Cleanroom reheat from chiller condenser heat
How a pharma plant with 60,000 m³/h of cleanroom air can do its AHU reheat with a heat pump on chiller condenser water, in place of electric reheaters.
▶Video: Waste-heat recovery heat pumps
V10 · 2–2.5 minLifting warm water from condensers, effluent and process cooling to useful heat
Video coming soon01Problem statement
- Cooling, then heating, the same air. To hold humidity, air is cooled below its dew point and then reheated, often electrically, which pays twice for the same air.
- Monsoon peaks. In humid months the reheat load rises sharply just as chillers work hardest.
- Condenser heat wasted. Chiller condenser heat goes to the cooling tower at 32 to 37 °C while reheat is bought as electricity.
- Electric heating is expensive heat. Resistance heaters turn one kWh of electricity into one kWh of heat, at the full commercial tariff. A heat pump moves two to four kWh of heat for the same unit.
- Large connected load. Heater banks take a big share of the sanctioned load and push up maximum-demand charges.
02Use case
The reference plant has graded cleanroom suites for oral solids and injectables served by six AHUs moving about 60,000 m³/h. Air is overcooled to remove moisture and reheated to hold 21 °C and 45% RH around the clock.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| AHU reheat after cooling coil | Air 12 → 18 °C | 60,000 m³/h × 1.2 kg/m³ × 1.005 kJ/kg·K × 6 K = 120.6 kW × 24 h × 0.4 load factor | 1,158 |
| Zone terminal reheat | Air +2 to 4 K | 12 zones × 2 kW × 20 h × 0.5 load factor | 240 |
| Storage and pipework standing losses | – | about 5% | 70 |
| Total useful heat | 1,468 | ||
Averaged over 20 running hours, the heat pumps need about 73 kW.
03P&ID
Tags: HP heat pump, TK tank, SG steam generator, P pump, PHE plate heat exchanger, TCV temperature control valve, TIC temperature indicating controller (panel), TT temperature transmitter, MT moisture transmitter, PT pressure transmitter, LT level transmitter, FS flow switch, NC normally closed. Process fluids are heated through their own exchanger, coil or jacket.
04Solution
System description
- 1 × SE-WW-80V (80 kW) (SE-WW water-source heat pump) delivering 50 °C, covering the day's 1,468 kWh in about 18.3 running hours.
- A 2,500 L insulated storage tank decouples the heat pumps from the process peaks.
- Heat source: chiller condenser water at about 35 °C. Taking heat from the condenser water lowers the condensing temperature, so the chillers use less power.
- The electric duct reheaters stays connected behind a normally closed valve as standby.
- A water-source heat pump takes heat from the chiller condenser water at about 35 °C and makes reheat water at 45–50 °C.
- Electric reheaters in each AHU are replaced or backed up by hot-water reheat coils.
- Zone terminal reheaters are fed from the same loop for fine room temperature control.
Selected equipment
| Model | SE-WW-80V × 1 |
|---|---|
| Heating capacity | 80 kW each, 80 kW total |
| COP | 5.0 at the data sheet's rated condition (55 °C outlet) |
| Power input | about 16.0 kW total at rated conditions |
| Rating | hot and chilled water at the same time, to 60 °C |
| Supply temperature | 50 °C |
| Storage | 2,500 L insulated tank |
Ratings from the Sunniva TDS 2026 data sheets.
Control philosophy
TT-101 holds the reheat water tank between 45 and 50 °C. TIC-201 on each AHU modulates the reheat coil to hold supply air temperature after the cooling coil sets the dew point, and TIC-202 trims each zone. Electric reheaters remain as standby and stage on only if the reheat loop falls short.
05Energy saving and ROI
Change any input to match a customer's site. Defaults are typical Indian prices for October 2026. The installed cost is a placeholder; replace it with the actual quotation.
| Existing | Heat pump | |
|---|---|---|
| Daily consumption | – | – |
| Annual energy cost | – | – |
| CO₂ per year | – | – |
06Benefits
Reheat from waste heat
Condenser heat that went to the tower now does the reheat.
