Heating Systems Best Practices II Alternative Systems & Approaches for Low Heat Load Homes

Transcription

1 Heating Systems Best Practices II Alternative Systems & Approaches for Low Heat Load Homes Skip Hayden Integrated Energy Systems Better Buildings by Design 2009 Burlington, VT February 2009 Natural Resources Canada Ressources naturelles Canada

2

3

4 CCHT Mid-to-Low-Load Research Houses Located in Ottawa Two identical research houses and townhouse-type demo/mtg centre Both houses are under Simulated Occupancy Protocol (virtual people/dog)

5 Objectives Discuss what constitutes a low heat load home See how certain oil-fired systems can function efficiently in low load homes, in spite of burner limitations Appreciate new gas burner technology, and the implications for low load homes See the good and the bad of combination systems Appreciate the new integrated systems now appearing in the marketplace, and how these have particular application in energy efficient homes Get a glimpse of the next generation of integrated systems, leading towards the net zero homes of the near future

6 ?? What are you looking for????

7 What is a low heat load home?

8 Oil-Fired Systems

9 Most crucial element to achieve good performance and high efficiency is the oil burner

10

11 High Static Burners

12 Decreasing Excess Air Hi Static Burner

13 High-Static Oil Burner Excellent fuel-air mixing (ExcessAir - 25%) Stable under stack (exhaust) pressure fluctuations due to wind/turbulence High resistance to house depressurization, which can be a char of low energy housing More suited to sealed combustion operation Zero off-cycle flow loss (ex post-purge) Firing rate down to 70kBtu with good excess air control Efficiency should be % Minimal sooting/degradation Should be burner of choice for low energy homes

14 Air Requirements of Conventional & High Static Oil Burners Air Changes/hour Conv Oil Burner Conv Bnr + Dilution Hi-Static Burner Hi-Static Bnr + Dilution

15 Oil in an Energy-Efficient Home?

16 Problems with Oil Nozzles at Low Firing Rates

17 Oil House Demand vs Heat Output Potential problem with oil and energy-efficient housing, with minimum firing rate ~ 70k Btu/h This results in a minimum heat output = Btu/h; many in industry feel more comfortable at Btu/h Canadian houses are now being designed at a Heat Load of Btu/h and below Means over-design of 1.7 Becomes more/less significant depending on how heating load is distributed re design temperature (Flat vs triangle)

18 Other Possibilities Nozzles of 0.4 gph, although they often clog or their spray pattern deteriorates quickly, leading to sooting, coking, failure Using a lighter fuel might help this problem, as might a very low S fuel I have a difficult time recommending keosene. Another possibility is...

19 However, well-conceived combined space and water heating systems can be an effective way around the technical limitation of oversizing with oil-fired equipment in energy efficient housing.

20 Tankless Coil Boiler or Tank-in-Tank Boilers not Recommended!

21 Oil-Fired Technologies That Can Work in Low Energy Homes Must be able to divert load, rather than just short cycle Must be able to withstand depressurization, or operate as sealed combustion Typically will use an external storage tank and water-to-water exchanger for service water

22 Efficient Oil-Fired Space/Water Heating Systems

23 Condensing Oil Boiler + External Storage Combined Space-Water Heating

24 Gas-Fired Systems

25 High Efficiency Condensing Furnace *****

26

27 Dewpoints for Gaseous Fuels o F Natural Gas Propane Excess Air, %

28 Natural Gas vs Propane Natural gas has a higher hydrogen content, so produces more water vapour Higher dewpoint with natural gas, so easier to condense than propane Propane condensing furnaces less efficient than NG Propane mid-efficiency furnaces or boilers more efficient than natural gas Propane boilers even more difficult to condense than natural gas

29 High-Efficiency Gas Furnace Powered exhaust Electronic ignition No dilution air High resistance to depressurization Excellent side-wall vent - plastic! Should be well above 90% Efficiency improves with slight oversizing Units are available at Btu/h, suiting low energy housing

30 What about two-stage furnaces?

31 What about two-stage condensing furnaces? Compared to condensing furnace with PSC circ fan motor, 2-stage furnace with ECM gave increased gas use to replace electrical heat Increased operation time (~ doubled) may lead to sig. increase in electrical use, unless ID fan is also ECM-type Loss of heat to distribution system may give less heat to some registers and result in homeowner upping the thermostat May give increased comfort Low firing rate may be more suitable for EE homes May be only way of getting ECM fan motor

32 Gas Boilers

33 Antique Conventional Boilers (natural draft) are still available! (at low real efficiencies and subject to depressurization) Dilution Air Combustion Air

34 Newer Gas-Fired Boilers

35 Major Advances in Gas Burners - High modulation - Power Burners

36 It s a New Gas Burner World Power burners (mainly forced draft) Gun, metal matrix or ceramic (cylinder, cone, plate) Low excess air (EA) Many have good modulation with excellent excess air control over operational range Ultra-Low NOx Usually on boilers Provide a more assured pathway to high efficiency condensing and turn-down suitable for a range of house heat load demands

37 Recent Major Advances in Gas Boilers

38 Can a condensing boiler condense in low energy housing? Yes, if radiant floor Likely, if fan coil Difficult but possible if conventional hydronic, by integrating outdoor reset, reduced flowrate/increased heat exchange, service water preheat, preheat ventilation air, as with...

