Malt kiln air heated by heat pumps
How a malt plant kilning 3 tonnes of malt a day can heat most of its kiln air with heat pumps, and what it saves against a furnace-oil fired air heater.
▶Video: Hot air from heat pump hot water
V05 · 2–2.5 minAir coils for spray dryers, stenters, kilns, paint booths and ovens
Video coming soon01Problem statement
- Huge air volumes. Free drying moves large volumes of air at 60–65 °C through the green malt bed for 12 hours or more. This phase uses most of the kiln's fuel.
- Burner control at low fire. Oil burners are sized for the curing peak and run at low fire for most of the cycle, which wastes fuel and risks smoke taint.
- Colour and enzyme sensitivity. Air that is too hot early in the cycle kills enzymes. Air temperature must follow the kiln programme closely.
- Losses between fuel and process. Burning furnace oil 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 plant makes about 3 tonnes of brewing and food malt a day from barley, using steeping tanks, germination boxes and a single-deck kiln on a 24-hour cycle. The kiln already has a glass-tube exhaust heat recovery unit.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Kiln free-drying phase | Air 60–65 °C | Green malt 44% → 12%: 1,870 kg water × 0.75 kWh/kg after exhaust recovery | 1,400 |
| Kiln curing phase | Air 80–95 °C | 12% → 4%: 273 kg water × 1.4 kWh/kg, plus 3 t malt × 1.6 kJ/kg·K × 60 K | 460 |
| Storage and pipework standing losses | – | about 5% | 93 |
| Total useful heat | 1,953 | ||
Averaged over 20 running hours, the heat pumps need about 98 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 SE-UHT air-source cascade, R245fa machine of about 100 kW, air-source cascade to 120 °C, sized per project.
- A 3,000 L insulated storage tank decouples the heat pumps from the process peaks.
- The furnace-oil fired kiln air heater stays connected behind a normally closed valve as standby.
- Hot water at 110 °C from the storage tank feeds finned coils in the kiln air inlet, downstream of the existing exhaust heat recovery unit.
- The heat pumps carry the whole free-drying phase and lift curing air to about 95 °C.
- The existing burner stays in place for the final cure from 95 °C to 105 °C, which is a short part of the cycle.
Selected equipment
| Machine | SE-UHT air-source cascade, R245fa |
|---|---|
| Capacity | about 100 kW, built to duty |
| Concept | air-source cascade to 120 °C, sized per project |
| COP used | 1.7 (estimate) |
| Supply temperature | 110 °C |
| Storage | 3,000 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 calls the heat pumps on below 104 °C and off at 110 °C. TT-102 at the bottom gives an early start before the curing phase. TIC-201 and TIC-202 set the coil valves to follow the kiln air temperature programme. The burner is enabled only when TIC-202 asks for air above 95 °C or the tank top falls below 100 °C.
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 malt | – | – |
| CO₂ per year | – | – |
06Benefits
No combustion in the air stream
Hot-water coils heat the air indirectly, so there is no risk of smoke or NOx taint on the malt during free drying.
Accurate kiln programme
Modulating coil valves follow the air-on temperature set points closely, which protects enzyme activity.
Most of the fuel replaced
Free drying is the largest energy use in the kiln and runs entirely on the heat pumps.
Lower energy cost
Each kWh of electricity delivers about 1.7 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
- Malt output per batch and kilning cycle
- Kiln airflow and air-on temperature programme
- Present fuel use per tonne of malt
- Exhaust heat recovery unit performance
- 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 fouling. Kiln inlet air carries dust and rootlet fragments. Fit a filter ahead of the coils and allow access for cleaning.
- Pressurised loop. Water at 110 °C must be held at about 2.5 bar. Size the expansion vessel and relief valve for this temperature.
- Fan power. New coils add pressure drop. Check the kiln fan can deliver the design airflow with the extra resistance.
- Ambient correction. Ratings are at 20 °C air. Ask Sunniva for the correction at your site's winter design temperature.
