Heatbank Xcel Standard Assemblies

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CONTENTS AND HISTORY

This page is currently a Work In Progress. 20-02-17

This page is intended to form a repository of information for the various standard assemblies that constitute an Xcel thermal store in its various permutations. It is also intended to form a kernel of content that will ultimately lead to an up to date set of Installation and User Instructions for the Xcel.

X2009-2-22

Mains pressure domestic hot water via plate heat exchanger:

Operation

This assembly generates domestic hot water (DHW) that is supplied to the taps and showers in the property. The assembly comprise a plate heat exchanger (PHE); a circulation pump; a flow switch; a blending (tempering valve).

It generates hot water only at the moment it is required when a tap is opened and its operation is similar to that of a combination (‘Combi’) when in hot water mode.

When a hot tap is opened, water starts flowing through the assembly and is sensed by the flow switch. This turns the circulation pump on which starts to draw primary hot water from the top of the cylinder and through one side of the PHE; simultaneously, cold mains water is flowing through the other side of the plate in the opposite direction. As the two channels of water pass each other, heat is transferred from the primary side to the secondary, cold mains side, and this cold water is transformed into domestic hot water. This passes out of the plate, through the blending valve to limit its temperature, then on out to the running outlet.

Under normal use patterns, there should always be sufficient energy stored in the top of the cylinder to provide small quantities of hot water at any time of day or night, however when taking showers or filling baths it is advisable to have the gas boiler available to provide a back up energy source. (See sections X2009-7; X2009-8; X2009-18A)

Image

Installation

  • Check the incoming cold mains water pressure. Although the plate heat exchanger is able to withstand static pressures of up to 10Bar, it is recommended that if the pressure is in excess of 6 Bar, that a pressure reducing valve is installed upstream of the cylinder to prevent excess pressures at the outlets in the property. Additionally, all fittings and appliances connected to the mains should be rated at 50% higher than the mains pressure.
  • Although operation at lower pressure is possible, it is recommended that a minimum cold mains pressure of 1 Bar is connected to the unit to deliver satisfactory performance though its full range. Flow rate performance is relative to pressure and at lower values, poor flow rates to taps and showers may be the result.
  • The characteristics of the plate will help to reduce the rate at which scaling up occurs, where the store is installed in hard water areas. However it will not ultimately prevent it; therefore it is recommended that scale inhibiting or water softening equipment is installed on the incoming supply to the property in locations where scale build up is a problem.
  • A cold mains water supply pipe from the incoming supply must be installed up to the unit, such that it can be connected to the flow switch pre-plumbed to the cylinder. This pipework should be installed in 22mm copper.
  • An isolating valve must be fitted to the cold mains supply upstream of the cylinder, in the vicinity of the unit (e.g. within the cupboard it is located in), and in clear sight.
  • A Y-pattern strainer (supplied loose) must be fitted to the cold mains supply to the cylinder, downstream of the isolating valve and in a position to permit servicing.
  • The cold mains supply pipework must be connected to the unit such that the body of the flow switch sits completely vertically, and thus permit reliable operation. If it sits out of line of the vertical, this may cause the switch to activate inconsistently and fail to run the heat exchanger pump.
  • The thermostatic valve fitted to the unit is to limit the temperature of DHW that is delivered to the outlets around the property, and thus reduce the risk of scalding. Note that the design operating temperature of the unit (the temperature of primary water stored in the cylinder) is in the region of 70° – 75°C and under certain conditions, the plate can deliver DHW within a few degrees of this to the inlet of the blending valve. The valve should therefore be adjusted to deliver a maximum temperature of 55°C, or a value of the client’s preference, and can then be locked to prevent tampering.
  • The plate heat exchanger pump should be set at a speed that permits adequate DHW delivery at the largest outlet in the property (or the combined outlet of the total of the largest outlets wished to be drawn simultaneously - if multiple draws are required). Note that the maximum 35 litres/min is only possible with a store held at a minimum 75°C. The faster the pump speed, the higher the potential DHW flow rate. The pump should not be set at a speed higher than is necessary, to prevent a reduction in efficiency and to permit greater draws of DHW from the store. The speed dial should be set in the right hand half of the range (constant differential pressure).

image of pump face here


Performance

Maximum DHW flow rate: 35 Litres/min [1] Maximum possible DHW temperature: 65°C
Maximum recommended DHW temperature: 55°C
Minimum flow rate: 3 Litres/min
Maximum heat transfer rate: 100KW (see attached data sheet)

  1. Limiting factor will ultimately include factors including: the pressure drop across the blending valve and plate. At 35 L/min, this is approx. 85KPa or 0.85 Bar.

Component List

Component Make / Model Part Code Data Sheet
 Plate Heat Exchanger  SWEP IC8 x 40  7066554  
 Pump  Wilo Yonos PARA RS 25/1-6  7070047  
 Flow Switch  Sika VKX15  702307  
 Blending Valve  Altecnic Mixcal III TMV 2  70200015  

Wiring Diagram

X2009-2

Mains pressure domestic hot water via plate heat exchanger – higher flow rate option:

This assembly has the same operational and installation details as assembly X2009-2-22: The difference is that the peak flow rate is higher at approx. 45 Litres/min. This is achieved by use of a larger blending / tempering valve.

