GUIDE FOR CHOOSING AN ACCUMULATOR TANK

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Samuel Chase
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1 GUIDE FOR CHOOSING AN ACCUMULATOR TANK Preliminary version

2 TABLE OF CONTENTS 1 OVERVIEW OPERATING PRINCIPLE DIMENSIONS. 8 4 PRODUCT RANGE SPATIAL REQUIREMENTS TECHNICAL DRAWINGS. 13

5 1 OVERVIEW The Guide for Choosing an Accumulator tank is meant to be used as a source of information for both designers of heating systems and private customers, who are intending to acquire a hot accumulator tank. This guide introduces the operating principles of the accumulator tank and its dimensions along with the technical characteristics and spatial requirements of different models. Akvaterm Oy already has over 20 years of experience in the manufacture of hot accumulator tanks. The manufacturing process is governed by a quality system monitored and awarded by Inspecta Oy, and the pressure safety of the tank is ensured through pressure testing in accordance with the Pressure Vessel Directive. For more information on accumulator tanks please visit Akvaterms web site at AKVATERM OY Jänismaantie Kokkola FINLAND Tel (0) Fax (0) info@akvaterm.fi

6 2 OPERATING PRINCIPLE Storing heat in water is an easy and practical way to store energy. The accumulator tank stores and levels the energy from the energy source. Energy can be generated the most efficient way or when it is at its cheapest. Heating equipment can be loaded at a high and steady level to ensure the highest operating efficiency and the lowest environmental emissions. The accumulator tank allows reaching a pleasantly low surface temperature for the heat distributor, a comfortable room temperature and copious amounts of hot water for domestic use when using the domestic hot water coil. A properly dimensioned accumulator tank does not bind the user to time and place. The accumulator tank allows you freedom. The accumulator tank is suitable for use in conjunction with a water-based central heating system, but it can also be used in conjunction with air heating systems. As the accumulator tank is suitable for use with several different heat sources, its use allows for the simultaneous use of several heat sources and allows you to alter the energy source in the future. Most heating methods require connecting the accumulator tank to the heating system. The hot accumulator tank is useful also with sources that function independent of an accumulator tank. For example, used in conjunction with oil-based heating systems, the accumulator tank reduces the number of start-ups for the burner and increases the total operating efficiency of the system.

7 Electricity or geothermal heat with storage Log boiler Solar power (also additional energy sources needed)

8 3 DIMENSIONS 3.1 Dimensions of the Accumulator tank The size of the accumulator tank is determined by the following factors, for example: The output requirement of the dwelling / output and efficiency of the heat source Water consumption (family size) Space Operating conditions Temperature of the heating circuit Geographical location The following examples of dimensions are for guideline only. More accurate dimensions can be requested from HVAC professionals Electrical Heating The heating energy required for full storage heating systems is produced during night time, when the price of electricity is at its lowest. Full storage heating systems nevertheless require high electrical output and a large accumulator tank. Partial storage heating systems generate the majority (80-90%) of the annual energy required for heating the rooms and the water in the night, but the remainder is produced during the day or via an additional heat source. Daytime heating is required when the outside temperature drops below -10 C. Partial storage heating systems enable the use of a significantly smaller accumulator tank and a lower output in comparison with a full storage heating system. The accumulator tank is dimensioned for an output of 40 W/m 2 (used in Finland), which covers 90% of the required overall output. This means that it is based on partial storage Accumulator size (litres) Dwelling size (square meter)

