11

Packaged Packaged HVAC HVAC

EquipmentEquipment

22

Packaged HVAC Packaged HVAC EquipmentEquipment

Is the most common source for HVAC Is the most common source for HVAC in small to medium commercial in small to medium commercial buildingsbuildings

Used in:Used in:

Retail StoresRetail Stores

SupermarketsSupermarkets

RestaurantsRestaurants

33

Packaged HVAC Packaged HVAC EquipmentEquipment

Rooftop units, better known as RTUs, Rooftop units, better known as RTUs, are popular because they are the are popular because they are the "least cost solution" to heating, "least cost solution" to heating, ventilating, and air conditioning a ventilating, and air conditioning a building.building.

44

Rooftop UnitsRooftop UnitsSome of the reasons for this are:Some of the reasons for this are: RTUs are unitary or packaged equipment RTUs are unitary or packaged equipment

and require no field refrigerant piping. and require no field refrigerant piping. RTUs provide heating, cooling, air moving, RTUs provide heating, cooling, air moving,

outside air introduction, and a filtration outside air introduction, and a filtration system. system.

RTUs do not take up valuable floor space. RTUs do not take up valuable floor space. RTU service time is reduced because all of RTU service time is reduced because all of

the components are together. the components are together. Routine service does not interfere with Routine service does not interfere with

store operation. store operation. RTU replacement is quicker and doesn't RTU replacement is quicker and doesn't

interfere with store operation.interfere with store operation.

55

Rooftop UnitsRooftop Units

Types of Rooftop Types of Rooftop Units:Units:

Multi-zoneMulti-zone

VAV (Variable Air Volume)VAV (Variable Air Volume)

Constant VolumeConstant Volume

66

Multi-zoneMulti-zone These systems are still available but are losing These systems are still available but are losing

favor because of their inherent energy inefficiency.favor because of their inherent energy inefficiency. A multi-zone unit typically consists of a hot and a A multi-zone unit typically consists of a hot and a

cold deck. cold deck. There are also three deck units, the third being the There are also three deck units, the third being the

bypass deck. bypass deck. This is more efficient because you add hot or cold This is more efficient because you add hot or cold

air to the return air. air to the return air. Some additional disadvantages are:Some additional disadvantages are:

You are limited to the number of zones You are limited to the number of zones available and the need to distribute the air available and the need to distribute the air proportioned to each zone evenly. proportioned to each zone evenly.

Building energy codes place restrictions on Building energy codes place restrictions on the use of reheat temperature control. the use of reheat temperature control.

77

VAV (Variable Air Volume)VAV (Variable Air Volume) These systems are becoming more These systems are becoming more

popular for their ability to provide popular for their ability to provide unlimited zoning control and ease of unlimited zoning control and ease of future reconfiguration of space and future reconfiguration of space and zones. zones.

VAV systems are available in the 15-VAV systems are available in the 15-ton and up range in cooling only or ton and up range in cooling only or cooling with heat versions. cooling with heat versions.

The heating section allows for The heating section allows for morning space warm-up and building morning space warm-up and building temperature setback.temperature setback.

88

Constant VolumeConstant Volume Most retail outlet stores have RTUs Most retail outlet stores have RTUs

with a single-zone heating and with a single-zone heating and cooling configuration. cooling configuration.

These units have constant air volume These units have constant air volume to a single zone with a single to a single zone with a single thermostat controlling them. thermostat controlling them.

They are the least expensive to They are the least expensive to purchase and are the simplest to purchase and are the simplest to install and maintain.install and maintain.

99

Roof Top UnitsRoof Top Units A typical RTU is a manufactured piece of A typical RTU is a manufactured piece of

equipment that is factory-assembled, equipment that is factory-assembled, delivered to the site in one piece and ready delivered to the site in one piece and ready to operate with a single-point control to operate with a single-point control interface. interface.

In most cases, they connect to utilities such In most cases, they connect to utilities such as natural gas and electric power. as natural gas and electric power.

In some configurations, they can be In some configurations, they can be connected to a system’s hot water or connected to a system’s hot water or steam system for heating, and chilled steam system for heating, and chilled water system for cooling. water system for cooling.

