111130 selecting roof top units rdb

Sharing our Guidance

Selecting Roof Top Units

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Selecting Rooftop Units

To optimize HVAC equipment to provide consistent occupant comfort, while

maximizing efficiency to conserve energy and contain costs.

The Challenge

Optimize HVAC

EquipmentProvide

Consistent

Occupant

Comfort

Conserve Energy

Contain Costs

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Selecting Roof Top Units

A single, packaged piece of equipment that provides basic HVAC functions, such as: Air moving Outside air induction Filtration, conditioning, heating, and cooling of the air supplied to the space

What is a Roof Top Unit (RTU)?

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Selecting Roof Top Units

Complete systems

Supply air fans

Filtration systems

Factory wiring with electrical connections

Factory tested for performance

What do RTUs Include when Delivered?

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Selecting Roof Top Units

Roof Top Unit Size: Small Units

Genera l ly

l imited in

opt ions

ava i lab le .

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Selecting Roof Top Units

Roof Top Unit Size: Large Units

Often

off ered with

component

sect ionsComponents

can be

mixed and

matched

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Selecting Roof Top Units

Summer cooling loads are the main

determinant factor.

The heating loads are usually dealt

with according to the size of the unit.

System Performance Requirements

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Selecting Roof Top Units

Interior Load – Calculated using the outside temperature plus solar heat gain

acquired due to heat transfer through the fabric of the building.

Outside Air Temperature – Will, in part, determine the cooling load of the

outside air brought into the building for ventilation.

Effectiveness of the Refrigeration System – If the refrigeration system is air

cooled, the outside temperature will influence the effectiveness of the

refrigeration system.

Effects of Outside Summer Design Temperature

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Selecting Roof Top Units

Initial cost to purchase and install vs.

the ongoing cost of operation and

maintenance.

Load vs. capacity

Deciding Factors When Choosing RTUs

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Selecting Roof Top Units

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Selecting Roof Top Units