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JASPI THERMAL TANKS - How do they work ?
A thermal storage tank, often also called an accumulator tank, is an essential part of a modern heating system. A standard domestic hot water cylinder is a thermal store although with limited capabilities.
The thermal tank is the 'hub' of a heating system where all the available heat is stored and from where the heat is transferred to the heating and hot water.
The principle of a thermal storage heating is simple and therefore the system is also extremely reliable. A standard thermal tank is filled with water which then is heated up either directly or indirectly by any available heat source.
The most common heat sources are wood / woodchip / pellet boilers, heat pumps, solar panels, direct electricity and wind power. Oil and gas boilers can also be used either on their own or in combination with other heat sources.
A modern thermal storage tank enables multiple heat sources to be connected into one point making the heating and hot water system flexible and future proof.
For this, the thermal store must have enough coils and as importantly, plenty of couplings to where the necessary pipework is connected.
Being large and the centre of a heating system, the thermal tank is usually put in place when the building is constructed.
Which one ?
A good quality thermal tank is large enough to accept multiple heat sources and has the required connections.
In normal domestic use, anything under 300 litres of volume cannot be considered an effective thermal store.
This is because the small volume of stored water does not store enough energy to be useful for heating when it is needed.
Future expandability is also a very important factor. As we are getting closer to the time when fossil fuels are becoming scarce and more expensive, our need to find alternative heat sources is already here.
Therefore it is hugely important that any heating system fitted now can also accept new heat sources and technologies.
A good quality thermal store is designed to do exactly that.
There are several important considerations when selecting a thermal storage system;
Size of the dwelling, number of rooms, room height, existing insulation, type & size of windows, amount of radiators and number of baths / showers. These will determine the total heat demand and the thermal store needs to be big enough to cope. If the hot water demand is unusually high this also needs to be taken into account when sizing up the system. Usually underfloor heating requires smaller size thermal tank compared to radiators.
A simple thermal calculation formula can be found here;
Heat Source. As a rule of a thumb, renewable energy sources like solar, heat pumps, pellet or log boilers need larger thermal storage tanks. For example solar panels will produce a good amount of heat throughout the day which then needs to be stored until it is needed, usually in the evenings. If the thermal store is too small, most of the solar panel output is wasted and when the heating is turned on, the storage will run out of heat very quickly. Wood boilers also need larger storage tanks as the heat output is high when the boiler is on but as soon as the fire goes off, there is no heat output at all. Oil and gas boilers can manage with smaller thermal tanks and on their own, they don't need tanks at all. However, if they are connected together with some other form of heat, for instance solar, then the tank will need to be sized on the solar output as too small a tank will limit the amount of available solar energy in the system.
Future. A good thermal tank can be connected to several heat sources. This should be taken into account when sizing up the system as again, too small a thermal tank will limit it's usability in the future.
Does it fit ? Thermal storage tanks can be big. The smallest are fridge / freezer size, the largest can be as large as a van. Therefore it is important that the doors, passageways and other narrow points are wide enough for a tank to pass through. It is common when a new house is built that the thermal tank is put in place before any internal, and sometimes external, walls are built. The lifetime of a quality thermal tank is decades and it does not need changing. Therefore it can be integrated into the building at an early stage. Due to the weight of the tank when filled up, it must be placed on a solid concrete floor. If there is no room available in the main house, the tanks are often put into the garage or other outbuilding nearby.
Plumbing, pipes, pumps and expansion vessel on the front, and sometimes also on top of the tank requires some room. It is also advisable to leave enough space for the plumber to work in.
A rough guide for selecting a Jaspi thermal tank;
GTV - Smaller dwellings with radiators or mid-size houses with underfloor heating and normal hot water demand. Excellent buffer tanks on wood / multifuel boilers.
OVAL - Mid-size and larger houses with narrow access. Radiator or underfloor heating. Possibility to connect several heat sources into one unit. Normal or high hot water demand.
THERMOSTORE - From mid-size to large and very large dwellings and office / industrial units. High or very high hot water demand. Needs wide access to fit in place. Excellent expandability.
