Date (5/3/2014)

1. Date (5/3/2014)

2. Selection and sizing of domestic hot water production and distribution Havid El khaoui

3. Content • DHW demand • House • Apartment Buildings (central domestic hot water) • Types of devices DHW production • Dimensioning • Recent developments 3

4. 4

5. DHW- Demand • Large variation in flow rate: periods with little or no usage alternate with peak demands • Simultaneity i.f.v. the size of the building • Difference week <-> weekend • Graphs: • Flow (L/min) i.f.v. time • Cummulated volume i.f.v. time • Input for dimensioning • Peak flow (L / min) • Maximum daily consumption (L / day) L/min ∑ L

6. DHW- Demand-House Weekday:

7. DHW- Demand-House Weekend:

8. DHW- Demand- Apartment Building

9. DHW- Demand- Apartment Building Weekend Weekday ∑ L @ 60°C ∑ L @ 60°C 277 appartements centrale DHW-production Uur (-)

10. DHW-production • Different types: • Instant production DHW is produced at time of DHW demand • Semi-instant • Semi-accumulation • Full accumulation (storage): DHW is produced before DHW demand and stored foto: I. Piette - ATIC

11. Instant gas water heater (house) • Open – closed (CO poisoning) • Ignition: pilot flame or turbine • Modulation (power control x% - 100%): • Hydraulic control • Thermal control

12. Instant gas water heater (house) • Modulation (power control x% - 100%): • Hydraulic (P ~ qDHW – assumes constant ∆ T) • Thermal (P ~ qDHW en TCW - important for solar energy) Minimum flow rate Minimum flow rate

13. Instant heater with CH (house) • Sometimes with limited accumulation • Limiting the waiting time • Less frequent startup • Lower power

14. Plate heat exchanger with boiler (apartment buildings) Boiler Heat exchanger DHW CW

15. Instantproduction No storage so less thermal losses lower investment less space With correct sizing: availability of an unlimited amount of hot water It must cover the DHW peak high power needed Sensitive to accumulation of lime stone (water softening) PRO’S CON’S

16. Accumulation • Ex: Electric boiler: low power to heat the total daily consumption at night rate

17. Accumulation Very good stability of the temperature = comfort Large peak flows possible with relatively limited capacity Takes large space in the building Major thermal losses Empty = Empty PRO’S CON’S

18. Semi-instant or semi-accumulation Storage Boiler Heat exchanger DHW CW Storage Boiler DHW CW Principe:

19. Semi-instant or semi-accumulation Smaller sizing Boiler Accumulation This system gives , if good dimensioned, a good temperature stability The power requirement is much less than instant production In comparison with full accumulation , still quite large boiler power required Requires more space than instant production Standby losses Pro’s Con’s

20. Semi-accumulation - Gas • With chimney or wall socket: • a closed unit •   good insulation Illustraties: Ariston/Eole – ACV/Heatmaster

21. DHW-production Central Decentral

22. DHW-production Central Decentral • Decentral: • Pros: • No distribution net • Independent production Cons: • Multiple devices • large installed power • Multiple chimneys

23. DHW-production Central Decentral • Central: • Pros: • Low investment • Limited space needed • One chimney Cons: • High distribution losses • Difficult to devide the cost

24. Dimensioning

25. Dimensioning Peak flow Foreign standards determine peak flow based on the taps in the installation: Used for sizing of pipes and instant DHW production

26. Nominal flow taps sum of all taps Dimensioning Peak flow Example: DIN 1988-300:2012 formula fordesign peak flow with coefficients (simultaneity!)

