1. 1
Introduction
From your morning hot shower to the daily cup of coffee, hot water plays an
important role in our everyday lives. Hot water is a necessity not only for domestic uses but
also for commercial uses, such as in hotels and hospitals. Hence, functional hot water
system is essential to meet the needs of different buildings from residential houses to high
rise buildings.
There are many different types of hot water supply systems which can be separated
into two main categories, localised and centralised system. These both systems are the
methods they distribute the water, and are then branched out to meet each personalised
requirements. Localised system is mainly for domestic use which emphasise more on its
small-scaled instantaneous yet affordable heating system. On the other hand, centralised
system has an advantage of having a large storage to accommodate its huge demand while
having efficient pipework to deliver to each drawing-point. Moreover, the awareness of going
green has gradually become more wide-spread globally and thus solar heating system has
been chosen as an alternative source of water heating.
2. 2
Hot Water System
Many aspects have to be taken into considerations when the designer is planning the
hot water system layout. This is to ensure the suitable type of system is incorporated into the
different buildings to meet the different requirements of what it was to be used for.
Here are some deciding factors that should be considered when determining the
suitable type of hot water system for the building.
Required consumption
Peak demands
Type of installation (local or central)
Required storage capacity
Methods of heating water
Insulation of pipework
Further actions that has to be taken to minimise future problems
Types of Hot
Water Supply
System
Localised
Instantaneous
single points
Storage type
single points
Centralised
Direct
Electric water
heating
Gas storage
heaters
Boiler-cylinder
system
Instantaneous
system
The multi-port
The water-jacketed
tube
heater
The combined
primary storage
unit
Indirect
With expansion
vessel
Vented storage
Unvented storage
Others
Solar heating
3. 3
Localised hot water distribution system
A localised system is a system single-point heater located above a sink which heats up
water to suffice its local needs. Commonly, the water is heated using gas and electricity as
its fuel. In some cases it also comes with a small storage vessel but mostly its instantaneous
system will be engaged. A long distribution pipe is necessary for this system to reach out to
all of the drawing points. This means a long wait might incur during peak periods. It also has
a greater risk of fire.
There are two types of localised systems:
Instantaneous single points
These heaters are usually located directly
above the sanitary appliances and its
water flow can be controlled through the
inside. They are also powered by either
gas or electricity. It does not require any
storage and the heating process only
begins when desired. After the water has
flowed into the heater, the electric heating
element will quickly heat up the water
surrounding it. The temperature of the
water will be directly proportional to the
power rating of the heater and the water
flow rate. By sensing the water flowing
through the heater through a flow switch
inside, electrical contacts are transferred
to the immersion heater element to
convert it into heat energy.
Storage type single points
Localised system (Blackwell Publishing, 2006)
These heaters are located near a sink and have a capacity not more than 15 litres. The
stored water is heated by an electric element until the water has expanded enough to
discharge from the discharge spout. Cool water from the base of the unit will then
replace the hot stored water that has discharge out. As after the discharging of hot water
the water will soon cool down again, it is only suitable for small quantities of draw off as
the hot water which can be discharged is limited.
4. 4
Centralised hot water distribution system
On the other hand, the water in a centralised system is heated in a hot storage vessel, a
boiler or a small gas circulator. They are connected by supply pipework and circulatory
pipework. The instruments are placed in a position where it is able to reach to every draw-off
points of the building through a system of pipework.
In a centralised system, the water is heated in the storage vessel and boiler that is located in
an appropriate position of the building. The water is fed to and fro from the boiler by what it is
called as primary flow and return pipes. This water circulates throughout the whole system
by convection or the aid of circulating pumps.
Moreover, the temperature of the water stored inside the storage vessel should not exceed
60◦C. If the temperature drops below 60◦C, health issues will arise as Legionella bacteria’s
survival time increases. An easy way to eliminate this risk is to install a thermostat to monitor
its temperature.
Direct hot water supply
A direct system heats the water in its storage cylinder and transfers heat “directly” to the
surrounding water. In a direct system, there are chances where precipitation of limestone
will occur when heated. This precipitation will then clog the boiler and the nearby
pipeworks. Therefore, direct system is only suitable to be used in areas of “soft” water.
This system could lead to damages or even explosion and is not suitable for hot water
central heating.
The following are some examples of the various types of centralised direct hot water
system.
