HIU Comparison

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Thermal Integration DATA HIU compared to Danfoss-SAV Termix

This article lists the differences between the Thermal Integration DATA and the Danfoss-SAV Termix Heat Interface Units.

The data used in this article is obtained from the published HIU test results from SP Technical Research Institute of Sweden, funded by DECC.

SP Test Report - TIL Data
SP Test Report - SAV Termix
VWART Calculation - TIL Data
VWART Calculation - SAV Termix
SP Test Report - Unbalanced Radiators

The purpose of the test regime is four-fold:

  • To enable the performance of different HIUs to be evaluated within the context of typical UK operating conditions, thereby enabling heat network developers to evaluate the performance of specific HIUs against design requirements.
  • To generate operating data on the expected performance of specific HIUs given “normal” operating parameters, to enable heat network operators to identify anomalous performance.
  • To provide a framework for HIU manufacturers to evaluate the performance of their equipment within the UK context, thereby feeding into their continuous improvement development programmes.
  • To provide data on the impact of different design and installation choices on HIU performance, thereby assisting designers of heat networks to optimise heat network performance.


For each tested HIU, the data enables the calculation of the Volume Weighted Average Return Temperature (VWART). VWART provides a figure that represents the average impact that a specific HIU will have on network return temperature, under normal operation, and has been agreed upon by all manufacturers who have taken part in the tests.

The following table summarises the data from the test results.

HIU Supplier
Thermal Integration SAV Systems
HIU Model
DATA Plus Danfoss Termix VVX-I-FI-1-5 RAD STD
Hot Water Priority Yes No
Design Pressure (Primary) 16 bar 10 bar
Design Pressure (Radiators) 3 bar 4.5 bar
Design Pressure (DHW) 10 bar 6 bar
Weighed Average Annual Volumes Used 77.4 m3/year 116 m3/year
Volume Weighed Average Return Temperature (VWART) 23.2°C 34.5°C
Return Temperature Protection Yes No
Typical return temperature with unbalanced radiators (test 1e) 50°C (settable) Significantly higher #2
Water Hammer Arrestor Optional Yes
Peak DHW Output 71.4 kW 70.5 kW
DHW response times to 50°C (55°C Setpoint) 26 seconds #1 23 seconds
DHW response times to 55°C (55°C Setpoint) 28 seconds #1 91 seconds
Central Heating Return Temperature (70C Flow, 4kW) 35.8°C 41.1°C
Provision of error codes to BMS/billing systems

Yes:
Tampering with Sensors
Component Failure
Network Response Times

None
Tamperproof Settings Yes No
Remote commissioning capabilities Yes No
Legionella Protection Cycle Yes No

#1 DHW response Times are with keep-warm at 25°C. With an increased keep-warm these times can be reduced to 6 seconds and 8 seconds accordingly.

#2 Direct comparison of current test data is questionable due to fluctuations in ambient air temperature. Refer to graphs.

The DHW temperature controller in the SAV Termix is flow proportional, meaning that the primary flow rate is proportional to the DHW flow. When a single tap is opened, the flow from the primary will be low, and it will take significant time to clear cold primary pipework. To avoid long delays of water to taps, the keep warm needs to be maintained over 40C.

By comparison, the Data HIU draws primary water at up to 20 litres/minute when primary temperatures are low and a tap is opened, in order to rapidly clear pipework. The independent test data on the DATA HIU shows how it delivers return temperatures of approximately 25C in a keep warm mode. This represents a fundamental improvement in efficiency, with a direct impact on plant and pipe sizing, and more importantly on running costs.

The diagram below shows how a heat network that requires all pipework to be maintained hot at all times compared to one that allows branches to go cold has approximately half the overall system efficiency. These calculations can be seen on our online heat network calculator, that enables you to fully analyse the performance of a network based on topology, HIU selection, and various operational parameters. Click here to view Heat Network Calculator.

The network on the left would be how the SAV Termix system works, with pipework permanently hot in order to keep DHW response times reasonable. No other mode of operation is possible.

By contrast, the DATA HIU enables the use of a reduced keep warm temperature, or simply to use a bypass at the top of risers, yet will still out-perform the SAV Termix unit on time it takes to achieve full temperatures at taps. The following graph shows the SP test results for DHW draww-off following overnight standby. The SAV Termix is shown in blue, the DATA HIU in red (keep warm off and keep warm set to reduced):

CompareDATAdrawoffs.jpg

For further information on the SP test results and the technologies concerned, please read our wiki article on the tests.

Thermal Integration DATA HIU compared to the Alfa Laval Mini City HIU

This article lists the differences between the Thermal Integration DATA and the Alfa Laval Minicity NP Heat Interface Units.

