Hot Water – a Hot Commodity
Better Buildings by Design, February 2012Burlington, VT
Gary KleinAffiliated International Management, LLC
916‐549‐[email protected]
© Gary Klein, 2012
Efficiency Vermont is a Registered Provider with The American Institute of Architects Continuing Education Systems (AIA/CES). Credit(s) earned on completion of this program will be reported to AIA/CES for AIA members. Certificates of Completion for both AIA members and non-AIA members are available upon request.
This program is registered with AIA/CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any material or product.
Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation.
Learning Objectives
Gain an understanding of the magnitude and trends of
water heating compared to space heating and cooling
Learn how a very efficient water heater can be the
thermal engine for the space conditioning system
Explore the ways to integrate this concept into very
efficient houses
Identify which products are there today and which are
emerging to implement this vision
Course EvaluationsIn order to maintain high‐quality learning experiences, please access the
evaluation for this course by logging into CES Discovery and clicking on the Course Evaluation link on the left side of the page.
Has Someone Moved Our Cheese?
Energy Pie 1990
Heating and CoolingWater HeatingRefrigerationLightingClothes DryingTelevisionComputersVampiresMiscellaneous
100 Units of Energy
Energy Pie 2010
Heating and CoolingWater HeatingRefrigerationLightingClothes DryingTelevisionComputersVampiresMiscellaneous
89 Units of Energy
Energy Pie 2020
Heating and CoolingWater HeatingRefrigerationLightingClothes DryingTelevisionComputersVampiresMiscellaneous
45 Units of Energy
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Combi Systems – One Thermal Engine
• How many days a year do we:1. Use hot water?2. Heat the house?3. Air condition the house?
• Size of heating peak? Cooling peak?• Size of water heating peak?• Why are we still so focused on condensing furnaces and not on condensing water heaters that can also heat the house?
Combi Systems: Distribution Options
• Radiant – floors, walls, ceilings• Hydronic baseboards and radiators• Forced air – hydronic air handlers• Combinations of the above?
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Hydronic Air Handler Schematic
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Cutaway of Air Handler
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Piping – Priority for Hot Water
Atmospheric Boiler with Side Arm Tank
Atmospheric Gas Water Heater
Atmospheric Gas Water Heater
• 50 Gallon• 63,000 Btu• Where does the
make-up air come from?
• Does the air handler cause the water heater to down draft?
Condensing Gas Water Heater
• Water Heater– 55 gallon tank– 199,000 Btu
• Air Handler– Heating coil– AC coil– 18-24,000 Btu
Condensing Gas Water Heater
• Water Heater– 50 gallon tank– 100,000 Btu
• Air Handler– Heating coil– AC coil– 18-24,000 Btu
Minneapolis – 25 year old system
Condensing Gas: Integrated System
• Integrated Design– Water heating– Space heating– Air-to-Air Heat Exchanger
Air-to-Water Heat Pump: Integrated System
Products• Water heaters, boilers, heat pumps, desuperheaters
• Fan coils– Heating only– Heating and air conditioning– Temperature drop– Pressure drop– Pumps
• Controls• Integration with air‐to‐air heat exchangers
What are the Potential Benefits?• One thermal engine• Highest efficiency for the largest thermal
peak and largest energy need• High efficiency for small space conditioning
loads• Sealed combustion and indoor air quality• Design and installation flexibility• More comfortable. Usually quieter.• Simpler? Reduced maintenance costs?• Other?
What are the Potential Problems?• Health and Safety:
– is a heat exchanger necessary?• Sizing:
– Capacity if heating both water and space?– What size air handlers?
• Will gas water heaters operate in condensing mode?
• How will efficiency be measured?• Which trade(s) will do:
– Installation– Maintenance
• Other?
What are the Markets?
• High Performance Buildings– New Construction– Retrofits
• Energy Star for Homes• Green Building Programs• Low Income Weatherization• Other?
Minneapolis – The Future is Now!
