
Air recovery is the simplest and cheapest to install: we connect a duct, a damper and a booster fan to the compressor cooler outlet and distribute the warm air, typically 25-45 degrees C, around the hall, warehouse or paint shop. An actuated damper lets you redirect the stream outside in summer. The limitation is obvious - the heat cannot be carried further than a dozen or so metres of duct and it cannot be stored.
Water recovery needs a heat exchanger, a circulation pump, a three-way valve and controls, but offers far greater possibilities: water at 55-75 degrees C can feed the central heating system, a domestic hot water tank or process water for washing, rinsing or preheating baths. Heat can be carried to the other end of the plant and stored in a buffer, so it keeps working even while the compressor is stopped. In practice plants with their own gas boiler room choose the water variant, while halls heated with air heaters choose the air variant.
How much you can save - a worked example
The most common question is how much heat the compressor you already have gives off. The calculation is simpler than it looks. Take a 37 kW screw compressor running 4000 hours a year, typical of a two-shift plant. Practically all the electrical power drawn is converted into heat, and about 34 kW of thermal power (oil circuit plus aftercooler) is realistically available for recovery.
Annual thermal energy is power multiplied by running time: 34 kW x 4000 h = 136,000 kWh, i.e. 136 MWh a year. Not all of it will be used - assuming a cautious 60% match to the plant's demand gives about 82 MWh of heat realistically replacing another source.
Next, compare it with what you heat with today. For gas heating, divide the thermal energy by the boiler efficiency (typically 0.9) and multiply by your gas price per kWh from your invoice - 82 MWh is then equivalent to about 91 MWh of gas. For electric heating the conversion is direct: 82 MWh less electrical energy, multiplied by your rate per kWh. We apply the same method for heating oil, only the price is entered per litre and divided by its calorific value.
We deliberately do not quote figures here - energy and gas rates vary too much between plants for any single number to be meaningful. What we provide instead is the method: thermal power x running hours x utilisation rate, converted at your own energy price. Put in your own invoice figures and you will immediately see the scale.
Heat recovery and the compressed air audit
Recovery potential is not a catalogue value - it results from how your machine actually runs. That is why we calculate it during an audit. We log power draw and load profile over a weekly cycle, measure oil and air temperature behind the cooler, check the share of idle running and how much heat the plant can absorb in each month. Without this data, sizing the exchanger is guesswork: too small limits recovery, too large raises cost with no benefit.
If you are planning heat recovery from a screw compressor, start with a compressed air audit. The report also reveals other reserves - leaks, oversizing, excessive working pressure - and heat recovery then becomes one of several coordinated actions rather than a single investment made in isolation from the rest of the installation.
Installation and servicing of heat recovery systems
We carry out all installation and servicing on site, at your compressor room - we do not accept machines brought to a workshop. Technicians arrive with the heat exchanger, fittings and measuring instruments, and we plan the work so production does not stop: connecting into the oil circuit is usually combined with a scheduled service visit, when the machine is already switched off anyway.
The heat exchanger is matched to the specific compressor model - what matters is oil flow and viscosity, connection diameters, the cooling system and whether the machine has a variable-speed drive and how often it runs at low load. On the water side we integrate the system with the existing central heating or storage tank: a three-way valve, pump, safety devices and controls set so that heat from the compressor is used first and the boiler only tops it up. The installation therefore works as the primary source, not a backup.
Later we inspect the recovery system during a screw compressor service - checking the cleanliness of the exchanger, tightness, pump and valve operation and temperatures on both sides, because a scaled-up exchanger quietly reduces recovery. Plants that want these dates tracked without reminders, we cover with a service agreement - the compressor and the recovery system are then serviced in a single visit.
Frequently asked questions
Screw compressor heat recovery - the questions production plants ask most often.
Need service or spare parts?
Our team will recommend the best solution and send a quotation the same day.
Check your compressor room's potential
Tell us which compressor you have and how many hours it runs - we will calculate how much heat can be recovered.
Contact
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ul. Słowackiego 201 26-600 Radom Mazovian Voivodeship, Poland
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ul. Słowackiego 201, 26-600 Radom