Electric water heating-
A system having an immersion heater installed in the hot water storage vessel. When
its thermostat senses a certain temperature, the heater automatically switches off.
The heater should be at least 50mm measuring from the base of the storage vessel to
avoid unwanted sediment disturbance.
Gas storage heaters-
The stored water are heated directly with gas burner installed below it. It incorporates
an open flue to convey exhaust gases out to the external environment.
5. 5
Boiler-cylinder system-
The hot water from the boiler is distributed via primary flow and return pipe. However.
It should not be used in hard water areas to prevent pipework blockage.
Centralised direct system (Blackwell Publishing, 2006)
Instantaneous system-o
Centralised instantaneous system (Blackwell
Publ ishing, 2006)
The multi-point-
This system contains a gas burner which is placed under the heat exchanger.
When hot water is required, the water will start circulating through the heater.
When this happens, they will be a sudden reduction of water pressure. This
pressure difference will open the gas line and starts heating.
o The water-jacketed tube heater (thermal storage system)
This system is a typical instantaneous system equipped with stored supply of
central heating water. As the water heats up, the water will expand and is retreated
to an expansion chamber.
o The combined primary storage unit (CPSU)
o This system comparing to the water-jacketed tube heater, differs only at this is
combined into the boiler without needing extra hot water storage vessel.
6. 6
Indirect hot water supply
An indirect system consists of an expansion, a
calorifier (or hot water storage vessel) and a
heat exchanger. Water from the boiler in the
primary pipework is passed through a cylinder
containing the heat exchanger, performing a
continuous circulation of water to heat up the
water. The closed circulation of water can
prevent clogging by limestone as there is no
new water input and the water in this
circulation does not mix up with the water in
the calorifier.
Indirect hot water system with expansion vessel
(Greeno, 1997)
Expansion vessel (Greeno, 1997)
Indirect hot water cylinder (Blower, 2002)
Indirect system (Greeno, 1997)
7. 7
Additionally, secondary circulation is needed to prevent dead legs and therefore
reducing in wastage of water. The secondary flow pipe must be avoided from having
excessive lengths and reverse circulation can be prevented by non-return valve if
pump is not running and water is drawn off. The secondary circulation carries
continuous flow of hot water but loses heat at the period of circulation.
Indirect hot water system with expansion vessel-
It is more economical when an expansion vessel is connected to the primary
circulation instead of expansion and feed cistern, expansion pipe and boiler feed
pipe. There is a temporary connection of the primary circulation to the water main.
A volume of nitrogen is used to absorb water expansion and is separated from
water by a diaphragm.
Vented storage hot water supply system-
The vent pipe which is included in this system is let open to the open air. Its
function is to allow the expansion of hot water when heated without increasing the
pressure of the system. Without its vent pipe, the storage vessel might burst
causing flood. Previous versions of this system made the vent pipe to discharge
out through the top of the roofs. However, most of the system nowadays has it
over the top of a cold water storage cistern with a return bend.
Unvented storage hot water supply system-
This type of system does not require high level cisterns. They supply both the
cold and hot water at the same pressure and instead of using large pipes, smaller
pipes may be used. The storage cylinder must be able to tolerate the main
pressure and overheating of the hot water. Overheating of water in this system
could lead to explosion and this is why this system is prohibited in some countries
such as the UK.
8. Vented storage hot water supply
system (http://www.home-heating-systems-
8
and-solutions.com/open-vented-
cylinders.html)
Unvented storage hot water supply system (Greeno, 1997)
9. 9
Others
Solar heating of water
This system is made up of feed and expansion cistern, hot-water cylinder and solar panel.
Solar panel (Solar collector) is installed at the roof to collect sufficient amount of solar energy
for water heating. In some buildings, a small pump is used to enhance the circulation.
Usually, in the solar panel, there are copper sheets with waterways attached and they are
backed by insulation.
The copper sheets are protected externally by one or two layers of glasses which allow solar
radiation to penetrate freely. The solar panel is linked to the indirect hot water system and
some space is needed for heat exchanger. Measures have to be taken by adding in
antifreeze to the circulating water to prevent freezing. Reverse circulation and heat loss to
cold night sky must be prevented in order for the system to function properly. As solar heat
couldn’t provide continuous supply of hot water on its own, immersion heater can be added
for additional heating of water, which means that both sources of heat work together. The
solar circuit and the boiler-fed
coil can be in one cylinder or
in separated cylinders. In this
case, the solar coil supplies
preheat the water and the
boiler-heated cylinder will heat
the water to the final or
required temperature. This
system depends largely on
the external weather condition
for better functioning.
