Data centre heat reused for campus hot water
How a 5 MW data centre on a technology campus can upgrade its cooling-water return to 75 °C hot water for kitchens, hostels and laundry, and what it saves against LPG-fired water heaters.
▶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
- All the IT power becomes heat. Every kilowatt of IT load ends up as heat that chillers and cooling towers reject to air.
- Campus burns LPG for hot water. On the same campus, kitchens, hostels and laundry heat water with LPG or electric heaters.
- Return water is too cool to use directly. Return water at 30–40 °C cannot serve showers, kitchens or laundry without a temperature lift.
- Losses between fuel and process. Burning LPG 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 site is a 5 MW IT load data centre on a technology campus with a staff hostel, cafeteria and laundry. The data centre runs every day of the year, and its liquid-cooled racks return water at about 35 °C.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Cafeteria and kitchen hot water | 28 → 65 °C | 8,000 L/day, 28 → 65 °C | 344 |
| Hostel and guest-house showers | 28 → 55 °C | 15,000 L/day, 28 → 55 °C | 470 |
| Campus laundry | 28 → 70 °C | 6,000 L/day, 28 → 70 °C | 293 |
| Storage and pipework standing losses | – | about 5% | 55 |
| Total useful heat | 1,162 | ||
Averaged over 20 running hours, the heat pumps need about 58 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 60 kW, two-stage water-source machine built to duty, lifting 35 °C to 75 °C.
- A 2,000 L insulated storage tank decouples the heat pumps from the process peaks.
- Heat source: data-centre chilled/liquid-cooling return water at about 35 °C. Every kWh the heat pump takes from the return water is a kWh the chillers and cooling towers do not have to reject.
- The LPG-fired water heaters stays connected behind a normally closed valve as standby.
- A side-stream from the cooling-water return passes through an isolating PHE to the heat pump evaporator, at about 35 °C.
- The heat pump lifts this to 75 °C and charges a storage tank that feeds the campus hot-water network.
- The data centre's chillers and towers stay fully sized, and the heat pump simply takes part of their load when hot water is needed.
Selected equipment
| Machine | Customized water-source cascade |
|---|---|
| Capacity | about 60 kW, built to duty |
| Concept | two-stage water-source machine built to duty, lifting 35 °C to 75 °C |
| COP used | 3.1 (estimate) |
| Supply temperature | 75 °C |
| Storage | 2,000 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 tank top starts the heat pump below 70 °C and stops it at 75 °C. The source side draws only a set flow from the return header, so data-centre cooling is never starved. Mixing valves on HW-201 and HW-202 deliver safe outlet temperatures, and TIC-203 holds the laundry exchanger. The LPG heaters remain 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
Year-round heat source
Data-centre load runs every day, so heat is available whenever the campus needs hot water.
High COP
A 35 °C source gives a far better COP than an air-source unit in summer or winter.
Less chiller work
Heat taken by the heat pump reduces what the chillers and towers must reject.
Lower energy cost
Each kWh of electricity delivers about 3.1 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
- IT load and cooling-water return temperature
- Distance from data centre to hot-water users
- Daily hot-water volumes by user
- Monthly LPG use for water heating
- 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
- Isolate the IT cooling loop. Always use an isolating PHE. The data-centre loop must not see any pressure or contamination from the heat pump side.
- Legionella. Store hot water at 60 °C or above and run a weekly thermal cycle on the shower and kitchen network.
- 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.
Talk to us
Data centre heat reused for campus hot water
How a 5 MW data centre on a technology campus can upgrade its cooling-water return to 75 °C hot water for kitchens, hostels and laundry, and what it saves against LPG-fired water heaters.
▶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
- All the IT power becomes heat. Every kilowatt of IT load ends up as heat that chillers and cooling towers reject to air.
- Campus burns LPG for hot water. On the same campus, kitchens, hostels and laundry heat water with LPG or electric heaters.
- Return water is too cool to use directly. Return water at 30–40 °C cannot serve showers, kitchens or laundry without a temperature lift.
- Losses between fuel and process. Burning LPG 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 site is a 5 MW IT load data centre on a technology campus with a staff hostel, cafeteria and laundry. The data centre runs every day of the year, and its liquid-cooled racks return water at about 35 °C.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Cafeteria and kitchen hot water | 28 → 65 °C | 8,000 L/day, 28 → 65 °C | 344 |
| Hostel and guest-house showers | 28 → 55 °C | 15,000 L/day, 28 → 55 °C | 470 |
| Campus laundry | 28 → 70 °C | 6,000 L/day, 28 → 70 °C | 293 |
| Storage and pipework standing losses | – | about 5% | 55 |
| Total useful heat | 1,162 | ||
Averaged over 20 running hours, the heat pumps need about 58 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 60 kW, two-stage water-source machine built to duty, lifting 35 °C to 75 °C.
- A 2,000 L insulated storage tank decouples the heat pumps from the process peaks.
- Heat source: data-centre chilled/liquid-cooling return water at about 35 °C. Every kWh the heat pump takes from the return water is a kWh the chillers and cooling towers do not have to reject.
- The LPG-fired water heaters stays connected behind a normally closed valve as standby.
- A side-stream from the cooling-water return passes through an isolating PHE to the heat pump evaporator, at about 35 °C.
- The heat pump lifts this to 75 °C and charges a storage tank that feeds the campus hot-water network.
- The data centre's chillers and towers stay fully sized, and the heat pump simply takes part of their load when hot water is needed.
Selected equipment
| Machine | Customized water-source cascade |
|---|---|
| Capacity | about 60 kW, built to duty |
| Concept | two-stage water-source machine built to duty, lifting 35 °C to 75 °C |
| COP used | 3.1 (estimate) |
| Supply temperature | 75 °C |
| Storage | 2,000 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 tank top starts the heat pump below 70 °C and stops it at 75 °C. The source side draws only a set flow from the return header, so data-centre cooling is never starved. Mixing valves on HW-201 and HW-202 deliver safe outlet temperatures, and TIC-203 holds the laundry exchanger. The LPG heaters remain 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
Year-round heat source
Data-centre load runs every day, so heat is available whenever the campus needs hot water.
High COP
A 35 °C source gives a far better COP than an air-source unit in summer or winter.
Less chiller work
Heat taken by the heat pump reduces what the chillers and towers must reject.
Lower energy cost
Each kWh of electricity delivers about 3.1 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
- IT load and cooling-water return temperature
- Distance from data centre to hot-water users
- Daily hot-water volumes by user
- Monthly LPG use for water heating
- 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
- Isolate the IT cooling loop. Always use an isolating PHE. The data-centre loop must not see any pressure or contamination from the heat pump side.
- Legionella. Store hot water at 60 °C or above and run a weekly thermal cycle on the shower and kitchen network.
- 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.