Performance

Maximum DHW flow rate: 45 Litres/min
Maximum possible DHW temperature: 50°C
Maximum recommended DHW temperature: 55°C
Minimum flow rate: 3 Litres/min
Maximum heat transfer rate: 120KW (see attached data sheet)

Component List

Component Make / Model Part Code Data Sheet
 Plate Heat Exchanger  SWEP IC8 x 40  7066554  
 Pump  Wilo Yonos PARA RS 25/1-6  7070047  
 Flow Switch  Sika VKX15  702307  
 Blending Valve  Reliance Solar Tempering Valve 22mm  70200004  

X2009-5

Direct boiler heat input assembly (’GX Assembly’):

Operation

This patented assembly heats the store from the top down enabling faster delivery of heat to DHW from cold and recovery rates that exceed most coil type cylinders/calorifiers. The assembly comprises a return temperature control valve; an immersed-type cylinder thermostat; Pre-installed pipework and fittings linking the top and bottom of the store and providing connections for boiler flow and returns. For details of this assemblies comparative performance, refer to Here:


When the cylinder thermostat calls for heat, a switched live is passed to the boiler and its pump. The boiler fires and primary heated water flows to the valve, is recirculated and back to the boiler return, without entering the store. Once the primary flow reaches 55°C, the valve starts to act as a mixer, opening the lower store connection: This draws cold water from the base of the store to regulate the water returning to the boiler at approx. 55°C. Simultaneously, primary heated water stars flowing into the top of the store, of at least 55°C. The process continues, heating the store from the top down until the cylinder thermostat at the lower part of the store becomes satisfied, and the switched live to the boiler is removed.

In this base form the assembly provides a single point, full store heating/recovery option. The assembly is normally associated with the following additional assemblies, particularly with pre-configured Data Sheet units with boiler input option;

  • X2009-7 – Second thermostat for buffered heating operation
  • X2009-8 – Economy Mode thermostat
  • X2009-18A – Two channel programmer for Economy Mode (‘Summer’) or Full Store buffered Mode (‘Winter’) heating control


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Installation

  1. This assembly is suitable for connection to a boiler of a maximum output of 30KW. If a larger boiler is to be connected, then assembly X2009-5B should be specified prior to purchase of the thermal store (up to 60KW).
  2. The assembly is designed to enable direct connection of the boiler to the thermal store, i.e. not using an interface such as a primary heating coil or plate heat exchanger. It is therefore imperative that the type of boiler being connected is compatible with the system type that the store will be installed as – e.g. if the store and heating system will be open vented, the boiler must be of a regular open vented type. If the store is to be open vented but the boiler will be of a sealed system or Combi type, then alternative, indirect boiler input assembly X2009-6 must be specified, as it comprises a PHE interface.
  3. If a solar thermal coil is fitted to the store, the assembly will be pre-installed such that the lower return connection will be located above the top of the coil to permit a solar reserve at the base. If it is required as an option that the boiler heats the entire store volume, including the solar reserve, an additional tapping at the base should be specified prior to ordering to permit the assembly to be altered on site.
  4. Connect the boiler flow and returns to the store assembly at the labelled positons: the flow connection is on a tee near the top of the store, above the mixer valve. The return connection is directly off the mixer valve, off the mixed hot/cold outlet port.
  5. If the store has been specified with optional fitted item X2009-11B (boiler circulation pump), this will be installed below the mixed hot / cold outlet of the valve. In this case, the boiler return connection will be off the bottom of the pump. If a pump is being separately sourced and installed on site, this must be on the boiler return leg so that circulation is pumped away from the store.
  6. Wiring:
    • Connect the ‘Switched Live/Call’ terminal on the boiler to Terminal 12 in the wiring centre. Also connect Permanent Live / Neutral /Earth from the boiler to Live / Neutral /Earth in the wiring centre.
    • If the boiler has or requires pump control, refer to the electrical Installation instructions of Section X2009-11B Boiler Pump. Note: If the store is not supplied with X2009-11B, first connect the separately sourced pump Live to Terminal 6, (plus Neutral-Neutral and Earth-Earth) then follow these instructions.
  7. Once all other hydraulic and electrical connections are made, and the store is filled & bled, set up of the boiler can commence:
    • Set the boiler thermostat to maximum. Create a call for heat to the boiler (e.g. active programmer).
    • Once the mixer valve opens up and starts heating the top of the store, monitor the boiler primary flow and return temperatures using appropriate measuring equipment (e.g. clamp on temperature sensors/probes). The return temperature should be in the region of 55° +/- 3°C. The boiler flow temperature should be in the region of 15 – 20° higher than this.
    • If the flow temperature is not within this range, adjust the boiler pump speed as required until within range.
    • The cylinder thermostat is pre-set at the factory to 65°C Under normal circumstances this will permit full heating of the store to at least this temperature, with temperatures at the top of the store approximately 10°C higher or so. This is intended to prevent the boiler from struggling to achieve high enough upper store temperatures to satisfy the base of the store, given store stratification / temperature differential top to bottom. If necessary, the cylinder thermostat temperature, or the boiler thermostat setting can be reduced slightly.


Component List

Assembly Component Make / Model Part Code Data Sheet
 X2009-5  Return Temp Control Valve  Esbe VTC 312, 55°, G1”  70200001  
   Cylinder Thermostat  Danfoss ICT 100 (tamperfroof)  7025442  
 X2009-5B  Return Temp Control Valve  Esbe VTC 511, 55°, RP1”  70200002  
   Cylinder Thermostat  Danfoss ICT 100 (tamperfroof)  7025442  


Wiring Diagram

X2009-6

Indirect boiler heat input assembly:

Operation

This assembly performs a similar function to assembly X2009-5/5B, that is to provide top-down heating and more rapid recovery of the store, compared to conventional coil-fed indirect solutions. It is used when the boiler type and store configuration are not compatible, e.g. System boiler, open vented thermal store.

The assembly comprises a plate heat exchanger; a flow setter; A circulation pump; Pre-installed pipework and fittings linking the top and bottom of the store via one channel of the plate, and provides connections for boiler flow and returns via the second channel.

When the cylinder thermostat calls for heat it both starts the circulation pump and sends a switched live to fire the boiler and its pump. In its operation, the assembly is the much the same as the DHW one (X2009-2/-22), although in this case the boiler primary flow & return flows from top to bottom on one channel, whilst the cooler stored primary water is pumped from the base of the store upwards through the second plate channel then out and into the top of the store having been heated by the boiler. The flow setter is adjusted during commissioning such that at the boilers maximum output, a delta of approximately 15°C can be maintained across the boiler flow and returns at a lower store (secondary flow) temperature of approx. 55°C.

