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Thermal Store FAQ's

All you need to know about our Heatbank™ Thermal Stores…

Q. What is a thermal store?

A. In its simplest terms – a storage unit for heat. Like hot water cylinders, a thermal store saves up the energy generated by a boiler or electric heaters, allowing the householder to use this energy quickly – to run a hot tap and a shower together, for example. Without storage, such as when using a combination (combi) boiler, then it is only possibly to run one outlet at once.

A thermal store differs from a hot water cylinder in that the hot water delivered to taps is heated instantaneously using the heat energy in the store. The water in the store stays in the store, and remains completely separate from the domestic water supplies.

Q. What are the guarantees on Heat Banks?

A. 1 year on site back-up (call-outs resulting from installer or user error will be charged).
2 years on components (not labour).
25 years on the store itself (provided inhibitor is refreshed every 5 years. Not including site damage).

Q. Are there any limits on the positioning of the stores?

A. No. Stores can generally go anywhere in the property you can get the pipework to. The location may affect the choice of controls, especially if there is a wood burner in the scenario that requires a gravity heat leak circuit. All we would say is that if the unit is to be located in a cold loft or cellar, that all pipework is lagged, and the store preferably boxed in to cut-down heat loss, as you would with any hot water system.

Q. Can I ha [Thermal Store] ve hot water outlets above the store?

A. Yes. As both your hot and cold water is supplied at full mains pressure, it is usually possible to supply outlets far above the store. This depends on you mains pressure – a pressure of 1 bar can lift water 10 metres, and likewise a pressure of 5 bar can lift water 50 metres.

Q. How far can the cylinder be from the boiler?

A. If there is a considerable distance (>20m), then it may be wise to use larger pipe sizes to accommodate, or to specify a higher head primary (boiler) pump.

Q. Where is the best place to start finding out what unit to order?

A. Click here and complete some simple questions on our designer page. We will then contact you if further information is required, otherwise we will email you a full detailed quotation along with supporting technical details and literature.

Q. Do I need to worry about too high pressure from the mains?

A. Not usually as the store can run at up to 6 bar continuous, 9 bar peak. You should however check that all your fittings (showers, washing machine hoses etc.) are suitable for your mains pressure. If you are worried then fit a pressure reducing valve set to 3.5 bar.

Q. If the standard size of store will not fit, is there another option?

A. Yes. We can make stores to suit (within reason). We have four different unit diameters allowing the same volume of storage in either a tall thin unit, or a short fat unit. Finally, it is possible to supply a horizontal store – one that lays on its side – that can be useful when there is very little head room. The standard size is however the best priced.

Q. Other thermal stores I have seen use coils to heat the water. Is this how a Heatbank™ works?

A. No. Coil type thermal stores use metal (typically copper) coiled tube(s) within the store, through which the domestic water flows and is heated. A Heat Bank however, circulates the water in the store (using a pump) from the top, through a plate heat exchanger, and back to the bottom of the store. The heat exchanger transfers the heat to the domestic water that also flows through the heat exchanger, while keeping the water separated.

We can still manufacture coil type stores however they were always more susceptible to limescale build up within the coils. Also, the temperature of water produced dropped gradually from the start temperature, rather than holding steady. The use of the plate heat exchanger overcomes these, and also boosts the maximum output considerably, with lower pressure losses. To learn more about this performance, click here.

Q. Do I need a new boiler?

A. Up to you. The standard options allow for all types of domestic boiler. A Heatbank™ can even be easily connected to a combination boiler to improve performance without replacing the boiler. If you have any queries regarding boilers, it is worth checking the size of the existing boiler (if there is one). If it is a new property or there is an extension or increased water loading (more bedrooms) then you may need a larger boiler. As it is not good to vastly oversize a new boiler, some reasonably accurate idea of the heating and hot water load (pattern of use) should be obtained.

Q. Can I use a Solid Fuel Boiler or Solar Panels to heat a Heat Bank?

A. Yes. We have options covering both. In fact, we have supplied stores that will connect to a gas boiler, solar panels, solid fuel stove, and heat pumps, all at the same time. Protection is included against overheating the unit (always a worry with an uncontrolled heat source) by the means of a dedicated hot water outlet (typically taken to a drain) that will relieve hot water when the store approaches overheat, and thereby prevent the temperature from further increasing. All the controls for this are factory fitted.

