1. Hydronic Heating & Cooling
System Design
Energy Efficient Building Design (EEBD) - HVAC
Presenter
Kshitiz Pandit
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2. What is Hydronic System?
 A hydronic system - composed of pumps, primary equipment (boilers, chillers)
piping, fittings, coils and control valves.
 Hydronic Heating system
 Hydronic Cooling system
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• Water is heated at boiler (gas, fuel, electric)
• Systems can be designed to handle multiple zones
• Water flows through piping that connects a boiler,
water heater, or chiller to suitable terminal heat
transfer units located at the space or process.

3.  Hot-water heating system opposed to steam and forced-warm-air heating systems.
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Pros
• More flexible than low-pressure steam
systems wide variation in temperatures
• Comfortable humidity levels.
• Less energy is used to circulate water
than blow air through the ducts.
• Quiet operation.
• Easy zoning.
Cons
• High initial installation cost, compared to forced-
warm-air (FWA) heating systems.
• Slower heat response
• Stagnant air caused by lack of ventilation
• Condensation in some Hydronic cooling systems

4.  Water systems can be classified by 1) Operating temperature 3) Flow generation
2) Pressurization 4) Piping arrangement
5) Pumping arrangement
Temperature classification
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I. Low-temperature water (LTW)
max. allowable working pressure =1100KPa
max. temp = 120°C.
• Low temp. heating system generally in
residential and small commercial building.
II. High-temperature water (HTW)
Operates at 175°C < temp. Max. 200°C
Usually at pressure about 2 Mpa
• High temp. heating system is widely used in
high rise, commercial and industrial buildings

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iii. Chilled-water (CW)
For cooling, normally operate with
a design supply water temp. of 4 to 13°C (usually
7°C), at a pressure ≤ 830 kPa.
• Antifreeze or brine solutions may be used
temp. < 4°C or for coil freeze protection.
• Well-water systems can use supply temperatures
of 15°C or higher.
iv. Dual temperature water (DTW)
Combine heating &cooling.
circulate hot & /or chilled water through
common piping and terminal heat transfer
apparatus.
• it operates within the pressure and
temperature limits of LTW system.
water temp. at winter 38°C to 65°C
summer 4°C to 7°C.

6.  CLOSED WATER SYSTEMS
Most hot and chilled water systems are closed.
These fundamental components are
• Loads
• Source
• Expansion chamber
• Pump
• Distribution system
Theoretically, a hydronic system could operate with only these five components.
The components are subdivided into two groups: thermal and hydraulic.
 Thermal components consist of - load, source, and expansion chamber.
 Hydraulic components consist of the distribution system, pump, and expansion chamber.
 The expansion chamber is the only component that serves both a thermal and a hydraulic function
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7.  Load
• A device that causes heat to flow out of or into the system to or from the space or process
• It is the independent variable to which the remainder of the system must respond.
• Outward heat flow characterizes a heating system
• Inward heat flow characterizes a cooling system.
Energy Efficient Building Design (EEBD) - HVAC 7

8.  Heat Source
 The source is the point where heat is added to (heating) or
removed from (cooling) the system
 Boiler - appliance that heats water using oil, gas, or electricity
as a heat source.
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• Hot-water generator or boiler
• Steam-to-water heat exchanger
• Water-to-water heat exchanger
• Solar heating panels
• Exhaust gas heat exchanger
• Incinerator heat exchanger
• Heat pump condenser
• Air-to-water heat exchanger

9.  Expansion chamber
 Also called an expansion or compression tank.
 It serves both a thermal and a hydraulic function.
It accommodate volumetric changes (water expand on heating)
and prevents excess pressure.
 Standard expansion tank is a large tank located above the boiler.
 Expansion tanks are of three basic configurations:
(1) A closed tank - which contains a captured volume of
compressed air and water, with an air/water
interface (sometimes called a plain steel tank)
(2) An open tank (i.e., a tank open to the atmosphere)
(3) A diaphragm tank - In which a flexible membrane is inserted
between the air and the water.
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10.  Pump/Pumping system
 Circulator/centrifugal pumps
 Most common type in hydronic system.
 Force hot water from heat source through piping to heat transfer units
and back to the boiler using centrifugal force.
 Pumps may be installed in parallel or series configurations.
 Air-source heat pumps, work best in well-insulated and airtight homes.
 Most hydronic heat pumps list a COP of between 3.0 and 3.5
 Variable-speed drives are becoming economical.
Two types:
 Parallel pumping
 Series pumping
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Primary/secondary or compound pumping

12.  Distribution/Piping system
 Piping - either steel or copper.
 Circuit can be dictated by such factors as,
- Shape or configuration of the building
- Economics of installation, energy economics
- Nature of the load and others
 Designed Piping system should maximize it’s simplicity
 Load distribution circuits are of four general types:
• Full series
• Diverting series
• Parallel direct return
• Parallel reverse return
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13.  Series Loop
Arrangement is basic, inexpensive & mostly used for residences.
Advantages
 lower piping costs & higher temperature drops
 Smaller pipe size and lower energy consumption
Disadvantage
 Different circuits cannot be controlled separately.
 Generally limited to residential and small commercial
systems.
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 Parallel piping
Most commonly used in hydronic systems - allow the
same temperature water to all loads.
 Direct return system (First In/First Out)
length of supply and return piping through the sub
circuits is unequal
Advantages
 Shorter pipes runs
 Lower initially cost
 Each terminal unit to be separately controlled and
serviced
Disadvantage
 Poor comfort - Does not insure adequate flow to all
terminal units .
 Not Self Balancing - Balance valves and balancing
required