Installation

  1. This assembly is suitable for connection to a boiler of a maximum output of 26KW. If a larger boiler is to be connected, then assembly X2009-6-40KW should be specified prior to purchase of the thermal store (up to 40KW).
  2. The assembly is designed to enable indirect connection of the boiler to the thermal store, i.e. where the primary boiler water does not mix with the water in the thermal store. It is important that the type of boiler being connected is compared with the system type that the store will be installed as – e.g. if the store and heating system will be both open vented, or both sealed, then direct assembly X2009-5/5B should be specified instead.
  3. If a solar thermal coil is fitted to the store, the assembly will be pre-installed such that the lower return connection will be located above the top of the coil to permit a solar reserve at the base. If it is required as an option that the boiler heats the entire store volume, including the solar reserve, an additional tapping at the base should be specified prior to ordering to permit the assembly to be altered on site.
  4. Connect the boiler flow and returns to the store assembly at the labelled positions on the plate heat exchanger: the flow connection is the upper open connection and the return the lower one.
  5. If the store has been specified with optional fitted item X2009-11 (boiler circulation pump), this will be fitted to the lower of the two connections mentioned above. In this case, the boiler return connection will be off the bottom of the pump. If a pump is being separately sourced and installed on site, this can be installed on site in the same location, unless Manufacturer’s Instructions state to pump the flow (In this case, if the pump is pre-installed this should be altered on site as required.
  6. Wiring:
    • Connect the ‘Switched Live/Call’ terminal on the boiler to Terminal 12 in the wiring centre. Also connect Permanent Live / Neutral / Earth from the boiler to Live / Neutral /Earth in the wiring centre.
    • If the boiler has or requires pump control, refer to the electrical Installation instructions of Section X2009-11B Boiler Pump. Note: If the store is not supplied with X2009-11B, first connect the separately sourced pump Live to Terminal 6, (plus Neutral-Neutral and Earth-Earth) then follow these instructions.
  7. Once all other hydraulic and electrical connections are made, and the store is filled & bled, set up of the boiler can commence:
    • Set the boiler thermostat to maximum. Create a call for heat to the boiler (e.g. active programmer).
    • Refer to Flow Setter Values for the correct setting of the flow setter for the rated output of the boiler, and adjust accordingly (see instructions (xxx). If necessary, also adjust the speed of the pre-installed pump on the store side to achieve the required flow.
    • Monitor the boiler primary flow and return temperatures using appropriate measuring equipment (e.g. clamp on temperature sensors/probes). The return temperature should be in the region of 55° +/- 3°C. The boiler flow temperature should be in the region of 15 – 20° higher than this.
    • If the flow temperature is not within this range, adjust the boiler pump speed as required until within range.
    • The cylinder thermostat is pre-set at the factory to 65°C Under normal circumstances this will permit full heating of the store to at least this temperature, with temperatures at the top of the store approximately 10°C higher or so. This is intended to prevent the boiler from struggling to achieve high enough upper store temperatures to satisfy the base of the store, given store stratification / temperature differential top to bottom. If necessary, the cylinder thermostat temperature, or the boiler thermostat setting can be reduced slightly.


Component List

Component Make / Model Part Code Data Sheet
 Plate Heat Exchanger  SWEP IC8 x 40  7066554  
 Pump  Wilo Yonos PARA RS 25/1-6  7070047  
 Flow Setter  Tacanova AV23 (8-30LPM)  7058302  

Wiring Diagram

Table of Flow Setter Values

Boiler Output (KW) Delta (°C) Flow Rate (Litres/Min)
 12  15  12.2
 15  15  13.3
 18  15  16.2
 21  15  19.1
 24  15  21.9
 28  15  27.6


X2009-7

Second thermostat and relay for buffered boiler input control:


NOTE: This assembly Must be combined with a single thermostat boiler input assembly X2009-5 or X2009-6

Operation

The use of two thermostats linked with a relay allows them to act as a latch, with one thermostat acting as the switch on (buffer on) and the other as the switch off (buffer off). With the switch off thermostat located at approximately the level of the boiler return tapping, the switch on thermostat is positioned at a distance vertically above this.

This arrangement is used to hold off firing of the boiler until there is a known volume of water at a low enough temperature to call for the boiler to fire. After the store has been fully heated and a heat demand is placed on it, heat will be draw out of the upper part of the store, whilst cooler water is returned to the base from the heating circuit return, or DHW plate heat exchanger assembly return. This effectively causes a cooler body of water (with a boundary region where the upper, hotter water meets the cooler, lower water bodies) to move up the store as it is depleted.

When the temperature of the store at the switch on thermostat falls below its set value, as the lower cooler body reaches it, the boiler fires. The boiler then continues to fire and heat the store downwards until the temperature of the store at the switch off thermostat rises to its set value. This process permits the boiler to fire for a longer period when called than when using a single point thermostat, thus reducing cycling and increasing the potential for higher boiler efficiency operation.

This assembly is often coupled with the following additional assemblies, particularly with pre-configured Data Sheet units with boiler input option;


A. X2009-18A – Two channel programmer for Economy Mode (‘Summer’) or Full Store buffered Mode (‘Winter’) heating control.
B. X2009-8 - Thermostat for boiler input control – Economy Mode.

Installation

  1. These thermostat options will be suppled pre-wired and fitted to the store from the factory (excepting bespoke ordering instructions from the client). If the unit is ordered with option X2009-18A (Two Channel Programmer) fitted, there is no additional on-site wiring required apart from connecting the electrical supply to the wiring centre.
  2. The thermostats will be preset at the factory to the following set point temperatures:
    • Buffer On thermostat: 60°C
    • Buffer Off thermostat: 65°C
  3. Under normal circumstances these values will result in the boiler operating in the mode described above (longer but less frequent burns, reduced cycling). However, as the particular characteristics of a heating system and boiler that the store will be connected to can vary, the installer may choose to adjust them to suit. In all cases:
    • The buffer on thermostat should be set at a lower temperature that the buffer on thermostat, and a differential of at least 5°C between the thermostats is recommended.
    • Temperatures should not be set at too low a value such as to unduly affect DHW performance.
    • The buffer off temperature should not exceed 75°C


Component List

Component Make / Model Part Code Data Sheet
 Cylinder Thermostat  Danfoss ICT 100 (tamperproof)  7025442  
 Relay  Tyco / Scrack PTF (DPDT 230Vac, 10A) or equivalent  702315  


Wiring Diagram

X2009-8

Thermostat for boiler input control – Economy Mode:


Operation

This additional thermostat can be used with the top-down boiler input assembly to provide store heating to a smaller store volume. Positioned higher up the store, this allows a smaller amount of stored heat to be created, for low to medium DHW demands. Alternatively, it can be used to provide supplementary / back up heat input to another heat source in a bivalent operating mode, such as if a wood burning boiler stove is connected and is alight.