The data on the DATA HIU used in this article is obtained from the published HIU test results from SP Technical Research Institute of Sweden, funded by DECC. The Mini City has not undergone independent performance testing against the new standards so the best available data has been extracted from literature available.

Alfa_Laval_Mini_City
SP Test Report - TIL Data
VWART Calculation - TIL Data

Without the test data it is impossible to determine the annual performance of the Mini City, or to derive a VWART figure (Volume Weighed Average Return Temperature). The most critical performance factor that effects plant efficiency is return temperatures from HIUs. Independent test provide figures for return performance in the three key areas of DHW generation, central heating, and standby keep-warm modes. The latter of the three has the greatest effect as it runs all day every day, and with traditional mechanical HIUs, such as the Mini City this return temperature will be expected to be above the DHW setpoint (typically over 55C). By comparison, the independent test data on the DATA HIU shows how it delivers return temperatures of approximately 25C in a keep warm mode. This represents a fundamental improvement in efficiency, with a direct impact on plant and pipe sizing, and more importantly on running costs.

HIU Supplier
Thermal Integration Alfa Laval
HIU Model
DATA Plus DMini City NP
Dimensions 490mm wide x 640 high x 271mm 430mm wide x 1480 high x 160mm
Hot Water Priority Yes No
Design Pressure (Primary) 16 bar 16 bar
Weighed Average Annual Volumes Used 77.4 m3/year Unknown (Estimated 170 m3/year)
Volume Weighed Average Return Temperature (VWART) 23.2°C Unknown (Estimated 50°C)
Surface Area of Casing (heat loss) 1.2m2 1.9m2
Return Temperature Protection Yes No
Typical return temperature with unbalanced radiators (test 1e) 50°C (settable) Significantly higher #2
Water Hammer Arrestor Optional No
Peak DHW Output 81 kW (80C Primary) 85 kW (80C Primary)
Central Heating Return Temperature (70C Flow, 4kW) 35.8°C Unknown
Central Heating Pump Exercise Yes No
Provision of error codes to BMS/billing systems

Yes:
Tampering with Sensors
Component Failure
Network Response Times

None
Tamperproof Settings Yes No
Remote commissioning capabilities Yes No
Legionella Protection Cycle Yes No

Heat loss from the HIU shows up in the form of hot cupboard spaces and corridors, as well as a constant use of paid for energy. This is especially detrimental on pre-pay systems where credit will disappear even when the system is not is use. A comparison of heat loss can only be made through comparing surface area and internal temperatures over ambient when in standby mode. For the Mini City HIU the surface area multiplied by the temperature difference comes to 33.6 m2C, where for the DATA it works out to only 3.6 m2C.

The other key points to consider when comparing performance is the fact that the Mini City lacks any of the important features provided by the electronic control system on the DATA, notable:

  • Return temperature limitation, to protect system from unbalanced radiators. Where the DATA HIU will ensure return temperatures never rise above a set level, the MiniCity will pass the inefficiencies from a radiant system back to the return, resulting in elevated return temperatures.
  • Primary flow temperature tracking and weather compensation. The DATA will follow the available primary temperatures and adjust its target heating temperatures accordingly. This means you can weather compensate the entire system from the plant room, with HIUs automatically adjusting to suit. With the Mini City, dropping primary flow temperatures will result in valves opening and return temperatures approaching those of the flow.
  • Legionella cycle. With DHW setpoints been set lower, sometimes as low as 45C, to improve plant-room efficiency, it becomes necessary to implement a Legionella protection cycle. The Mini City, arguably, should not be set below 55C (DHW and keep-warm) or questions regarding Legionella safety arise. WRAS approval procedure is currently under review in this respect.
  • Remote connection. It is a standard practice with the DATA HIU to extend the 2-core data connection cable to the risers, in order to enable commissioning and inspection of error history without gaining access to properties. Service engineers can check if units have been tampered with, as well as alter setpoints, without ever needing to arrange access to the property. The system can be further extended for off-site monitoring and control. As a mechanical HIU, the Mini City provides no remote connection, no error log, no tamper alarms, and will require access to properties for any checks or alterations.

Thermal Integration DATA HIU compared to the Herz Dublin HIU

This article lists the differences between the Thermal Integration DATA and the Alfa Laval Minicity NP Heat Interface Units.

The data on the DATA HIU used in this article is obtained from the published HIU test results from SP Technical Research Institute of Sweden, funded by DECC. The Mini City has not undergone independent performance testing against the new standards so the best available data has been extracted from literature available.