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 Reverse return system (First In/Last out)
 Ideally, Provides nearly equal total lengths for all
terminal circuits.
Advantages
 Improved comfort
 Greater assurance of adequate flow to all terminal
units all times
 Self Balancing
Disadvantage
 Longer pipe run
 Higher pipe cost

16.  Non residential Heating Systems
Possible approaches to enhance the economics of large heating systems include
 Higher supply temperatures
 Primary-secondary pumping
 Terminal equipment designed for smaller flow rates.
The three techniques may be used either singly or in combination.
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 Combination piping system
• It is combination of some of four basic ways.
• It takes the best features of each.
• It is chosen for high rise building where separate control is not needed.
• Mainly reverse return system is coupled with other systems.
• It is simple and has low cost as compared to complete reverse return

17. What is Hydronic Cooling system?
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• Simply the removal of heat from the
space utilizing chilled water as the
heat exchange medium.
• water is chilled by a chiller, dry
cooler, or cooling tower. circulated
via pump through the system into
heat exchanger units (air handlers
or fan coils) then back to the chiller.

18.  Benefits of CHILLED WATER Cooling System
 Reduced electrical energy usage
 Availability of many chillers
 Easy zoning
 Adaptability to radiant panel cooling
 Adaptability to chilled-beam cooling
 Lower refrigerant volume
 Adaptability to thermal storage
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illustrates a very basic chilled-water cooling system using a reversible water-
to-water heat pump as the chiller.

20.  Chilled Water Sources
 Geothermal water to water heat pumps
 Electrically driven air to water heat pumps
 Air cooled condenser
 Direct lake water cooling
 Ground well water cooling
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Dual temperature system

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Cooling Source Devices
• Electric compression chiller
• Thermal absorption chiller
• Heat pump evaporator
• Air-to-water heat exchanger
• Water-to-water heat exchanger

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Heating load devices
• Heating coils in central units
• Zone or central reheat coils
• Finned-tube radiators
• Baseboard radiators
• Convectors
• Unit heaters & air handling units
• Fan-coil units
• Water-to-water heat exchangers
• Radiant heating panels &Snow-melting panels
Cooling load devices
Coils in central units
• Fan-coil units
• Induction unit coils
• Radiant cooling panels
• Water-to-water heat exchangers
Terminal Heat transfer units

24. The principles and procedures for designing and selecting piping and components for low-temperature water,
chilled water, and dual-temperature water systems.
Principle
Energy Efficient Building Design (EEBD) - HVAC 24
Effective and economical water system
design is affected by complex relationships
between the various system components.
The design water temperature, flow rate,
piping layout, pump selection, terminal unit
selection, and control method are all
interrelated.
In a practical sense, no component can be selected
without considering its effect on the other elements.
For example, design water temperature and flow
rates are interrelated, as are the system layout and
pump selection. The type and control of heat
exchangers used affect the flow rate and pump
selection, and the pump selection and distribution
affect the controllability

25.  METHOD OF DESIGN
 Determine system and zone loads - ASHRAE Handbook—Fundamentals.
The load determines the flow of the hydronic system, which ultimately affects
the system’s heat transfer ability and energy performance.
 Select comfort heat transfer devices
This often means a coiler water-to-air heat exchanger (terminal)
 Select system distribution style(s).
Based on the load and its location, different piping styles may be appropriate
for a given design to optimize building performance.
 Size branch piping system.
Based on the selection of the coil, its controlling devices, style of installation, and location,
branch piping is sized to provide required flow, and pressure loss is calculated.
 Calculate distribution piping pressure loss.
understanding the relationship and effect of distribution system pressure loss is important
in establishing that all terminals get the required flow for the required heat transfer.
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26.  Lay out piping system and size pipes.
After preliminary calculations of target friction loss for the pipes, sketch the system..
 Select pump specialties.
 Select air management methodology.
All hydronic systems entrain air in the circulated fluid. Managing
the collection of that air as it leaves the working fluid is essential
to management of system pressure and the safe operation of
system components
 Select pump (hydraulic components).
Unless a system is very small (e.g., a residential hot-water heating system), the pump is
selected to fit the system. A significant portion of energy use in a hydronic system is transporting the
fluid through the distribution system. Proper pump selection limits this energy use, whereas improper
selection leads to energy inefficiency and poor distribution and heat transfer.
 Determine installation details, iterate design.
Increase performance and cost effectiveness
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27. 27 References
2008 ASHRAE Handbook—HVAC Systems and Equipment. ASHRAE, 1791 Tullie
Circle, Atlanta, Georgia.
https://www.ahscansw.com.au/sites/default/files/idronics_13_us.pdf

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