This assembly is often coupled with the following additional assembly, particularly with pre-configured Data Sheet units with boiler input option;

A. X2009-18A – Two channel programmer for Economy Mode (‘Summer’) or Full Store buffered Mode (‘Winter’) heating control.
B. X2009-7 - Second thermostat and relay for buffered boiler input control.

Installation

  1. This thermostat option will be suppled pre-wired and fitted to the store from the factory (excepting bespoke ordering instructions from the client). If the unit is ordered with option X2009-18A (Two Channel Programmer) fitted, there is no additional on-site wiring required apart from connecting the electrical supply to the wiring centre.
  2. The thermostat will be preset at the factory to 65°C


Component List

Component Make / Model Part Code Data Sheet
 Cylinder Thermostat  Danfoss ICT 100 (tamperproof)  7025442  

Wiring Diagram

X2009-9

Overheat Thermostat:

Operation

This thermostat is installed near the top of the store and acts as a safety device. Its purpose is to pass a switched live to a central heating pump to initiate heating of a circuit or zone once the store reaches 90° in its upper region. This thereby cools the store and prevents it overheating due to continued heat input from uncontrolled connected sources such as wood burners, or others sources with failed controls, e.g. solar panels.

The circuit that is to be enabled for heat dumping may be either radiators or underfloor heating (UFH), or even both, however see following installation notes regards controls methodology. In general the requirement is that the thermostat engages the circulation pump and overrides any programmer and valve/actuator that provides normal operation control of the circuit.

Installation

  1. Ensure that the enabled circuit for dumping of heat is capable of dispersing enough energy from the store / heat input. This will depend on the type of appliance that overheat protection is being provided for. In the case of a wood burning or multi fuel boiler stove without thermostatic control, this will be the maximum rated output of the stove to the water jacket burning the most calorific fuel it is designed for. For example, if a stove has a maximum output to water of 20KW, and there are two separate heating zones in the property of 10KW each, it will be necessary to enable both circuits from the overheat thermostat.
  2. If motorised valves or actuators are installed on the heating circuit/s then the overheat thermostat must be wired so as to first open the appropriate valve/s and then initiate the circulation pump.
  3. If for example the central heating control system comprises Programmer -> room thermostat ->motorised valve -> circulation pump, then the switched live from the overheat thermostat must be wired to bypass the programmer and room thermostat, and directly energise the motorised valve first (then the pump).
  4. Furthermore, ensure that any fitted radiator thermostats do not prevent heat transfer, even when rooms are up to temperature. To achieve this it may be necessary to leave some radiators without thermostatic valves.
  5. If dumping heat into a UFH system, it will be necessary to integrate with that system’s normal controls. It will be generally necessary to simulate a call for heat that ignores the set/target room temperature of the zone/s being dumped to, but without overriding any high limit safety functions of the UFH’s own controls. This may require additional relays and wiring.
  6. NOTE: In order for the pre-wired overheat thermostat to engage with the central heating controls in the property, it will be necessary to supply the permanent live/neutral/earth of those controls from the permanent supply from the wiring centre of the thermal store. Alternatively, the wiring for this thermostat may be demounted from the store’s wiring centre and connected to the wiring centre of the central heating controls, if these are installed separately.
caption

HOWEVER: If this is done, it is IMPERATIVE that the installer clearly labels this information on the overheat thermostat and store, to show that that it is electrically separate from the rest of the store’s controls, and from where it can be safely isolated from for servicing / maintenance.

This assembly is often used in conjunction with option X2009-13 – Overheat ‘discharge to drain’ assembly. This therefore provides two levels of overheat protection, with the overheat thermostat being the first level and the X2009-13 assembly providing a secondary, back up level in the event of power or component failure.


Component List

Component Make / Model Part Code Data Sheet
 Cylinder Thermostat  Danfoss ICT 100 (tamperproof)  7025442  


Wiring Diagram

X2009-13

Overheat ‘discharge to drain’ assembly:

Operation

This assembly is installed near the top of the store and acts as a safety device. Its purpose is to pass cold mains water through a heat exchanger if the store overheats and reaches approximately 90°C: The water becomes heated by the stored energy in the cylinder, and then discharged, and must be carried to a safe termination point. This thereby cools the store and prevents it reaching boiling point due to continued heat input from uncontrolled connected sources such as wood burners, or others sources with failed controls, e.g. solar panels. This assembly is also referred to as a ‘quench coil’.

The assembly comprises a heat exchanger (‘quench’) coil installed in the upper part of the store, a thermo-mechanical safety relief valve, and a flow regulating valve. A connection from the DHW plate heat exchanger assembly (X2009-2/-22) outlet is continued up the store, passes through the thermo-mechanical valve, flow regulator, and into the heat exchanger. A discharge outlet from the heat exchanger is left for the installer to connect to on site. The thermo-mechanical valve has a temperature probe which is installed in a pocket near the top of the cylinder and connects to the valve via a flexible capillary. When the store temperature reaches the activation temperature of the valve of approximately 90°C (this is factory set and cannot be adjusted), a phase change in the probe exerts pressure on the valve and opens it, allowing mains water to pass through the heat exchanger. The valve starts to open at approximately 90 °C and is fully open at 94°C.

