Post on 09-Apr-2018
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HOT WATER SUPPLY
• Hot water can either be generated by thecentral boiler plant and stored, or producedclose to the point of use by using asecondary fuel
Central
heatingboiler
Indirect
heating HotWaterCylinder
Return
FlowFuel
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HOT WATER SUPPLY
COLD
WATERTANK
HOT WATER
STORAGE
TANK
HOT AND COLD
WATER USAGE
SERVICEPIPE
AIR VENT
Fuel(Direct Heating)
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HOT WATER SUPPLY
HOT WATER
STORAGE
TANK
AIR VENT
DEAD LEGS
DEAD LEGS:
Connections from thehot water source (orsecondary flow) to thetaps are known asdead-legs.
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HOT WATER SUPPLY • In central systems there are pipework linking the
central supply with the draw-off points.
• In its simplest form a single pipe serving the outletsform a dead leg.
• Between draw-offs the water in the pipe will cool andthe next draw off will involve running the cold water towaste before it reaches the tap, creatingdissatisfaction, waste of water and heat.
• In these systems in order to keep consumption withinreasonable limits dead legs of pipework serving hot-water taps are governed to following maximum
lengths:• 12 m for pipes not exceeding 20 mm diameter
• 7.6 m for pipes not exceeding 25 mm diameter
• 3 m for pipes exceeding 25 mm diameter
• 1 m for pipes serving spray taps
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HOT WATER SUPPLY
Estimation of hot-water storageCode of Practice 342 (Centralized Hot-Water Supply, UK)
Type of Building Storage per person(litres)
Type of Building Storage per person(litres)
Colleges & Schools:
Boarding
Day
23
4.5
Dwelling houses 45.5
Factories 4.5
Flats 32 Hostels 32
Offices 4.5
Sports pavilions 36
Hotels (Average) 35
Hospitals:
General
Infectious
Maternity
Nurses’ homes
27
45.5
32
45.5
By use of the table, a dwelling with 3 occupants will require
45.5 x 3 = 136.5 litres of hot water-storage.
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HOT WATER SUPPLY
Estimation of hot -water storageIf the number of occupants is not known the following table may be used
APPLIANCE VOLUMES OF HOT
WATER (Litres)
WASH BASIN
Hand wash
WashHair wash
1.5
36
SHOWER 13
BATH 70
WASHING MACHINE 70
SINK
Wash up
Cleaning15
5
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HOT WATER SUPPLY
1
23
4
6
5
1. Thermostat2. Flue pipe
3. Cold water feed
4. Hot water outlet5. Burner6. Buffer
Storage-type gas water heater
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HOT WATER SUPPLY
Instantaneous gas water heater
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HOT WATER SUPPLY
Instantaneous electrical water heater
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HOT WATER SUPPLY
Water Heating by Solar Energy
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ThermosiphonThermosiphon
ActionAction
Air vent pipe
Cold Water Tank
Hot Water Cylinder
Collectors
Cold Water Feed
Circulation of Waterby THERMOSIPHON
action
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HOT WATER SUPPLY
Indirect heater-type hot water cylinder
Coil
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HOT WATER SUPPLY
Solar Collectors integrated into the roof structure
COLD
WATER
TANKSOLAR
ENERGY
HOTWATERTANK
INCLINED
ROOF
AIR
VENT
Cold
feed
Hot
water
SOLAR
COLLECTORS