Combustion Safety Testing: What we learn from Standards and Research. Objectives. Objectives 2/24/2016

Transcription

1 Combustion Safety Testing: What we learn from Standards and Research Better Buildings Better Business Conference March 2016 Experience. Innovation. Results. Confiden al 2015 Objectives Identify differences in worst case depressurization testing protocols Recognize changes and confluence Review testing procedures and discuss potential impact on results and recommendations Objectives Recognize primary vs. secondary drivers for potential failures and prolonged spillage Recognize the importance of proper vent design and visual inspection to predicting failures in susceptible homes 1

2 Worst Case Depressurization Testing Protocols BPI Building Analyst ANSI/BPI 1200 S 2015 RESNET Chapter 8 ANSI/ACCA 12 QH 2014 Protocol Differences BPI Worst case and spillage Isolates supplied air only rooms Defines Warm vs. Cold vent Fails spillage at 2 vs. 5 minutes Requires cumulative testing (when commonly vented) ANSI/BPI 1200 S 2015 replaces (entire) Building Analyst Standard BPI CO measurement Protocol Differences Action levels for ambient CO > 9 35 ppm detected level > ppm elevated level > 70 ppm evacuate 2

3 Protocol Differences RESNET Worst case and spillage Allows interaction of fireplace Removes explicit baseline conditions Require sequential testing ANSI/ACCA 12 QH 2014 Sec 3 and 4 replace RESNET Chapter 8 Section 807 and 808 Protocol Differences RESNET CO measurement Added joints (in vent piping) as location for detection Action levels for ambient CO > 9 and > 25 ppm Direct vent tested under worst case Photo credit: Keith Williams Protocol Similarities RESNET / BPI Worst case and spillage No natural conditions testing No draft measurements No CAZ depressurization limits 3

4 Protocol Similarities RESNET / BPI CO measurements Sample after 5 minutes CO Air free (as applicable) Includes vent free and/or gas log appliances ANSI confluence CO Thresholds Worst Case Testing Procedures and Potential Impacts Pre testing Baseline configuration Fans on Air handler impact Door position 4

5 Pre Testing BPI Sample ambient air for CO (and combustible gases) upon entry and throughout the house Inspect gas piping /fuel delivery systems for deficiencies/leakage Inspect Combustion Appliance Zone (CAZ) and combustion appliances (including solid fuel appliances) 10% LEL BPI House in Blower Door testing mode except: CAZ door(s) closed Supplied air only interior doors closed Measure and record pressure in CAZ with respect to (WRT) outside* Exhaust Fans On Highest fan setting Check/clean dryer filter/ext. vent Do not operate whole house cooling fan Measure and record CAZ pressure WRT outside (CAZ door remains closed) 5

6 Air Handler On Measure and record pressure in CAZ WRT outside (CAZ door remains closed) If CAZ more negative WRT outside Blower to remain on for spillage and CO test If CAZ more positive WRT outside Blower to be turned off for spillage and CO test Door Position Open interior door(s) directly leading to the CAZ Measure and record pressure in CAZ WRT outside If CAZ more negative (WRT outside), after the door(s) are open, door(s) to remain open during spillage and CO test Pre Testing RESNET Testing disclosure (for occupants with environmental sensitivities) Operate CO detector continuously in CAZ during CO and depressurization testing Check for combustible gases upon entry 6

7 NOT REQUIRED! RESNET Close all exterior windows, doors, attic hatches Drain traps must be filled Turn on all indoor (exhaust) fans Including powered attic ventilation fan Excluding whole house exhaust fan Air Handler On RESNET If CAZ more negative WRT outside Leave blower on If CAZ more positive WRT outside Turn blower off Door Position RESNET (open or close): Interior door to CAZ Rooms with exhaust fans Other interior rooms to achieve the highest pressure differential in the CAZ WRT the outdoors Don t Use Smoke 7

8 ANSI/ACCA Worst Case Testing Procedures RESNET Ensure the vent is at room temperature Fireplace damper closed OR a simulator must be operating in the fireplace with damper open Check for spillage after 5 minutes of operation Appropriate vent materials Pitch ¼ rise per 1 run 6 to 8 initial rise Proper Vent Design Visual Inspection Photo credit: Keith Williams Proper Vent Design Vent connector length Chimney height Photo courtesy Cory Chovanec WECC Photo credit: Keith Williams Photo courtesy Cory Chovanec WECC 8

9 Signs of corrosion Vent Inspection (Unusually) small or large vent connectors Vent Inspection Commonly vented Vent order: Small above larger appliance Increased vent diameter after 2 nd appliance Photo courtesy of PA Weatherization Training Center Photo courtesy Cory Chovanec WECC CAZ Inspection Excessive depressurization? Photo credit: Keith Williams 9

10 BPI Requirements If CO measurements exceed threshold limits: Advise occupant that appliance(s) should be serviced immediately If appliance(s) fail spillage, address cause Air handler on CAZ door closed Fans on If both, recommend appliance(s) be shut down RESNET Requirements If CO measurements exceed threshold limits: Notify client of need to call qualified technician and; Document appliance is unsafe for use; and Document client was informed of this condition Shall not perform air sealing (or any other tasks*) on home (until address) RESNET Requirements If appliance(s) fail spillage remediation must be in work scope via: Targeted air/duct sealing Room balancing Exhaust make up air Appliance replacement (or isolation) 10

