caz pressure testing

8/2/2019 CAZ Pressure Testing

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CAZ P R E S S U R E

T E S T I N G

Presented by Rich MooreInvisible EnergyDenver, CO

[email protected] 31, 2011


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Goals of this session

Some Combustion and Equipment Basics

Recognize the need for combustion safety testing on gas

fired equipment

Test In/Test Out

Recognize the interaction and impact of various features

of the home on combustion equipment

Learn how and where to test for CO, draft spillage, and

CAZ pressure

Be familiar with some testing protocols and equipment


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Introduction

Who are you?

HERS Raters?Weatherization Technicians?

Home Performance Contractors?

Home Improvement Contractors? BPI Certifications?

Is anyone doing combustion safety testing?

What protocol?Why do you feel the need for this testing?


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Finish this sentence

The house is a


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Systems Thinking-Before


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Systems Thinking-After


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Combustion-How It Works

Combustion of any fuel (natural gas, propane)

requires three things:

Fuel

Air

Ignition Source

Equals


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Fuel-Natural Gas

Composed mainly of methane (81%)

Lighter than air (specific gravity .65)

BTU content/cu.ft. =700 to 1200

Ignition temperature of 1100 to 1200F

Typical manifold pressure = 3.5 WC


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Propane

Composed mainly of propane (95%)

Heavier than air (specific gravity 1.53)

BTU content/cu.ft. =2500 to 2700

Ignition temperature of 920 to 1020F

Typical Manifold pressure = 11 WC


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Heating Oil

Grade Heating Value(Btu/ gal) Fuel Oil No. 2 137,000 - 141,800 Residential Heating

Fuel Oil No. 6 151,300 - 155,900


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Air

Combustion Air

Primary

Secondary

Dilution

Excess

Natural gas appliances needs ~10 cubic feet of air for

combustion for every 1 cubic foot of fuel.

Propane appliances needs ~25 cubic feet of air for

combustion for every 1 cubic foot of fuel.


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Combustion Air Guidelines

Uniform Mechanical Code Chapter 7:

Two openings, with each opening having one square

inch/4000 btu

Other variations on this, depending on jurisdiction (local

codes), equipment type and location.

Some jurisdictions allow for combustion air from

the volume of the home, a combination of volumeand exterior, or only from the exterior.


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How much air is needed for combustion?

Assuming 1000 btu/cubic foot of gas, then:

A 100,000 btu furnace requires 1000 cubic feet of

air for every hour it burns.

(100,000 btu = 100 cubic feet of gas x 10 cubic feet

of combustion air/ft3 = 1000 cubic feet of air)

Where is this air coming from? How is combustion

air allowed to the appliances?


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Ignition Sources

Standing Pilots Electronic

Spark Ignitors

Hot Surface Ignitors

Others

Matches,candlesmanualignition!

(Not a good idea!)


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Open & Closed Combustion Appliances

Open Combustion:

An appliance that gets its combustion air from the same area as

the unit is located

(you could reach in and touch the flame)

Closed Combustion: (aka Sealed Combustion)

An appliance that gets its combustion air from the outdoors,

piped directly to the units burner area (the combustion

chamber is completely sealed and isolated from the zone it is

located in)


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Drafting / Venting

Since all combustion appliances create combustion

byproducts, they must be removed to the outside via aventing system (masonry chimney, single or double

wall metal pipe, or plastic vent, etc.).

Drafting: (Negative pressure) A current of warm exhaust gasses. This

effect creates a slight negative pressure, carrying the gasses out

of the home via a chimney or vent stack.

Positive pressure venting involves the use of a fan to push

exhaust products out of the home.


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Drafting

Most residentialfurnaces are eitherCategory I(standard or mid-efficiency) orCategory IV (highefficiency).


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Four Factors for Good Drafting

Delta T = Delta P

The greater the temperature difference, the greater the pressuredifference (draft)

Vent Height

The greater stack height, the greater the draft Friction

Venting design & installation

Air Flow Is there enough (combustion or make-up) air? If air is removed

during the combustion process, is there a supply of air toreplace it?


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Open Combustion Appliances

These are both open combustion appliances. Air for

combustion is drawn from the same area (zone) as the

appliance. It is often house air.


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Category I Furnaces

Each of these furnaces,though different

AFUEs, are Category I

appliances.(The left unit is

~ 65%, the right is80%. Each has negative

pressure venting, non-condensing)


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Open or Closed? High Efficiency?

