Standard Booster WSHP vs Flexible ST2P-range W/W | Pure Thermal

Pure Thermal Technical Bulletin

Subject: System Comparison.

                Comparing Standard Booster Water Source Heat Pumps to more Flexible ST2P range Stage 2 Water/Water units.

Issue date: May 2024

Subject area: Two Stage Heat Pump Applications

Detail reviewed: Standard Booster WSHP vs Flexible ST2P-range W/W

Overview:

Standard booster Water Source Heat Pumps (WSHP) can offer application restrictions due to three main areas:

  • Standard Booster units can utilise high GWP refrigerants such as R134a (GWP of 1430)

The Global Warming Potential of these refrigerants is above a safe ceiling of 700 GWP. This can be a selection barrier on low carbon and low GWP applications and also projects that require future proofing with respect to F-Gas phase out restrictions.

  • Standard Booster units operate with a narrow delta T of 7°C to 10°C on the condenser/hot delivery side of the Heat Pump.

This renders standard booster WSHP to be less suitable for retrofit applications which require a wider delta T to maximise the system efficiency based on current system operating temperatures.

  • Standard Booster units achieve a 78°C leaving temperature which can restrict retrofit application.

This means that applications requiring above 78°C are restricted by the leaving temperature of the heat pump. For example, retrofit 82/71°C applications can call for 85°C heat pump flow temperatures on the heat pumps side of a break/plate heat exchanger which booster units are unable to provide.

Alternative:

To overcome these application restrictions Pure Thermal are able to provide options for Stage 2 heat pump units that include standard booster units and also more flexible Low GWP, wide DT and high leaving temperature FLEXIBLE ST2-P heat pumps.

Application flexibility – Stage 2 Heat Pump units:

  • Pure Thermal provide:

Standard Booster units – Bronze range

BUT Pure Thermal ALSO provide:

Flexible STAGE 2 units – ST2-P range units

Flexible STAGE 2 units – ST2P range

  • Low GWP Refrigerant:

The Pure Thermal Flexible Stage 2 ST2P range Water/Water units utilise Low GWP Refrigerants with options to deliver GWP 1 system designs.
A low GWP enables a Two Stage System (or single stage water source) to be applied within more demanding applications where low carbon and F-Gas future proofing are design priorities.

  • Wide DT capability 50 °C to 10 °C:

The Pure Thermal Flexible Stage 2 ST2P range units are capable of operating on a wide delta T up to 50 °C to provide new build and retrofit application flexibility.

A low return temperature and wide DT can increase heat pump efficiency and increase heat pump capacity. This capability enables the ST2-P range units to operate with the widest DT possible to enable straightforward retrofit application for both Heating and Hot Water applications.

  • High Temperature Capability 95 °C:

The Pure Thermal Flexible Stage 2 ST2P range units are capable of operating with up to 95°C output temperatures.

This design flexibility means that a Two Stage Low GWP Heat Pump System can be applied within the most demanding applications and removes any operating temperature restrictions that may be associated with standard booster units.

Summary:

These three key factors enable a Two Stage Heat Pump System to deliver higher system efficiencies and provide application flexibility:

Standard Booster + Flexible ST2P Detailed image

 

 

 

 

This flexible high-performance approach means that the heat pump has the capability to match the exact requirements of an application whilst providing a future proofed system design.

Low GWP 1 + Wide DT 50 °C to 10 °C + High Temperature 95 °C

Contact the Pure Thermal team at info@purethermal.co.uk or on 0203 488 4618

Flexible ST2P Operating Envelope P60

 

 

 

 

 

 

 

 

 

 

 

 

Standard Booster Operating Envelope
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