The purpose of the flow regulating valve is to control the flow rate of water passing through the heat exchanger such as to permit, ideally, a steady flow of water and heat transfer that matches the maximum heat input of the uncontrolled device. This is to reduce the possibility of ‘cycling’ of the discharge valve when it operates. This valve is factory adjusted to allow a minimum flow rate of approximately 4 - 5 litres/min, so that it cannot be fully shut off.


Installation

  1. Connect pipework to the outlet of the quench coil to a safe termination point, via a tundish, in accordance with the requirements of Approved Document G3
  2. Once the cold mains water supply has been connected to the store, test the function of the control valve by pressing on the red test button: Hold the test button for approximately 20 – 30 seconds to ensure that water is discharged satisfactorily to the safe termination point; then gently release the test button.
  3. The minimum rate of the flow regulating valve should be sufficient to discharge heat input from stoves of up to approximately 8 – 10KW output to water. For stoves of greater output (15 – 20KW) the valve should be adjusted to flow approximately 8 – 10 litres/min.
  4. The operation of the safety valve should be checked again during commissioning and thereafter on an annual basis.


Component List

Component Make / Model Part Code Data Sheet
 Safety Relief Valve  Esbe VST112  70101675  
 Flow Regulator  Lockshield gate valve - 15mm  7016968  

X2009-5C

Direct Wood Burner Heat Input Assembly on Pumped Circulation:

Operation

This assembly is generally used when gravity circulation (thermosyphon) is difficult to, or cannot be, achieved between a wood burner and the thermal store, e.g. the stove and store are on the same level and / or are some distance apart horizontally. It may also be used to assist in efficient operation of a stove and capture of energy on high output appliances, where a simple gravity install is possible and would normally be considered.

The assembly heats the store from the top down much like boiler input assembly X2009-5; It is normally assembled so as to heat the entire volume of the store from top to bottom, inclusive of any solar thermal reserve. The assembly comprises a pump; a return temperature control valve (‘back end protection’); a gravity valve (supplied loose); a flue thermostat, for pump control (supplied loose); Pre-installed pipework and fittings that provide connections for the flow and returns from the stove to be connected.

When the stove is lit and combustion established, the stove structure and the connecting flue pipe will gradually increase in temperature. When the flue pipe reaches the set point temperature of the flue thermostat, this passes a switched live to the pump. Primary heated water from the stove flows to the valve, is recirculated and back to the boiler return, without entering the store. Once the primary flow reaches 60°C, the valve starts to operate as a mixer, opening the lower store connection: This draws cold water from the base of the store to regulate the water returning to the boiler at approx. 60°C. Simultaneously, primary heated water stars flowing into the top of the store, of at least 60°C. The process continues, heating the store from the top down whilst the stove is alight. When the stove dies down after firing is complete, the flue temperature drops until the flue thermostat disengages the pump.

In conditions when the pump is not running but the stove is generating heat (e.g. during warm up / cool down, or if there is a component or power failure during normal operation), the gravity valve enables a gravity circulation path to be established to allow this heat to be transferred to the store or heatleak circuit. The valve is a swing check, or one way valve: When the pump is running, the circulation forces hold the flap shut against the gravity circulation path, shutting off that particular path. When the pump stops, this pressure is removed. This then allows gravity circulation to establish and push past the flap.


Image and / or drawing


The location of the valve is determined by the install configuration (see below).

Installation

There are two principle installation configurations that this assembly can be connected to and work with. It is imperative that the appropriate configuration is determined prior to any setting out of work or first fix installation to ensure that all pipework and other components will be located and installed correctly: Furthermore, establishing this is key to determining the configuration of the store prior to its purchase, to ensure that it is supplied with the appropriate assemblies pre-installed.
These configurations are:

  • Partial gravity circulation – where pumped circulation will be most effective in delivering heat to the store, but where gravity circulation to the store is possible, e.g. in a component or electrical power failure scenario.
  • Fully pumped circulation – where gravity circulation to the store is not possible at all.


Depending on which configuration is appropriate, this will determine how overheat protection for the system is accommodated, and the location of key components.
It is for the installing / commissioning engineer, consultant or other professional concerned with the installation to determine which configuration is appropriate. Therefore, Thermal Integration Ltd and Specflue Ltd does not accept responsibility for the effectiveness of an installation or system that includes our products.


Partial Gravity Circulation

Also referred to as ‘Pump Assist’ or ‘Gravity Fallback’.

  • The pipework installation between the stove and the store should be undertaken in a similar way to a conventional gravity installation, i.e. minimum 28mm diameter pipework, as few elbows/changes of direction as possible, use swept bends where possible, horizontal sections to have a slight rise towards store. This is to ensure that gravity circulation can be achieved to the store when the pump is not in operation.
  • The flow pipe is connected to the branch of the tee on the upper part of the pre-installed pipework. Note that although the pre-assembled pipework is in 22mm, because the distance from this tee to the store inlet is small compared to the rest of the circuit, the effect of resistance on circulation under gravity is negligible.
  • Because the heat from the stove will be delivered to the store in all circumstances, a suitable circulation path must be available out of the store that bypasses the pump and back end protection valve when the pump is not running: This is achieved by fitting the gravity valve to the base of the store and then installing pipework from the pump outlet to the inlet (upper port) of the tee. The outlet (lower port) of the tee then connects to the return pipe to the stove.
  • The cylinder must be provided with overheat protection: All models intended for connection to wood burning stove feature a high limit thermostat (X2009-9). Standard Data Sheet models with pumped wood burner assemblies are provided with tappings to allow a quench coil to be fitted – if the configuration is specified at the time of quotation the quench assembly will be pre-installed when the unit is ordered. Alternatively, the necessary components can be purchased separately from Thermal Integration for assembly on site; or the installer may choose to provide an alternate means of overheat protection, e.g. installation of a temperature relief, or combined temperature and pressure relief valve.