39 Dewpoints for Different Fuels o F Natural Gas Propane No. 2 Oil Excess Air, %

40 Enhancing Condensing Boiler Operation Increased heat exchange Increase Heat Exchange Preheat Ventilation Air Lower circ flow rate Outdoor reset lowers supply temp. Condensing Boiler Condensing Boiler Preheat service water Ventilation air Preheat preheat Service Preheat Water with Service boiler Water return Get return water below flue gas dewpoint! Return water below dewpoint

41 Condensing boiler with good modulation ideally suited to radiant floors and low energy housing

42 Air Requirements of Conventional Gas Boilers & High Efficiency Condensing Gas Furnaces Air Changes/hour Conv Gas Boiler Conv Gas Blr + Dilution Condensing Gas FurnaceHi-Static Burner

43 Water Heating A comparable load to space heating in EE + homes

44 Natural draft continuous pilot gas water heaters do not belong in today s tighter, energy efficient housing

45 Power-Vented Water Heaters Pilot light or not Draft hood High on- and offcycle losses High resistance to depressurization Most use a lot of house air, and have low efficiencies

46 Condensing Tank Water Heater > 90% efficient, as mains water provides driving force for condensing

47 Tankless Water Heaters Wide range of technologies and efficiencies ACT examining performance in lab and field, as well as hot water use trial, to optimize performance and develop appropriate seasonal efficiency test procedure

48 Combined Space-Water Heating Systems

49 CCHT Performance of Combo Systems in almost real-life conditions

50 Efficiency of Tank-Based Combo s vs Outdoor Temperature

51 Efficiency with Tankless Combo

52 Inefficient Instantaneous Segregated, Non-Condensing Boiler with Modulation SU02, Mixed Flue Gas Analysis Flue Gas T O2 CO2 13:47 13:53 13:58 14:03 14:07 14:12 14:17 14:22 14:27 14:32 14:37 14:42 14:47 Time Temp [C] Conc [% ]

53 Non-Segregated Condensing Tank-Based Space/Water Systems

54 Efficient Low Mass Condensing Boilers with Segregated Tap water

55 In new and renovated housing: - Space Heating falling - Water Htg very inefficient - Need for fresh air - Ventilation

56 ekocomfort (AIMS) Advanced Integrated Mechanical Systems A major Canadian initiative to develop and market high efficiency, integrated space-water-ventilating systems

57 ekocomfort Low Mass Condensing Boiler at IES

58 ekocomfort Advanced Integrated Mechanical Systems A major Canadian initiative to develop and market high efficiency, integrated space-water-ventilating systems

59 What s coming in the future (today)?

60 Renewable Liquid Fuels Bio-oils Biodiesel Blends Alcohols...

61 Condensing Alcohol-Fired Furnace

62

63 Since people always seem to want a fireplace, let s take the fireplace as the centre of our integrated system

64 Next Generation Integrated System: Condensing Fireplace-Based

65 Characteristics of High Efficiency Condensing Integrated Gas Fireplace Efficiency > 90% Heats space & tap water + ventilation Radiant heat from flame in winter by fire Central house heating No radiation in summer, but still hot water Pleasure of a fire!!

66 Cooling_Air Conditioning: Do we need/want it in Vermont? If yes, how so, with hydronic heating? Window Portable

67 Think about a...

68 Mini-Split

69 Mini-Splits in the World More than 50 % of the air conditioning market in the world is mini-splits Less than 3% of the North American market is mini-splits What s going on?

70 Mini-Splits

71 Mini-Split Advanced Technology Inverter technology to control/vary compressor speed Scroll compressor Better fan design Efficient motor Enhanced dehumidification Modern shapes and systems...

72 Mini-Split Advantages Can be a way to AC electric baseboards or hydronic at lower intrusive cost, while heating the former Very high SEER >20, as opposed to central air 14 With it easy and comprehensive automatic/hand remote control Varying direction, low air velocity with efficient fan/motor set and continual operation can mean comfort, good distribution & low electric use Effective dehumidification means comfort at higher temperatures Low noise; advanced air cleaning Efficient way to zone cool/heat for comfort, yet much lower overall demand

73 Heating Efficiencies HSPF Heating Seasonal Performance Factor: measures the heating efficiency over the entire heating season, dividing the total heat provided over the season by the energy (electricity) used by the appliance Varies depending on region (climate) Can be as high as 4 for a mini-split, in comparison to an electric furnace at 1.

