Electroplating baths heated without electric immersion heaters
How a job plating shop handling 6 tonnes of parts a day can heat its nickel, chrome and hot rinse tanks with heat pumps, and what it saves against electric immersion heaters.
▶Video: Process heat for engineering and utilities
V06 · 2–2.5 minPlating, phosphating, washers, curing and boiler feedwater
Video coming soon01Problem statement
- Heaters sit in the chemistry. Electric immersion heaters fail often in nickel and chrome baths. Sheaths corrode, elements burn out when the level drops, and every failure stops the line while the bath cools.
- Morning reheat drives the bill. Baths cool overnight and are brought back to temperature at the start of the shift, which pushes the connected load and the maximum demand charge up.
- Open tanks lose heat all day. Agitated baths at 55–60 °C lose heat steadily through the surface and the fume extraction, so the heaters cycle the whole shift.
- 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 plant is a job plating shop for automotive and hardware parts. It runs bright nickel, decorative chrome and zinc lines over two shifts, about 16 hours a day, and plates around 6 tonnes of parts daily.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Nickel bath reheat after night cool-down | 40 → 55 °C | 6,000 L bath, 15 K reheat each morning | 104 |
| Chrome bath reheat | 38 → 50 °C | 4,000 L bath, 12 K reheat each morning | 56 |
| Surface and extraction losses, all heated baths | 50–60 °C | 12 m² bath surface × 0.8 kW/m² × 16 h | 154 |
| Hot rinse make-up | 30 → 60 °C | 8,000 L/day fresh water, 30 → 60 °C | 279 |
| Storage and pipework standing losses | – | about 5% | 30 |
| Total useful heat | 622 | ||
Averaged over 18 running hours, the heat pumps need about 35 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 75 °C, covering the day's 622 kWh in about 12.4 running hours.
- A 1,500 L insulated storage tank decouples the heat pumps from the process peaks.
- The electric immersion heaters stays connected behind a normally closed valve as standby.
- Each bath gets a PTFE or titanium immersed coil fed from the hot-water loop, so no electric element sits in the plating solution.
- The storage tank is charged before the shift starts and covers the morning reheat without a spike in electrical demand.
- The existing immersion heaters stay in place, switched off, as standby for each bath.
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 | 75 °C |
| Storage | 1,500 L insulated tank |
Ratings from the Sunniva TDS 2026 data sheets.
Control philosophy
TT-101 at the tank top starts the heat pumps below 70 °C and stops them at 75 °C. TIC-201 and TIC-202 hold the nickel and chrome baths within ±1 K by modulating their coil valves. TIC-203 holds the hot rinse at 60 °C. If a bath falls 3 K below set point the PLC raises an alarm and the operator can enable that bath's immersion heater.
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 parts plated | – | – |
| CO₂ per year | – | – |
06Benefits
Fewer heater failures
Coils fed with 75 °C water run at a low surface temperature and avoid the burn-out and sheath corrosion seen with electric elements.
Lower maximum demand
The morning reheat comes from stored hot water, so the plant's contract demand can often be reduced.
Steadier bath temperature
A low-temperature coil gives gentle, even heating, which helps deposit brightness and thickness consistency.
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
- Bath volumes, chemistry and set temperatures
- Bath surface areas and agitation method
- Overnight cool-down temperatures
- Rinse water flow rates
- Rectifier ratings and plating current
- 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
- Coil material. Use PTFE or titanium coils in nickel and chrome baths, and keep coils clear of anode baskets and the cathode rail.
- Chrome baths can self-heat. Hard chrome at high current density may need cooling during plating. Check the rectifier load before sizing heat for the chrome tank.
- Leak detection. Fit a conductivity check on the hot-water return so a coil leak into the bath is picked up early.
- 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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Electroplating baths heated without electric immersion heaters
How a job plating shop handling 6 tonnes of parts a day can heat its nickel, chrome and hot rinse tanks with heat pumps, and what it saves against electric immersion heaters.
▶Video: Process heat for engineering and utilities
V06 · 2–2.5 minPlating, phosphating, washers, curing and boiler feedwater
Video coming soon01Problem statement
- Heaters sit in the chemistry. Electric immersion heaters fail often in nickel and chrome baths. Sheaths corrode, elements burn out when the level drops, and every failure stops the line while the bath cools.
- Morning reheat drives the bill. Baths cool overnight and are brought back to temperature at the start of the shift, which pushes the connected load and the maximum demand charge up.
- Open tanks lose heat all day. Agitated baths at 55–60 °C lose heat steadily through the surface and the fume extraction, so the heaters cycle the whole shift.
- 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 plant is a job plating shop for automotive and hardware parts. It runs bright nickel, decorative chrome and zinc lines over two shifts, about 16 hours a day, and plates around 6 tonnes of parts daily.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Nickel bath reheat after night cool-down | 40 → 55 °C | 6,000 L bath, 15 K reheat each morning | 104 |
| Chrome bath reheat | 38 → 50 °C | 4,000 L bath, 12 K reheat each morning | 56 |
| Surface and extraction losses, all heated baths | 50–60 °C | 12 m² bath surface × 0.8 kW/m² × 16 h | 154 |
| Hot rinse make-up | 30 → 60 °C | 8,000 L/day fresh water, 30 → 60 °C | 279 |
| Storage and pipework standing losses | – | about 5% | 30 |
| Total useful heat | 622 | ||
Averaged over 18 running hours, the heat pumps need about 35 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 75 °C, covering the day's 622 kWh in about 12.4 running hours.
- A 1,500 L insulated storage tank decouples the heat pumps from the process peaks.
- The electric immersion heaters stays connected behind a normally closed valve as standby.
- Each bath gets a PTFE or titanium immersed coil fed from the hot-water loop, so no electric element sits in the plating solution.
- The storage tank is charged before the shift starts and covers the morning reheat without a spike in electrical demand.
- The existing immersion heaters stay in place, switched off, as standby for each bath.
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 | 75 °C |
| Storage | 1,500 L insulated tank |
Ratings from the Sunniva TDS 2026 data sheets.
Control philosophy
TT-101 at the tank top starts the heat pumps below 70 °C and stops them at 75 °C. TIC-201 and TIC-202 hold the nickel and chrome baths within ±1 K by modulating their coil valves. TIC-203 holds the hot rinse at 60 °C. If a bath falls 3 K below set point the PLC raises an alarm and the operator can enable that bath's immersion heater.
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 parts plated | – | – |
| CO₂ per year | – | – |
06Benefits
Fewer heater failures
Coils fed with 75 °C water run at a low surface temperature and avoid the burn-out and sheath corrosion seen with electric elements.
Lower maximum demand
The morning reheat comes from stored hot water, so the plant's contract demand can often be reduced.
Steadier bath temperature
A low-temperature coil gives gentle, even heating, which helps deposit brightness and thickness consistency.
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
- Bath volumes, chemistry and set temperatures
- Bath surface areas and agitation method
- Overnight cool-down temperatures
- Rinse water flow rates
- Rectifier ratings and plating current
- 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
- Coil material. Use PTFE or titanium coils in nickel and chrome baths, and keep coils clear of anode baskets and the cathode rail.
- Chrome baths can self-heat. Hard chrome at high current density may need cooling during plating. Check the rectifier load before sizing heat for the chrome tank.
- Leak detection. Fit a conductivity check on the hot-water return so a coil leak into the bath is picked up early.
- 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.