Chillers run cooler
Lower condenser water temperature improves chiller efficiency.
Smooth humidity control
Modulating hot-water coils hold room conditions more steadily than staged electric heaters.
Lower energy cost
Each kWh of electricity delivers about 5.0 kWh of heat at the required temperature, against well under one kWh of useful heat per kWh of fuel burnt.
Smaller electrical load
The heat pump draws roughly 1/5.0 of the power of the heaters it replaces, which frees sanctioned load and cuts demand charges.
Solar-ready
Running hours can be placed in daylight so rooftop solar supplies much of the electricity, which also cuts CO₂ further.
07Engineering pointers
Site data to collect
- AHU airflows, off-coil and supply temperatures
- Room temperature and humidity specifications
- Electric reheater ratings and logged consumption
- Chiller capacity and condenser water temperatures
- Operating hours of each AHU
- Present fuel or electricity use and monthly bill
- Sanctioned electrical load and spare capacity
- Space for the heat pumps and storage, with service access
Design notes
- GMP change control. AHU reheat is part of the qualified HVAC system. Plan requalification of temperature and humidity after the change.
- Condenser water quality. Open cooling tower water fouls exchangers. Use a cleanable plate exchanger between the tower loop and the heat pump.
- Desiccant wheels. Low-humidity rooms with desiccant wheels need hotter reactivation air. Treat them as a separate duty.
- Electrical. About 16 kW of heat pump input at rated conditions, plus pumps and fans. Check spare sanctioned load before ordering.
- Source stream. The source must give up roughly two-thirds of the heat delivered. Confirm its flow and temperature over a full production day, and filter it before the evaporator.
Service and warranty
Sunniva has supplied 5,000+ heat pumps since 2012, with nine service technicians across India, including remote sites such as Leh. All components carry a one-year warranty.
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Cleanroom reheat from chiller condenser heat
How a pharma plant with 60,000 m³/h of cleanroom air can do its AHU reheat with a heat pump on chiller condenser water, in place of electric reheaters.
▶Video: Waste-heat recovery heat pumps
V10 · 2–2.5 minLifting warm water from condensers, effluent and process cooling to useful heat
Video coming soon01Problem statement
- Cooling, then heating, the same air. To hold humidity, air is cooled below its dew point and then reheated, often electrically, which pays twice for the same air.
- Monsoon peaks. In humid months the reheat load rises sharply just as chillers work hardest.
- Condenser heat wasted. Chiller condenser heat goes to the cooling tower at 32 to 37 °C while reheat is bought as electricity.
- Electric heating is expensive heat. Resistance heaters turn one kWh of electricity into one kWh of heat, at the full commercial tariff. A heat pump moves two to four kWh of heat for the same unit.
- Large connected load. Heater banks take a big share of the sanctioned load and push up maximum-demand charges.
02Use case
The reference plant has graded cleanroom suites for oral solids and injectables served by six AHUs moving about 60,000 m³/h. Air is overcooled to remove moisture and reheated to hold 21 °C and 45% RH around the clock.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| AHU reheat after cooling coil | Air 12 → 18 °C | 60,000 m³/h × 1.2 kg/m³ × 1.005 kJ/kg·K × 6 K = 120.6 kW × 24 h × 0.4 load factor | 1,158 |
| Zone terminal reheat | Air +2 to 4 K | 12 zones × 2 kW × 20 h × 0.5 load factor | 240 |
| Storage and pipework standing losses | – | about 5% | 70 |
| Total useful heat | 1,468 | ||
Averaged over 20 running hours, the heat pumps need about 73 kW.
03P&ID
Tags: HP heat pump, TK tank, SG steam generator, P pump, PHE plate heat exchanger, TCV temperature control valve, TIC temperature indicating controller (panel), TT temperature transmitter, MT moisture transmitter, PT pressure transmitter, LT level transmitter, FS flow switch, NC normally closed. Process fluids are heated through their own exchanger, coil or jacket.