This is a Category Iopen com bustion

furnace.The combustion air

source is house air, asfor the hot water tanknext to it.

AFUE = 80%


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Category IV Furnaces

This 90+ AFUE(condensing)is a Category IV, with apositive pressure ventsystem.


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Closed Combustion Appliance

Both the hot waterheater and furnaceshown here are closedcombustion appliances.They each drawcombustion air fromoutdoors, not the house

volume.


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Closed Combustion Appliance


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So what? (moving on)

If code is met, will the appliance work properly?

If a new home has a CO, is everything OK?

If the air changes are above .35 NACH, is there enough air

for combustion?

Can I tighten a house below .35 and have enough air for

combustion? If there is sufficient ventilation per ASHRAE, can it

interfere with combustion?


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Air Sealing

Taking a House As A System look, what

are some typical improvements made toreduce air leakage in the home?

Attics-top plates, open walls, drop ceilings,

plumbing and electrical penetrations, etc.Wall insulation (dense pack)

Basements

Rim joists. Wall penetrations, windows, etc.

Ductwork


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Pressure Problems

Know the impact of your air sealing work on

combustion appliances:

Over-tightening or under-ventilating a home

Exhaust appliances

fans, dryers, fireplacesDuct Leakage


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Pressure Problems

A home may not have had a pressure problem

beforeyou began improvements.

The effects of tightening a home may create

adverse conditions afterwards. (Backdrafting,

pressure imbalances, etc.)

Dont assume anything. Test in, test out.


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Ductwork

The impact of leakyductwork can never be

emphasized enough.

Sealing only supplyductwork can lead to

catastrophic results,including backdrafting inthe CAZ, or excessive

positive pressure in thecore of the home.


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Effect of Duct Leakage On Open

Combustion Appliances The leaky cold air return on

this furnace can draw

combustion products down the

flue and into the ductwork, for

delivery into the living space.

In addition, it robs the

appliances of necessary

combustion air, possibly

leading to CO production.


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Combustion Appliance Zone Pressures

Combustion

appliance zone (CAZ)pressures can easilyovercome the draftpressure required tosafely exhaust hot

water tanks andfurnaces.Typical draftpressures may be-5 pa or less.


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House to Garage Connections

If air sealing isperformedthroughout the home,

makeup air forappliances may nowonly be available via thehouse-garage connection.Be careful!


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Please Note

IN NO CASE SHOULD ANY HOME

IMPROVEMENTS BE MADE IF THERE ARE

UNVENTED APPLANCES IN THE HOME.

THIS INCLUDES FREE STANDING SPACE

HEATERS AND COOKING APPLIANCES*.

*Gas fired cooking appliances should have exhaust fansinstalled as an upgrade


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Carbon Monoxide

An odorless, colorless, tasteless toxic gas that can be

lethal at high concentrations.

Low level poisoning contributes to health problems.

Has distinct odor when combined with byproducts of

incomplete combustion.

Is caused byincomplete combustion


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Carbon Monoxide

Other byproducts of combustion can be harmful or

damaging to the occupants and dwelling, including:

Carbon Dioxide (CO2)

Moisture

Oxides of Nitrogen (NOx)


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This is the BPI protocol for CAZ

Testing. Other protocols may

be used in other programs.

BPI certified contractors should

adhere to BPI auditing

standards as well.


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Testing Overview (before the CAZ setup and test)

Check all accessible fuel lines for leaks

Check the venting systems to see that they are safeand intact.

Be sure the vent is cool to the touch

Hand check venting integrity

Check for carbon in the heat exchanger, draft hoodand gas vent(s) of all appliances being tested.

Another hand check

Visually check for cracks in the heat exchanger.

Drill test holes in the gas vent(s) of atmosphericdrafting appliances.


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Combustion Safety Testing (CAZ)

Testing is performed to determine the CAZ (CombustionAppliance Zone) pressure

This test ultimately determines thepoten tial (not the reality) of anappliance backdrafting exhaust gasses into the home.

Measurements of CO, draft , spillage

Other items that can or should be tested:

Cracked heat exchanger

Gas leaks

High limit operation Pilot safety controls

Combustion Efficiency

Stack Temp, O2, excess Air


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CAZ.HELP!!!

