Mould heating and resin drying from heat pumps
How an injection moulding shop with 20 machines can supply mould temperature units and resin dryers from one heat pump hot-water loop, in place of electric heaters.
▶Video: Hot air from heat pump hot water
V05 · 2–2.5 minAir coils for spray dryers, stenters, kilns, paint booths and ovens
Video coming soon01Problem statement
- Many small electric heaters. Every mould temperature unit and hopper dryer has its own resistance heater, which adds up to a large connected load.
- Slow start-ups. Moulds and dryers heat from cold at each start or mould change, delaying good parts.
- Heat thrown out by the same machines. Hopper dryers exhaust warm air and mould units dump heat to cooling water while heaters run elsewhere.
- 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 shop runs 20 injection moulding machines on three shifts, making engineering parts in ABS, nylon and polycarbonate. Each machine has a water mould temperature unit and a hopper dryer.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Mould temperature units | 60–90 °C | 20 units × 1.5 kW average heater load × 20 h | 600 |
| Hopper dryer air | Air 30 → 85 °C | 1,200 kg/h air × 1.005 kJ/kg·K × 55 K = 18.4 kW × 20 h | 368 |
| Storage and pipework standing losses | – | about 5% | 48 |
| Total useful heat | 1,016 | ||
Averaged over 20 running hours, the heat pumps need about 51 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
- 4 × SE-SHT-16C (64 kW total) (SE-SHT cascade heat pump) delivering 95 °C, covering the day's 1,016 kWh in about 15.9 running hours.
- A 2,000 L insulated storage tank decouples the heat pumps from the process peaks.
- The electric heaters in mould temperature units and dryers stays connected behind a normally closed valve as standby.
- The heat pumps charge a storage tank at 90–95 °C that feeds a heating header along the machine line.
- Each mould temperature unit takes heat through a small exchanger, keeping its own pump, cooling and control.
- Hopper dryers get a hot-water air coil ahead of their existing heater, which then trims only for higher set-points.
Selected equipment
| Model | SE-SHT-16C × 4 |
|---|---|
| Heating capacity | 16 kW each, 64 kW total |
| COP | 2.7 at A20 °C / W90 °C (data sheet T1) |
| Power input | about 23.8 kW total at rated conditions |
| Rating | cascade R410A + R515B, rated 90 °C, 95 °C maximum |
| Supply temperature | 95 °C |
| Storage | 2,000 L insulated tank |
Ratings from the Sunniva TDS 2026 data sheets.
Control philosophy
TT-101 starts the heat pumps below 88 °C and stops them at 95 °C. Each unit's own controller (TIC-201) opens its hot-water valve before using its electric heater, and TIC-202 holds hopper air at set-point. Electric heaters remain as standby and for set-points above the loop temperature.
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 tonne of moulded parts | – | – |
| CO₂ per year | – | – |
06Benefits
Lower connected load
Most heater duty moves to the heat pumps, cutting maximum demand charges.
Faster start-up
Hot water on the header brings moulds and dryers up to temperature quickly.
Drier resin, fewer rejects
Steady dryer air temperature reduces splay and moisture defects.
Lower energy cost
Each kWh of electricity delivers about 2.7 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 1/2.7 of the power of the heaters it replaces, which frees sanctioned load and cuts demand charges.
Built-in redundancy
Several machines share the load. If one is serviced, the others and the storage carry most of the day, with the existing heater in reserve.
07Engineering pointers
Site data to collect
- Number of machines and mould temperature set-points
- Resin types, dryer throughput and air temperatures
- Heater ratings and logged power use
- Shift pattern and mould change frequency
- Space for a header along the machine line
- 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
- Water quality. Mould channels scale and block easily. Keep the heat pump loop closed and separate from mould water through exchangers.
- High-temperature resins. Some resins need dryer air hotter than the loop can give. Leave those dryers on their electric heaters.
- Desiccant regeneration. Desiccant dryers regenerate at high temperature. The heat pump coil preheats only the process air.
- Electrical. About 24 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.