27. Dimensioning Peak flow

28. Dimensioning Peak flow Used for sizing: pipes For each section, a design peak flow is calculated -> pipe size instant DHW-production The needed power is calculated from the peak flow

29. Dimensioning Distribution (pipes) • The size of each pipe section is calculated from peak flow in the section, taking into account: • Available pressure after the water meter • Minium needed pressure at tap (typical 1 bar) • Pressure losses of height • Pressure losses: • Pipes (i.f.v. diameter) • Fittings (bends, tees, ...) • Appliances • Maximum pipe velocity (avoid noise)

30. Dimensioning Instant production • Pmin = qDHW,peak * c * (TDHW-TCW)/60.000 (kW) • With: • Pmin the minimum capacity of the water heater (kW) • qDHW,peak peak flow (L/min) • specific heat of water c = 4186 J / (kg.K) • for TCW is usually 10 ° C Example: Power needed for qDHW,peak = 9 L/min @ 60°C: Pmin = 9 * 4186 * (60-10)/60.000 = 31 kW

31. Dimensioning Maximum daily volume • DIN 4708: 50 L/day/person @ 45 °C = 35 L/dag @ 60°C • WTCB: 30 L/day/person @ 60 °C • Ecofys (NL) about : 25 - 50 l/day/person Bron: Ecofys Nl + diverse projecten in België

32. Cummulative used volume ( ∑ L) Heating ∆t heating Consumtion period (uur) 6 12 18 24 6 Dimensioning Accumulation Maximum daily volume

33. Dimensioning Accumulation • Volume accumulator: • Vacc= Vmax. day,DHW / f • With: • - Vacc en Vmax. day,DHW in L @ 60°C • f: tap efficienty accumulator - 0.9 voor 100 % accu’s • 0.8 voor boilers met ingebouwde ww Power accumulator: Pmin = Vacc * c * (TDHW-TCW) / ∆theating / 1000 (kW) With: • Δtheating time without use, available for heating accumulator (s) • specific heat of water c = 4186 J / (kg.K) • for TCW is usually 10 ° C taken

34. Dimensioning Accumulation • Example: • electric boiler for family of 5 on nightly rate • Vmax. day,DHW = 5 * 30 L = 150 L • Vacc, min = 150 L/ 0,9 = 167 L If: ∆theating = 6 u = 6*60 min*60 s = 21600 s • Pmin = 167 * 4186 * (60-10) / 21600 / 1000 = 1,6 kW

35. A Kitchen Living room B Bath room Bed room 1 Bed room 2 E C D Dimensioning Exercise: • 3 person appartment: • Select: • Pipe diameter • Power of Instant production • Power and Volume of Accumulation production

36. A Kitchen Living room B Bath room Bed room 1 Bed room 2 E C D Dimensioning Exercise: • 3 person appartment: • Select: • Pipe diameter • Power of Instant production • Power and Volume of Accumulation production

37. A 4m 2 B 1 E 1m D 3 C 1m 6 5 4 7 2m 2m 2m 1m 0,5m Dimensioning Exercise: • Isometric view • Select: • Pipe sections • Pipe distance • Exact location taps and production

38. Dimensioning Exercise: • Netherlands standard • Select: • The flow rate at each tap is given • Calculate the Tapping Unit at each tap • Calculate flow in each joint section • Simultaneity Q2 TU2 Q3 TU3 Q=(ΣTU)*0,083 Q1 TU1

39. 2,25 TU 0,12 L/s 7 6 b 0,083 L/s 1 TU B-HOT 0,107 L/s 2TU 0,042 L/s 0,25 TU 3,25 TU 0,15 L/s 0,167 L/s 4 TU 0,167 L/s 4 TU 0,083 L/s 1 TU 0,042 L/s 0,25 TU B-COLD D E A a C 5 1 2 3 4 12,5 TU 0,29 L/s 8,5 TU 0,24 L/s 5,25 TU 0,19 L/s 1,25 TU 0,09 L/s Dimensioning Exercise: Netherlands standard Select:

40. Dimensioning Prod Spec Exercise: 2 • Netherlands standard • Select: • Calculate pipe sections 100kPa 1 • Pressure loss by height • Pressure loss by valve • Pressure loss by the pipe 3 rho*g*h/1000 200kPa ? 100kPa

