Objectives - Seventhwave | ·  · 2017-07-18¾No CAZ depressurization limits • RESNET / BPI – Worst case and spillage. 2/24/2016 4 ... Test Procedure Comprehensive BPI 2015 Simplified

2/24/2016

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Experience. Innovation. Results.Confiden al │ © 2015Confiden al │ © 201

Combustion Safety Testing:What we learn from Standards and 

Research

Better Buildings Better Business ConferenceMarch 2016

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

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Worst Case Depressurization TestingProtocols

• BPIBuilding 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” ventFails spillage at 2 vs. 5 minutes

Requires “cumulative” testing (when commonly vented)

ANSI/BPI‐1200‐S‐2015 replaces (entire) Building Analyst Standard

Protocol Differences

• BPI ‐ CO measurement

Action levels for ambient CO > 9 ‐ 35 ppm detected level> 35 ‐ 69 ppm elevated level > 70 ppm “evacuate”

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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

No “natural” conditions testing

No draft measurements

No CAZ depressurization limits

• RESNET / BPI – Worst case and spillage

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Protocol Similarities

Sample after 5 minutes

CO Air free (as applicable)

Includes “vent free” and/or “gas log” appliances

• RESNET / BPI – CO measurements

CO Thresholds• ANSI “confluence”

Worst Case Testing Procedures and Potential Impacts

• Pre‐testing

• Baseline configuration

• Fans on

• Air handler impact

• Door position

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Pre‐Testing

• BPISample 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

• BPIHouse 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 settingCheck/clean dryer filter/ext. ventDo not operate whole house cooling fan

• Measure and record CAZ pressure WRT outside (CAZ door remains closed)

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Air Handler On

If CAZ more negative WRT outsideBlower to remain on for spillage and CO test

If CAZ more positive WRT outsideBlower to be turned off for spillage and CO test

• Measure and record pressure in CAZ WRT outside (CAZ door remains closed)

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

• RESNETTesting disclosure (for occupants with environmental sensitivities)

Operate CO detector continuously in CAZ during CO and depressurization testing

Check for combustible gases upon entry

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• RESNETClose all exterior windows, doors, attic hatches

Drain traps must be filled

Turn on all indoor (exhaust) fansIncluding powered attic ventilation fanExcluding whole house exhaust fan

NOT REQUIRED!

Air Handler On

If CAZ more negative WRT outsideLeave blower on

If CAZ more positive WRT outsideTurn blower off

• RESNET

Door Position

Interior door to CAZRooms with exhaust fansOther interior rooms

… to achieve the highest pressure differential in the CAZ WRT the outdoors

• RESNET (open or close):

Don’t Use Smoke

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ANSI/ACCA  Worst Case Testing Procedures

• RESNETEnsure 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

Proper Vent DesignVisual Inspection

Appropriate vent materials

Pitch ¼” rise per 1’ run

6” to 8” initial rise

Photo credit: Keith Williams

Proper Vent Design

Vent connector length

Chimney height

Photo courtesy Cory Chovanec WECC

Photo courtesy Cory Chovanec WECC

Photo credit: Keith Williams

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Vent Inspection

Signs of corrosion

(Unusually) small or large vent connectors

Vent InspectionCommonly vented

Vent order: Small above larger appliance

Increased vent diameter after 2nd appliance

Photo courtesy of PA Weatherization Training Center Photo courtesy Cory Chovanec WECC

CAZ Inspection

• Excessive depressurization?

Photo credit: Keith Williams

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BPI  Requirements• If CO measurements exceed threshold limits:

Advise occupant that appliance(s) should be serviced immediately

• If appliance(s) fail spillage, address causeAir handler onCAZ door closedFans 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; andDocument client was informed of this condition

• Shall not perform air sealing (or any other tasks*) onhome (until address)

RESNET Requirements

• If appliance(s) fail spillage remediation must be in work scope via:

Targeted air/duct sealingRoom balancingExhaust make‐up airAppliance replacement (or isolation)

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Experience. Innovation. Results.Confiden al │ © 2015Confiden al │ © 201

Combustion Safety Testing:What we learn from Standards and 

Research

Better Buildings Better Business ConferenceMarch 2016

2/29/2016

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Combustion Products Spillage from

Gas Water HeatersMonitoring Results

Dan CautleySeventhwave

B4 Wisconsin Dells, March 4, 2016

What’s this “Spillage”?

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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

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Building America project objective

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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

Simplified Test Conditions

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Test ProcedureComprehensive BPI 2015 Simplified

Dryer & Kitchen On On OnNext Largest Exhaust Fan On On On

Other Exhaust Fans On On Off

CAZ Door Check Check ClosedOther 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

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

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Source: CEE

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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

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Monitoring setupCO2 near vent used to identify spillage

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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

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Spillage by minute of operation, by site

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What caused this?

Two sites showed excessive spilling;both had venting defects

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• MN_04 had an undersized water heater vent (vent capacity = 75% of burner input)

• WI_01 had a large opening downstream of the water heater (unused, partially repaired connection for a furnace)

3” vent, 6’ run, 4 elbows

Water heater and unused furnace vent

Images courtesy CEE

Effect of first minute of operation and outdoor temperature

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MN_05 MN_06 MN_07 MN_08

MN_09 MN_10 WI_01

1st min. of operation beyond 1st min.

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Estimated probabilities from logistic regression model

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Logistic regression: Effect of first minute, outdoor temp, & zone pressure

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Site 1st minute of operation (binary)

Outdoor temperature (F) Combustion zone depressurization relative to outside (Pa)§

MN 01 1,005.01 *** 1.10 *** 1.46 ***

MN 02 213.78 *** 1.23 *** 4.29 ***

MN 03 171.39 *** 1.07 *** 1.65 ***

MN 04 0.65 * 1.10 *** 1.21 *

MN 05 15.61 *** 1.06 *** 2.36 ***

MN 06 3.69 *** 1.10 *** 1.39 ***

MN 07 31.48 *** 1.03 2.32 ***

MN 08 244.16 *** 1.27 *** NA†

MN 09 13.81 *** 1.09 * 2.79 ***

MN 10 396.99 *** 1.13 ** 2.74 ***

WI 01 NA‡ 1.13 *** 1.07 *

Remember, most absolute values quite small!

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

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Downdrafting – vents goin’ crazy

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2/29/2016

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Downdrafting observed

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Site Number of episodes

Number of minutes in down‐drafting

Maximum duration (minutes)

MN 01 34 283 44MN 02 27 140 63MN 03 71 791 92MN 04 48 1,038 383MN 05 1 1 1MN 06 0MN 07 142 1,670 102MN 08 0MN 09 1 6 6MN 10 18 406 137WI 01 105 1,042 211Total 447 5,377

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.

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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

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