- 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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Malt kiln air heated by heat pumps
How a malt plant kilning 3 tonnes of malt a day can heat most of its kiln air with heat pumps, and what it saves against a furnace-oil fired air heater.
▶Video: Hot air from heat pump hot water
V05 · 2–2.5 minAir coils for spray dryers, stenters, kilns, paint booths and ovens
Video coming soon01Problem statement
- Huge air volumes. Free drying moves large volumes of air at 60–65 °C through the green malt bed for 12 hours or more. This phase uses most of the kiln's fuel.
- Burner control at low fire. Oil burners are sized for the curing peak and run at low fire for most of the cycle, which wastes fuel and risks smoke taint.
- Colour and enzyme sensitivity. Air that is too hot early in the cycle kills enzymes. Air temperature must follow the kiln programme closely.
- Losses between fuel and process. Burning furnace oil 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 plant makes about 3 tonnes of brewing and food malt a day from barley, using steeping tanks, germination boxes and a single-deck kiln on a 24-hour cycle. The kiln already has a glass-tube exhaust heat recovery unit.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Kiln free-drying phase | Air 60–65 °C | Green malt 44% → 12%: 1,870 kg water × 0.75 kWh/kg after exhaust recovery | 1,400 |
| Kiln curing phase | Air 80–95 °C | 12% → 4%: 273 kg water × 1.4 kWh/kg, plus 3 t malt × 1.6 kJ/kg·K × 60 K | 460 |
| Storage and pipework standing losses | – | about 5% | 93 |
| Total useful heat | 1,953 | ||
Averaged over 20 running hours, the heat pumps need about 98 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 SE-UHT air-source cascade, R245fa machine of about 100 kW, air-source cascade to 120 °C, sized per project.
- A 3,000 L insulated storage tank decouples the heat pumps from the process peaks.
- The furnace-oil fired kiln air heater stays connected behind a normally closed valve as standby.
- Hot water at 110 °C from the storage tank feeds finned coils in the kiln air inlet, downstream of the existing exhaust heat recovery unit.
- The heat pumps carry the whole free-drying phase and lift curing air to about 95 °C.
- The existing burner stays in place for the final cure from 95 °C to 105 °C, which is a short part of the cycle.
Selected equipment
| Machine | SE-UHT air-source cascade, R245fa |
|---|---|
| Capacity | about 100 kW, built to duty |
| Concept | air-source cascade to 120 °C, sized per project |
| COP used | 1.7 (estimate) |
| Supply temperature | 110 °C |
| Storage | 3,000 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 calls the heat pumps on below 104 °C and off at 110 °C. TT-102 at the bottom gives an early start before the curing phase. TIC-201 and TIC-202 set the coil valves to follow the kiln air temperature programme. The burner is enabled only when TIC-202 asks for air above 95 °C or the tank top falls below 100 °C.
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 malt | – | – |
| CO₂ per year | – | – |
06Benefits
No combustion in the air stream
Hot-water coils heat the air indirectly, so there is no risk of smoke or NOx taint on the malt during free drying.
Accurate kiln programme
Modulating coil valves follow the air-on temperature set points closely, which protects enzyme activity.
Most of the fuel replaced
Free drying is the largest energy use in the kiln and runs entirely on the heat pumps.
Lower energy cost
Each kWh of electricity delivers about 1.7 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
- Malt output per batch and kilning cycle
- Kiln airflow and air-on temperature programme
- Present fuel use per tonne of malt
- Exhaust heat recovery unit performance
- 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 fouling. Kiln inlet air carries dust and rootlet fragments. Fit a filter ahead of the coils and allow access for cleaning.
- Pressurised loop. Water at 110 °C must be held at about 2.5 bar. Size the expansion vessel and relief valve for this temperature.
- Fan power. New coils add pressure drop. Check the kiln fan can deliver the design airflow with the extra resistance.
- Ambient correction. Ratings are at 20 °C air. Ask Sunniva for the correction at your site's winter design temperature.
- 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.