A heat exchanger in an air handling unit is almost always a worthwhile investment - regardless of whether the exchanger in question is a rotary or a plate type.
All our units save so much energy that the investment can be repaid in no time.
Where significant air volumes are treated, the amortisation period may be less than a year in some cases.
There is generally a solution for any air volume that offers a maximum payback time of two and a half years.
Air-to-Air Heat Exchangers: Comparison of Payback Times
Viability: Example of Axalta Coating Systems
The savings and amortisation effect can be seen in the following viability calculation using the example of Wuppertal-based Axalta Coating Systems Germany GmbH. Despite an estimated investment outlay of some €625,000 in an overall ventilation system with twelve heat wheels and despite additional energy requirements for ventilators, the potential energy savings are so great that the investment was repaid in just 16 months.
Exhaust Air from Paint Manufacture/Workshop Air
| System | 12 rotary heat exchangers (RWTs) - rotor diameters from 2150 to 5000 mm |
| Airflow | 900.000 m³/h |
| Rotor heat recovery | 2.740 kW |
| Production hours per year | 6.200 h/a (52Wo x 5T x 24h) |
| Annual heat recovery | 16.988.000 kWh |
| Gas cost per kWh | 0,0329 €/kWh (estimated) |
| Savings per year | 558.905,- € |
Additional Costs for Fans in Ventilation System
| Volume flow 1 | 900.000 m³/h |
| Pressure loss 1 | 100 Pa |
| Volume flow 2 | 900.000 m³/h |
| Pressure loss 2 | 159 Pa |
| Electricity requirement | 92,5 kW |
| Production hours per year | 6.200 h |
| Electricity cost per kWh | 0,1395 €/kWh (estimated) |
| Additional electricity costs | 80.003,- € |
Additional Costs for Rotor Drive Motor
| Rating | 0,55 kW |
| Production hours per year | 6.200 h |
| Additional electricity costs | 5.708,- € |
Amortisation of Ventilation System Overall
| Interest rate used for calculation | 4 % |
| Income from interest per year | 22.356,- € from cost savings |
| Maintenance costs | 2.000,- € (estimated) |
| Estimated investment | 625.000,- € (estimated) |
| Payback period | 1.33 years or approx. 16 months |
Design and calculation: Klingenburg GmbH