Solar hot water supply (Greeno, 1997)
10. 10
Installation of Hot Water Supply in High Rise Building
The installation part of a hot water supply are easily understood through theoretical studies
but when it comes to practical, it is a lot more complicated when you are installing the piping
for the entire high rise building. High rise building are buildings which are normally 10 stories
high and above. We can imagine the amount of pipes connecting up from the water supply
at the ground floor and penetrating into each floor. It is because there are waste water pipes,
storm water pipes, air-conditioning vent in the building which looks alike and which we need
to carefully identity and handle.
There are few considerations to be taken in order to achieve a well-planned installation. First
and foremost, the developer has to decide which type of hot water supply to use in the
building. There are two types; centralised or localised of hot water supply are suitable for
high rise buildings. Different high rise buildings have different purpose, like in a hotel. It is
more convenient and efficient to have centralised hot water supply. Centralised hot water
supply is designed to heat the water in a centralised water boiler tank and distribute to
consumers in the building. For this installation, it is suitable for building where water
consumption is high like hotels. During the vacation peak season, hotels are mostly fully-booked
and occupied. The consumption of hot water is at its peak, and this is the time where
a centralized hot water storage tank shows a great contribution. Centralised hot water
system can store a huge amount of hot water in the tank waiting to be consumed by the
customers. Localised hot water supply is designed to be installed in specific places where
hot water supply is needed. For example, in a multi-storey office building, the consumption of
hot water is low. It is because office is usually only for people to work so, they do not
consume much hot water. They only need hot water when making a cup of hot coffee or
washing their hands when needed. But there are some office buildings that allow people to
take shower and the hot water is only need for that specific situation. Although there are
people taking the shower, the consumption of water only increases slightly compare to
hotel’s consumption.
It is possible for any building to use any type of hot water supply but when it comes to
considering the efficiency of the system used. Centralised hot water supply is usually
suitable where there is high consumption of water. If a localised hot water supply is replaced
with centralised hot water supply, it will result in an expensive cost for installing each and
every hot water boiler for every rooms needed. On the other hand, replacing a localised hot
water system with a centralised hot water system will result in an excessive hot water
storage and during the preservation of hot water, components of the hot water storage will
tend to fail as time goes by.
11. During the installation of hot water supply, developer or contractor will normally install
insulators to protect the piping. Insulator is a soft material like a sponge, and it keeps the
pipes from frost or prevent from hurting others by burning other’s arms. It is because during
the winter, the room temperature is very low and non-peak season. Hotels aren’t so actively
been used, many piping will become frosted due to lack hot water travelling through those
piping. Hot waters that stay in the pipes will become ice if we did not wrap the pipes with
insulators.
Another important consideration is choosing the right materials for all the piping in the
building. The right material chosen will give great benefits in the long term run. The cost of
maintenance will reduce dramatically by installing good and durable material pipes. There
are a few materials that is generally used in the industry; Copper, Cross-link Polyethylene
(PEX) and Polybutylene (PB).
11
Copper is a metal material which is very high in thermal
conductivity. It is commonly used in the industry due to its
low cost and easily obtained from hardware store. The
lifespan of copper is also one of the great advantages
which require less maintenance. Piping are normally
hidden and covered with different finishes; a low
maintenance material will ease the user for a long period
of time. People normally only change the pipes after
buying old houses which are more than a decade old.
Copper pipe
Cross-link Polyethylene also known as PEX, is a high-temperature
resistant and flexible plastic pipe. Using
PEX as piping materials will eventually speed up the
whole installation process. The flexibility of PEX will
allow the contractor for ease of installation although the
structure of the house is complicated. The cost of this
PEX pipe
material is also reasonable. However, the high temperature resistance have a limit of 100oC
for any significant length of time.
12. 12
Lastly, Polybutylene also known as PB is a plastic resin
material that is low cost and is easy to install. In the early
90’s, this product is commonly used in the overseas country.
However, as years goes by, this product was found not to be
resistant to oxidants. This product is no longer popular after
the discovery of poor chemical resistivity.
PB pipe
As for our case, hotels normally incorporate copper piping as it is durable and not so costly.
