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PLUMBING CONNECTION
WINTER 2016
water systems have a maximum thermostat temperature
of 65-70˚C depending on the system type, whereas a
commercial water heater must be capable of delivering and
maintaining water at or around 80˚C.
MULTIPLE DWELLINGS
Most capital cities in Australia are seeing considerable
increases in apartment living, where centralised water
heating plants are being used to provide heated water in a
“flow and return” designed system.
Typically each individual apartment is metered on
consumption of the volume of hot water used by an energy
provider.
Advantages of a centralised water heating plant include:
∫ More cost effective systems to supply and install
∫ Diversity in system design allows larger users more
volume of hot water
∫ Where meters are used to measure volumes, occupants
pay for what they use
∫ Hot water meters assist in special tariff arrangements
with energy suppliers
∫ System redundancy allowing for partial shut down for
service and maintenance needs.
RECOMMENDATIONS FOR MULTIPLE DWELLINGS
∫ Locate the system as close as possible to pipe risers in
the building
∫ Use service ducts and cavities to run piping
∫ All heated water piping is to be insulated to minimise heat
loss as required by local authorities.
∫ An allowance of 10% storage of the first hour delivery
requirement will provide an adequate diversity buffer.
TABLE HEADING
Application
Suggested peak period
Hot water requirements, 60°C supply temperature (unless indicated otherwise)
Snack bars, take-away
foods
1 to 2 h
12 to 1 pm or 12 to 2 pm
Allow 3.1L for each meal. This covers cooking and washing, e.g. 200 meals over
2h=620L.
Note: Water is required greater than 77°C for sanitising.
Canteens, cafes, hotel
kitchens, restaurants
1 to 2 h
12 to 1 pm or 12 to 2 pm
Allow 5.5L for each 3 course meal. This covers cooking and washing, e.g. 200 meals
over 2h = 1100L.
Note: Water is required greater than 77°C for sanitising.
Holiday flats, hotels,
motels, guest houses
1 h
7.30 am to 8.30 am
Allow 20-25 L per head over the peak hour,
e.g. 40 guests = 1000L over 1h. For 4 and 5 star accommodation allow 35-50L per
head.
Apartments
1 h
7 am to 8 am
Allow for each type of apartment in the building.
e.g. studio = 25L, 1 bed apartment = 40L, 2 bedroom = 70L
3 bedroom = 90L, 4 bedroom = 110L, Penthouse = 150L
Caravan parks, camping
areas
Spread over 2 h
Allow 20 L per person; average 4 persons per van, e.g. 30 vans = 120 people =
2400L over 2h. In parks used mainly for long-term holiday or residential purposes,
the peak period may extend over a much longer time. The actual usage pattern
should be ascertained.
Hairdressing salons
3 to 4 h
Each installation to be individually evaluated, but as a guide allow 10L per customer.
Squash courts
spread over 4 h
Allow 20L per player; average 16 players per court over 4h,
e.g. 4 courts = 20 x 4 x 16 = 1280L over 4h.
Office amenities
spread over 8 h
Allow 3-4L per person per day. Showers seldom used or 1.5L per person over a
1hour peak.
Factory change rooms
(light industry)
1 h
4 pm to 5 pm
Average of 30% use showers. Allow 20L per head. Average of 70% use hand basins.
Allow 3L per head. (This is equivalent to 8 to 9 L per person.)
Factory change rooms
(heavy or dirty industry)
1 h
4 pm to 5 pm
Allow 30L per head. In some industries, such as mining projects, up to 50L may be
required.
Coin-operated
laundries
spread over 8 h
Allow 70L per machine per hour. e.g. 6 machines = 70 x 6 x 8 = 3360L over 8h. For
large commercial laundries allow 10L per kilogram of dry washing.
Glass washing
machines
usually over 2 h
Determine quantity of glasses to be washed over peak period Allow 3 glasses
per litre of beverage sold. Most machines require 7L of hot water per wash of 25
glasses and can handle one wash per minute, e.g. 1000L of beverage over 2 hours
requires 1000 x 3 x 7 / 25 = 840L of hot water.
Alternatively, allow 3 glasses per person (use licensed capacity as a guide).
Notes: (1) Temperature required by regulations is 82°C (2) Where beverage
consumption is known in gallons, multiply by 4.55 to convert to litres.
Note this sizing guide should be taken as an average only and individual site assessments may be necessary.
HOT WATER CLINIC
JON PALFREY