Tel: 0044(0) 01483 77 1910 Designing and commissioning low - - PowerPoint PPT Presentation

Designing and commissioning low carbon variable volume systems

Tel: 0044(0) 01483 77 1910 Web: www.sav-systems.com

SAV Systems

Scandia House Boundary Road Woking Tel: 0044(0) 1483 77 1910 Web: www.sav-systems.com

Helping Building Services Engineers Apply Low Carbon Technologies

Designing and commissioning low carbon variable volume systems

Tel: 0044(0) 01483 77 1910 Web: www.sav-systems.com

1. Delta T – Delta T – Delta T 2. Design to Maximum Delta T all seasons 3. Variable Volume 4. Flow temp a Function of Return

Focus on OPEX to Achieve Low Carbon

Designing and commissioning low carbon variable volume systems

Tel: 0044(0) 01483 77 1910 Web: www.sav-systems.com

Delta T 40 / 21,500 Litres Delta T 30 / 28,667 Litres Delta T 20 / 43,00 Litres Delta T 10 / 86,000 Litres

Delivering 4MWh

Designing and commissioning low carbon variable volume systems

Tel: 0044(0) 01483 77 1910 Web: www.sav-systems.com

Challenge is that most systems are running inefficiently Aim is to lower the return temperature

80 65

How to achieve well functioning low carbon central plant systems

Designing and commissioning low carbon variable volume systems

Tel: 0044(0) 01483 77 1910 Web: www.sav-systems.com

Design Condition -4°C 70/40°C Shoulder Months 60/40°C Summer 55/40°C

Low Return Under All Load Conditions

Designing and commissioning low carbon variable volume systems

Tel: 0044(0) 01483 77 1910 Web: www.sav-systems.com

Danish Model

The adoption of low carbon technologies in Denmark is being driven by the operators of district heating schemes, combined with high carbon taxes.

Designing and commissioning low carbon variable volume systems

Tel: 0044(0) 01483 77 1910 Web: www.sav-systems.com

Low returns save money!

Less heat lost in the distribution pipework Reduced electricity cost to run pump No need to extend the DH distribution pipe Potential higher electricity production at the CHP plant Less cost for the DH operator Less cost for you the customer

Designing and commissioning low carbon variable volume systems

Tel: 0044(0) 01483 77 1910 Web: www.sav-systems.com

Why are low returns important?

Designing and commissioning low carbon variable volume systems

Tel: 0044(0) 01483 77 1910 Web: www.sav-systems.com

Management Objective Continuous Monitoring of Return Temperatures and Calculating Delta T

Ultrasonic heat meter

Designing and commissioning low carbon variable volume systems

Tel: 0044(0) 01483 77 1910 Web: www.sav-systems.com

Distribution Heat Losses

Wast

Designing and commissioning low carbon variable volume systems

Tel: 0044(0) 01483 77 1910 Web: www.sav-systems.com

Objective – Achieving the lowest possible energy consumption and avoiding unnecessary energy wastage! Strategy – Follow the Danish experience and focus on system return temperatures.

80 65

Designing and commissioning low carbon variable volume systems

Tel: 0044(0) 01483 77 1910 Web: www.sav-systems.com

✔

Strategy - Focus on system return temperatures

AM12/2013 – Combined heat and power for buildings

“It is recommended that, for new systems, radiator circuit temperatures of 70 °C (flow) and 40 °C (return) are used with a maximum return temperature of 25 °C from instantaneous domestic hot water heat exchangers.”

Designing and commissioning low carbon variable volume systems

Tel: 0044(0) 01483 77 1910 Web: www.sav-systems.com

• Supply Side
• The Central plant
• Thermal Store Control
• Pipe & Flow sizing
• Variable Flow
• Demand Side
• Radiator Systems
• FCUs
• DHW generation
• Soft Landings
• Continues Monitoring

Complete System Approach Needed!

Designing and commissioning low carbon variable volume systems

Tel: 0044(0) 01483 77 1910 Web: www.sav-systems.com

• Primary energy efficiencies 80/60°C

Heat Pump/Condensing Boiler

Supply Side - Heating Plant

Designing and commissioning low carbon variable volume systems

Tel: 0044(0) 01483 77 1910 Web: www.sav-systems.com

• Primary energy efficiencies 80/60°C

𝑄 = 4.2 ∙ 𝑅 ∙ ∆𝑢

Energy storage

Supply Side – Thermal Stores

Designing and commissioning low carbon variable volume systems

Tel: 0044(0) 01483 77 1910 Web: www.sav-systems.com

1000 litres storage with delta T of 20 deg. (80/60) has capacity of 23 kW. 1000 litres storage with delta T of 40 deg. (80/40) has capacity of 46 kW.

