SAV Systems Scandia House Boundary Road Woking Tel: 0044(0) 1483 77 1910 Helping Building Services Engineers Apply Low Carbon Technologies Web: www.sav-systems.com Tel: 0044(0) 01483 77 1910 Designing and commissioning low carbon variable volume systems Web: www.sav-systems.com
Focus on OPEX to Achieve Low Carbon 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 Tel: 0044(0) 01483 77 1910 Designing and commissioning low carbon variable volume systems Web: www.sav-systems.com
Delivering 4MWh Delta T 40 / 21,500 Litres Delta T 30 / 28,667 Litres Delta T 20 / 43,00 Litres Delta T 10 / 86,000 Litres Tel: 0044(0) 01483 77 1910 Designing and commissioning low carbon variable volume systems Web: www.sav-systems.com
How to achieve well functioning low carbon central plant systems Challenge is that most systems are running inefficiently 80 65 Aim is to lower the return temperature Tel: 0044(0) 01483 77 1910 Designing and commissioning low carbon variable volume systems Web: www.sav-systems.com
Low Return Under All Load Conditions Design Condition -4 ° C 70/40 ° C Shoulder Months 60/40 ° C Summer 55/40 ° C Tel: 0044(0) 01483 77 1910 Designing and commissioning low carbon variable volume systems 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. Tel: 0044(0) 01483 77 1910 Designing and commissioning low carbon variable volume systems 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 Tel: 0044(0) 01483 77 1910 Designing and commissioning low carbon variable volume systems Web: www.sav-systems.com
Why are low returns important? Tel: 0044(0) 01483 77 1910 Designing and commissioning low carbon variable volume systems Web: www.sav-systems.com
Management Objective Continuous Monitoring of Return Temperatures and Calculating Delta T Ultrasonic heat meter Tel: 0044(0) 01483 77 1910 Designing and commissioning low carbon variable volume systems Web: www.sav-systems.com
Distribution Heat Losses Wast Tel: 0044(0) 01483 77 1910 Designing and commissioning low carbon variable volume systems Web: www.sav-systems.com
Objective – Achieving the lowest possible energy consumption and avoiding unnecessary energy wastage! 80 65 Strategy – Follow the Danish experience and focus on system return temperatures. Tel: 0044(0) 01483 77 1910 Designing and commissioning low carbon variable volume systems 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.” ✔ Tel: 0044(0) 01483 77 1910 Designing and commissioning low carbon variable volume systems Web: www.sav-systems.com
Complete System Approach Needed! • Supply Side • The Central plant • Thermal Store Control • Pipe & Flow sizing • Variable Flow • Demand Side • Radiator Systems • FCUs • DHW generation • Soft Landings • Continues Monitoring Tel: 0044(0) 01483 77 1910 Designing and commissioning low carbon variable volume systems Web: www.sav-systems.com
Supply Side - Heating Plant • Primary energy efficiencies 80/60°C Heat Pump/Condensing Boiler Tel: 0044(0) 01483 77 1910 Designing and commissioning low carbon variable volume systems Web: www.sav-systems.com
Supply Side – Thermal Stores 𝑄 = 4.2 ∙ 𝑅 ∙ ∆𝑢 • Primary energy efficiencies 80/60°C Energy storage Tel: 0044(0) 01483 77 1910 Designing and commissioning low carbon variable volume systems Web: www.sav-systems.com
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. ” 1000 litres storage with delta T of 20 deg. (80/60) 1000 litres storage with delta T of 40 deg. has capacity of 23 kW. (80/40) has capacity of 46 kW. Tel: 0044(0) 01483 77 1910 Designing and commissioning low carbon variable volume systems Web: www.sav-systems.com
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. ” CHP System Tel: 0044(0) 01483 77 1910 Designing and commissioning low carbon variable volume systems Web: www.sav-systems.com
Supply Side - District Heating Plant • Primary energy efficiencies 70/40C Condensing boiler, Heat Pump Tel: 0044(0) 01483 77 1910 Designing and commissioning low carbon variable volume systems Web: www.sav-systems.com
Supply Side – Central Plant – Low Load (20%) Tel: 0044(0) 01483 77 1910 Designing and commissioning low carbon variable volume systems Web: www.sav-systems.com
Supply Side – Central Plant – Medium Load (40%) Tel: 0044(0) 01483 77 1910 Designing and commissioning low carbon variable volume systems Web: www.sav-systems.com
Supply Side – Central Plant – High Load (100%) Tel: 0044(0) 01483 77 1910 Designing and commissioning low carbon variable volume systems Web: www.sav-systems.com
Supply Side – Flow Rate 3𝑙𝑋 𝑅 = 4.2 ∙ 10𝐿 = 0.071 𝑙/𝑡 80/70°C 3𝑙𝑋 𝑅 = 4.2 ∙ 30𝐿 = 0.024 𝑙/𝑡 70/40°C Decreasing Flow Rates Decreasing pipe sizes • Decreasing pump sizes • Decreasing pump energy • Increasing terminal units sizes? • Tel: 0044(0) 01483 77 1910 Designing and commissioning low carbon variable volume systems Web: www.sav-systems.com
Plant Pumping Energy Control pumps at extremities • Local Differential Pressure Control • Bypasses kept to a minimum • Tel: 0044(0) 01483 77 1910 Designing and commissioning low carbon variable volume systems Web: www.sav-systems.com
Flow Temperature Function of Return Tel: 0044(0) 01483 77 1910 Designing and commissioning low carbon variable volume systems Web: www.sav-systems.com
Pressure and Temperature DHW control The valve consist of following: Temp (4) (1) The proportional valve / Pilot sensor. valve. (2) (2) Thermostatic control valve. DH Flow. DHW (3) Differential pressure 70C controller. 50C (4) Thermostat with sensor. DH Return. 20C 10C Cold water (1) (3) supply. Proportional Differential valve. pressure controller. Tel: 0044(0) 01483 77 1910 Designing and commissioning low carbon variable volume systems Web: www.sav-systems.com
Demand Side – DHW Tel: 0044(0) 01483 77 1910 Designing and commissioning low carbon variable volume systems Web: www.sav-systems.com
System design: units, pipe and central plant Tel: 0044(0) 01483 77 1910 Designing and commissioning low carbon variable volume systems Web: www.sav-systems.com
Management Objective Continuous Monitoring of Return Temperatures and Calculating Delta T Ultrasonic heat meter Tel: 0044(0) 01483 77 1910 Designing and commissioning low carbon variable volume systems Web: www.sav-systems.com
Delivering 4MWh Delta T 40 / 21,500 Litres Delta T 30 / 28,667 Litres Delta T 20 / 43,00 Litres Delta T 10 / 86,000 Litres Tel: 0044(0) 01483 77 1910 Designing and commissioning low carbon variable volume systems 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 Tel: 0044(0) 01483 77 1910 Designing and commissioning low carbon variable volume systems Web: www.sav-systems.com
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