ZIP INSTANTANEOUS HOT WATER THE ULTIMATE IN COMFORT AND EFFICIENCY
Zip Heaters (Aust) Pty Ltd 67-77 Allingham St, Condell Park NSW 2200 Australia
1800 42 43 44 | zipwater.com
The following report compares the various options for the provision of domestic water heating plant to commercial residential buildings.
Capital and operating cost considerations have been developed for the following types of installation :
• Centralised gas-storage plant
• Centralised gas-boosted solar plant
• Individual electric storage units
• Instantaneous continuous flow electric units
Two building scenarios were considered, these being:
• Low-rise: 4 levels of 10 apartments = 40 units
• High-rise: 12 levels of 10 apartments = 120 units
This report compares domestic water heating options for two hypothetical residential buildings. These are :
• A low-rise building of 40 units • A high-rise building of 120 units
Four options for water heating plant have been considered for each building. These are :
• Centralised gas-storage plant • Centralised gas-boosted solar plant • Individual electric storage units • Instantaneous continuous flow electric units
The above options were analysed to review comparative capital costs and energy consumption of each plant.
The following assumptions were made :
Buildings
Building apartment numbers comprised :
• Low-rise : 4 levels of 10 apartments = 40 units • High-rise : 12 levels of 10 apartments = 120 units
Centralised Hot Water Plant
For each building, a centralised hot water plant was located at roof level, requiring a thermally insulated, pumped hot water recirculation system, reticulating vertically through the building from a header pipe, with a common return line to the plant - a configuration typically known as a flow-and-return system. Five vertical droppers were located to service groups of two apartments, each with a hot-water meter recording consumption. Reference should be made to the water schematic included as ANNEXURE A, which represents a typical building reticulation, with authority sub-metering of the cold water service.
Two such plants were considered :
• Gas-storage : plant comprising manifolded commercial gas-storage heaters • Gas-boosted Solar : roof-mounted solar panel collectors with tanks and gas continuous flow
burners
Individual Unit Water Heaters
The case of individual electric water heaters installed in each apartment was considered, in a typical domestic arrangement with an electrical connection from the apartment’s power supply.
Two such installations were considered :
• Direct electric storage heater • Instantaneous electric continuous flow heater
Capital Costs
The costs of each installation was estimated, including the following components :
• Water heating plant • Electrical services comprising consumer and sub-mains, metering, distribution boards and
circuitry [extra over costs just associated with the water heating plant] • Hydraulic services comprising pipework, drainage, hot water metering, valves and fittings
[extra over costs just associated with the water heating plant]
Electrical Considerations
Calculation of additional electrical demand imposed on the buildings by 3-phase instantaneous electric continuous flow heaters was based on :
• Maximum demand calculations from AS/NZS.3000 guidelines (Table C1: Maximum Demand - Single & Multiple Dwelling units - Load Group E)
• An allowance of 5 KVA per apartment, excluding IHWU’s • Each IHWU drawing 27KW on an average 0,8 p.f.
Standard transformer capacities for the two buildings excluding IHWU’s were determined as :
• 40 units x 5KVA = 200KVA - power supply authority would normally provide a 300KVA transformer
• With IHWU’s added, load increases to between 260 and 290 KVA • Depending on supply authority, load may still be within acceptable transformer capacity
• 120 units x 5KVA = 600KVA - power supply authority would normally provide a 750KVA
transformer • With IHWU’s added, load increases to between 690 and 736 KVA • Depending on supply authority, load may still be within acceptable transformer capacity
For the purposes of comparing capital costs of options, it was assumed that the supply authority did not require the upgrade of the building transformer to the next capacity, and the cost of the transformer was therefore neutral across the comparisons.
In reality then, this assumption is only valid if additional load imposed by the IHWU’s can be taken up by spare capacity in a standard transformer, which would otherwise have been required for the building without IHWU’s.
Also, it was assumed that the metering panels associated with the installation of the IHWU’s were located in, or immediately adjacent the main switchboard, eliminating the need for uprating cabling between the main switchboard and individual DB’s.
Energy Consumption
The four water heating solutions in each building were considered in terms of energy consumption. Because two fuel sources were used, ie gas and electrical power, energy consumption including thermal losses through comparative inefficiencies were computed in KWh, which was converted to CO2 emissions for a final comparison.