Using copper may also give advantage in the preservation of hot water during non-peak
season.
Installation of hot water supply at hotels widely uses centralised hot water storage which
places the hot water storage tank on top of the building or installing a reasonable size of
storage tank at every 10 levels. Due to the water pressure needed to pump the water,
installing several storage tanks every 10 levels will increase the water pressure compared to
pumping the cold water to the top floor and boil the water on the top floor and let the hot
water flow throughout the whole building. Building centralised hot water storage on top floor
maybe expensive due to the electricity usage of keeping the temperature of hot water. We
recommend installing hot water storage at every 10 floors due to cost savings and eco-friendly.
This way of building installing the hot water supply will give a consistent temperature
of hot water supply to the user in that range of floor.
Zoning valves will also be installed at every floor for safety purpose. Zone valves are
designed to be installed at the main pipe before pipes separating to every rooms in that
particular floor. Stopping the zone valve will block the supply of water to the specific floor.
This will allow the maintenance work need on those piping in that specific floor.
13. 13
MAINTENANCE
It is crucial to carry out periodic hot water supply system’s maintenance as it can significantly
extend the system’s life and control the loss of efficiency to be at minimum.
First of all, monitoring the temperature of the hot water supply system is one of the most
essential maintenance to ensure the hot water supplied is at a suitable temperature. For hot
water supply systems in hotels, which are circulating hot water supply systems that are of
larger scales, there will be principal loop, which will supply hot water to a group of outlets,
and the smaller loops are known as subordinate loops. Furthermore, there will be localized
loops in the hot water systems in hotels which can be identified as tertiary loops which
supply hot water to a smaller amount of outlets. Monitoring temperature should be
conducted at sentinel points, which are points that are specifically selected to represent the
condition in the system (HSE, 2014). Monitoring the temperature at selected sentinel points
should be carried out every month ideally in order to ensure the hot water to be at a suitable
temperature.
Besides, water softening should be carried out at the connection in between cold water
supply to the hot water system. Although light scale formation on the inner surfaces of pipes
can prevent leaching of metals, heavier deposits are more likely to happen in hard water
areas (HSE, 2014). These deposits will increase the surface area and can cause microbial
colonization, which will then cause the water to be infected by microorganisms. Water
softening should be carried out to reduce the risk of scale being deposited at the base of the
calorifier and heating coils, and the potential of formation of scale within the system pipe
work and components which will reduce the flow significantly and cause a huge impact on
the efficiency of the system (HSE, 2014).
Furthermore, the calorifiers should be inspected internally by removing the inspection hatch
and if there is no inspection hatch, the initial flush from the base of hot water heaters should
be collected and to be inspected for the clarity, quantity of debris, and temperature (HSE,
2014). This inspection should be carried out annually and the frequency has to be increased
as indicated by the risk assessment or whenever the result of inspection findings is not
satisfying.
Moreover, since chlorine will be used in the water system for disinfection purposes, the
amount of chlorine should be inspected quarterly every year to ensure the concentration of
chlorine is at a suitable range of 0.5 – 1.0 mg per liter (HSE, 2014). If the chlorine
concentration is over the preferred range, it will cause a lot of health problems to the users,
such as skin infections, irritations, and etc.
14. Last but not least, water samples at final outlets should be collected randomly on a weekly
basis for inspection purposes. This has to be done to ensure that the hot water supplied
contains no contamination and all the required elements in the water are of suitable dosage.
If the inspection shows that there is contamination or the elements in the water is overdosed,
further inspection has to be carried out throughout the entire system, especially on the
storage and piping system and essential repair should be conducted in order to prevent any
possible harm and to prolong the hot water supply system’s life and maintain the efficiency
of the system.
14
15. 15
Advantages and Disadvantages
According to the hot water supply system for high rise building, commonly they are
using indirect hot water system. There are some advantages in using indirect hot water
supply system.
Indirect system
Separate circuit for the water drawn off at taps
Used in hard water areas to prevent scaling of boiler and pipes
Used when heating is combined with the system
Less maintenance cost
Other than indirect hot water system, we also have direct hot water system. There are
also some advantages in using direct hot water supply system.
Direct system
Water through the boiler can be drawn off for the taps
Saves the cost of a storage and expansion cistern and associated pipework
Heat quicker
Adequate pressure on the main
Sealed primary circuit can be pumped or can circulate by natural convection
Besides that, they is also vented and unvented hot water system. They also have their
own advantages and disadvantages.