9 Dimensions of the accumulator tank Output Energy conveyance capacity in the day time /h (16h) Combined capacity of electric resistors used in the night Size of the dwelling Main fuse / connection 500 l 29 kwh 1,8 kw 5,5 kw 45 m 2 25 A 750 l 44 kwh 2,8 kw 8,5 kw 70 m 2 25 A 1,000 l 58 kwh 3,6 kw 11,0 kw 90 m 2 25 A 1,500 l 87 kwh 5,4 kw 16,0 kw 135 m 2 25 A 2,000 l 116 kwh 7,3 kw 22,0 kw 182 m 2 35 A 3,000 l 174 kwh 11,0 kw 33,0 kw 275 m 2 50 A For example, dwelling sized 90m 2 The required amount of heating is: 90m 2 40 W/m 2 = 3600 W =3,6kW Output: 16h 3,6kW 58kWh. This determines the capacity of the required accumulator tank, which for a dwelling sized 90m 2 is 1,000 l. A rough guideline to measuring the combined capacity of electric resistors used in the night: 3,6kW 24h 86,4kWh 86,4kWh/8h 11,0kW Other forms of heating Dimensioning according to the instructions supplied by the supplier/manufacturer. 3.2 Domestic Hot Water Coil In the Akva and Akvasan models, the flow is 35 l/min and in the Akvantti model, the standard flow is 45 l/min. Standard coils Output kw Flow l/min AKVA 35 LK AKVA 60 LK AKVA 80 LK AKVA 100 LK AKVA 120 LK We recommend the installation of a 35 l/min preheating coil in the lower hatch in order to considerably increase the amount of domestic hot water available and to improve the heat layering of the accumulator tank. 3.3 Expansion vessel The capacity of the expansion vessel should be: 10% of the entire water capacity when using electricity, wood and peat 5% of the entire water capacity when using oil and geothermal heat

10 4 PRODUCT RANGE The Akvaterm product range contains a model for all purposes. When the required dimensions are known, the accumulator tank characteristics should be reviewed with regards to the technical space, as the accumulator tank model is largely determined by the height of the technical space and the width of the doorways. Small spaces and narrow doorways are catered for by the ranges AKVASAN and AKVANTTI. Should the location of the accumulator tank be under design, the AKVA standard accumulator tank is recommended. It should be brought to the technical space during construction phase at latest. AKVA Standard Accumulator tank Is recommended as the primary alternative. Insulation is 100 mm seamless polyurethane. The upper hatch has a standard domestic hot water coil and a domestic hot water preheating coil, a solar heat coil, the heat collector exchanger etc. can be placed in the lower hatch. There are in-built guide pipes that ensure the proper layering of heat. Upon order, it is possible to deliver an un-insulated accumulator tank, an accumulator tank that has been painted with corrosion protector paint or an accumulator tank equipped with detached insulation. Dimensions, AKVA standard hot accumulator tanks Model Capacity (l) Diameter Height Weight (kg) AKVA 300 EK , AKVA 500 EK , AKVA 750 EK , AKVA 1000 EK 1,000 1,050 2, AKVA 1500 EK 1,500 1,250 2, AKVA 2000 EK 2,000 1,400 2, AKVA 2500 EK 2,500 1,500 2, AKVA 3000 EK 3,000 1,600 2, AKVA 4000 EK 4,000 1,800 2, AKVASAN Retrofitting Accumulator tank Resistor Units This model has been developed for constrained spaces and narrow openings. Its diameter is only 800 mm. The efficient cylinder format has been retained, and the insulation is the same as in the standard accumulator tanks, but its strength is 50 mm due to the smaller surface area. The EK-models are equipped with a domestic hot water coil and both day time and night time resistor units. When further equipped with an electric resistor, its characteristics make it an excellent domestic hot water heater. When only domestic hot water is required, for example in the summer, the E-model can be disconnected. Dimensions, AKVASAN repair accumulator tank Model Capacity (l) Diameter Height Weight (kg) AKVASAN 0,5 EK , AKVASAN 0,5 E , AKVASAN 0,7 EK , AKVASAN 0,7 E , The E-models do not contain a domestic hot water coil. Resistor Units