11 Combustion Safety Testing: What we learn from Standards and Research Better Buildings Better Business Conference March 2016 Experience. Innovation. Results. Confiden al

12 2/29/2016 Combustion Products Spillage from Gas Water Heaters Monitoring Results Dan Cautley Seventhwave B4 Wisconsin Dells, March 4, 2016 What s this Spillage? 2 Why Building America interest? Prior work suggesting spillage in normal operation isn t well predicted by current testing methods Building America Hazard Test Methods Cautley LBNL Combustion Appliance Venting Rapp Prior work suggesting venting problems are responsible for much spillage under normal operation CEE Ventilation Depressurization Bohac & Cheple 3 1

13 2/29/2016 Building America project objective Can we develop a simplified test procedure that: Is easier to perform & more repeatable Reduces failures for acceptable situations Still finds hazardous situations Source: Larry Brand, GTI 4 Simplified Test Conditions Test Procedure Comprehensive BPI 2015 Simplified Dryer & Kitchen On On On Next Largest Exhaust Fan On On On Other Exhaust Fans On On Off CAZ Door Check Check Closed Other Doors Check Open= exhaust fan or return register in room Open= exhaust fan or return register in room Air Handler Check Check Check Check= which ever produces lowest CAZ pressure Source: CEE 5 Simplified and BPI Test Methods Maximum spillage duration Water heaters & warm vent furnace/boiler = 2 minutes Cold vent furnace/boiler = 5 minutes Draft pressure not used for pass/fail CAZ depressurization not used for pass/fail Source: CEE 6 2

14 2/29/2016 Our Field Study 11 homes, MN and WI Atmospheric draft natural gas water heaters in basements FAILED simplified spillage test, PASSED with one fan less depressurization Depressurization very similar compared to WCD Monitored operation, spillage, driving forces Collected data for 3 to 6+ months, 1500 days total 7 Monitoring setup CO2 near vent used to identify spillage 8 Basic factors affecting spillage Minutes into burner cycle (spillage more likely at start) Outdoor temperature (spillage more likely in warm weather) Depressurization Venting configuration Two of these factors were dominant in our field study results 9 3

15 2/29/2016 Spillage by minute of operation, by site What caused this? 10 Two sites showed excessive spilling; both had venting defects MN_04 had an undersized water heater vent (vent capacity = 75% of burner input) 3 vent, 6 run, 4 elbows WI_01 had a large opening downstream of the water heater (unused, partially repaired connection for a furnace) Water heater and unused furnace vent Images courtesy CEE 11 Effect of first minute of operation and outdoor temperature MN_01 MN_02 MN_03 MN_04 Probability of spillage F 20F 40F 60F 80F 0F 20F 40F 60F 80F 0F 20F 40F 60F 80F 0F 20F 40F 60F 80F MN_05 MN_06 MN_07 MN_08 0F 20F 40F 60F 80F 0F 20F 40F 60F 80F 0F 20F 40F 60F 80F 0F 20F 40F 60F 80F MN_09 MN_10 WI_01 0F 20F 40F 60F 80F 0F 20F 40F 60F 80F 0F 20F 40F 60F 80F 1st min. of operation beyond 1st min. Estimated probabilities from logistic regression model 12 4

16 2/29/2016 Logistic regression: Effect of first minute, outdoor temp, & zone pressure Site 1 st minute of operation (binary) Outdoor temperature (F) Combustion zone depressurization relative to outside (Pa) MN 01 1, *** 1.10 *** 1.46 *** MN *** 1.23 *** 4.29 *** MN *** 1.07 *** 1.65 *** MN * 1.10 *** 1.21 * MN *** 1.06 *** 2.36 *** MN *** 1.10 *** 1.39 *** MN *** *** MN *** 1.27 *** NA MN *** 1.09 * 2.79 *** MN *** 1.13 ** 2.74 *** WI 01 NA 1.13 *** 1.07 * Remember, most absolute values quite small! 13 Carbon monoxide Observed in CAZ, a few feet from water heater Highest single observation: 7 ppm One site had a number of hours between 3 and 7 ppm 14 Downdrafting vents goin crazy Flue & vent CO vp_xbee1 i_fan2 p_whvent p_zone t_whbrn t_whvnt ppm_co2_whvent ppm_co2_zone ppm_co t_whsp1 t_whsp2 t_whsp3 t_whsp Pressures Spill temps CO2 Dryer 10 0 Kit fan /29, 1h 7/29, 2h 7/29, 3h Date, h 15 5

17 2/29/2016 Downdrafting observed Site Number of episodes Number of minutes in downdrafting Maximum duration (minutes) MN MN MN MN , MN MN 06 0 MN , MN 08 0 MN MN WI , Total 447 5, Conclusions BPI-1200-S is almost identical to our Simplified Test Procedure Current test methods are probably conservative, tend to fail systems that generally operate safely Typical systems as monitored don t spill excessively Vent defects are an important cause, perhaps the largest cause, of excessive spillage. Vent inspection is critically important in evaluating safe operation. 17 Conclusions, cont d Downdraft formation remains somewhat mysterious, is not addressed in current testing, and needs more work Carbon monoxide is a serious risk, identifying high levels is a priority Carbon monoxide alarms can offer protection in the case of: Future CO production from a burner problem or replacement water heater Future venting problems, e.g. a collapsed chimney Other sources of CO, e.g. a generator set used indoors 18 6