In most cases, each unit is factory-tested to In most cases, each unit is factory-tested to insure quality control. insure quality control.

Having said this, it is still very important Having said this, it is still very important that a responsible contractor perform the that a responsible contractor perform the start-up or commissioning service.start-up or commissioning service.

1010

Roof Top UnitsRoof Top UnitsThe following points are essential parts of The following points are essential parts of

commissioning:commissioning: Check operation of heating and cooling.Check operation of heating and cooling. Adjust the air/fuel mixture for your altitude.Adjust the air/fuel mixture for your altitude. Adjust belts. Adjust belts. Tighten bolts, particularly in the blower Tighten bolts, particularly in the blower

section.section. Remove shipping braces.Remove shipping braces. Check for refrigerant leaks.Check for refrigerant leaks.

1111

Construction andConstruction andInstallationInstallation

Rooftop units are constructed of galvanized Rooftop units are constructed of galvanized steel with a primer and a final UV-resistant steel with a primer and a final UV-resistant paint coat. paint coat.

The exterior panels are insulated with glass The exterior panels are insulated with glass fiber with a thickness of 1- to 2- inches. fiber with a thickness of 1- to 2- inches.

Units being manufactured with a solid Units being manufactured with a solid metal liner are becoming more common metal liner are becoming more common due to IAQ (Indoor Air Quality) concerns.due to IAQ (Indoor Air Quality) concerns.

1212

Construction and Construction and InstallationInstallation

• Condensate drain pans are constructed Condensate drain pans are constructed using steel with a mastic coating, using steel with a mastic coating, galvanized steel, PVC, or stainless steel. galvanized steel, PVC, or stainless steel.

• Deeper pans with two-way sloping to drain Deeper pans with two-way sloping to drain are desirable to remove condensate from are desirable to remove condensate from the unit completely and prevent ponding of the unit completely and prevent ponding of water, where algae and microbial will water, where algae and microbial will proliferate and reduce air quality.proliferate and reduce air quality.

1313

Construction and Construction and InstallationInstallation

• An RTU mounts on a curb, which is a perimeter frame that An RTU mounts on a curb, which is a perimeter frame that supports the unit off of the roof deck. supports the unit off of the roof deck.

• The top of the curb has a mating flange that adapts to the The top of the curb has a mating flange that adapts to the RTU. When you are replacing an RTU with another one RTU. When you are replacing an RTU with another one having a different footprint, it is common to use an "Adapt-a-having a different footprint, it is common to use an "Adapt-a-Curb". Curb".

• This device adapts the new RTU to the existing curb. This device adapts the new RTU to the existing curb. Properly manufactured and installed with gaskets, the Adapt-Properly manufactured and installed with gaskets, the Adapt-a-Curb is an acceptable way to install a replacement RTU a-Curb is an acceptable way to install a replacement RTU while not disturbing the existing roofing. while not disturbing the existing roofing.

• Ductwork connections and gravity are usually not enough to Ductwork connections and gravity are usually not enough to keep an RTU in place during high winds. Straps, sheet metal keep an RTU in place during high winds. Straps, sheet metal screws or welding are common ways of fastening the RTU to screws or welding are common ways of fastening the RTU to the curb.the curb.

1414

Construction and Construction and InstallationInstallation

• RTUs should be placed near the area where they RTUs should be placed near the area where they will heat or cool. will heat or cool.

• This saves ductwork installation and thermal duct This saves ductwork installation and thermal duct losses. Location relative to exhaust air fans or losses. Location relative to exhaust air fans or vents, plumbing vents, and process exhaust, such vents, plumbing vents, and process exhaust, such as kitchen hoods, should be taken into account. as kitchen hoods, should be taken into account.

• Additionally, ambient, prevailing wind conditions Additionally, ambient, prevailing wind conditions affect movement of air on the roof into the outside affect movement of air on the roof into the outside air intake louvers. air intake louvers.

• Wind conditions also affect the operation of the Wind conditions also affect the operation of the condenser fans. When not energized, the fans can condenser fans. When not energized, the fans can begin freewheeling or wind milling due to wind.begin freewheeling or wind milling due to wind.

