economizer training - hvac-talk
TRANSCRIPT
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An Arrangement of….
Dampers
Actuators
Controls
...that allow the use of OUTDOOR AIR to achieve FREE COOLING without the use of mechanical stages.
What is an Economizer?
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Components in an Economizer System
•Logic Module - The “Brains” of the system, makes the decisions based
on input from sensors
•Sensors Determine the conditions and give feedback to the logic
module
•Actuator The dumb workhorse, changes damper position based on
a signal from the logic module
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Typical Economizer
OA Sensor
OA Dampers
RA Damper
Mixed Air
Sensor
RA Sensor (optional)
Fresh Air Intake
Actuator and Logic
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Why Have an Economizer?
IT SAVES MONEY IMMEDIATELY
Reduce Compressor Run Time and energy usage
Prevents Excessive Outdoor Air During Heating Season
IT SAVES MONEY LONG TERM
Reduced Equipment Maintenance and Service Costs
Extends Equipment Life and Eliminates Premature Replacement Costs
THE “COMFORT FACTOR”
To Provide Fresh Air to Building Occupants
To Meet “Indoor Air Quality” Standards
Why Use an Economizer?
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How Does an Economizer Work?
Thermostat
Economizer Logic Module
Rooftop Unit
Y1 Cool 1
Damper
Actuator
NO FREE
COOLING
AVAILABLE
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How Does an Economizer Work?
Thermostat
Economizer Logic Module
Rooftop Unit
Y1 Cool 1
Damper
Actuator
NO FREE
COOLING
AVAILABLE
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How Does an Economizer Work?
Thermostat
Economizer Logic Module
Rooftop Unit
Y1 Cool 1
Damper
Actuator
NO FREE
COOLING
AVAILABLE
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How Does an Economizer Work?
Thermostat
Economizer Logic Module
Rooftop Unit
Y1 Cool 1
Damper
Actuator
FREE
COOLING
AVAILABLE
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How Does an Economizer Work?
Thermostat
Economizer Logic Module
Rooftop Unit
Y1 Cool 1
Damper
Actuator
FREE
COOLING
AVAILABLE
Modulates
Open
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How Does an Economizer Work?
Thermostat
Economizer Logic Module
Rooftop Unit
Y1 Cool 1
Damper
Actuator
FREE
COOLING
AVAILABLE
Modulates
Open
Y2
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How Does an Economizer Work?
Thermostat
Economizer Logic Module
Rooftop Unit
Y1 Cool 1
Damper
Actuator
Modulates
Open
Y2
NO FREE
COOLING
AVAILABLE
Cool 2
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Components in an Economizer System
•Logic Module
•Sensors
•Actuator
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Economizer Sensors
C7150 Mixed Air Sensor
• Senses mixed air temperature and proportions dampers to maintain 55 degrees
• 3000 ohms at 25 deg C
C7400 Enthalpy Sensor
• Solid state humidity and temperature sensors
• Provide Enthalpy reading to economizer logic module
• Logic module uses this to determine if free cooling is available
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Economizer Actuators
M7415 A and B ‘Black Motor’
• 25 Lb/in foot mounted spring return actuator
• ‘A’ model rotates CCW to open
• ‘B’ model rotates CW to open
• Motor position controlled by thermistor sensor resistance of C7150 mixed air sensor
M7215A ‘Black Motor’
• 25 lb/in foot mounted spring return actuator
• Rotates CCW to open
• Motor position controlled by 2-10VDC output from advanced economizer logic modules
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W7459 Very Large installed base
Uses M7415 “black” motor exclusively
Typically mounted directly on actuator
Modulating signal based on resistance
from C7150 mixed air sensor
On board Potentiometers for min
position and enthalpy change over
W7459 Economizer Logic Module
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W7212 Enhanced Economizer Logic Module
W7212 Offered the benefits of the W7459 with
added features:
Used any 0-10 or 2-10 volt actuator
Provided control of exhaust fans
Added occupancy input
Provided input for a CO2 sensor, allowed
demand controlled ventilation
Readily adopted by OEMS
Good opportunity for upgrade to
Demand Ventilation
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What do Contractors say about Economizers?
• It is sometimes difficult to know if they are working properly
• They can be difficult to set up
• How do I know if the minimum position is set correctly?