The results of costs and energy consumption are tabulated below :
A breakdown of costs and energy calculations is included in ANNEXURE B.
Operational Considerations
In summary, the selection of the appropriate water heating solution will likely be influenced by the following considerations, and will likely differ from building to building :
Central hot water plants considerations :-
• operation and maintenance of the unit would be by Body Corporate • diversity of hot water consumption over a number of users may allow reduction in total
energy application, depending on building occupancy • ring main and recirculation systems through the building result in thermal and therefore
energy losses • hot water meters required • plant space allocation may be provided in basement or on rooftop • solar preheating, if preferred, is more practically applied to plant on rooftop than in
basement • risk of failure of hot water service is mitigated by redundancy built into plant and
recirculation pipework • opportunity exists to enter into Serviced Hot Water Plant Agreement with energy provider,
sometimes resulting in zero capital cost of plant, and maintenance of plant by provider
Individual direct electrical heating and storage considerations :-
• operation and maintenance of the unit would be by the owner • plant space and drainage required in each apartment • no requirement for hot water meters or recirculation pipework • failure of plant results in loss of hot water service • considered least energy efficient option
PlantHeaters
Cost/Energy
Building40 apartments $120,105 100 $163,805 69 $210,000 243 $127,400 98
120 apartments $300,165 227 $355,765 147 $601,800 730 $361,600 294
Gas-storageCentral Plant
Gas-booster Solar Electrical Storage Instaneous ElectricalIndividual Apartment Heaters
Capital Cost
CO2
Emissions[kgCO2-e]
Capital Cost
CO2
Emissions[kgCO2-e]
Capital Cost
CO2
Emissions[kgCO2-e]
Capital Cost
CO2
Emissions[kgCO2-e]
Individual instantaneous electrical heating considerations :-
• operation and maintenance of the unit would be by the owner • plant space minimal – wall mounted • no requirement for hot water meters or recirculation pipework • water is heated only when required • failure of plant results in loss of hot water service • electrical infrastructure requirements could increase if spare capacity in building
transformer unavailable
ANNEXURE A : TYPICAL WATER SCHEMATICS RO
OFTO
P HO
TW
ATER
PLA
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B ME
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ATER
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ANT
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AS-F
IRED
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ANNEXURE B : COST AND ENERGY COMPARISONS
40 Apartment Low-Rise Development Total installation cost $120,105
Centralised Gas Storage Water HeatingCommercial Storage Gas Heaters x 4 sum $25,000150W, 0.65A each, including flueGas service, including meter and authority connection sum $10,000
$35,000Building Reticulation
Recirculation pumpset, duty/standby $5,000Pipework
Header and risers 135 m $100 $13,500Return service Ø32 75 m $50 $3,750Fire collars 25 no $65 $1,625Apartment connection 40 no $500 $20,000Hot water meters 40 no $500 $20,000
Balancing valves 5 no $500 $2,500$66,375
DrainagePipework 10 m $50 $500Safe-tray sum $500Fire collars 2 no $65 $130
$1,130Valves
Isolation 40 no $295 $11,800Tempering 40 no $100 $4,000
$15,800Electrical connection
Circuits to Gas Heaters, single phase - 10A 4 no $150 $600Recirculation pumpset, duty/standby 2 no $150 $300Circuit breakers 6 no $150 $900
$1,800Energy Consumption