41. Dimensioning Exercise: • Netherlands standard • Select: • Calculate pipe sections Rmax = pressure loss pipe (kPa/m) Pnet = supply pressure (kPa) Ptap = pressure needed at tap (kPa) ∆Ph = pressure loss by height (kPa) ∆Papp = pressure loss by valve (kPa) L = length route (m) f = factor for fittings

42. Dimensioning Exercise: • Netherlands standard • Select: • Calculate pipe sections Maximum speed (vmax) = 1,5 m/s Supply pressure (Psup) = 200 kPa Pressure at each tap (Ptap) = 100 kPa pressure loss by valve (∆Papp) = 50kPa Factor for fittings (f) = 1,2 Temperature cold (T) = 10°C Temperature hot (T) = 60°C Material = copper Mass density = 990 kg/m³ g = 9,81 m/s²

43. A 4m 2 B 1 E 1m D 3 C 1m 6 5 4 7 2m 2m 2m 1m 0,5m Dimensioning Exercise: • Netherlands standard • Select: • Calculate pipe sections L = Longest route and highest tap route D,hot = 9,5 m

44. A 4m 2 B 1 E 1m D 3 C 1m 6 5 4 7 2m 2m 2m 1m 0,5m Dimensioning Exercise: • Netherlands standard • Select: • Calculate pipe sections L = Longest route and highest tap route D,hot = 9,5 m route A,hot = 12,5 m

45. Dimensioning Exercise: • Netherlands standard • Select: • Calculate pipe sections Height of the tap

46. Dimensioning Exercise: • Netherlands standard • Select: • Calculate pipe sections

47. A 4m 2 B 1 E 1m D 3 C 1m 6 5 4 7 2m 2m 2m 1m 0,5m Dimensioning Exercise: • Netherlands standard • Select: • Calculate pipe sections

48. 2,25 TU 0,12 L/s 6 7 13 10 13 10 8 b 0,083 L/s 1 TU B-HOT 0,107 L/s 2TU 0,042 L/s 0,25 TU A C D 0,167 L/s 4 TU B-COLD 0,167 L/s 4 TU 0,083 L/s 1 TU 0,042 L/s 0,25 TU a E 13 10 8 13 13 19,8 19,8 10 1 13 2 5 3 4 12,5 TU 0,29 L/s 8,5 TU 0,24 L/s 5,25 TU 0,19 L/s 1,25 TU 0,09 L/s Dimensioning Exercise: • Netherlands standard • Select: • Calculate pipe sections

49. Dimensioning Exercise: • Netherlands standard • Select: • Instant production • Pmin = qDHW,peak * ρ * c * (TDHW-TCW)/1.000 (kW) • With: • Pmin is the minimum capacity of the water heater (kW) • qDHW,peak peak flow at the water heater is 0,15 L/s @ 60°C • specific heat of water c = 4,19 kJ / (kg.K) • TDHW = 60 ° C • TCW = 10 ° C • mass density ρ = 980 (kg/m³) Pmin = 0,15 *980*4,19 * (60-10)/1.000 = 30 kW

50. Dimensioning Exercise: • Netherlands standard • Select: • accumulation production • Vacc = Vmax. day,DHW / f • Pmin = Vacc * ρ * c * (TDHW-TCW)/(1.000*∆theating) (kW) • With: • Vacc is the accumulator volume (L) • Vmax. day,DHW is the daily demand DHW per person per day (L) • Volume per person is 30L/day • F is the tap efficienty of the accumulator • Pmin the minimum capacity of the water heater (kW) • qDHW,peak peak flow at the water heater (L/s) • specific heat of water c = 4,19 kJ / (kg.K) • TDHW = 60 ° C &TCW = 10 ° C • mass density ρ = 980 (kg/m³) • Δtheating time available for heating accumulator (s)