Some ideas to help CAZ and Mechanical testing

go smoothly Do this test first.

If you find that there are serious mechanical system or CAZproblems, you may not be able to/need to proceed with further

home testing.

Determining Worst Case can be tricky. While doingyour client interview and house walkthrough, close and

lock all exterior windows and doors. Open all interiordoors. Start setting up the test as you take notes on thehome, while listening to the homeowner (thatsrightmulti-task)

C b ti S f t T t P d f V t d


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Combustion Safety Test Procedure for Vented

Appliances

1. M e a su r e th e Ba s e P r e s su r e .

Start with all exterior doors and windows closed and thefireplace damper closed. Set all combustion appliances to the

pilot setting or turn off the service disconnect. Combustion

appliances include: boiler, furnace, space-heaters, and water

heater. With the home in this configuration, measure and

record the baseline pressure of the mechanical room WRT

outside.


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CAZ Testing

Measuring Baseline

Find an easy spot to run a reference tube to the outdoors

from the CAZ.

If the Blower Door is set up, can you run a long tube to

the exterior from the CAZ?Rim joist penetrations (Line Set, Gas line, electrical

penetrations, etc.)

Under the sill plate?Use a window and tape over the remaining gap.

Use time averaging feature if windy conditions exist.



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Combustion Safety Test Procedure for VentedAppliances

2. E s ta b lis h t h e W o r s t Ca s e .

Turn on the dryer and all exhaust fans. Close all interior doorsthat make the CAZ pressure more negative. Turn on the air

handler, if present, and leave (it) on if the pressure in the CAZ

becomes more negative, then recheck the door positions.

Measure the net change in pressure from the CAZ to outside,

correcting for the base pressure. Record the worst case

depressurization and compare to the CAZ Depressurization

Limit Table.


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CAZ Dep r essu r iza t ion Lim it s

Orphan natural draft water heater (including outside chimneys) -2 pa

Natural draft boiler or furnace commonly vented with waterheater

-3 pa

Individual natural draft boiler or furnace -5 pa

Induced draft boiler or furnace commonly vented with waterheater

-5 pa

Power vented, induced draft boiler, furnace alone or fan assistedDHW alone

-15 pa

Chimney-top draft inducer; exhaust type or equivalent; high staticpressure flame retention head oil burner; direct ventedappliances; sealed combustion appliances

-50 pa


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CAZ Testing

Turn on regular fans and dryer first, then proceed with air

handler. The air handler must be run at the highestspeed used.

If possible, observe CAZ change with each fan.

Gourmet Cooktop Exhaust? Add separately.

DryerDont forget to clean lint filter.

Fireplace? Is air handlers filter clean?

Cooling present? Run cooling from thermostat, with outdoor

unit off. (You are only concerned about air pressure, not

temperatures.)

No cooling? Run air handler with fan control (summer switch),

or you may have to run heating.


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CAZ Testing

Positioning interior doors-use smoke. Rooms that are

positively pressurized should have doors closed.Negatively pressurized rooms should have doors open.

A good rule of thumb is: If the smoke comes toward you, the doorcomes toward you. If the smoke goes away from you, the door goesaway from you. (Note this only applies to bedroom or otherdoors that open in to the room, away from the CAZ.)

Worst case CAZ pressure is the strongest negativepressure in the appliance zone, of whatever configuration

the fans/doors, etc. minus the baseline (stack effect).



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3. Mea su r e W or s t Ca se Sp i lla ge , Dr a ft , CO.

Fire the appliance with the smallest Btu capacity first, test for

spillage at the draft diverter with a mirror or smoke test, and

test for the CO at the flue at steady-state (if steady state is not

achieved within 10 minutes, take the CO readings at the10

minute mark). If the spillage test fails under worst case, go toStep 4. If spillage ends within 1 minute, test the draft in the

connector 1 - 2 after the diverter or first elbow.

Fire all other connected appliances simultaneously and test

the draft diverter of each appliance for spillage. Test for CO inall appliances before the draft diverter.



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4. Mea su r e Sp illa ge , Dr a ft , CO u n d e rn a tu r a l con d it ion s ( if sp illa ge fa ils u n d e r

w o r s t ca s e ) .

If spillage fails under worst case, turn off the appliance,the exhaust fans, open the interior doors and allow the

vent to cool before re-testing. Test for CO, spillage, anddraft under natural conditions. Measure the netchange in pressure from worst case to natural in the CAZto confirm the worst case depressurization taken inStep 2 outside. Repeat the process for each appliance,allowing the vent to cool between tests.