Hot water load 75 L/aprtmnt/day 3000 L/dayDaily energy input 45 °C delta T 567 MJSystem efficiency 70 % 810 MJEquivalent KWh 225 KWhStorage losses over 4 x 275L tanks 2.5 KWh/24hrs 10 KWhCirculation losses @ average 30W/m 315 m 227 KWh
Daily energy consumption 462 KWhCorresponding CO2 emission 100 kgCO2-e
40 Apartment Low-Rise Development Total installation cost $163,305
Gas Boosted SolarRoof mounted solar panels x 15 plus sum $55,000315L storage tanks x 5250L tank + 4 burners sum $15,000Gas service, including meter and authority connection sum $10,000
$80,000Building Reticulation
Recirculation pumpset, duty/standby $5,000Pipework
Header and risers 135 m $100 $13,500Return service Ø32 75 m $50 $3,750Fire collars 25 no $65 $1,625Apartment connection 40 no $500 $20,000Hot water meters 40 no $500 $20,000
Balancing valves 5 no $500 $2,500$66,375
DrainagePipework 10 m $50 $500Safe-tray sum $500Fire collars 2 no $65 $130
$1,130Valves
Isolation 40 no $295 $11,800Tempering 40 no $100 $4,000
$15,800Electrical connection
Circuits to Gas Heaters and tank, single phase - 10A 6 no $150 $900Recirculation pumpset, duty/standby 2 no $150 $300Circuit breakers 7 no $150 $1,050
$2,250Energy Consumption
Hot water load 75 L/aprtmnt/day 3000 L/dayDaily energy input 45 °C delta T 567 MJSystem efficiency 80 % 709 MJEquivalent KWh 197 KWhAfter solar contribution saving at 60 % 79 KWhStorage losses over 5 x 315L tanks 2.7 KWh/24hrs 14 KWhStorage losses over 250L tank 2.5 KWh/24hrs 3 KWhCirculation losses @ average 30W/m 315 m 227 KWh
Daily energy consumption 322 KWhCorresponding CO2 emission 69 kgCO2-e
40 Apartment Low-Rise Development Total installation cost $210,000
Individual Electric Storage250L Electric Storage Water Heater 40 no $2,000 $80,0002 x 3.6KW elements
$80,000Drainage
Pipework 80 m $50 $4,000Safe-tray 40 no $200 $8,000Fire collars 40 no $65 $2,600
$14,600Valves
Isolation 40 no $295 $11,800Tempering 40 no $100 $4,000
$15,800Electrical connection
Transformer NILConsumer mains 40 m $100 $4,000[HW only - AS.3000, Table C1 Load group - E]MSB sum $15,000Metering 40 no $250 $10,000Metered submains 40 no $840 $33,600+ 2 offpeak actives [20m x $42/m = $840]DB's 40 no $600 $24,000Circuits, single phase from DB 40 no $75 $3,000 [10m x $7.50/m = $75]Isolators 40 no $250 $10,000
$99,600Energy Consumption
Hot water load 75 L/aprtmnt/day 3000 L/dayDaily energy input 45 °C delta T 567 MJSystem efficiency 95 % 597 MJEquivalent KWh 166 KWhStorage losses 2.4 KWh/24hrs 96 KWh
Daily energy consumption 262 KWhCorresponding CO2 emission 243 kgCO2-e
40 Apartment Low-Rise Development Total installation cost $127,400
Individual Instantaneous Electric Continuous Flow27KW, 39A 40 no $950 $38,000
$38,000Valves
Isolation 40 no included $0$0
Electrical connectionTransformer sum NILConsumer mains 40 m $80 $3,200[HW only - AS.3000 table C1, Load Group E]MSB sum $15,0003-phase metering 40 no $320 $12,800Metered submains [20m x $12/m = $440] 40 no $440 $17,600DB's 40 no $600 $24,000Circuits, 3-phase from DB [10m x $12/m = $120] 40 no $120 $4,800Isolators 40 no $300 $12,000
$89,400Energy Consumption
Hot water load 75 L/aprtmnt/day 3000 L/dayDaily energy input 30 °C delta T 378 MJSystem efficiency 99.8 % 379 MJEquivalent KWh 105 KWhStorage losses 0 KWh
Daily energy consumption 105 KWhCorresponding CO2 emission 98 kgCO2-e
120 Apartment High-Rise Development Total installation cost $300,165
Centralised Gas Storage Water HeatingCommercial Storage Gas Heaters x 12 sum $75,000150W, 0.65A each, including flueGas service, including meter and authority connection sum $10,000
$85,000Building Reticulation
Recirculation pumpset, duty/standby $5,000Pipework
Header and risers 260 m $100 $26,000Return service Ø32 100 m $50 $5,000Fire collars 80 no $65 $5,200Apartment connection 120 no $500 $60,000Hot water meters 120 no $500 $60,000