NOTE: The following schematics are for general guidance only and do not constitute a complete system circuit. It is the responsibility of the installation / commissioning engineer to ensure that the system is installed in such a way as to meet the requirements of the relevant Building Regulations.

image and drawing of pump assist


Fully Pumped Circulation

  • Because there is no possibility of gravity circulation to the store in this scenario, overheat protection for the stove must comprise a gravity circuit that generally rises vertically above it. This should then rise to a heatleak radiator. This pipework must be undertaken in minimum 22mm; If it is deemed necessary by the installer this should be increased to 28mm.
  • In order to further protect the stove and to ensure a safe installation, this gravity circuit should form the cold feed and vent paths to the header tank, continuing up above the heatleak radiator; this therefore provides a free path to the vent from the stove. This pipework should be undertaken in minimum 22mm (although the final connections to the radiator can be made in 15mm). In order to counteract the positive pressure conditions that would otherwise exist in this circuit, potentially resulting in ‘pumping over’ into the header tank, the vent and cold feed pipe should be unified in a formation known as a ‘London Loop’ or Shepherd’s Crook’ (See schematic).
  • The pumped circuit to the store can be undertaken in 22mm pipe.
  • The pumped flow/gravity flow/vent, and pumped return/gravity return/cold feed circuits must join to make unified flow and return connections to the stove. Where the pumped return from the store meets the gravity return for the heatleak radiator, the gravity valve needs to be installed so as to prevent circulation around the heatleak whilst the pump is running, but to allow free gravity circulation when it is not.


NOTE: The following schematics are for general guidance only and do not constitute a complete system circuit. It is the responsibility of the installation / commissioning engineer to ensure that the system is installed in such a way as to meet the requirements of the relevant Building Regulations.

image and drawing of fully pumped – distant/same floor
image and drawing of fully pumped – stove above store
image and drawing of gravity valve install


Component List

Component Make / Model Part Code Data Sheet
 Pump  Wilo Yonos PARA RS 25/1-6  7070047  
 Return Mixer Valve  Esbe VTC 312 20-3.2, 60°, G1”  70200030  
 Flue Thermostat  Esbe CTF150  70200077  
 Gravity Valve  VCH brass horizontal swing check valve FxF 1"  70200055  


Wiring Diagram

X2009-4

Secondary Circulation of Domestic Hot Water (DHW):

Operation

This assembly can be used in properties where there are long pipe runs between the store and the most distant outlets (‘Dead Leg’), or multiple outlets in a large, multi bathroom dwelling. Its purpose is to reduce the time and amount of cold water drawn from a hot outlet, until the outlet runs hot. This aids in conserving both water and energy. This is achieved by installing pipework from the most distant hot outlet/s back to the thermal store, thus creating a loop, with a bronze pump fitted to circulate the water round this loop.

The pump requires time control in order to operate only during periods of occupancy and higher demand. The pre-installed assembly comprises: A bronze circulation pump with pump valves (suitable for connecting to cold potable & DHW systems); A one-way/check valve. A pipe thermostat is also supplied loose.

When the bronze pump is activated, it circulates water through the plate heat exchanger (PHE) and blending valve, out towards the various hot outlets, and then back round to the pump in a continuous loop. Note however that the water in this circuit does not pass through the flow switch, therefore primary heat from the store is not transferred into the circuit in the normal way. To achieve this, the pipe thermostat monitors the circuit temperature and is wired so that if it falls below a pre-determined (by installer/client) temperature, it activates the primary PHE pump and heat is transferred into this secondary loop; when the circuit temperature reaches the target the primary pump stops but the bronze one continues. This the secondary loop is held at a temperature to allow rapid delivery of DHW when an outlet opens. When this happens, the flow switch activates as normal and DHW is created/delivered in the normal way. The check valve is installed between the bronze pump and the point at which it tees into the DHW PHE assembly: This prevents the cold mains supply forcing itself backwards round the loop and disrupting the flow of DHW.


Installation

  • The DHW distribution pipework in the dwelling needs to be installed such that it runs from the blending value outlet on the store to the various hot outlets, as normal, continues onwards from the furthest outlet/s, and then returns back to the thermal store.
  • The bronze pump and check valve are pre-installed on the store, with one open connection on the pump inlet: The return of the DHW loop is to be connected here.
  • The pipe thermostat needs to be attached to this return pipe within 1 Meter of the bronze pump.
  • The pipe thermostat to be wired into the store wiring centre (WC) as follows: Thermostat Common (1) to WC Terminal 2; Thermostat Break on Rise (2) WC Terminal 3.
  • The pipe thermostat should be set at a temperature that the client wishes the secondary loop to be maintained at when in operation. A suggested initial setting is 38°C.
  • A programmer/timer (supplied by Others) should be installed such that the client can set suitable time periods for the secondary loop to be in operation. The ’Call’ from this programmer should be wired into Terminal 2 of, and permanent Live/Neutral/Earth taken from, the store wiring centre.


Component List

Component Make / Model Part Code Data Sheet
 Bronze Pump  Wilo SB30  7067972  
 Pipe Thermostat  Danfoss ATF Frost Thermostat  7018159  


Wiring Diagram

X2009-11A

Pump for radiator circuit

Operation

The assembly consists of a standard ‘A’ rated pump to act as a circulator to a central heating radiator circuit. The pump is connected to the ‘Flow’ connection of the cylinder, i.e. pumping away from the store.The installer is provided with a pushfit Tectite fitting on the pump outlet, plus compression fitting on the return port on the cylinder to connect the circuit to. All other controls required for the operation of the central heating system (e.g. programmer, room thermostat or programmable thermostat, motorised zone valves) are not included in this assembly and are to be provided by the installer [1]

This option could also be specified if connecting to an Underfloor Heating circuit (UFH) where an additional circulator is required to act as a shunt between the store and manifolds.

