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  - The ideal choice for heat pumps - space heating and hot water

The Optima’s unique construction (pat.) provides optimal working conditions  for heat pumps with a diverter valve for prioritizing domestic hot water production, whilst at the same time providing a buffer vessel in the same unit. The buffer vessel functions as energy storage for space heating requirements, while the heat pump is producing domestic hot water.

The unique 2-in1 tank on tank construction provides maximum COP (Coefficient of Performance) for the heat pump of your choice up to 12 kW. The buffer vessel of 100 litres is located at the lower part of the unit, in its own temperature zone suitable for low temperature space heating such as under floor heating or fan convectors. The suitable space heating temperature in the buffer tank transfers heat upwards to the domestic hot water tank through the cylinder, thereby reducing return temperature to the heat pump and maximizing COP. Should the heat pump fail, there is full electric backup through the 9 kW immersion heaters. 

Once there is domestic hot water use, the variable valve in the heat pump switches its flow into the 1.8 m² heating coil in the upper cylinder, providing

maximum heat transfer and domestic hot water production. The 3 kW immersion heater heats the water up to 65°C.
During this time, the buffer vessel continues to provide consistent temperature to the space heating system, without compromising performance. The heating coil supports optimum heat transfer for heat pumps up to 12 kW and is made from smooth pipes to prevent limescale accumulation.

The energy efficiency of the system is unsurpassed, since the Optima minimizes heat loss (1 cylinder instead of 2), maximizes COP for the heat pump and increases domestic hot water production.

Key advantages:

  • All in one solution with minimum heat loss and considerable space saving.
  • Maximizes COP for heat pumps up to 12 kW, and significantly improves working conditions.
  • Higher domestic hot water production than other solutions and electric backup.
  • OSO ECO Foam insulation and 25 year guarantee.
Solarcyl Twin Coil RI TC
PowerCyl RI F1
Technical Specifications
Quick Facts
Choose volume

Optima EPC is available in 1 volume, suitable for the number of people in the table.



Prod. nr. Product description Capacity Hot water - 40°C Heat-up (best) - 15°C - max. Recovery (best) - after 75% ERP Rating Heat loss - 24 hours/W Dia x H mm.
EPC360 Optima - 3+9 kW/1/3x240V + coil 1,8m² 3-4 pers. 332 ltr. Heat Source Heat Source C 1.7 - 1.3 kWh/ 71 - 54W ø580x1900
Product Data Sheet
  - click to expand   - click to collapse
Direct Electric Unit Type      
Product Optima EPCI 360      
Produkt No. OSO no. 1 324 740      
Product Capacity Persons 3-4      
Product Segment   Domestic      
Product Cost Estimate - Rating - £/££/£££ OSO Standard £££      
Weight - Net kg 89      
Height - Max mm. 1900      
Diameter mm. 580      
Volume - Actual ltr. 260+100      
Usable hot water draw off at 40°C (ltr) ltr. 332      
Heat Up - 1 element - 15°C - max Temp. minutes 125      
Heat Up - 2 elements - 15°C - max Temp. minutes -      
Heat Up - Coil(s) - 15°C - max Temp. minutes Heat Source      
Recovery - 1 elements after 75% draw off minutes 94      
Recovery - 2 elements after 75% draw off minutes -      
Recovery - Coil(s) - 15°C - max Temp. minutes Heat Source      
Standing Heat Loss - 24 hours kWh/24 hours 2,48      
Standing Heat Loss - Watts Watts 71/54      
ERP Rating C/C      
Expansion Solution   External      
Dimensions - Cardboard Box LxWxH mm. 585x585x1900      
Volume - Cardboard Box 0,65      
Inner Cylinder Stainless Steel AISI 444 (DIN WN 1.4521)      
Coil(s) Stainless Steel AISI 444 (DIN WN 1.4521)      
Electric Element(s) Stainless Steel Incoloy 825      
Electric Box and Lid(s) Plastic V0 Plastic      
Insulation PUR ECO Foam      
Outer Casing Steel Epoxy Coated      
Energy Source
Type - Primary   Heat Pump      
Type - Secondary   -      
Temperature - Primary / Lower   Low Temp.      
Temperature - Secundary / Upper   -      
Heating Coil(s)
Surface area - Primary / Lower 1,80      
Surface area - Secondary / Upper -      
Dedicated Volume ltr. 100      
Recommended Flow Rate ltr./min. Heat Pump      
Immersion Heater - Capacity kW 3+(9)      
Immersion Heater - Phase Phase 1/(3)      
Immersion Heater - Voltage Volt 240/(400)      
Thermostat Type   Surface      
Upper Working Thermostat - Temp. Range °C 40-70      
Upper Working Thermostat - Set Temp. °C 60      
Lower Working Thermostat - Temp. Range °C 30-60      
Lower Working Thermostat - Set Temp. °C 35      
Electrical Installation   IEEE regs      
IP Classification   IP 24      
Cold Feed / Balanced Cold / Hot Water Compression 22mm      
Pressure Reducing Valve " (inches) 3/4 - Female      
Safety Valve " (inches) 3/4 - Male      
P&T Valve (factory fitted) " (inches) 1/2 - Male      
Drain Valve " (inches) 3/4 - Female      
Secondary Return   Use T-piece      
Immersion Heater(s) (factory fitted) " (inches) 5/4 - Male      
Expansion Vessel   External      
Primary Flow / Return " (inches) 3/4 - Female      
Secondary Flow / Return " (inches) -      
Sensor Connection " (inches) 1/2 - Female      
Safety Valve - Opening Pressure +/- 5 % Bar 8      
P&T Valve - Opening Pressure/Temp. Bar/°C 10/90      
Safety Thermostat - Cut-out Temp. °C 85      
Inner Cylinder - Design Pressure /Temp. Bar/°C 10/99      
Coil(s) - Design Pressure Bar 50      
Certifications / Approvals
Product Certifications Certificates CE / KIWA / WRAS
Manufacturing Plant Approvals Standards ISO 9001:2008 / ISO 14001:2008 / OHSAS 18001
Environmental Declaration 100 % Recyclable / >60 % Recycled Materials / Ozone Depletion Potential of 0 / Global Warming Potential of 1
Warranty - Water Quality EN 98/83EC
Water - Chloride Content Max - Cl ppm 250      
Water - Sulphate Content Max - So4 ppm 250      
Water - Chloride/Sulphate Content Max ppm 250      
Warranty Period - Inner Cylinder / Parts Years 25 / 2