Supply Side – Thermal Stores

AM12/2013 – Combined heat and power for buildings “A thermal store will only be successful with a variable flow building heating system that can maintain low and constant return temperatures, so that the stored energy is maximised.”

Designing and commissioning low carbon variable volume systems

Tel: 0044(0) 01483 77 1910 Web: www.sav-systems.com

CHP System

Supply Side – CHP

AM12/2013 – Combined heat and power for buildings “Normally, a fixed flow temperature is required from the CHP unit, and the mixing circuit should be used to control the flow temperature off the unit by injecting flow water into the return as required.”

Designing and commissioning low carbon variable volume systems

Tel: 0044(0) 01483 77 1910 Web: www.sav-systems.com

• Primary energy efficiencies 70/40C

Condensing boiler, Heat Pump

Supply Side - District Heating Plant

Designing and commissioning low carbon variable volume systems

Tel: 0044(0) 01483 77 1910 Web: www.sav-systems.com

Supply Side – Central Plant – Low Load (20%)

Designing and commissioning low carbon variable volume systems

Tel: 0044(0) 01483 77 1910 Web: www.sav-systems.com

Supply Side – Central Plant – Medium Load (40%)

Designing and commissioning low carbon variable volume systems

Tel: 0044(0) 01483 77 1910 Web: www.sav-systems.com

Supply Side – Central Plant – High Load (100%)

Designing and commissioning low carbon variable volume systems

Tel: 0044(0) 01483 77 1910 Web: www.sav-systems.com

Supply Side – Flow Rate

80/70°C 70/40°C Decreasing Flow Rates

• Decreasing pipe sizes
• Decreasing pump sizes
• Decreasing pump energy
• Increasing terminal units sizes?

𝑅 = 3𝑙𝑋 4.2 ∙ 30𝐿 = 0.024 𝑙𝑕/𝑡 𝑅 = 3𝑙𝑋 4.2 ∙ 10𝐿 = 0.071 𝑙𝑕/𝑡

Designing and commissioning low carbon variable volume systems

Tel: 0044(0) 01483 77 1910 Web: www.sav-systems.com

Plant Pumping Energy

• Control pumps at extremities
• Local Differential Pressure Control
• Bypasses kept to a minimum

Designing and commissioning low carbon variable volume systems

Tel: 0044(0) 01483 77 1910 Web: www.sav-systems.com

Flow Temperature Function of Return

Designing and commissioning low carbon variable volume systems

Tel: 0044(0) 01483 77 1910 Web: www.sav-systems.com

The valve consist of following:

(1) The proportional valve / Pilot valve. (2) Thermostatic control valve. (3) Differential pressure controller. (4) Thermostat with sensor.

Pressure and Temperature DHW control

Cold water supply. DH Flow. DH Return. DHW

(2) (4)

Temp sensor.

(3)

Differential pressure controller.

(1)

Proportional valve. 70C 20C 10C 50C

Designing and commissioning low carbon variable volume systems

Tel: 0044(0) 01483 77 1910 Web: www.sav-systems.com

Demand Side – DHW

Designing and commissioning low carbon variable volume systems

Tel: 0044(0) 01483 77 1910 Web: www.sav-systems.com

System design: units, pipe and central plant

Designing and commissioning low carbon variable volume systems

Tel: 0044(0) 01483 77 1910 Web: www.sav-systems.com

Management Objective Continuous Monitoring of Return Temperatures and Calculating Delta T

Ultrasonic heat meter

Designing and commissioning low carbon variable volume systems

Tel: 0044(0) 01483 77 1910 Web: www.sav-systems.com

Delta T 40 / 21,500 Litres Delta T 30 / 28,667 Litres Delta T 20 / 43,00 Litres Delta T 10 / 86,000 Litres

Delivering 4MWh

Designing and commissioning low carbon variable volume systems

Tel: 0044(0) 01483 77 1910 Web: www.sav-systems.com

Going forward

• Lack of design standards
• Coming at the end of this year
• Poor understanding of functioning of HIU and its purpose – all about the

return

• Lack of product standards
• Design Issues – Diversities
• Change is needed for central designs

with HIUs to continue