Dairy farm hot water from milk cooling heat
How a 600-cow dairy farm producing 6,000 litres of milk a day can recover heat from milk precooling to make 75–80 °C washing water, and what it saves against electric water heaters.
▶Video: Heating and cooling from one machine
V11 · 2–2.5 minWater-source heat pumps that chill and heat at the same time
Video coming soon01Problem statement
- Milk must cool fast. Milk leaves the cow at about 35 °C and must reach 4 °C within a few hours to keep bacteria counts low.
- Hot water for every milking. Milking system cleaning needs 70–75 °C water three times a day. Electric heaters work hard at the same time as the milk chiller.
- Two energy bills for one job. The farm pays to remove heat from the milk and pays again to heat washing water.
- 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 farm milks 600 cows three times a day in a parlour, producing about 6,000 litres a day. Milk passes a plate precooler before the bulk milk chiller, and the farm washes the milking system, bulk tanks and parlour with hot water after each milking.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Milking system CIP | 25 → 75 °C | 3 cleans × 600 L, 25 → 75 °C | 104 |
| Bulk tank washing | 25 → 70 °C | 2 washes × 500 L, 25 → 70 °C | 52 |
| Parlour, udder and floor washing | 25 → 45 °C | 4,000 L/day, 25 → 45 °C | 93 |
| Calf milk replacer | 25 → 40 °C | 800 L/day, 25 → 40 °C | 14 |
| Storage and pipework standing losses | – | about 5% | 13 |
| Total useful heat | 277 | ||
Averaged over 10 running hours, the heat pumps need about 28 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
- A Customized water-source cascade machine of about 30 kW, two-stage water-source machine built to duty, lifting 30 °C to 80 °C.
- A 1,000 L insulated storage tank decouples the heat pumps from the process peaks.
- Heat source: milk precooler water outlet at about 30 °C. Colder precooler water lowers milk temperature before the bulk chiller, cutting its power use.
- The electric water heaters stays connected behind a normally closed valve as standby.
- Water leaving the milk plate precooler at about 30 °C passes through the heat pump evaporator and returns at 15–18 °C to the precooler.
- Colder precooler water brings milk into the bulk tank at a lower temperature, so the bulk milk chiller runs less.
- The heat pump condenser makes 75–80 °C water into an insulated tank sized for one full milking-system clean.
- Parlour and calf feeding water is mixed down from the same tank with a thermostatic valve.
Selected equipment
| Machine | Customized water-source cascade |
|---|---|
| Capacity | about 30 kW, built to duty |
| Concept | two-stage water-source machine built to duty, lifting 30 °C to 80 °C |
| COP used | 2.6 (estimate) |
| Supply temperature | 80 °C |
| Storage | 1,000 L insulated tank |
Capacity is sized from the heat demand above. COP is an estimate until Sunniva engineering confirms the design.
Control philosophy
TT-101 at the top of the tank starts the heat pump below 74 °C and stops it at 80 °C. A flow switch on the precooler loop allows heat recovery only while milk is flowing, and TT-102 at the tank bottom brings the heat pump on early before each clean. 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 | – | – |
| Cost per 1,000 L milk | – | – |
| CO₂ per year | – | – |
06Benefits
Hot water ready after every milking
The tank refills with heat taken from the milk during the same milking.
Smaller chiller load
Milk enters the bulk tank colder, which shortens chiller running time and reduces peak electrical demand.
Better milk quality
Faster cooling helps keep bacteria counts within buyer limits.
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.
Smaller electrical load
The heat pump draws roughly 1/2.6 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
- Milk volume per milking and number of milkings
- Precooler type and water flow
- CIP and bulk tank washing volumes and temperatures
- Existing water heater ratings
- Water hardness
- 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
- Milk hygiene. The heat pump works only on the precooler water loop and never touches milk. Keep the precooler water potable.
- CIP temperature. Milking system detergents need about 70 °C at the end of the wash. Insulate CIP lines and check the return temperature.
- Hard water. Farm borewell water is often hard. Soften water feeding the 75–80 °C tank to limit scaling.
- 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.
- 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.
- Performance figure. The COP on this page is an engineering estimate, not a data sheet value. Sunniva engineering will confirm it for the actual source and supply temperatures.