• Two Low Income Weatherization Programs– 400 homes– Weatherize homes first
• Get below 20 Btu/hour/square foot at peak• Combustion safety
– Install combi-air systems• Expecting contractors will settle on certain packages• 10% will have air-to-air heat exchangers
• Process– Evaluate systems in a controlled setting– Collaborate with contractors and manufacturers on
what is needed and what works together– Feedback on all aspects in integral to project– Concentrated roll-out creates critical mass
Special Thanks
• Sustainable Resources Center• Ben Schoenbauer, Minneapolis Center for Energy and the Environment
• Northern Star Building America Team
Storage Water Heater
DHW Loads
Cold In from Mains
Supply to AH
Return from AH
Hydronic Air
Handler
Hot Space Heating Air
Open Loop
Storage water heater based system
Tankless water heater based systemDHW Loads
Cold In from Mains
Supply to AH
Return from AH
Hydronic Air
Handler
Hot Space Heating Air
Electric Electric Gas
TWH
Combi boiler based system
DHW Loads
Cold In from Mains
Supply to AH
Return from AH
Hydronic Air
Handler
Hot Space Heating Air
HE
DHW Loop
Space loop
Primary Loop Secondary Loop
Closed Loop
Combi Boiler
PROBLEM– Some contractor’s had little experience– System schematics often developed on site– Little or no sizing information provided– System components came from several manufacturers– Manufacturer’s settings may not lead to best performance
• Decided to design and optimize systems in a laboratory • Could then provide contractors with more detail
installation guidelines
Installation and Sizing
• Idle losses• Steady state efficiency• Air handler capacity testing• Full system tests
– Cyclical performance– Maximum capacity
Lab work
Idle Losses
Setpoint = 140 F$1/therm$0.12/kWh
Boiler 1 – Combi boiler with 12 gal DHW tank
Tankless Water Heater 1
Storage Tankless Hybrid
TANK 2
Steady‐State Simulated Heating Load Test
Work Horse Heating Plant
Constant Return Water
Temp
Tested Heating Plant
TWHTANKBOILER
Heating
Supply
Return
DHW
Supply
Return
Electric Gas
Water TempWater FlowConsumption
Steady- State Heating Plant Efficiency at Tset=130, GPM=4
Going from 90% to 80% increases heating bills about $150/year in MN
• Minimum supply air temperature (110 F) for comfort dictates minimum flow rate
• Maximum return water temperature (105 F) dictates maximum flow rate
• Coil capacity is bounded by these flow rates
Air Handler Performance Mapping
Air Handler Performance Mapping
52,500 – 57,000 kBtu/hr
45,500 – 54,000 kBtu/hr
Low Use Transient Performance
Low Use Transient Performance
Low Use Transient Performance
Max Capacity Testing
Next Slide
DWH Supply
Up to 400 installs in Minnesota before December 2012
– Utility bill analysis on all 400 sites– Detailed pre/post monitoring on 20 sites
Field Implementation and Monitoring
Existing Equipment
DHW LoadsCold In from Mains
Hot Space Heating Air
Runtime
Air Temp
Ambient T
Gas
ND Tank Water Heater
Electric Gas
Single Stage
Furnace
Conditioned Space
Outdoor
Dual‐Integrated Appliance Installation
DHW LoadsCold In from Mains
Supply to AH
Return from AH
Hydronic Air
Handler
Hot Space Heating Air
Water TempWater Flow
Consumption
Air TempAir Flow
Electric
Ambient T
Electric Gas
Water Heater
Conditioned Space
Outdoor
FieldMonitoringInstallation
• Looking at sites with complete data– On average calculation was 22% oversized– About 20% oversized when only looking at “good” fits
Field Study: Expected Results
• Better understanding of installed costs for different systems after contractors have become familiar
• System design specifications and quality control requirements
• Installed efficiencies of Dual‐Integrated Appliance systems and savings potential
PRELIMINARY: Energy Consumption Data
Represents about a 100 therm/yr savings or about 10% of the natural gas space heating bill
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Questions
Given human nature, it is our job
that supports efficient behaviors.to provide the infrastructure