Unvented system
Provide hot water constantly at main pressure
No requirement for a cold water storage tank
Extra pipework to link it up
Give greater flexibility to the design of taps, mixers and shower heads
Less installation cost
× Need specialist installation
× Installation fees expensive than the traditional vented system
× Rely on automatic control (require periodic maintenance)
× Will run out of water
× Very inconvenient
16. 16
Vented system
Less complicated
Easier to install
Cost less to buy and maintain
Can be two type (indirect and direct vented system)
× Require cold water storage tank
Types of water heater
There are several different types of hot water heaters such as conventional storage
water heaters, tankless or demand-type water heaters, heat pump water heater, solar water
heaters, tankless coil and indirect water heaters. Different types of water heaters have some
advantages and disadvantages:
Conventional storage water heater
Low product cost and low installation cost
Inexpensive and widely available in a variety of sizes (for replacement)
Instant hot water (provide hot water faster)
× Higher utility bill (it heat and reheat the water)
× Can run out of hot water
× Storage space needed
× Less durable
Tankless or demand-type water heaters
Energy savings / Operating Cost
Lifespan
Compact size (space saving)
Durable
Can be shift easily
The unit never run out of hot water
× Limited Output
× Expensive for initial cost
× Best performance come from gas units
17. 17
Tankless coil
Does not required tank
Most efficient during cold weather
× Inefficient for those in warmer climate
Solar Water Heater
Use the free energy of the sun to heat your water
Lower monthly electric (or gas) utility bills
It is suitable at our country cause our country is tropical climate
Renewable (no fuels required)
Non-polluting
Lower maintenance fee
High efficiency
× High initial cost
× Installation is complicated
× High maintenance cost
Heat pump water heater
Big volume of hot water
Long lifespan
Low maintenance cost
Very convenient (can be installed indoors and outdoors)
Anti-freezing
Safe and eco-friendly (no burning, no gas)
Efficiency
× High initial cost
× Sizes of heat pump could be big
× Quality are various
Indirect water heater
Efficient choice for most home
Saves energy
Can be fired by gas, oil, propane, electric or solar energy
Efficient life span (made of stainless steel)
× Required storage tank
18. 18
Problems in Hot Water Supply System
Hot water supply system may have some flaws in its design and result in problems in its
function. There are several defects that may occur in hot water supply system.
1. Air locks
Air locks when air enters into the system either through a cylinder vent, when the tank
runs low and when the water is heated. So when there is air in the system, it will rise
and accumulate at high points which will cause restriction of water flow. Air may also be
trapped where pipes have fall or dips in reverse direction and this also causes water
flow to stop.
In order to eliminate air locks in the water pipes, sufficient pressure is required to push
the air through the pipe. The pipes will need be drained and refilled or by blowing
through the pipework. Another way is to design the hot water system by placing vent
points in which pipes will rise to so that air can escape through the vents.
19. 19
2. Noises
Generally, noises may occur in high pressure systems, in primary flow and return pipes or
in the boiler. These noises occur due fluctuations in velocity of water flow which causes
the pipes to vibrate and make ‘knocking’ or ‘hammering’ sounds. ‘Knocking’ or
‘hammering’ usually occurs in metal pipes but it can also happen in plastic pipes. It can
also result from water expansion due to corrosion of pipes. These pipes will need to be
descaled or replaced with new pipes. Besides that, noises are one of the main defects in
boilers. The noises result from inadequate flow of water or unsuitable design.
There are few methods to reduce and prevent the occurrence of noises in hot water
services:
a) Pipes should not be in direct contact with building structure
b) Use rubber insulated clips to clip over pipes
c) Pipework should be fixed rigidly to prevent movement
d) Design suitable size of pipework to avoid excessive velocity water
3. Poor water flow
Air locks, clogged pipes, mineral clogging in the water tank or tankless coil or insufficient
water supply and even air drawn through the vent can cause poor flow of water in the hot
water services. If air is drawn into the system through vents, a larger cold feed pipe can
be inserted or the storage cistern can be raised so that the pressure of water flow will
increase. The increased pressure will then be able to push and eliminate the entrained
air and therefore, increase water flow.