Herz Dublin HIU
SP Test Report - TIL Data
VWART Calculation - TIL Data

Without the test data it is impossible to determine the annual performance of the Dublin, or to derive a VWART figure (Volume Weighed Average Return Temperature). The most critical performance factor that effects plant efficiency is return temperatures from HIUs. Independent test provide figures for return performance in the three key areas of DHW generation, central heating, and standby keep-warm modes. The latter of the three has the greatest effect as it runs all day every day.

The DHW temperature controller in the Dublin HIU is flow proportional, meaning that the primary flow rate is proportional to the DHW flow. When a single tap is opened, the flow from the primary will be low, and it will take significant time to clear cold primary pipework. To avoid long delays of water to taps, the keep warm needs to be maintained over 40C.

By comparison, the Data HIU draws primary water at up to 20 litres/minute when primary temperatures are low and a tap is opened, in order to rapidly clear pipework. The independent test data on the DATA HIU shows how it delivers return temperatures of approximately 25C in a keep warm mode. This represents a fundamental improvement in efficiency, with a direct impact on plant and pipe sizing, and more importantly on running costs.

The diagram below shows how a heat network that requires all pipework to be maintained hot at all times compared to one that allows branches to go cold has approximately half the overall system efficiency. These calculations can be seen on our online heat network calculator, that enables you to fully analyse the performance of a network based on topology, HIU selection, and various operational parameters. Click here to view Heat Network Calculator.

The network on the left would be how the Herz system works, with pipework permanently hot in order to keep DHW response times reasonable. No other mode of operation is possible.

By contrast, the DATA HIU enables the use of a reduced keep warm temperature, or simply to use a bypass at the top of risers, yet will still out-perform the Herz unit on time it takes to achieve full temperatures at taps.


HIU Supplier
Thermal Integration Herz
HIU Model
DATA Plus Dublin
Dimensions 490mm wide x 640 high x 271mm 440mm wide x 750high x 360mm
Hot Water Priority Yes Yes
Design Pressure (Primary) 16 bar 10 bar
Weighed Average Annual Volumes Used 77.4 m3/year Unknown (Estimated 120 m3/year)
Volume Weighed Average Return Temperature (VWART) 23.2°C Unknown (Estimated 40°C)
Return Temperature Protection Yes No - RTL Valve used as thermal bypass
Typical return temperature with unbalanced radiators (test 1e) 50°C (settable) Significantly higher #2
Water Hammer Arrestor Optional No
Peak DHW Output 81 kW (80C Primary) 45 kW (81C Primary)
Central Heating Return Temperature (70C Flow, 4kW) 35.8°C Unknown
Differential Pressure Control Via stepper motor up to 2.5 bar Externally fitted
Central Heating Pump Exercise Yes No
Provision of error codes to BMS/billing systems

Yes:
Tampering with Sensors
Component Failure
Network Response Times

None
Tamperproof Settings Yes No
Remote commissioning capabilities Yes No
Legionella Protection Cycle Yes No

Heat loss from the HIU shows up in the form of hot cupboard spaces and corridors, as well as a constant use of paid for energy. This is especially detrimental on pre-pay systems where credit will disappear even when the system is not is use. A comparison of heat loss can only be made through comparing surface area and internal temperatures over ambient when in standby mode. For the Mini City HIU the surface area multiplied by the temperature difference comes to 33.6 m2C, where for the DATA it works out to only 3.6 m2C.

The other key points to consider when comparing performance is the fact that the Herz Dublin lacks any of the important features provided by the electronic control system on the DATA, notable:

  • Return temperature limitation, to protect system from unbalanced radiators. Where the DATA HIU will ensure return temperatures never rise above a set level, the Herz Dublin will pass the inefficiencies from a radiant system back to the return, resulting in elevated return temperatures.
  • Primary flow temperature tracking and weather compensation. The DATA will follow the available primary temperatures and adjust its target heating temperatures accordingly. This means you can weather compensate the entire system from the plant room, with HIUs automatically adjusting to suit. With the Herz Dublin, dropping primary flow temperatures will result in valves opening and return temperatures approaching those of the flow.
  • Legionella cycle. With DHW setpoints been set lower, sometimes as low as 45C, to improve plant-room efficiency, it becomes necessary to implement a Legionella protection cycle. The Herz Dublin, arguably, should not be set below 55C (DHW and keep-warm) or questions regarding Legionella safety arise. WRAS approval procedure is currently under review in this respect.
  • Remote connection. It is a standard practice with the DATA HIU to extend the 2-core data connection cable to the risers, in order to enable commissioning and inspection of error history without gaining access to properties. Service engineers can check if units have been tampered with, as well as alter setpoints, without ever needing to arrange access to the property. The system can be further extended for off-site monitoring and control. As a mechanical HIU, the Herz Dublin provides no remote connection, no error log, no tamper alarms, and will require access to properties for any checks or alterations.