• Am I providing too much or not enough ventilation to the building?
• They tend to get broken or damaged easily, don’t tend to last too long
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W7220 Economizer Interface and Programming
2 LINE LCD
16 CHARACTERS/LINE
SELECT (ENTER)
BUTTON SCROLL(UP/DOWN)
BUTTONS
MENU UP (EXIT)
BUTTON
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Economizer System Sensors
C7400S Sylkbus sensors
C7250A 20k temperature sensors
3 position DIP switch
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Kit part number:
50053060-001
Economizer Sensors Duct Mounting
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W7220 Inputs / Outputs
Mixed Air Temperature
Outdoor Air Temperature
(when not using enthaply)
Enthalpy Sensor for MA/OA/RA
CO2 Sensor Inputs for DCV
2-10 vdc to actuator
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W7220 Inputs / Outputs
Shut Down (Conventional)
O/B (Heat Pump
Auxiliary Output: -Exhaust 2
-ERV Enable
-System Alarm Output
Y1 In from Thermostat / Out to Equipment
24Vac System power
Y2 In from Thermostat / Out to Equipment
Occupancy Input
Exhaust 1
Earth Ground
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Enthalpy Based System
Y2 in
Y2out
Y1out
Y2 in
Y2out
Y1out
Y1 in
Y1 Y2
Y1
N
Y2
OCC
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Enthalpy Based System ~ No Free Cooling
Y2 in
Y2out
Y1out
Y2 in
Y2out
Y1out
Y1 in
Y1 Y2
Y1
N
Y2
OCC
No Free Cooling
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Enthalpy Based System ~ No Free Cooling
Y2 in
Y2out
Y1out
Y2 in
Y2out
Y1out
Y1 in
Y1 Y2
Y1
N
Y2
OCC
No Free Cooling
Stage 1
Stage 2
1st Stage Cooling
2nd Stage Cooling
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Enthalpy Based System ~ Free Cooling Avail
Y2 in
Y2out
Y1out
Y2 in
Y2out
Y1out
Y1 in
Y1 Y2
Y1
N
Y2
OCC
Free Cooling
Modulates Open...
...based on MA Setpoint
1st Stage Cooling
2nd Stage Cooling
Stage 1
After a predetermined
Amount of time
With Y2 calling...
Stage 2
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•Top 5 Selling Points
-Simple to use
-Easy setup and maintenance
-Meets codes for maximum energy efficiency
-Enhanced quality for long life
-Lower total installed cost
The Value of JADE
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JADE: Simple to Use
• Simplified installations - ‘Plain English’ used throughout
• Expanded information eliminates guessing - Damper ventilation settings are clear & readily available
• Elimination of added components – System Cost Savings - Ability to stage exhaust fans without extra hardware
- Less inventory for different models/ SKUs
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JADE: Easy Setup & Maintenance
• Fault detection and diagnostics
- No more guessing
- LCD screen delivers clear fault messages and key diagnostic information
• Auto commissioning
- Saves valuable labor time and checks for wiring accuracy
- Eliminates tooling expense
• Simplified Wiring
- Removable connectors save time and eliminate wiring errors
- Sylkbus allows multiple sensors to sit on the same 2 wire pair
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JADE: Meets Code Requirements
• Meets the new 2010 codes with the base model, and will be able to address future codes
• Code Adherence: CEC Title 24
- Level 1 - Min requirement to be sold in CA
- Level 2 - Energy Star
- Level 3 - Maximum Energy Efficiency Economizer self test or protocol for field test – Keypad or PC
Verification of initial operation at OEM or during commissioning – PC interface
- 15 year MTBF for economizer and economizer sensors
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• No potentiometers; rugged push buttons
• Conformal coated for environmental protection
• Five year warranty for complete system
JADE: Enhanced Quality for Long Life
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• Modular platform
- Saves equipment cost
- Enables more applications for less SKUs
• Advanced applications eliminates the need for additional components
- Additional cooling capacity and energy savings
- Elimination of freeze stat
- Ability to stage exhaust fans without extra hardware
JADE: Lower Total Installed Cost
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How do I get JADE?
• Available as individual components
• Available as a ‘Retrofit Kit’
- Y7220S7215
Economizer module
Temperature and Enthalpy sensor
M7215 actuator
• Good Targets for Upgrade:
W859 T7400
Legacy Honeywell
Economizer Systems
Competitor’s
‘Orphaned’ systems
Systems that have been
neglected or aren’t working
H205
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Why do we Ventilate Buildings?
