PW and WFI loops sanitised without steam
How a pharma plant can keep its WFI loop hot and sanitise its purified-water loop at 65–85 °C with heat pumps, against a PNG-fired steam boiler.
▶Video: Heat pumps for pharma, chemicals and FMCG
V04 · 2–2.5 minJacketed reactors, hot loops, cleanroom reheat and solvent recovery
Video coming soon01Problem statement
- Steam running all night. The boiler runs at night and weekends just to keep the WFI loop hot and to sanitise PW, at very low and inefficient load.
- Reheating cooled water. Water cooled for points of use is reheated before it returns to the hot loop, so heat is added and removed many times a day.
- Sanitisation time. Slow heat-up stretches the daily sanitisation window and holds up production.
- Losses between fuel and process. Burning PNG in a boiler or heater and distributing the heat loses a quarter or more of the fuel's energy before it reaches the process.
- Compliance, safety and handling. Fired equipment brings boiler inspections, fuel storage and unloading, flue emissions and an attendant on every shift.
02Use case
The reference plant makes oral and injectable formulations. It has a 6,000 litre purified-water system sanitised daily, and a WFI storage tank and loop held hot around the clock with a cooled sub-loop for points of use.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| PW loop daily hot sanitisation | 80–82 °C | 6,000 L tank and loop, 25 → 82 °C, once a day | 397 |
| WFI loop heat losses | 80 °C | 300 m loop × 35 W/m = 10.5 kW × 24 h | 252 |
| WFI sub-loop reheat | 30 → 80 °C | 4,000 L/day returned from point-of-use coolers | 232 |
| Storage and pipework standing losses | – | about 5% | 44 |
| Total useful heat | 925 | ||
Averaged over 20 running hours, the heat pumps need about 46 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-SHT-50C (50 kW) (SE-SHT cascade heat pump) delivering 90 °C, covering the day's 925 kWh in about 18.5 running hours.
- A 1,500 L insulated storage tank decouples the heat pumps from the process peaks.
- The PNG-fired steam boiler stays connected behind a normally closed valve as standby.
- The heat pumps charge a storage tank at 90 °C, which serves sanitary double-tube-sheet exchangers on the PW and WFI loops.
- The WFI loop is held at 80 °C continuously, and the PW loop is heated to 82 °C for its daily sanitisation hold.
- The tank stores enough heat for the PW sanitisation, so the heat pumps run steadily overnight.
Selected equipment
| Model | SE-SHT-50C × 1 |
|---|---|
| Heating capacity | 50 kW each, 50 kW total |
| COP | 2.6 at A20 °C / W90 °C (data sheet T1) |
| Power input | about 18.6 kW total at rated conditions |
| Rating | cascade R410A + R515B, rated 90 °C, 95 °C maximum |
| Supply temperature | 90 °C |
| Storage | 1,500 L insulated tank |
Ratings from the Sunniva TDS 2026 data sheets.
Control philosophy
TT-101 starts the heat pumps below 85 °C and stops them at 90 °C. TIC-202 holds the WFI loop return above 80 °C at all times, and TIC-201 runs the PW sanitisation sequence from the water system PLC. If either loop falls below its limit, the PLC alarms and opens the standby steam valve.
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 | – | – |
| Cost per 1,000 L purified water | – | – |
| CO₂ per year | – | – |
06Benefits
No night-time boiler
The boiler no longer runs at low load just to keep the WFI loop hot.
Faster sanitisation
Stored hot water brings the PW loop up to temperature quickly, shortening the daily window.
Steady loop temperature
Hot water gives smoother control than steam on the loop exchangers.
Lower energy cost
Each kWh of electricity delivers about 2.6 kWh of heat at the required temperature, against well under one kWh of useful heat per kWh of fuel burnt.
No flame on site
No burner, flue or fuel tank for this duty, and no fuel deliveries to schedule.
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
- PW and WFI tank volumes and loop lengths
- Sanitisation schedule and hold temperature
- WFI loop temperature and point-of-use cooling arrangement
- Present steam use for the water system
- Exchanger type on each loop
- Present fuel or electricity use and monthly bill
- Sanctioned electrical load and spare capacity
- Space for the heat pumps and storage, with service access
- Winter minimum ambient at site
Design notes
- Sanitary exchangers. Use double-tube-sheet or double-wall exchangers with the PW or WFI side at higher pressure, so any leak goes away from the pharma water.
- Validation. Loop temperature and sanitisation records are GMP data. Keep the existing loop temperature sensors and recorders as the validated reference.
- WFI generation. WFI stills need steam at higher temperature. This note covers loop heating and sanitisation only.
- Electrical. About 19 kW of heat pump input at rated conditions, plus pumps and fans. Check spare sanctioned load before ordering.
- Winter output. The SE-SHT cascade gives about 80% of rated output at 7 °C ambient and still runs at −20 °C. Size on the coldest design day for northern sites.
- Water quality. Scale forms quickly above 60 °C. Use softened make-up and keep the heat pump loop closed, with process fluids on the far side of an exchanger or coil.
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.
