ZIP INSTANTANEOUS HOT WATER · PDF fileZIP INSTANTANEOUS HOT WATER ... • A low-rise building of 40 units • A high-rise building of 120 units ... pumped hot water recirculation

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

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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


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






$1,130Valves



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


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



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



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


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



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


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


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






$1,065Valves



Circuits to Gas Heaters, single phase - 10A 12 no $150 $1,800Recirculation pumpset, duty/standby 2 no $150 $300Circuit breakers 6 no $150 $900


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



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






$1,065Valves



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


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



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



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


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


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


Documents

ZIP INSTANTANEOUS HOT WATER · PDF fileZIP INSTANTANEOUS HOT WATER ... • A low-rise building of 40 units • A high-rise building of 120 units ... pumped hot water recirculation