Balancing valves 5 no $500 $2,500$163,700
DrainagePipework 10 m $50 $500Safe-tray sum $500Fire collars 1 no $65 $65
$1,065Valves
Isolation 120 no $295 $35,400Tempering 120 no $100 $12,000
$47,400Electrical connection
Circuits to Gas Heaters, single phase - 10A 12 no $150 $1,800Recirculation pumpset, duty/standby 2 no $150 $300Circuit breakers 6 no $150 $900
$3,000Energy Consumption
Hot water load 75 L/aprtmnt/day 9000 L/dayDaily energy input 45 °C delta T 1701 MJSystem efficiency 75 % 2268 MJEquivalent KWh 630 KWhStorage losses over 12 x 270L tanks 2.5 KWh/24hrs 30 KWhCirculation losses @ average 30W/m 540 m 389 KWh
Daily energy consumption 1049 KWhCorresponding CO2 emission 227 kgCO2-e
120 Apartment High-Rise Development Total installation cost $355,765
Gas Boosted SolarRoof mounted solar panels x 42 plus sum $100,000315L storage tanks x 142 x 250L tanks + 12 burners sum $30,000Gas service, including meter and authority connection sum $10,000
$140,000Building Reticulation
Recirculation pumpset, duty/standby $5,000Pipework
Header and risers 260 m $100 $26,000Return service Ø32 100 m $50 $5,000Fire collars 80 no $65 $5,200Apartment connection 120 no $500 $60,000Hot water meters 120 no $500 $60,000
Balancing valves 5 no $500 $2,500$163,700
DrainagePipework 10 m $50 $500Safe-tray sum $500Fire collars 1 no $65 $65
$1,065Valves
Isolation 120 no $295 $35,400Tempering 120 no $100 $12,000
$47,400Electrical connection
Circuits to Gas Heaters and tanks, single phase - 10A 15 no $150 $2,250Recirculation pumpset, duty/standby 2 no $150 $300Circuit breakers 7 no $150 $1,050
$3,600Energy Consumption
Hot water load 75 L/aprtmnt/day 9000 L/dayDaily energy input 45 °C delta T 1701 MJSystem efficiency 75 % 2268 MJEquivalent KWh 630 KWhAfter solar contribution saving at 60 % 252 KWhStorage losses over 14 x 315L tanks 2.7 KWh/24hrs 38 KWhCirculation losses @ average 30W/m 540 m 389 KWh
Daily energy consumption 679 KWhCorresponding CO2 emission 147 kgCO2-e
120 Apartment High-Rise Development Total installation cost $601,800
Individual Electric Storage250L Electric Storage Water Heater 120 no $2,000 $240,0002 x 3.6KW elements
$240,000Drainage
Pipework 5m per aprtmnt 600 m $50 $30,000Safe-tray 120 no $200 $24,000Fire collars 120 no $65 $7,800
$61,800Valves
Isolation 120 no $295 $35,400Tempering 120 no $100 $12,000
$47,400Electrical connection
Transformer NILConsumer mains 40 m $120 $4,800MSB sum $30,000Metering 120 no $250 $30,000Metered submains + 2 offpeak actives [20m x $42/m = $840] 120 no $840 $100,800DB's 120 no $400 $48,000Circuits, single phase from DB [10m x $7.50/m = $75] 120 no $75 $9,000Isolators 120 no $250 $30,000
$252,600Energy ConsumptionHot water load 75 L/aprtmnt/day 9000 L/dayDaily energy input 45 °C delta T 1701 MJSystem efficiency 95 % 1791 MJEquivalent KWh 497 KWhStorage losses 2.4 KWh/24hrs 288 KWhDaily energy consumption 785 KWhCorresponding CO2 emission 730 kgCO2-e
120 Apartment High-Rise Development Total installation cost $361,600
Individual Instantaneous Electric Continuous Flow27KW, 39A 120 no $950 $114,000
$114,000Valves
Isolation 120 no included $0$0
Electrical connectionTransformer NILConsumer mains 40 m $100 $4,000[HW only, AS.3000, Table C1, Load Group E]MSB sum $30,0003-phase metering 120 no $320 $38,400Metered submains [20m x $12/m = $440] 120 no $440 $52,800DB's 120 no $600 $72,000Circuits, 3-phase from DB [10m x $12/m = $120] 120 no $120 $14,400Isolators 120 no $300 $36,000
$247,600Energy Consumption
Hot water load 75 L/aprtmnt/day 9000 L/dayDaily energy input 30 °C delta T 1134 MJSystem efficiency 99.8 % 1136 MJEquivalent KWh 316 KWhStorage losses 0 KWh
Daily energy consumption 316 KWhCorresponding CO2 emission 294 kgCO2-e
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