Q. How can I ensure that I have hot water instantly available at hot taps?

A. Although the Heatbank™ will generate hot water instantaneously, you may still get dead-legs in pipework – that is a length of supply pipe between the store and the tap that goes cold over time. The only way to overcome this (insulating pipes helps) is by plumbing in a secondary return circuit. In such a setup, the hot water supplies are in a loop around the property, returning to the store. A small pump can be used to keep hot water circulating around the loop keeping pipework hot. This is an factory-fitted option.

Q. What are the advantages of a Heatbank™ over an unvented cylinder?

A. There are several important benefits:

No discharge pipe
No annual maintenance
Allows connection to any heat source
Can be integrated with central heating

Q. Does the Heatbank™ boost the mains supply?

A. No. It simply heats what is already provided by the mains water pipework. This is limited by the water pressure in your area, as well as the pipe size into the property. Both are important and should be checked.

Q. What are my options if my mains is not very powerful?

A. First thing is carefully check all valves, stopcocks on the supply are open (a long shot).

It is always worth contacting your water supplier to see if they can up the pressure into the property. Sometimes, nearly always in flats, there are pressure limiting valves, that can be increased in setting.

Maybe ask a plumber you know if he can see anything obvious – never go to an unknown (not IOP registered for example) person asking to spot problems in your house – they may magically appear.

Failing these, it may be necessary to increase the pipe size of the mains coming into and within the property. Sometimes the weak point is a short link of pipework where the supply enters the house, sometimes the entire length of pipework under a driveway will need renewing in a larger size. If embarking on such a venture as digging up your drive – always talk things over closely with the water suppliers as they legally only have to provide 1 bar pressure, and 9 litres per minute (some are more co-operative than others).

If renewing the mains supply is not an option, then there are only two options left. The first is to stick to a traditional cold tank fed system, using pumps if needed to boost pressures.

However, if cold tanks in the loft are not an option either, then a pump set is required. This is simply a cold storage tank at lower level, in the garage for example, with pumps to boost the pressure into the house. Once the pump set is operating the property can go ahead with a high pressure and high flow rate cold water supply. Typically two pumps are used in unison – to reduce ware and provide temporary backup if one fails – as the cold tank is lower than outlets, a pump failure will result in a complete failure of water supply, so automatic backup is advised.

Q. How can I work out the size of cylinder I need?

A. We of course can do that for you, but if you want to use a simple calculator, please click here to a partner site. It also depends on the inputs. For example, Solar Thermal requires up to 50 litres per square meter of exposed panel. We need to understand all the inputs before we can accurately size.

Q. Can the plate heat exchanger scale up?

A. It is possible but very uncommon. We are often asked by service engineers experienced with combi-boilers about this happening, as they also use a plate heat exchanger to heat water, which can scale up. The main difference between a thermal store and a combi-boiler is the output of the heat exchanger – typically 3 times larger on a Heat Bank. The much higher flow rates generated through the Heat Bank heat exchanger helps to clean it and prevent scale from depositing. It is very rare for performance to be adversely affected even in hard water areas.

However, in hard water areas, we advise choosing the option to factory fit an electronic water conditioner on the Heatbank™. This provides permanent and complete protection against limescale deposits with the heat exchanger. It also protects the rest of the property.

Q. Who can I get to install the unit?

A. Any trained plumber, but depending on the appliances used, specialist certification and competence may also be required. We can of course undertake the complete installation on all heat inputs.

Q. Can I see a unit before I buy one?

A. Yes, we have our product in our Energy Centres, many of them working displays. Please contact us here and we will ask your nearest display centre to contact you.

Q. How does the system comply with the new regulations concerning overheat protection in immersion heaters and thermostatic control of hot water?

A. Our immersion heater have both overheat and dry-fire protection, and we fit a thermostatic blending valve to limit hot water temperatures as standard. If units are to go to care homes requiring special types of temperature control valves, these are available.

Q. How long has the Heatbank™ been around?

A. 15 years

Q. What happens is something goes wrong with the unit?

A. We provide 1 year on site backup against failures of our equipment. A further 2 year warranty is on all parts, and a 25 year guarantee on the Cylinder itself.

If you have any further questions about our Heatbank™ or other storage cylinders, please give us a call or send us an email.