•The reasons we ventilate buildings are:
-To ensure a healthy atmosphere for occupants by diluting indoor contaminants and providing fresh air
-To pressurize the building positively to prevent unfiltered and unconditioned air from entering the building
-To provide cooling and save energy
-To replace exhausted air (provide make-up air)
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Ventilation
Ventilation removes contaminants in a space through dilution....
• You can bring in lots of fresh air through your ventilation system to do this...
• ...but it costs a lot of money to bring in fresh air
• The answer is better control of fresh air!
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ASHRAE Standards... May be Seen as Conflicting
•ASHRAE 62.1-2004 Ventilation for Acceptable Indoor Air Quality
- The purpose of this standard is to specify minimum ventilation rates and indoor air quality that is acceptable to human occupants
•ASHARE 90.1-2004 Energy Standard for Buildings Except Low-Rise Residential Buildings
-The purpose of this standard is to provide minimum requirements for the energy- efficient
design of buildings except low-rise residential
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Demand Control Ventilation (DCV) is growing rapidly in popularity and required in many locations...
• CO2 does a good job of determining occupancy
• When tied in with an economizer, DCV can bring in the right amount of ventilation for the actual number of occupants
• This can save energy (money!) when spaces are not occupied at design densities
Demand Control Ventilation
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How Demand Control Ventilation Works…
With a traditional economizer system, the required amount of fresh air is brought in based on the minimum position setting…
Damper Position
100% Open
Min Positon
0% Open
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How Demand Control Ventilation Works…
Damper Position
100% Open
Min Positon
0% Open
With a Demand Ventilation System there are three settings:
DCV SETPOINT
VENT MAX
VENT MIN
VENT Max Position
VENT Min Position
CO2 Level
450 ppm 800 ppm 2000 ppm *
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How Demand Control Ventilation Works…
Damper Position
100% Open
Min Positon
0% Open
VENT Min Position is set to provide enough fresh air to counteract off-gassing of building components
VENT Max Position
VENT Min Position
CO2 Level
450 ppm 800 ppm 2000 ppm *
As space CO2 level rises above DCV Setpoint dampers mod open, allowing more fresh air to bring CO2 down to setpoint
Dampers modulate open up to VENT Max Position (but do not exceed this position)
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How Demand Control Ventilation Works…
Damper Position
100% Open
Min Positon
0% Open
Savings are achieved by ventilating based on occupancy rather than by the building’s design ventilation requirement .
VENT Max Position
VENT Min Position
CO2 Level
450 ppm 800 ppm 2000 ppm *
Savings
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How Much Ventilation Do we Need?
Occupant Component
Category Rp Discussion
0 0 CFM per person Applies to spaces where the ventilation requirements are dominated by building related sources, e.g., storage rooms and warehouses
1 5 CFM per person Applies to spaces where primarily adults involved in passive activities, e.g., office work
2 7.5 CFM per person Applies to spaces where occupants involved in higher levels of activities but not strenuous, e.g., lobbies and retail stores.
3 10 CFM per person Applies to spaces where occupants involved in more strenuous activities but not exercise level, e.g., most classrooms and other school occupancies.
4 20 CFM per person Applies to spaces where occupants involved in very high levels of activities or high contaminant generation, e.g. beauty salons, dance floors and exercise rooms.
Building Component Ra Discussion
1 0.06 cfm/ft2 Applies to spaces where building related contaminants are generated at rates similar to office spaces, e.g., conference rooms and lobbies.
2 0.12 cfm/ft2 Applies to spaces where building related contaminants are generated at rates significantly higher than office spaces, e.g., class rooms and museums.
3 0.18 cfm/ft2 Applies to spaces where building related contaminants are generated at even higher rates, e.g., laboratories and art classrooms.
4 0.30 cfm/ft2 Last two are for sports and entertainment category where there is no people based ventilation requirement, all building ventilation.
5 0.48 cfm/ft2 Source for data: ASHRAE Standard 62.1-2004 User’s manual 2005 edition
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How Much Ventilation Do We Need?