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Mould heating and resin drying from heat pumps
How an injection moulding shop with 20 machines can supply mould temperature units and resin dryers from one heat pump hot-water loop, in place of electric heaters.
▶Video: Hot air from heat pump hot water
V05 · 2–2.5 minAir coils for spray dryers, stenters, kilns, paint booths and ovens
Video coming soon01Problem statement
- Many small electric heaters. Every mould temperature unit and hopper dryer has its own resistance heater, which adds up to a large connected load.
- Slow start-ups. Moulds and dryers heat from cold at each start or mould change, delaying good parts.
- Heat thrown out by the same machines. Hopper dryers exhaust warm air and mould units dump heat to cooling water while heaters run elsewhere.
- 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 shop runs 20 injection moulding machines on three shifts, making engineering parts in ABS, nylon and polycarbonate. Each machine has a water mould temperature unit and a hopper dryer.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Mould temperature units | 60–90 °C | 20 units × 1.5 kW average heater load × 20 h | 600 |
| Hopper dryer air | Air 30 → 85 °C | 1,200 kg/h air × 1.005 kJ/kg·K × 55 K = 18.4 kW × 20 h | 368 |
| Storage and pipework standing losses | – | about 5% | 48 |
| Total useful heat | 1,016 | ||
Averaged over 20 running hours, the heat pumps need about 51 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
- 4 × SE-SHT-16C (64 kW total) (SE-SHT cascade heat pump) delivering 95 °C, covering the day's 1,016 kWh in about 15.9 running hours.
- A 2,000 L insulated storage tank decouples the heat pumps from the process peaks.
- The electric heaters in mould temperature units and dryers stays connected behind a normally closed valve as standby.
- The heat pumps charge a storage tank at 90–95 °C that feeds a heating header along the machine line.
- Each mould temperature unit takes heat through a small exchanger, keeping its own pump, cooling and control.
- Hopper dryers get a hot-water air coil ahead of their existing heater, which then trims only for higher set-points.
Selected equipment
| Model | SE-SHT-16C × 4 |
|---|---|
| Heating capacity | 16 kW each, 64 kW total |
| COP | 2.7 at A20 °C / W90 °C (data sheet T1) |
| Power input | about 23.8 kW total at rated conditions |
| Rating | cascade R410A + R515B, rated 90 °C, 95 °C maximum |
| Supply temperature | 95 °C |
| Storage | 2,000 L insulated tank |
Ratings from the Sunniva TDS 2026 data sheets.
Control philosophy
TT-101 starts the heat pumps below 88 °C and stops them at 95 °C. Each unit's own controller (TIC-201) opens its hot-water valve before using its electric heater, and TIC-202 holds hopper air at set-point. Electric heaters remain as standby and for set-points above the loop temperature.
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 tonne of moulded parts | – | – |
| CO₂ per year | – | – |
06Benefits
Lower connected load
Most heater duty moves to the heat pumps, cutting maximum demand charges.
Faster start-up
Hot water on the header brings moulds and dryers up to temperature quickly.
Drier resin, fewer rejects
Steady dryer air temperature reduces splay and moisture defects.
Lower energy cost
Each kWh of electricity delivers about 2.7 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 1/2.7 of the power of the heaters it replaces, which frees sanctioned load and cuts demand charges.
Built-in redundancy
Several machines share the load. If one is serviced, the others and the storage carry most of the day, with the existing heater in reserve.
07Engineering pointers
Site data to collect
- Number of machines and mould temperature set-points
- Resin types, dryer throughput and air temperatures
- Heater ratings and logged power use
- Shift pattern and mould change frequency
- Space for a header along the machine line
- 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
- Water quality. Mould channels scale and block easily. Keep the heat pump loop closed and separate from mould water through exchangers.
- High-temperature resins. Some resins need dryer air hotter than the loop can give. Leave those dryers on their electric heaters.
- Desiccant regeneration. Desiccant dryers regenerate at high temperature. The heat pump coil preheats only the process air.
- Electrical. About 24 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.