Silkworm rearing rooms held at 24–28 °C
How a chawki rearing centre with 400 m² of rearing rooms can hold the warm, humid climate young silkworms need using heat pumps, and what it saves against electric room heaters.
▶Video: Space heating for buildings and farms
V13 · 2–2.5 minFloor heating, fan coils and air handlers, from homes to poultry sheds
Video coming soon01Problem statement
- Young worms are sensitive. Chawki worms need 26–28 °C. Cold rooms slow feeding and moulting and lead to uneven batches.
- Heaters dry the air. Electric heaters and charcoal braziers dry the room, while young worms need 80–90% relative humidity.
- Disease from poor control. Swings in temperature and humidity stress worms and encourage grasserie and muscardine.
- 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 centre rears young-age (chawki) silkworms for farmers covering about 1,000 acres of mulberry. It has four 100 m² rearing rooms that must stay at 26–28 °C and 80–90% relative humidity, including cool winter nights.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Rearing room heating | Rooms 26–28 °C | 600 m² envelope × 2 W/m²K × 12 K × 16 h | 230 |
| Fresh-air heating | Supply air 27 °C | 1,000 m³/h × 1.2 kg/m³ × 1.005 kJ/kgK × 12 K = 4 kW × 24 h | 96 |
| Tray and equipment disinfection washing | 60 °C | 1,000 L/day, 25 → 60 °C | 41 |
| Storage and pipework standing losses | – | about 5% | 18 |
| Total useful heat | 385 | ||
Averaged over 18 running hours, the heat pumps need about 21 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-AH-25U (25 kW) (SE-AH air-source heat pump) delivering 45 °C, covering the day's 385 kWh in about 15.4 running hours.
- A 1,000 L insulated storage tank decouples the heat pumps from the process peaks.
- The electric room heaters stays connected behind a normally closed valve as standby.
- Low-speed fan coils in each rearing room give even warmth without drafts across the rearing trays.
- A small fresh-air unit preheats ventilation air so worms get fresh air without a temperature drop.
- Humidity is topped up with a separate humidifier, controlled from the same room sensors.
- Hot water from the tank also supports washing of trays and equipment between batches.
Selected equipment
| Model | SE-AH-25U × 1 |
|---|---|
| Heating capacity | 25 kW each, 25 kW total |
| COP | 4.2 at A20 °C / W50 °C (data sheet T1) |
| Power input | about 6.0 kW total at rated conditions |
| Rating | rated 55 °C, 60 °C maximum, R410A |
| Supply temperature | 45 °C |
| Storage | 1,000 L insulated tank |
Ratings from the Sunniva TDS 2026 data sheets.
Control philosophy
TT-101 at the top of the tank starts the heat pumps below 40 °C and stops them at 45 °C. TIC-201 in each room holds 27 °C by modulating the fan coil valve, and a humidity sensor drives the humidifier to 85%. The existing electric heaters stay as standby.
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
Uniform batches
Steady temperature and humidity give even feeding and moulting across the batch.
No smoke in rearing rooms
No charcoal or kerosene heaters, which can harm worms and workers.
Lower power bill
Heat pumps use about a third of the electricity of resistance heaters for the same warmth.
Lower energy cost
Each kWh of electricity delivers about 4.2 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 1/4.2 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
- Room sizes, construction and insulation
- Rearing calendar and target temperature and humidity by instar
- Lowest winter temperatures at site
- Current heater ratings and hours
- Ventilation arrangement
- 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
- Air movement. Keep air speed over trays low. Use fan coils on low speed and direct air away from the trays.
- Disinfection. Rooms are disinfected with chlorine or formalin between batches. Protect fan coils and controls and switch them off during fumigation.
- Insulation. Seal and insulate rooms first. Poorly sealed rooms make humidity hard to hold.
- Electrical. About 6 kW of heat pump input at rated conditions, plus pumps and fans. Check spare sanctioned load before ordering.
- Winter output. Air-source output falls in cold weather: about two-thirds of rated capacity at 5 °C ambient. Size on the coldest design day for northern sites.