HYBRID - Very good hot water supply from a small footprint tank. Designed to work with heat pumps, solar and underfloor heating combinations. Tank can be kept on lower temperature without compromising the hot water supply. Small to mid-size dwellings with normal or high hot water demand.
ELEGANT - The first in it's class modular domestic hot water cylinder. Ready connected safety valves & expansion vessel with no visible pipework outside. Classy, clean appearance for easy siting. Stainless Steel, mains pressure with a 3kW ultra long life alloy immersion heater. Direct & indirect models.
JAMA - For mid-size houses or smaller office / industrial units. Insulated tanks but without outer steel sheath so need a dedicated room. Normal or high hot water demand.
JASPI THERMAL STORAGE TANKS
| Model | Capacity - Litres |
Size H x W x D |
Max. indirect coils |
Coils included |
Price £ excl. VAT no coils |
With 1 coil £ excl. VAT |
With 2 coils £ excl. VAT |
With 3 coils £ excl. VAT |
| GTV 270 | 270 | 1406 x 593 x 593 | 1 | 0 | £780 | £1027 | - | - |
| GTV 500 | 500 | 1665 x 743 x 743 | 1 | 0 | £1096 | £1322 | - | - |
| GTV 700 | 700 | 2000 x 780 x 820 | 3 | 0 | £1692 | £2068 | £2359 | £2650 |
| Oval 1.0EPK | 1000 | 1720 x 1230 x 780 | 3 | 2 | - | - | £2293 | £2584 |
| Oval 1.2EPK | 1200 | 2020 x 1230 x 780 | 3 | 2 | - | - | £2382 | £2673 |
| Oval 1.5EPK | 1500 | 1720 x 1770 x 780 | 3 | 2 | - | - | £2710 | £3001 |
| Oval 1.8EPK | 1800 | 2020 x 1770 x 780 | 3 | 2 | - | - | £2842 | £3133 |
| Oval 2.4EPK | 2400 | 2020 x 2310 x 780 | 3 | 2 | - | - | £3487 | £3778 |
| ThermoStore 500 | 500 | 1980 x 790 x 790 | 3 | 1 | - | £1266 | £1557 | £1848 |
| ThermoStore 700 | 700 | 2130 x 870 x 870 | 3 | 1 | - | £1454 | £1745 | £2036 |
| ThermoStore 1500 | 1500 | 2290 x 1260 | 3 | 1 | - | £1709 | £2000 | £2291 |
| ThermoStore 2000 | 2000 | 2300 x 1410 | 3 | 1 | - | £2186 | £2477 | £2768 |
| ThermoStore 3000 | 3000 | 2440 x 1610 | 3 | 1 | - | £2725 | £3016 | £3307 |
| Hybrid 500 | 340 + 160 | 1980 x 790 x 790 | 1 | 0 | £1894 | £2185 | - | - |
| Hybrid 700 | 500 + 200 | 2130 x 870 x 870 | 1 | 0 | £2089 | £2380 | - | - |
| Jama 1150 | 1150 | 1700 x 1470 x 780 | 2 | 2 | - | - | £1866 | - |
| Jama 1800 | 1800 | 1700 x 2170 x 780 | 2 | 2 | - | - | £2178 | - |
| J-Immersion heaters | 3-7.5kW | 3kW - £209 | 4.5kW - £216 | 6kW - £223 | 7.5kW- £252 |
Domestic hot water
Domestic hot water can be made in two ways;
Indirectly with coil(s) where the cold water passes through one or two coils immersed in the main body of water in the tank. The use of two coils, pre-heat and main, minimizes the heat transfer loss and the domestic hot water can be produced on the lower thermal store temperature.
Directly by the use of a secondary tank inside the main thermal store. Our Hybrid range have this facility with the advantage of a no heat loss in the heat transfer from the main body of the water to the domestic hot water.
Radiators & Underfloor heating
The water within the heating system is heated directly by the boiler or other heat source(s). The water never changes but passes through the radiators or underfloor heating circuit and returns back to the tank to be reheated.
As the thermal store temperature often varies, it is advisable to install a flow temperature control valve between the thermal store and the heating circuit.
If two different temperature heating circuits are installed, usually radiators upstairs and underfloor heating downstairs, then two separate flow temperature control valves should be used.