11 AKVANTTI Accumulator tank The entry dimensions are only 800 mm. Available in capacities 1400 litres, 2000 litres and 2400 litres. The most efficient domestic hot water coil in the market (45 l/min), available also without the domestic hot water coil. Dimensions, AKVANTTI Accumulator tank Model Capacity (l) Diameter Height Weight (kg) Resistor Units AKVANTTI 1400 EK 1, ,650 1,630 3 AKVANTTI 1400 E 1, ,650 1,630 3 AKVANTTI 2000 EK 2, ,820 2,060 4 AKVANTTI 2000 E 2, ,820 2,060 4 AKVANTTI 2400 EK 2, ,150 2,060 4 AKVANTTI 2400 E 2, ,150 2,060 4 Accumulator tanks for Apartment Buildings Suitable, for example, multi-storey buildings and terraced houses. The structural pressure is usually 3 or 4 bar. The capacity, hatches, units, hot water coils etc. according to the customer s requirements. Special Accumulator tanks According to the specifications and requirements of the customer. Standard Coils We are also able to manufacture according to your specifications and images. Dimensions, Standard Coils Model Capacity (kw) Diameter Length Flow (l/min) AKVA 35 LK ¾ 35 AKVA 60 LK , AKVA 80 LK ¼ 80 AKVA 100 LK ,000 1 ½ 100 AKVA 120 LK ,

12 5 SPATIAL REQUIREMENTS When designing a new technical space, it is useful to make it flexible and sufficiently spacious, as the use of the accumulator tank allows for the alteration of the heat source in the future. For example, when the heat source is a wood-burning stove, the technical space must be large to accommodate the handling of the fuel and the easy removal of the ashes. The location of the actual accumulator tank is not guided by many requirements. The most important thing is to pay attention to the mass of the accumulator tank and the resulting need to reinforce the floor plate. The location should be chosen in such a way that the connection will not be too difficult to make and that the future maintenance will be easy to carry out. The accumulator tank can be located next to the wall, and no more room is required at the top of the tank than what is needed for the connections. The round tank models require a slightly larger space on the floor than the AKVANTTI model. The safety distance of the boiler must be ascertained by contacting the boiler manufacturer. Should the accumulator tank be brought into the space on its side, the diagonal length must be noted when lifting the tank upright. When designing the technical space, it is imperative to take into account the transportation measurements of the accumulator tanks. The AKVASAN and AKVANTTI models are 800 mm wide, so they can be transported in through the doorway. The standard AKVA models are, however, relatively wide, and they cannot often be transported through normal-sized doorways. In these situations the accumulator tank can be taken to the technical space during the construction phase, or alternatively the accumulator tank can, upon order, be manufactured with detached insulation to allow the tank s diameter to be reduced by up to -200 mm depending on the model.

13 6 TECHNICAL DRAWINGS AKVA Standard Accumulator tank 1. Hatch 2. Heating Circuit + Guide Pipes 3. Drain Coupling 4. Thermometer Unit / Thermostat Unit (4 pcs) 5. Accumulator tank Unit + Guide Pipes 6. Electrical Resistor Unit (2-4 pcs) 7. Domestic Hot Water Coil, copper comb, capacity 90 kw, standard 35 l/min, +5 55/75C, structural pressure 10 bar 8. Pressure Relief / Air Bleeder 9. Polyurethane Insulation 10. Coating, coated galvanised tin plate 11. Tank maximum pressure 1.5 bar maximum temperature +110 ºC

14 AKVASAN Repair Accumulator tank 1. Pressure Relief / Air Bleeder 2. Thermometer Unit / Thermostat Unit (2 pcs) 3. Electrical Resistor Unit (2 pcs) 4. Hatch 5. Domestic Hot Water Coil 6. Drain Coupling maximum pressure 1.5 bar maximum temperature +110 ºC

15 AKVANTTI Accumulator tank AKVANTTI 1400 EK Note! Pipe connections from the top of the accumulator tank. Top Front 1. Entry from the boiler 2. Return into the boiler 3. Exit to the heating circuit 4. Return to the heating circuit 5. Domestic Hot Water Coil 45 l/min 6. Pressure Relief / Air Bleeder 7. Drain Coupling 8. Electrical Resistor Unit 3 pcs 9. Thermostat Unit / Thermometer Unit ] AKVANTTI 2000 EK, 2400 EK Pipe connections from the side as normal. 1. Tank Unit 2. Domestic Hot Water Coil 45 l/min 2b. Connection for a second coil 3. Thermostat Unit /Thermometer Unit 4. Electrical Resistor Unit (4 pcs) 5. Heating Circuit 6. Drain Coupling 7. Pressure Relief / Air Bleeder In the AKVANTTI models, the maximum pressure is 1.5 bar and the maximum temperature is +110ºC.

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