Installation

Installation comprises connecting the switched live ‘call for heat’ from the other central heating controls, to the pump live wire. The pump live will be pre-wired to terminal 9 in the wiring centre (neutral & earth pre-wired to the common N-E positions in the centre). The installer therefore has two options:

  1. Connect the Permanent Live plus Neutral and Earth of their central heating controls to the permanent L-N-E of the stores wiring centre, and connect the ‘call for heat’ from the controls to Terminal 9 in the wiring centre. This therefore means that the central heating controls as well as the thermal store & boiler controls are all supplied from and can be isolated at, the same source.
  2. Demount the pre-wired L-N-E connections of the pump and re-wire them into a separate wiring centre that the installer fits for the wiring of the central heating controls. This means that the central heating controls are separate from the thermal store & boiler controls for the purposes of control & isolation.
caption

HOWEVER: If this is done, it is IMPERATIVE that the installer clearly labels this information on the pump and store wiring centre, to show that that it is electrically separate from the rest of the store’s controls, and from where it can be safely isolated from for servicing / maintenance.


  1. In the greater majority of installations it is found that the client and/or installer will wish to choose one from a considerable range of space heating controls solutions in the market, for functionality and aesthetics reasons. For this reason Thermal Integration usually expects that these works and their sourcing fall outside the scope of the service we provide. However, if a simple control system is requested to be supplied with the store, we can offer these options:
  • Danfoss RMT 230 room thermostat plus TS715si single channel programmer, or
  • Danfoss TP5000si programmable room thermostat


Component List

Component Make / Model Part Code Data Sheet
 Pump  Wilo Yonos PARA RS 25/1-6  7070047  


Wiring Diagram

X2009-11B

Pump for boiler circuit

Operation

This assembly consists of a standard ‘A’ rated pump to act as a circulator between the store and a conventional boiler. A pump will usually be required when connecting to a conventional, open vented boiler which has no internal circulator: As such, this assembly is intended to be paired with X2009-5 /-5B Direct boiler heat input assembly (although can be paired with indirect assembly X2009-6 if the install requires).

Control of the pump will by default be from the cylinder thermostat when a call for heat is generated, however if the connected boiler has pump control functionality (e.g. pump overrun), the factory wiring needs to be modified slightly to enable this.


Installation

Note: The following guidance is provided assuming the store is supplied with any of options X2009-5 /-6 /-8P

Hydraulic:

  • Connect the boiler flow and returns to the store assembly at the labelled positions: The flow connection is on a tee near the top of the store, above the mixer valve. The return connection will be off the bottom of the pump

Electrical:

  • If the connected boiler does not require or have the option for pump control, then the pre-wired boiler & pump controls require no further work asides from connecting the switched live to the boiler to Terminal 12 (plus Permanent Live, Neutral & Earth).
  • If the boiler does require pump control the following alterations should be made to the factory wiring:
    • Remove the link wire between Terminals 6 and 12
    • Connect the ‘Pump Live’ terminal on the boiler to Terminal 6 in the wiring centre
    • Connect the ‘Switched Live/Call’ from the boiler to Terminal 12


Component List

Component Make / Model Part Code Data Sheet
 Pump  Wilo Yonos PARA RS 25/1-6  7070047  


Wiring Diagram

X2009-14 / 14-30L

Plate Heat Exchanger assembly for indirect central heating circuit

Operation

This assembly can be used to deliver primary heat to a space heating circuit (radiators or UFH) indirectly using the energy in the thermal store, as opposed to tapping directly off it. It can be used in situations where there is a requirement to separate the two circuits, often where the store is installed as an open vented system, e.g.: Needing to feed radiators installed above the header tank; or supplying a UFH system that has minimum head requirement, or small bore pipework & fitting and where the store is linked to a wood/multi fuel burner. Note that two pumps comprise this circulation system: The pre-installed one on the assembly, and the one that circulates across the other side of the plate and around the radiators/UFH (supplied by installer).

The pre-installed assembly comprises: A plate heat exchanger (PHE); a flow setter; A circulation pump; Pre-installed pipework and fittings linking the standard ‘Radiator’ flow & return connections on the store via one channel of the plate; and provides connections for the space heating circuit flow & return on the other channel. All other controls required for the operation of the central heating system (e.g. programmer, room thermostat or programmable thermostat, motorised zone valves and circulation pump) are not included in this assembly and are to be provided by the installer.

NOTE: The independent circuit this assembly supplies requires its own feed / expansion and filling provision. The installer may choose to supply their own equipment, alternatively a 'Robokit' can be purchased from Thermal Integration in 8 or 12 Litre versions (ROBOKIT-8L / ROBOKIT-12L).

When a ‘Call for Heat’ is received from the central heating system, this energises the pump on that circuit; Simultaneously, the pump on the PHE assembly is also energised. This draws heat out of the upper part of the store and down through one channel of the plate. At the same time the return from the space heating is pumped upwards through the second channel in counter current, collect heat then flows out to the emitters. Both pumps then stop at the same time when the demand is satisfied.


Installation

Electrically, installation comprises connecting the switched live ‘call for heat’ from the other central heating controls, to the pre-installed pump live wire. The pump live will be pre-wired to Terminal 9 in the wiring centre (neutral & earth pre-wired to the common N-E positions in the centre). The installer therefore has two options:

  1. Connect the Permanent Live plus Neutral and Earth of their central heating controls to the permanent L-N-E of the stores wiring centre, and connect the ‘call for heat’ from the controls to Terminal 9 in the wiring centre. This therefore means that the central heating controls as well as the thermal store & boiler controls are all supplied from and can be isolated at, the same source.
  2. Demount the pre-wired L-N-E connections of the pump and re-wire them into a separate wiring centre that the installer fits for the wiring of the central heating controls. This means that the central heating controls are separate from the thermal store & boiler controls for the purposes of control & isolation.
caption

HOWEVER: If this is done, it is IMPERATIVE that the installer clearly labels this information on the pump and store wiring centre, to show that that it is electrically separate from the rest of the store’s controls, and from where it can be safely isolated from for servicing / maintenance.


Hydraulic Installation:

  • Connect the space heat ‘Flow’ pipe to the upper of the two free PHE connections. The ‘Return’ pipe to be connected to the lower fitting.
    • It is suggested that the heating circuit pump is installed on the Flow pipework, pumping away from the upper PHE connection.
  • Adjust the flow setter on the assembly to correspond with the calculated heatload of the connected circuit. The table below gives a range of settings based on an average Flow/Return delta of 15°C. Note that the pump speed can also be altered as required to achieve this value. If the installation is working off different delta’s please refer to the Power and Flow calculator on our website to calculate your own specific requirements.