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
Silkworm rearing rooms held at 24–28 °C
How a chawki rearing centre with 400 m² of rearing rooms can hold the warm, humid climate young silkworms need using heat pumps, and what it saves against electric room heaters.
▶Video: Space heating for buildings and farms
V13 · 2–2.5 minFloor heating, fan coils and air handlers, from homes to poultry sheds
Video coming soon01Problem statement
- Young worms are sensitive. Chawki worms need 26–28 °C. Cold rooms slow feeding and moulting and lead to uneven batches.
- Heaters dry the air. Electric heaters and charcoal braziers dry the room, while young worms need 80–90% relative humidity.
- Disease from poor control. Swings in temperature and humidity stress worms and encourage grasserie and muscardine.
- 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 centre rears young-age (chawki) silkworms for farmers covering about 1,000 acres of mulberry. It has four 100 m² rearing rooms that must stay at 26–28 °C and 80–90% relative humidity, including cool winter nights.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Rearing room heating | Rooms 26–28 °C | 600 m² envelope × 2 W/m²K × 12 K × 16 h | 230 |
| Fresh-air heating | Supply air 27 °C | 1,000 m³/h × 1.2 kg/m³ × 1.005 kJ/kgK × 12 K = 4 kW × 24 h | 96 |
| Tray and equipment disinfection washing | 60 °C | 1,000 L/day, 25 → 60 °C | 41 |
| Storage and pipework standing losses | – | about 5% | 18 |
| Total useful heat | 385 | ||
Averaged over 18 running hours, the heat pumps need about 21 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-AH-25U (25 kW) (SE-AH air-source heat pump) delivering 45 °C, covering the day's 385 kWh in about 15.4 running hours.
- A 1,000 L insulated storage tank decouples the heat pumps from the process peaks.
- The electric room heaters stays connected behind a normally closed valve as standby.
- Low-speed fan coils in each rearing room give even warmth without drafts across the rearing trays.
- A small fresh-air unit preheats ventilation air so worms get fresh air without a temperature drop.
- Humidity is topped up with a separate humidifier, controlled from the same room sensors.
- Hot water from the tank also supports washing of trays and equipment between batches.
Selected equipment
| Model | SE-AH-25U × 1 |
|---|---|
| Heating capacity | 25 kW each, 25 kW total |
| COP | 4.2 at A20 °C / W50 °C (data sheet T1) |
| Power input | about 6.0 kW total at rated conditions |
| Rating | rated 55 °C, 60 °C maximum, R410A |
| Supply temperature | 45 °C |
| Storage | 1,000 L insulated tank |
Ratings from the Sunniva TDS 2026 data sheets.
Control philosophy
TT-101 at the top of the tank starts the heat pumps below 40 °C and stops them at 45 °C. TIC-201 in each room holds 27 °C by modulating the fan coil valve, and a humidity sensor drives the humidifier to 85%. The existing electric heaters stay as standby.
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
Uniform batches
Steady temperature and humidity give even feeding and moulting across the batch.
No smoke in rearing rooms
No charcoal or kerosene heaters, which can harm worms and workers.
Lower power bill
Heat pumps use about a third of the electricity of resistance heaters for the same warmth.
Lower energy cost
Each kWh of electricity delivers about 4.2 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 1/4.2 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
- Room sizes, construction and insulation
- Rearing calendar and target temperature and humidity by instar
- Lowest winter temperatures at site
- Current heater ratings and hours
- Ventilation arrangement
- 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
- Air movement. Keep air speed over trays low. Use fan coils on low speed and direct air away from the trays.
- Disinfection. Rooms are disinfected with chlorine or formalin between batches. Protect fan coils and controls and switch them off during fumigation.
- Insulation. Seal and insulate rooms first. Poorly sealed rooms make humidity hard to hold.
- Electrical. About 6 kW of heat pump input at rated conditions, plus pumps and fans. Check spare sanctioned load before ordering.
- Winter output. Air-source output falls in cold weather: about two-thirds of rated capacity at 5 °C ambient. Size on the coldest design day for northern sites.
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.