Dishwasher rinse water at 82 °C without electric boosters
How a central kitchen serving 3,000 meals a day can supply dishwasher rinse, wash tank and kitchen hot water with heat pumps, and what it saves against electric booster heaters.
▶Video: Sanitary and commercial hot water
V14 · 2–2.5 minHotels, hospitals, kitchens and laundries
Video coming soon01Problem statement
- Final rinse must be hot. Sanitising rinse water must reach 82–85 °C at the plates. Electric booster heaters of 30–50 kW run whenever the machine is on.
- High electrical demand. Booster and tank heaters add a large block to the kitchen's maximum demand and power bill.
- Steam and heat in the kitchen. Hot water and wash tank heating add heat and moisture to an already hot workspace.
- 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 kitchen serves about 3,000 meals a day for a hospital, campus or industrial canteen. It runs a flight-type dishwasher for 12 hours and uses hot water for pot washing and cleaning.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Dishwasher final rinse | 25 → 85 °C | 400 L/h × 12 h, 25 → 85 °C | 334 |
| Wash tank heat losses and top-up | 60 °C held | 6 kW average × 12 h | 72 |
| Pot wash and kitchen hot water | 25 → 60 °C | 6,000 L/day, 25 → 60 °C | 244 |
| Storage and pipework standing losses | – | about 5% | 33 |
| Total useful heat | 683 | ||
Averaged over 16 running hours, the heat pumps need about 43 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 683 kWh in about 13.7 running hours.
- A 1,500 L insulated storage tank decouples the heat pumps from the process peaks.
- The electric booster and tank heaters stays connected behind a normally closed valve as standby.
- Heat pumps charge a 90 °C storage tank. A PHE heats the incoming rinse water to 82–85 °C on demand.
- A coil in the dishwasher wash tank replaces its electric element for holding 60 °C.
- Kitchen sinks and pot wash take mixed-down water from the same system.
- The existing electric booster stays in line and only tops up if rinse temperature falls.
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 at the top of the tank starts the heat pumps below 86 °C and stops them at 90 °C. TIC-201 holds rinse water at 84 °C through the PHE valve, and the electric booster switches on only below 82 °C. TIC-202 controls the wash tank coil.
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 meals | – | – |
| CO₂ per year | – | – |
06Benefits
Lower maximum demand
Booster and tank elements rarely switch on, which cuts the kitchen's peak electrical load.
Rinse temperature assured
Stored heat holds the rinse at 82–85 °C even at full machine speed.
Cooler kitchen
Indoor heat pump units can give some cooling to stores or dish rooms.
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
- Dishwasher type, rinse flow and operating hours
- Wash tank volume and heater rating
- Kitchen hot water use
- Existing electrical 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
- Winter minimum ambient at site
Design notes
- Soft water. Hard water at 85 °C scales fast. Feed rinse water and the tank through a softener.
- Food hygiene. Rinse water is heated through a PHE, so it stays potable and separate from tank water.
- Machine data. Check the dishwasher's rinse flow and required temperature at the arms before sizing.
- 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.
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Dishwasher rinse water at 82 °C without electric boosters
How a central kitchen serving 3,000 meals a day can supply dishwasher rinse, wash tank and kitchen hot water with heat pumps, and what it saves against electric booster heaters.
▶Video: Sanitary and commercial hot water
V14 · 2–2.5 minHotels, hospitals, kitchens and laundries
Video coming soon01Problem statement
- Final rinse must be hot. Sanitising rinse water must reach 82–85 °C at the plates. Electric booster heaters of 30–50 kW run whenever the machine is on.
- High electrical demand. Booster and tank heaters add a large block to the kitchen's maximum demand and power bill.
- Steam and heat in the kitchen. Hot water and wash tank heating add heat and moisture to an already hot workspace.
- 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 kitchen serves about 3,000 meals a day for a hospital, campus or industrial canteen. It runs a flight-type dishwasher for 12 hours and uses hot water for pot washing and cleaning.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Dishwasher final rinse | 25 → 85 °C | 400 L/h × 12 h, 25 → 85 °C | 334 |
| Wash tank heat losses and top-up | 60 °C held | 6 kW average × 12 h | 72 |
| Pot wash and kitchen hot water | 25 → 60 °C | 6,000 L/day, 25 → 60 °C | 244 |
| Storage and pipework standing losses | – | about 5% | 33 |
| Total useful heat | 683 | ||
Averaged over 16 running hours, the heat pumps need about 43 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 683 kWh in about 13.7 running hours.
- A 1,500 L insulated storage tank decouples the heat pumps from the process peaks.
- The electric booster and tank heaters stays connected behind a normally closed valve as standby.
- Heat pumps charge a 90 °C storage tank. A PHE heats the incoming rinse water to 82–85 °C on demand.
- A coil in the dishwasher wash tank replaces its electric element for holding 60 °C.
- Kitchen sinks and pot wash take mixed-down water from the same system.
- The existing electric booster stays in line and only tops up if rinse temperature falls.
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 at the top of the tank starts the heat pumps below 86 °C and stops them at 90 °C. TIC-201 holds rinse water at 84 °C through the PHE valve, and the electric booster switches on only below 82 °C. TIC-202 controls the wash tank coil.
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 meals | – | – |
| CO₂ per year | – | – |
06Benefits
Lower maximum demand
Booster and tank elements rarely switch on, which cuts the kitchen's peak electrical load.
Rinse temperature assured
Stored heat holds the rinse at 82–85 °C even at full machine speed.
Cooler kitchen
Indoor heat pump units can give some cooling to stores or dish rooms.
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
- Dishwasher type, rinse flow and operating hours
- Wash tank volume and heater rating
- Kitchen hot water use
- Existing electrical 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
- Winter minimum ambient at site
Design notes
- Soft water. Hard water at 85 °C scales fast. Feed rinse water and the tank through a softener.
- Food hygiene. Rinse water is heated through a PHE, so it stays potable and separate from tank water.
- Machine data. Check the dishwasher's rinse flow and required temperature at the arms before sizing.
- 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.