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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Dairy farm hot water from milk cooling heat
How a 600-cow dairy farm producing 6,000 litres of milk a day can recover heat from milk precooling to make 75–80 °C washing water, and what it saves against electric water heaters.
▶Video: Heating and cooling from one machine
V11 · 2–2.5 minWater-source heat pumps that chill and heat at the same time
Video coming soon01Problem statement
- Milk must cool fast. Milk leaves the cow at about 35 °C and must reach 4 °C within a few hours to keep bacteria counts low.
- Hot water for every milking. Milking system cleaning needs 70–75 °C water three times a day. Electric heaters work hard at the same time as the milk chiller.
- Two energy bills for one job. The farm pays to remove heat from the milk and pays again to heat washing water.
- 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 farm milks 600 cows three times a day in a parlour, producing about 6,000 litres a day. Milk passes a plate precooler before the bulk milk chiller, and the farm washes the milking system, bulk tanks and parlour with hot water after each milking.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Milking system CIP | 25 → 75 °C | 3 cleans × 600 L, 25 → 75 °C | 104 |
| Bulk tank washing | 25 → 70 °C | 2 washes × 500 L, 25 → 70 °C | 52 |
| Parlour, udder and floor washing | 25 → 45 °C | 4,000 L/day, 25 → 45 °C | 93 |
| Calf milk replacer | 25 → 40 °C | 800 L/day, 25 → 40 °C | 14 |
| Storage and pipework standing losses | – | about 5% | 13 |
| Total useful heat | 277 | ||
Averaged over 10 running hours, the heat pumps need about 28 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
- A Customized water-source cascade machine of about 30 kW, two-stage water-source machine built to duty, lifting 30 °C to 80 °C.
- A 1,000 L insulated storage tank decouples the heat pumps from the process peaks.
- Heat source: milk precooler water outlet at about 30 °C. Colder precooler water lowers milk temperature before the bulk chiller, cutting its power use.
- The electric water heaters stays connected behind a normally closed valve as standby.
- Water leaving the milk plate precooler at about 30 °C passes through the heat pump evaporator and returns at 15–18 °C to the precooler.
- Colder precooler water brings milk into the bulk tank at a lower temperature, so the bulk milk chiller runs less.
- The heat pump condenser makes 75–80 °C water into an insulated tank sized for one full milking-system clean.
- Parlour and calf feeding water is mixed down from the same tank with a thermostatic valve.
Selected equipment
| Machine | Customized water-source cascade |
|---|---|
| Capacity | about 30 kW, built to duty |
| Concept | two-stage water-source machine built to duty, lifting 30 °C to 80 °C |
| COP used | 2.6 (estimate) |
| Supply temperature | 80 °C |
| Storage | 1,000 L insulated tank |
Capacity is sized from the heat demand above. COP is an estimate until Sunniva engineering confirms the design.
Control philosophy
TT-101 at the top of the tank starts the heat pump below 74 °C and stops it at 80 °C. A flow switch on the precooler loop allows heat recovery only while milk is flowing, and TT-102 at the tank bottom brings the heat pump on early before each clean. 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 | – | – |
| Cost per 1,000 L milk | – | – |
| CO₂ per year | – | – |
06Benefits
Hot water ready after every milking
The tank refills with heat taken from the milk during the same milking.
Smaller chiller load
Milk enters the bulk tank colder, which shortens chiller running time and reduces peak electrical demand.
Better milk quality
Faster cooling helps keep bacteria counts within buyer limits.
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.
Smaller electrical load
The heat pump draws roughly 1/2.6 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
- Milk volume per milking and number of milkings
- Precooler type and water flow
- CIP and bulk tank washing volumes and temperatures
- Existing water heater ratings
- Water hardness
- 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
- Milk hygiene. The heat pump works only on the precooler water loop and never touches milk. Keep the precooler water potable.
- CIP temperature. Milking system detergents need about 70 °C at the end of the wash. Insulate CIP lines and check the return temperature.
- Hard water. Farm borewell water is often hard. Soften water feeding the 75–80 °C tank to limit scaling.
- 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.
- 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.
- Performance figure. The COP on this page is an engineering estimate, not a data sheet value. Sunniva engineering will confirm it for the actual source and supply temperatures.
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.