4. Insufficient hot water
Lack of hot water supply may stem from unsuitable size of hot water cylinder or boiler,
excessive primary flow and return pipes, leakages, air locks or poor quality fuel used for
heating water. Insufficient hot water may also be due to mineral deposits and blockage in
a hot water tank.
20. 20
5. Leaks
Boilers used for heating water and pressure relief valves are susceptible to leaks. These
boilers should be regularly checked every 15-20 years. Leakage in boilers, pressure
relief valves or expansion vessel will result in loss of pressure. Leakages in boi lers
happen due to the corrosion of pipes and problems in the boiler limit control. Thermal
expansion in closed water system will cause leaks from the pressure relief valve
periodically.
6. Overheating and failure of heating element
Immersion heaters and the thermostats also need to be checked. The thermostats may
get faulty over time. So, if the thermostats give wrong temperature readings, the hot
water supply will not be very efficient. The boiler or water heater will continue to heat the
water even though the maximum temperature has reached. Sometimes, mineral deposits
may build up on the heating elements thus damaging them.
7. Back siphonage
Back siphonage is the backflow of water due to the existence of negative pressure, which
is below the atmospheric pressure, in the supply pipework. This phenomenon occurs due
to the excessive demand of water by user or when there is water supply failure. Under
some circumstances such as when suitable precautions do not exist in the system,
content in the sanitary appliances might flow back into the supply pipework and creates
unwanted problems. The risks of back siphonage are contamination risk, health risk and
water quality affecting risk. In order to prevent back siphonage, certain precaution
measures such as air gap to separate supply pipework from the installation pipework.
21. 21
FUTURE IMPROVEMENT
We studied on the improvements of the water heater system. The defects in hot water
supply system can be repaired and regularly checked to enhance the supply of hot water in
a building.
For the electrical water heaters; inspection, diagnosis and repair can be done. If one
heating element on the electric water heater has burned out, expect more rapid hot water
(the lower element is still working but the upper one is disfunctional) or less quantity of
hot water (the upper element works and the lower one is disfunctional).
Install extra tanks to increase hot water; pre-heat the hot water absorbing ambient
building heat or increase hot water quantity with cascaded, staged, multiple water
heaters, possibly using more than one energy source. Adding extra tanks can improve
both temperatures (water is pre-heated) and quantity of hot water.
Hot water delivery time can be increased by installing hot water pump and recirculating
loop systems for instant, hot water system which are incorporated in large buildings. This
won’t give you a higher water temperature overall but it will reduce the time between
turning on that hot water faucet and when hot water appears.
Hot water pressure loss and insufficent hot water may be due to blockage at the water
heater or mineral clogging in plumbing fixture. In order to fix this, the cold water supply
and plumbing fixture needs to be checked for any blockage. Installing extra hot water
tanks can improve the water pressure and even the flow and volume of hot water that
can be supplied to a whole building. Also, if the initial source of water heater is for
example, tankless coil, which does not provide adequate pressure and quantity of hot
water, installing a separate water heater such as gas fired water heater or an
instantaneous water heater can solve the problem and also reduce cost at the same time.
22. 22
Case study I (Local)
Ruemz Hotel
Ruemz Hotel@Taylor’s Lakeside Campus
On 12th of November, 2014, at 2.30 p.m., we paid a visit to Ruemz Hotel which is located at
the Syopz Mall, the commercial block of Taylor’s University Lakeside Campus. Every
member took this opportunity to have a look at the type of hot water supply system installed
in the hotel. Ruemz Hotel has 84 hotel rooms and has been operating for approximately 4
years until now. It is well known for its idea being a unique hotel-in-a-campus concept.
We were brought to one of the hotel rooms by Muhammad Izzat Ilyasa bin Shihabuddin, who
is the maintenance staff of Ruemz Hotel. Mr. Izzat showed us the water storage heater
which is located above the ceiling of the bathroom. According to Mr. Izzat, each of these
water storage heaters has the capacity of 135 litre and each hotel room is allocated with one.
He compared it with the standard 60-70 litre domestic water heater that can be found in
residential areas to show how high the hot water supply hotels require to maintain its
business flow. By then, we can safely deduce that the system this hotel uses is localized
instantaneous water storage heater powered by electricity.
23. There are two pipes connected to the water heater. One is the blue ABS pipe which carries
blue water and another is a copper pipe which carries hot water to every draw off points in
the room. The stored water is heated by an electric element until the water has expanded
enough to discharge from the discharge spout. Cool water from the base of the unit will then
replace the hot stored water that has discharge out. As after the discharging of hot water the
water will soon cool down again.
