Hot Water – a Hot Commodity

Better Buildings by Design, February 2012Burlington, VT

Gary KleinAffiliated International Management, LLC

916‐549‐7080gary@aim4sustainability.com

© 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