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Lämpöässä TV Thermal Store

All Lämpöässä tanks are designed to provide 45 litres of water per minute (an average shower requires 8 litres per minute).

A thermal store contains water which is heated by a heat pump or other means. Its role however is to store heat, rather than to deliver hot tap water – although it does this as well.

A traditional hot water tank is heated by a coil or immersion heater within it. The hot water then flows from the tank, to be replaced by cold mains water. The water has to be kept at a temperature in excess of 60°C, in order to ensure that there is no risk of Legionella developing. This is inefficient from an energy perspective a) as the water is hotter than you would want to bathe and so has to be cooled down by adding cold water and b) it takes proportionally more energy to heat water from 55 to 60°C than it does from say 50 to 55°C.

A thermal store works the opposite way around. The water within the tank is heated directly by the hot gas from the heat pump. This water is then pumped around the heating system to warm the house. The thermal store produces hot tap water by heating water within a coiled copper pipe which passes through the thermal store, thus generating domestic hot water on demand. As no hot water is stored, it is not necessary to heat it to 60°C.

Lämpöässä heat pumps employ superheat technology, which uses the compressed gas at its hottest to heat a low flow of water, which is deposited directly into the upper part of the thermal store. The remainder of the hot gas energy is extracted via a second stage to heat the lower section of the thermal store at a lower temperature.

This system allows Lämpöässä heat pumps to generate all domestic hot water without the need for an immersion heater. This is called a monovalent system and allows the heat pump to maintain a consistently high COP for both heating and hot water generation.

The coil within the thermal store can however be upgraded to provide up to 60 or even 80 litres per minute for applications where a lot of hot water is required.

Akvaterm, the leading European manufacturer of accumulator and cold water tanks, supply a wide range of thermal stores to Lämpöässä for use with their Esi, Emi and Eli heat pump systems. Designed to cover all requirements from modest homes to large stately houses, or commercial premises, the Lämpöässä range of thermal stores, coupled with the appropriate Lämpöässä ground source heat pump, can provide sufficient heat and hot water for any requirement.

Using Lämpöässä’s patented superheat technology, all of the thermal stores are capable of providing the entire hot water supply for a building, as well as heating, without the need for an electric or other backup system. This enables Lämpöässä to maintain its superb level of efficiency for all applications, thus reducing your costs and maximising your returns under the RHI.

Lämpöässä’s thermal stores are also available in a wide range of sizes and shapes to enable installation into a variety of spaces. If entry space into the building is tight, the external insulation can also be temporarily removed, reducing the space required. We are also able to specify differing hot water coil sizes allowing you to increase hot water generation from the standard of 45 litres per minute to 60, 80 or 120 litres per minute. Finn Geotherm will always be pleased to advise you of the best thermal store and coil combination to allow your Lämpöässä heat pump to best meet your requirements.


Diameter (cm)

450l capacity66.5
500l capacity81
750l capacity105
1000l capacity105
1500l capacity125
2000l capacity140
2500l capacity150
3000l capacity160
4000l capacity180
5000l capacity200

Height (cm)

450l capacity182
500l capacity155
750l capacity210
1000l capacity210
1500l capacity215
2000l capacity220
2500l capacity225
3000l capacity230
4000l capacity245
5000l capacity250

Weight (kg)

450l capacity225
500l capacity170
750l capacity235
1000l capacity250
1500l capacity300
2000l capacity350
2500l capacity380
3000l capacity420
4000l capacity500
5000l capacity620
Diameter (cm)Height (cm)Weight (kg)
450l capacity66.5182225
500l capacity81155170
750l capacity105210235
1000l capacity105210250
1500l capacity125215300
2000l capacity140220350
2500l capacity150225380
3000l capacity160230420
4000l capacity180245500
5000l capacity200250620