Talk to us
PW and WFI loops sanitised without steam
How a pharma plant can keep its WFI loop hot and sanitise its purified-water loop at 65–85 °C with heat pumps, against a PNG-fired steam boiler.
▶Video: Heat pumps for pharma, chemicals and FMCG
V04 · 2–2.5 minJacketed reactors, hot loops, cleanroom reheat and solvent recovery
Video coming soon01Problem statement
- Steam running all night. The boiler runs at night and weekends just to keep the WFI loop hot and to sanitise PW, at very low and inefficient load.
- Reheating cooled water. Water cooled for points of use is reheated before it returns to the hot loop, so heat is added and removed many times a day.
- Sanitisation time. Slow heat-up stretches the daily sanitisation window and holds up production.
- Losses between fuel and process. Burning PNG in a boiler or heater and distributing the heat loses a quarter or more of the fuel's energy before it reaches the process.
- Compliance, safety and handling. Fired equipment brings boiler inspections, fuel storage and unloading, flue emissions and an attendant on every shift.
02Use case
The reference plant makes oral and injectable formulations. It has a 6,000 litre purified-water system sanitised daily, and a WFI storage tank and loop held hot around the clock with a cooled sub-loop for points of use.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| PW loop daily hot sanitisation | 80–82 °C | 6,000 L tank and loop, 25 → 82 °C, once a day | 397 |
| WFI loop heat losses | 80 °C | 300 m loop × 35 W/m = 10.5 kW × 24 h | 252 |
| WFI sub-loop reheat | 30 → 80 °C | 4,000 L/day returned from point-of-use coolers | 232 |
| Storage and pipework standing losses | – | about 5% | 44 |
| Total useful heat | 925 | ||
Averaged over 20 running hours, the heat pumps need about 46 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-SHT-50C (50 kW) (SE-SHT cascade heat pump) delivering 90 °C, covering the day's 925 kWh in about 18.5 running hours.
- A 1,500 L insulated storage tank decouples the heat pumps from the process peaks.
- The PNG-fired steam boiler stays connected behind a normally closed valve as standby.
- The heat pumps charge a storage tank at 90 °C, which serves sanitary double-tube-sheet exchangers on the PW and WFI loops.
- The WFI loop is held at 80 °C continuously, and the PW loop is heated to 82 °C for its daily sanitisation hold.
- The tank stores enough heat for the PW sanitisation, so the heat pumps run steadily overnight.
Selected equipment
| Model | SE-SHT-50C × 1 |
|---|---|
| Heating capacity | 50 kW each, 50 kW total |
| COP | 2.6 at A20 °C / W90 °C (data sheet T1) |
| Power input | about 18.6 kW total at rated conditions |
| Rating | cascade R410A + R515B, rated 90 °C, 95 °C maximum |
| Supply temperature | 90 °C |
| Storage | 1,500 L insulated tank |
Ratings from the Sunniva TDS 2026 data sheets.
Control philosophy
TT-101 starts the heat pumps below 85 °C and stops them at 90 °C. TIC-202 holds the WFI loop return above 80 °C at all times, and TIC-201 runs the PW sanitisation sequence from the water system PLC. If either loop falls below its limit, the PLC alarms and opens the standby steam valve.
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 | – | – |
| Cost per 1,000 L purified water | – | – |
| CO₂ per year | – | – |
06Benefits
No night-time boiler
The boiler no longer runs at low load just to keep the WFI loop hot.
Faster sanitisation
Stored hot water brings the PW loop up to temperature quickly, shortening the daily window.
Steady loop temperature
Hot water gives smoother control than steam on the loop exchangers.
Lower energy cost
Each kWh of electricity delivers about 2.6 kWh of heat at the required temperature, against well under one kWh of useful heat per kWh of fuel burnt.
No flame on site
No burner, flue or fuel tank for this duty, and no fuel deliveries to schedule.
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
- PW and WFI tank volumes and loop lengths
- Sanitisation schedule and hold temperature
- WFI loop temperature and point-of-use cooling arrangement
- Present steam use for the water system
- Exchanger type on each loop
- Present fuel or electricity use and monthly bill
- Sanctioned electrical load and spare capacity
- Space for the heat pumps and storage, with service access
- Winter minimum ambient at site
Design notes
- Sanitary exchangers. Use double-tube-sheet or double-wall exchangers with the PW or WFI side at higher pressure, so any leak goes away from the pharma water.
- Validation. Loop temperature and sanitisation records are GMP data. Keep the existing loop temperature sensors and recorders as the validated reference.
- WFI generation. WFI stills need steam at higher temperature. This note covers loop heating and sanitisation only.
- Electrical. About 19 kW of heat pump input at rated conditions, plus pumps and fans. Check spare sanctioned load before ordering.
- Winter output. The SE-SHT cascade gives about 80% of rated output at 7 °C ambient and still runs at −20 °C. Size on the coldest design day for northern sites.
- Water quality. Scale forms quickly above 60 °C. Use softened make-up and keep the heat pump loop closed, with process fluids on the far side of an exchanger or coil.
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.