23
ABS pipe and copper pipe
24. According to Mr. Izzat, the problems faced in this hot water supply in the hotel is mainly that
sometimes, the electricity will trip due to overheating of the water heater coil element. The
standard temperature of the hot water supplied is between 60C to 75C. In normal cases,
the thermostat in the water heaters will observe and detect the water temperature to gauge it
to be around that optimal range. This is to prevent damages on the heaters internal
components. However, the thermostat may become faulty due to wear and tear and fail to
accurately detect the temperature of water thus, causing the water heater to overheat.
24
Group photo with Mr. Izzat
25. 25
Case Study II (Overseas)
Royal Orchid Sheraton Hotel @ Bangkok, Thailand
Royal Orchid Sheraton Hotel started operating since 22nd July, 1983 and currently, the hotel
has a total of 726 guest rooms and suites. It is located at 2 Charoen Krung Soi 30, Siphya,
Bangrak, Bangkok, 10500, Thailand. (Royal Orchid Sheraton, 2014)
Originally, Royal Orchid Sheraton Hotel uses a hot water supply system which is made up of
2 boilers, where 1 of them is used as a stand-by boiler. The boiler is capable of producing 5
tons per hour each to produce steam for domestic hot water supply, kitchen and laundry
services (SETAtWork, 2009). The average fuel consumption of a boiler was about 2,000 liter
per day (SETAtWork, 2009). The system supplies hot water using 5 hot water generators
which use steam as heat source. The temperature of domestic hot water supply is controlled
at around 55ºC. The average hot water consumption is about 95m3 per day at 70%
occupancy (SETAtWork, 2009).
When the price of fuel oil was increased to about USD0.70 per liter in 2008, the hotel has
decided to use Solar Water Heating System as shown in Figure 2 in order to save energy
cost (SETAtWork, 2009). The sola++r water heating system consists of 360m2 flat plate
solar collectors, two hot water storage tanks where each of them has a capacity of 23,000
liters, circulation pumps, and a control system. The system can produce about 24,000 liter of
water per day at an average temperature of 55oC (SETAtWork, 2009) and it is installed on
the concrete roof top.
Figure 2: Schematic Diagram of Solar Water Heating System used in Royal Orchid Sheraton
Hotel
26. Differential thermostat is used in the Solar Water Heating System to determine when the
circulation pumps need to be switched on. When the temperature of solar collector is about
10oC higher than the water temperature in the storage tank, the circulation pumps will be
switched on and the pumps will be switched off when the temperature difference is around
5oC (SETAtWork, 2009). The hot water from the storage tank will flow into existing hot water
generators and will be discharged to the existing hot water piping system.
However, one of the biggest concerns about Solar Water Heating System is that the weather
plays a significant role in the system. In order to ensure that there is always enough hot
water supply in the storage tank, Royal Orchid Sheraton Hotel has also installed 5 units of
heat pump to produce additional hot water to the hot water storage tank. Each unit has a
capacity of producing around 2,000 Liter of hot water at 50oC per unit (SETAtWork, 2009).
The heat pumps will only start to operate once the temperature of solar heated water is
below a set point, which usually happens in the evening and night time.
26
Figure 3: Heat Pumps Installed on the Roof Top of Royal
Orchid Sheraton Hotel
27. 27
Learning Outcomes
Through this assignment, we were able to determine the types of systems in hot
water services and understand the differences between each system and the installation and
requirements of the different types of hot water supply system. Besides that, we were able to
identify the advantages and disadvantages of each different types of system, and also
problems that may be encountered in hot water supply system. Knowledge of the benefits
and problems can help us to determine how to choose the right hot water supply system
which is to be installed in a particular building. Not only that, it also enables us to determine
how to properly maintain the system so that we can avoid and prevent problems in the
system and thus, have a better, functional and long-term hot water supply system. As the
technology is improving, we were able to identify several improvements that could be made
to hot water supply system in order to enhance the system and eliminate or reduce problems
in the system.
We had the opportunity to visit Ruemz Hotel as a part of our case study. From this case
study, we were able to understand how does an instantaneous water heater looks like and
also where it could be located in building. This case study enabled us to understand better
about the application of different types of hot water system according to the requirements of
the building.
28. 28
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