Component list

Component Make / Model Part Code Data Sheet
 Plate Heat Exchanger  SWEP IC8 x 40  7066554  
 Pump  Wilo Yonos PARA RS 25/1-6  7070047  
 Flow Setter  Tacanova AV23 (8-30LPM)  7058302  


Wiring Diagram

X2009-15

UFH Temperature Control Valve
To be combined with Pump for UFH Circuit (X2009-11C)

Operation

This assembly is used to provide temperature limitation or control to a space heating circuit being supplied by the store. Typically this is used in underfloor heating (UFH) systems, although it can also be deployed on radiators circuits as well where flow limitation to 65°C maximum or less is required. It should be considered that in nearly all UFH systems, temperature control as well as circulation requirements are catered for in the manifolds that are supplied with the rest of the UFH equipment and the need for additional temperature control on the store is not normally required. Furthermore: This assembly is regarded as an optional extra item to be coupled with a UFH circulation pump X2009-11C, principally as the pump needs to pump away from the store and through the valve. Therefore, pre-installation of the valve alone is not envisaged.

In operation, when heat is called for and the pump circulates, the valve delivers primary heat from the upper/mid part of the store to the heating circuit, and the circuit return is delivered to the lower/base part of the store. If the primary heat into the valve exceeds the valve set point, the cold inlet port opens and allows the circuit return to be fed back into the flow, thus blending the flow temperature down to the set point.

Component List

Component Make / Model Part Code Data Sheet
 Blending Valve  Reliance ‘Heatguard’ UFH Tempering Valve  7018283  


Wiring diagram

X2009-16A / -16J

3KW Immersion Heater


Operation

Immersion heaters, where installed, are generally for the provision of temporary back up DHW where other heat sources have failed, or as a secondary / supplementary heat source (e.g. Solar PV) depending on the particular configuration of the store, number of heaters, and the client’s system requirements. Standard immersion heaters are rated at 3KW, 230 VAC, 50Hz, Single Phase.

Each immersion heater comprises an element and two thermostats: A control thermostat and a high limit / overheat thermostat. The control thermostat is factory set to 72°C and should not require adjustment at Commissioning. The overheat thermostat is factory set to 90°C and should not be altered. In normal operation, when energised the element will heat the store down to its level, to the set temperature of the control thermostat. In the event of store overheating, the overheat thermostat features a non self-resetting Energy Cut Out button that pops out and disconnects the power supply to the element if the water reaches the temperature it is set to.

Immersion X2009-16J is usually specified for temporary back up use. Immersion X2009-16A is usually specified where it is intended for supplementary heat input. It features a longer (lower Watt-Density, quieter operation) element than -16J and also features dry fire protection of the element. The immersions are not supplied pre-wired therefore all wiring and controls/timers (if applicable) are for the installing engineer.

Installation

All wiring must comply with the relevant IEE Wiring Regulations, Building Regulations and BS:EN Standards, and be carried out by a Competent Person.

Each 3KW 230VAC immersion heater must be supplied from a dedicated supply from the Consumer Unit, protected with a suitably rated MCB (e.g. 16 Amp), via a fused Double Pole Isolator. The heater must be wired using cable that is heat resistant to 90°C or better.
Warning: The heater must be Earthed.
The Live connection must be made onto the overheat thermostat, and the Neutral connection onto the element terminal, as per the diagram below. The Earth must be connected onto the post on the immersion body. The cable must be secured via the cable clamp onto its outer insulation.

Warning: The immersion heater must be isolated from the mains supply before and whilst the outer cover is removed.

If it is intended that the heaters are operated on a regular, periodic basis then a suitable programmer/timer should be installed (e.g. Grasslin ‘Ecosave’ timeswitch).


Wiring Diagram

X2009-16B

6KW Immersion Heater

This heater has the same operational and installation details as X2009-16A/-J except that:

  1. The Consumer Unit supply to be suitably rated & protected (e.g. 32 Amp MCB).
  2. A suitable Contactor relay must be installed to switch the load to the element: If required the internal link wire from thermostat to element must be removed and the thermostat output connected to the Contactor switch (refer to the below diagram).


X2009-19 / -A / -B / -C

Primary Sealed System kit for thermal store

The Xcel thermal store can, subject to the heating appliances being connected to it, be installed on either open vented or sealed system configurations. To permit sealed system operation, this pre-fitted option (X2009-19) is available, comprising:

  • Temporary filling loop; expansion relief valve; connection point for expansion vessel; Combined Temperature & Pressure Relief valve; Temperature/Pressure gauge; Auto Air Vent (supplied loose).

Alternative options also include a floor standing expansion vessel (supplied loose), as follows:

  • X2009-19A – includes 50 Litre vessel
  • X2009-19B – includes 80 Litre vessel
  • X2009-19C – includes 100 Litre vessel

These vessels should be sized to accommodate both the volume of the thermal store and total connected systems (heat sources, heating circuits).

Installation

Refer to the ‘Installation and Commissioning Instructions’ for full details. In brief:

  • Complete all hydraulic connections: Fit Auto Air Vent to top vent connection on store
  • Perform system flushing, pressure testing/leak detection
  • Adjust Pressure Reducing Valve to 1 Bar
  • Dose system with corrosion inhibitor; Connect temporary filling loop; Fill system cold until 1 Bar observed on temp/pressure gauge; Disconnect filling loop.


Component List

Component Make / Model Part Code Data Sheet
 Temp. Filling Connection + DCV / Isolation Valve  Altecnic Ecofil  7069559  
 Expansion Relief Valve  Altecnic 2.5 Bar PRV  70674  
 PRV with gauge  Caleffi PRV 15mm  7026131  
 Auto Air Vent  Advantay AAV 1/2"  7026187  
 TPRV  Altecnic 3/4" 3 Bar 90°C  7069034