Ventilation
For Occupant
Comfort
+ Ventilation
For Building
Component
= Ventilation
Required in
Building
Max Number of Occupants
X
Occupant Comfort
Factor
Building Area
X
Building Component
Factor
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Demand Control Ventilation
Occupant Component
Category Rp Discussion
0 0 CFM per person Applies to spaces where the ventilation requirements are dominated by building related sources, e.g., storage rooms and warehouses
1 5 CFM per person Applies to spaces where primarily adults involved in passive activities, e.g., office work
2 7.5 CFM per person Applies to spaces where occupants involved in higher levels of activities but not strenuous, e.g., lobbies and retail stores.
3 10 CFM per person Applies to spaces where occupants involved in more strenuous activities but not exercise level, e.g., most classrooms and other school occupancies.
4 20 CFM per person Applies to spaces where occupants involved in very high levels of activities or high contaminant generation, e.g. beauty salons, dance floors and exercise rooms.
Building Component Ra Discussion
1 0.06 cfm/ft2 Applies to spaces where building related contaminants are generated at rates similar to office spaces, e.g., conference rooms and lobbies.
2 0.12 cfm/ft2 Applies to spaces where building related contaminants are generated at rates significantly higher than office spaces, e.g., class rooms and museums.
3 0.18 cfm/ft2 Applies to spaces where building related contaminants are generated at even higher rates, e.g., laboratories and art classrooms.
4 0.30 cfm/ft2 Last two are for sports and entertainment category where there is no people based ventilation requirement, all building ventilation.
5 0.48 cfm/ft2
Source for data: ASHRAE Standard 62.1-2004 User’s manual 2005 edition
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Example:
• 5000 Sq ft office space
• 40 employees
• 1 rooftop unit, 5000 CFM capacity
Ventilation Requirement
• Occupant Component:
- Category 1: 5 cfm/ person = 200 CFM
• Building Component:
- Category 1: 0.06 cfm / sq ft = 300 CFM
• Total Fresh Air Requirement = 500 CFM
(10% of total CFM)
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The formula for setting ventilation air
( OAT – RAT ) x % Ventilation air + RAT= MAT
OAT – Outside air temperature
RAT – Return air temperature
MAT – Mixed air temperature
Important! There should be at least a 10 degree difference
between the return and outside air temperature.
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The formula for setting ventilation air
(( OAT – RAT ) x % Ventilation air) + RAT= MAT
OAT – Outside air temperature
RAT – Return air temperature
MAT – Mixed air temperature
Important! There should be at least a 10 degree difference
between the return and outside air temperature.
((80 - 68) x 10%) + 68 = ?
(12 x 10%) + 68 = ?
1.2 + 68 = 69.2
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80° OA
Outdoor air reading taken at fresh air inlet
80
Unit not “calling ” for cooling
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80° OA
68° RA
Return air temperature taken in return duct
68
Unit not “calling ” for cooling
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80° OA
68° RA
69.2° MA
Slowly adjust minimum position until this reading
matches your calculations.
69
Unit not “calling ” for cooling
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“Savings Estimator” Software
Not useful as an energy audit tool for a specific building, however allows user to study the impact of the following variables:
- Climate
- Building Size
- Occupancy schedule
- Utility rates
- Equipment efficiency
- Cost of controls
http://customer.honeywell.com/Business/Cultures/en-US/Products/Applications+and+Downloads/Economizer+Logic+Module+%28W7212%29+Simulator+and+Demand+Control+Ventilation+Savings-Estimator.htm
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Savings Example adding DCV and Economizer
• 20,000 square foot retail store
• Located in Toronto
• 4 Rooftop units
• $ 0.08 / KWh
• $ 0.33 / M3 natural gas
• Currently has T874 Mechanical Thermostats
Result
• Gas usage goes from 8,700 to 4,000 M3
• Electrical usage goes from 24,000 Kwh to 16,000Kwh
• Utility savings of $2,182
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Savings Example adding DCV and Economizer
• 4,000 square foot Casual Dining Restaurant
• Located in Toronto
• 2 Rooftop units
• $ 0.08 / KWh
• $ 0.33 / M3 natural gas
• Currently has T874 Mechanical Thermostats
Result
• Gas usage goes from 16K to 5.5K M3
• Electrical usage goes from 48 Kwh to 36 Kwh
• Utility cost savings of $4,500 per year