04Solution
System description
- 1 × SE-WW-80V (80 kW) (SE-WW water-source heat pump) delivering 50 °C, covering the day's 1,468 kWh in about 18.3 running hours.
- A 2,500 L insulated storage tank decouples the heat pumps from the process peaks.
- Heat source: chiller condenser water at about 35 °C. Taking heat from the condenser water lowers the condensing temperature, so the chillers use less power.
- The electric duct reheaters stays connected behind a normally closed valve as standby.
- A water-source heat pump takes heat from the chiller condenser water at about 35 °C and makes reheat water at 45–50 °C.
- Electric reheaters in each AHU are replaced or backed up by hot-water reheat coils.
- Zone terminal reheaters are fed from the same loop for fine room temperature control.
Selected equipment
| Model | SE-WW-80V × 1 |
|---|---|
| Heating capacity | 80 kW each, 80 kW total |
| COP | 5.0 at the data sheet's rated condition (55 °C outlet) |
| Power input | about 16.0 kW total at rated conditions |
| Rating | hot and chilled water at the same time, to 60 °C |
| Supply temperature | 50 °C |
| Storage | 2,500 L insulated tank |
Ratings from the Sunniva TDS 2026 data sheets.
Control philosophy
TT-101 holds the reheat water tank between 45 and 50 °C. TIC-201 on each AHU modulates the reheat coil to hold supply air temperature after the cooling coil sets the dew point, and TIC-202 trims each zone. Electric reheaters remain as standby and stage on only if the reheat loop falls short.
05Energy saving and ROI
Change any input to match a customer's site. Defaults are typical Indian prices for October 2026. The installed cost is a placeholder; replace it with the actual quotation.
| Existing | Heat pump | |
|---|---|---|
| Daily consumption | – | – |
| Annual energy cost | – | – |
| CO₂ per year | – | – |
06Benefits
Reheat from waste heat
Condenser heat that went to the tower now does the reheat.
Chillers run cooler
Lower condenser water temperature improves chiller efficiency.
Smooth humidity control
Modulating hot-water coils hold room conditions more steadily than staged electric heaters.
Lower energy cost
Each kWh of electricity delivers about 5.0 kWh of heat at the required temperature, against well under one kWh of useful heat per kWh of fuel burnt.
Smaller electrical load
The heat pump draws roughly 1/5.0 of the power of the heaters it replaces, which frees sanctioned load and cuts demand charges.
Solar-ready
Running hours can be placed in daylight so rooftop solar supplies much of the electricity, which also cuts CO₂ further.
07Engineering pointers
Site data to collect
- AHU airflows, off-coil and supply temperatures
- Room temperature and humidity specifications
- Electric reheater ratings and logged consumption
- Chiller capacity and condenser water temperatures
- Operating hours of each AHU
- Present fuel or electricity use and monthly bill
- Sanctioned electrical load and spare capacity
- Space for the heat pumps and storage, with service access
Design notes
- GMP change control. AHU reheat is part of the qualified HVAC system. Plan requalification of temperature and humidity after the change.
- Condenser water quality. Open cooling tower water fouls exchangers. Use a cleanable plate exchanger between the tower loop and the heat pump.
- Desiccant wheels. Low-humidity rooms with desiccant wheels need hotter reactivation air. Treat them as a separate duty.
- Electrical. About 16 kW of heat pump input at rated conditions, plus pumps and fans. Check spare sanctioned load before ordering.
- Source stream. The source must give up roughly two-thirds of the heat delivered. Confirm its flow and temperature over a full production day, and filter it before the evaporator.
Service and warranty
Sunniva has supplied 5,000+ heat pumps since 2012, with nine service technicians across India, including remote sites such as Leh. All components carry a one-year warranty.