Thermal Integration DATA HIU compared to Pegler Yorkshire GB00049

This article lists the differences between the Thermal Integration DATA and the Pegler Yorkshire GB00049 Heat Interface Units.

The data used in this article is obtained from the published HIU test results from SP Technical Research Institute of Sweden, funded by DECC.


SP Test Report - TIL Data
SP Test Report - Pegler Yorkshire GB00049
VWART Calculation - TIL Data
VWART Calculation - Pegler Yorkshire GB00049
SP Test Report - Unbalanced Radiators
Literature on Pegler Yorkshire HIU

The purpose of the test regime is four-fold:

  • To enable the performance of different HIUs to be evaluated within the context of typical UK operating conditions, thereby enabling heat network developers to evaluate the performance of specific HIUs against design requirements.
  • To generate operating data on the expected performance of specific HIUs given “normal” operating parameters, to enable heat network operators to identify anomalous performance.
  • To provide a framework for HIU manufacturers to evaluate the performance of their equipment within the UK context, thereby feeding into their continuous improvement development programmes.
  • To provide data on the impact of different design and installation choices on HIU performance, thereby assisting designers of heat networks to optimise heat network performance.


For each tested HIU, the data enables the calculation of the Volume Weighted Average Return Temperature (VWART). VWART provides a figure that represents the average impact that a specific HIU will have on network return temperature, under normal operation, and has been agreed upon by all manufacturers who have taken part in the tests.

The following table summarises the data from the test results.

HIU Supplier
Thermal Integration Pegler Yorkshire
HIU Model
DATA Plus GB00049
Hot Water Priority Yes Yes
Design Pressure (Primary) 10 bar 10 bar
Design Pressure (Radiators) 3 bar 3 bar
Design Pressure (DHW) 10 bar ?
Weighed Average Annual Volumes Used 77.4 m3/year 167.5 m3/year
Volume Weighed Average Return Temperature (VWART) 23.2°C 44.6°C
Return Temperature Protection Yes No
Typical return temperature with unbalanced radiators (test 1e) 50°C (settable) 61°C
Water Hammer Arrestor Optional No
Peak DHW Output 71.4 kW @ 55C 52.2 kW @ 48.8C
DHW response times to 50°C (55°C Setpoint) 26 seconds #1 26 seconds
DHW response times to 55°C (55°C Setpoint) 28 seconds #1 35 seconds
Central Heating Return Temperature (70C Flow, 4kW) 35.8°C 38.7°C
Provision of error codes to BMS/billing systems

Yes:
Tampering with Sensors
Component Failure
Network Response Times

None
Tamperproof Settings Yes No
Remote commissioning capabilities Yes No
Legionella Protection Cycle Yes No

#1 DHW response Times are with keep-warm at 25°C. With an increased keep-warm these times can be reduced to 6 seconds and 8 seconds accordingly.

#2 Direct comparison of current test data is questionable due to fluctuations in ambient air temperature. Refer to graphs.

The DHW temperature controller in the Pegler-Yorkshire HIU is flow proportional, meaning that the primary flow rate is proportional to the DHW flow. When a single tap is opened, the flow from the primary will be low, and it will take significant time to clear cold primary pipework. To avoid long delays of water to taps, the keep warm needs to be maintained over 40C.

By comparison, the Data HIU draws primary water at up to 20 litres/minute when primary temperatures are low and a tap is opened, in order to rapidly clear pipework. The independent test data on the DATA HIU shows how it delivers return temperatures of approximately 25C in a keep warm mode. This represents a fundamental improvement in efficiency, with a direct impact on plant and pipe sizing, and more importantly on running costs.

The diagram below shows how a heat network that requires all pipework to be maintained hot at all times compared to one that allows branches to go cold has approximately half the overall system efficiency. These calculations can be seen on our online heat network calculator, that enables you to fully analyse the performance of a network based on topology, HIU selection, and various operational parameters. Click here to view Heat Network Calculator.

The network on the left would be how the Pegler-Yorkshire system works, with pipework permanently hot in order to keep DHW response times reasonable. Dropping keep warm temperatures, while possible, will result in longer delays for DHW.

By contrast, the DATA HIU enables the use of a reduced keep warm temperature, or simply to use a bypass at the top of risers, yet will still match, and slightly better, the Pegler-Yorkshire unit on time it takes to achieve full temperatures at taps. The following graph shows the SP test results for DHW draw-off following overnight standby. The Pegler-Yorkshire is shown in purple, the DATA HIU in red (keep warm off and keep warm set to reduced):

CompareDATAdrawoffs.jpg

For further information on the SP test results and the technologies concerned, please read our wiki article on the tests.

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