74 A mini-split is basically a local, rather than a central, cooling/heating system

75

76 For any local cooling/heating appliance to be truly efficient & effective, it must be properly sized & located!

77 If not properly sized & located, efficient mini-splits can Be ineffective in supplying cold/heat to house Result in significant local overheating or overcooling Cause significant client dissatisfaction

78 How can a mini-split be an effective tool to lower overall and peak demands of energy?

79

80

81 Consider the use of a properly-sized, efficient, advanced-combustion woodstove/fireplace located in a major living area which sees other parts of the house as the primary heat source of an EE + house

82

83

84 Advanced Technologies to supply both Heat and Electricity

85 Micro-cogeneration Generating both heat and power on site to serve the thermal load 5-15 kw th and electrical load of 1-3 kw el plus the grid May employ any combination of electrical generation and storage technologies that are on or off grid Technologies Stirling Engines, IC Engines, Fuel cells, microturbines, thermophotovoltaics, thermoelectrics, solar

86 Micro-Cogen Concept

87 Why Microgeneration? Security of Power Supply Control Over Assets/Destiny Reduce need for new power generation facilities Reduce GHG s 2-3 fold increase in efficiency compared to central power plant Move toward net-zero housing/buildings and sustainability

88 Micro-Cogeneration Units for EE Housing in the Lab

89 Stirling Engine Being an external combustor, it can also use renewable green fuels (bio-derived) Working on increasing its relative electrical output How should its BOP be optimized? Can it be cascaded with another technology to get more electricity?

90 External Combustion Stirling Engine Cogeneration in EE Housing with Hot Water Phase Change Storage

91 Fuel Cells BOP/TUM Performance & Modelling FCT anode flow (cfm) 0.17 Fuel Utilization (%): 80 System Efficiency cathode flow (cfm) Power (kw): 1.5 LHV: exhaust flow(cfm) 10.4 Cell Temperature (C): HHV: Current Density: Elec Eff: AH flow (cfm) Operating Voltage (V): Hot water flow (gpm) Nernst Pot'l:

92 Thermophotovoltaic (TPV) Thermoelectric (TE) Heat & Power Research Performance of advanced PV cells for combined heat & power Investigations into highlyefficient heat-to-radiation conversion materials in our TPV furnace facility Novel cascaded radiant burner developed Now working on cascaded TPV and TE (thermoelectric) system for higher electric output

93 Cogeneration in Energy Efficient Housing with Borehole Storage R2000 house (40k btu/h design load) Micro-cogen engine with 6 kw electric & 10:1 turndown 40% efficient gen. Heat not use for space or hot water is put down into boreholes, for seasonal storage & utilization

94 Electricity Storage Vanadium Redox (VRB) Battery Energy Conversion occurs in the cell stack Energy is stored in the electrolyte tanks Benefits: long cycle life ease of scalability Disadvantage: Large footprint Li-ion batteries

95 Drake Landing Solar Community in Okotoks, Alberta 52 two-story, R-2000 detached homes Heat provided by Solar District Energy System short term: 2 hot water storage tanks long term: borehole thermal energy storage with 144 boreholes backup: natural gas boiler

96 Drake Landing Solar Community

97 Drake Landing has won more than 20 National and International Awards, including: United Nations Livable Communities Gold Award, International Solar Association Most Innovative Solar Project Award,

98 Summary For low heat load houses: Oil boilers equipped with high static burners, for space and water heating, and having external, segregated hot water storage, can satisfy low heat loads and comfort at high efficiency With gas, the new, highly-modulating burners in combined condensing boilers allow the satisfaction of any heat load. Efforts in installation and control must be made to ensure condensing While Vermont has a history of hydronic heating, consideration should be given to ekocomfort-type systems, which can supply space and water heating, along with heat recovered ventilation, through a fan coil-based warm air system Local, efficient heat sources, such as advanced combustion woodstoves or minisplits may be a strategic and effective energy source for load load homes Micro-cogeneration systems, just appearing on the market, offer high efficiency heating, along with at least partial grid independence, while minimizing central peaking

99 Review of Objectives Discuss what constitutes a low heat load home See how certain oil-fired systems can function efficiently in low load homes, in spite of burner limitations Appreciate new gas burner technology, and the implications for low load homes See the good and the bad of combination systems Appreciate the new integrated ekocomfort space/water/ventilating systems now appearing in the marketplace, and how these have particular application in energy efficient homes Get a glimpse of the next generation of integrated systems, leading towards the net zero homes of the near future

100 Review of Objectives Discuss new space & water heating technologies for oil, gas and wood Understand what makes heating systems efficient Appreciate advantages & disadvantages of various new high efficiency systems Be better able to assess suitability of newer technologies for comfort andhigh efficiency operation in new or existing housing

101 Review of Objectives What is a low heat load home See how certain oil-fired systems can function efficiently in low load homes, in spite of burner limitations Appreciate new gas burner technology, and the implications for low load homes See the good and the bad of combination systems Appreciate the new integrated systems now appearing in the marketplace, and how these have particular application in energy efficient homes Get a glimpse of the next generation of integrated systems, leading towards the net zero homes of the near future

102 Heating Publications nrcan.gc.ca/index_e.cfm under Consumers: Heating, Cooling & Ventilation

103 Kansas City, MO 2009 affordablecomfort.org

104 If further questions, contact me (Skip Hayden) Advanced Combustion Technologies, tel: (613) fax: (613)