1515

Construction and Construction and InstallationInstallation

• Single-speed motors, when started, want Single-speed motors, when started, want to continue in the direction the fan was to continue in the direction the fan was freewheeling. freewheeling.

• This could block air movement through the This could block air movement through the condensing unit. A three-phase unit will condensing unit. A three-phase unit will only run in one direction without changing only run in one direction without changing electrical connections. electrical connections.

• If freewheeling in the wrong direction when If freewheeling in the wrong direction when energized, the fan will draw additional energized, the fan will draw additional amperage and possibly damage the motor, amperage and possibly damage the motor, fan blades, and or the fan supports.fan blades, and or the fan supports.

1616

Construction and Construction and InstallationInstallation

• The architect, roofing consultants, and The architect, roofing consultants, and engineer should consider access to rooftop engineer should consider access to rooftop equipment in building design.equipment in building design.

• Wear or walk pads to the units can minimize Wear or walk pads to the units can minimize future damage to the roof by individuals and future damage to the roof by individuals and service equipment.service equipment.

• With all of the choices available in RTUs today, With all of the choices available in RTUs today, there is sure to be something that will fit your there is sure to be something that will fit your needs. needs.

• Discuss the options with your HVAC provider Discuss the options with your HVAC provider and, after considering all of the options, pick and, after considering all of the options, pick the one that will satisfy your needs. the one that will satisfy your needs.

1717

Packaged HVAC Packaged HVAC EquipmentEquipment

In 2000 the U.S. Department of In 2000 the U.S. Department of Energy estimates that rooftops and Energy estimates that rooftops and unitary air-conditioning equipment unitary air-conditioning equipment accounts for 62% of total energy accounts for 62% of total energy consumption for cooling commercial consumption for cooling commercial buildings.buildings.

1818

Service and Maintenance Service and Maintenance of Packaged HVAC of Packaged HVAC

EquipmentEquipment

Packaged equipment isPackaged equipment is : : Smaller in sizeSmaller in size More numerous in numberMore numerous in number Usually not as well maintainedUsually not as well maintained

1919

Why are they not as well Why are they not as well maintained?maintained?

Out of sight out of mind!Out of sight out of mind! Often ignored and forgotten until they have Often ignored and forgotten until they have

degraded to a point of failure.degraded to a point of failure. Effects of failure are limited to small number Effects of failure are limited to small number

served.served. Large buildings have so many that preventive Large buildings have so many that preventive

maintenance would require a lot of a service maintenance would require a lot of a service technicians time. technicians time.

In many cases the unit is all contained within the In many cases the unit is all contained within the unit. i.e. – no chiller, no pumps, no additional unit. i.e. – no chiller, no pumps, no additional piping, and no separate refrigerant piping. piping, and no separate refrigerant piping.

2020

Packaged HVAC UnitsPackaged HVAC Units “No Air Calls” “No Air Calls”

Control Errors – 21%Control Errors – 21% Electrical Problems – 20%Electrical Problems – 20% Refrigerant Leaks – 12%Refrigerant Leaks – 12% Condenser – 7%Condenser – 7% Air Handling – 7%Air Handling – 7% Evaporator – 6%Evaporator – 6% Compressor – 5%Compressor – 5% Cooling Water Loop – 4%Cooling Water Loop – 4% Plugged Filters – 2%Plugged Filters – 2% Personnel Error – 2%Personnel Error – 2% Expansion Device – 2%Expansion Device – 2% Can’t Classify – 1%Can’t Classify – 1%

2121

Packaged HVAC UnitsPackaged HVAC Units Service Call Cost Breakdown Service Call Cost Breakdown

Compressor – 24%Compressor – 24% Control Errors – 10%Control Errors – 10% Condenser – 9% Condenser – 9% Electrical Problems – 7%Electrical Problems – 7% Evaporator – 6% Evaporator – 6% New Installation – 6%New Installation – 6% Air Handling – 5%Air Handling – 5% Refrigerant Leaks – 5%Refrigerant Leaks – 5% Installation/Start-up – 4%Installation/Start-up – 4% Cooling Water Loop – 4%Cooling Water Loop – 4% Fan Belt – 2%Fan Belt – 2% Others – 18%Others – 18%