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yAppliances

5. Am bien t CO.

Always monitor the ambient CO in the breathing zone during

the test procedure and abort the test if ambient CO goes over

35 ppm. Turn off the appliance, ventilate the space, and

evacuate the building.

The appliance must be repaired and the problem correctedprior to completing the combustion safety diagnostics.

If the ambient levels exceed 35 ppm during testing under

natural conditions, disable the appliance and instruct the

homeowner to have the appliance repaired prior to operating

it again.

h


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Other Notes

Newer two-stage and variable input equipmentshould be tested at various firing levels to ensure safe

operation.

Consult with the equipment manufacturer as to howthe unit can easily attain high-fire and high fan speed

(for optimum depressurization). Remember, the object here is to try and force the

combustion appliances perform poorly (backdraft,

create CO, etc.). It may necessitate setting the houseup a bit differently than the protocols tell you. (i.e.

what if there are two air handlers?)

Test Equipment


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Test Equipment

Fi V ti P bl


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Fix Venting Problems

This is from a new home!

Combustion spillage

Brother-in-lawinstallation

Learn to observe!

Whats wrong with these pictures?

R b


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Remember

Houses with central returns vs. returns in everyroom may quite likely change your door arrangement

when the air handler is operating.

Leaky ductwork can cause a zone to go positive,negative, or remain neutral.

If there is an operable and usedfireplace, it may benecessary to run a blower door at a low (~200 to 400cfm or higher) flow in order to simulate its drafting.

T t L ti 6 % F


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Test Locations-65% Furnaces

The vent on thisfurnace should bedrilled approximately18 from the top ofthe draft hood. Thishole is for testing

only the draft, notCO.

Drill and test here

Test Locations 80% Furnaces


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Test Locations-80% Furnaces

The test hole on this furnace should bein the adaptor section above the

combustion blower. Avoid drilling intodouble wall vent. This test hole is formeasuring draft and CO.Spillage tests are not usually taken on

furnaces like this. (They do not have adraft hood, but a test can be done at theburner area.)

Drill and test here

Test Locations 90+ Furnaces


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Test Locations-90+ Furnaces

It is preferred that PVCventing not be drilled.

Always try to test at the venttermination. Somemanufacturers will allowdrilling of the vent pipe,however it must be

completely sealed aftertesting is done, withapproved material.

CO only is measured on 90+

furnaces (positive pressureventing).

T t L ti CO t ti f 6 % F


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Test Locations-CO testing of 65% Furnaces

The top picture shows thecorrect location for COmeasurement on a 65%efficiency unit. Do notmeasure CO in the ventpipe when a draft hood is

present. One CO reading is taken

at every port under thedraft hood; one for each

burner. The numbers arenotaveraged.

This

Not this

Test Locations-Spillage


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Test Locations-Spillage

On a draft hood furnace,

spillage is tested usingsmoke, matches, or amirror, to check for thepresence of combustion

products. If spillage is present, the CO2will extinguish a flame.

A mirror will fog over fromthe moisture content of the

gasses.

Test Locations Hot Water Tanks


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Test Locations Hot Water Tanks

An atmospheric water heater is

tested for spillage around thebase of the draft hood, againusing smoke, matches or amirror.

CO is measured inside thedraft hood, underneath it,before dilution air enters. Thereare two readings taken, one

from each side of the baffle.

CAZ Testing


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CAZ Testing

(Optional) While running furnace in the Heat mode,install thermometers to measure heat rise at 5 minutes.

Supply air minus return air.

While running furnace (whatever speed), use smoke to findduct leaks. (Youve got ~ 5 minutes to get the equipment toSteady State!)

Listen for air flow noises, duct popping, or whistling. Theseare signs of leakage, excessive pressures, or other ductproblems.

At steady state, measure the CO, draft & spillage.

Ap p lia n ce s m u s t r e m a in ign it e d fo r t h e e n t i r e t e s t !

Ovens & Cooktops


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Ovens & Cooktops

Oven CO levels are

tested at the outletport, usually located atthe top/back of theunit. Testing is done

after 15 minutes ofoperation, and levelsshould not exceed 800

ppm air free.

Stove courtesy of Warp 8 Model courtesy of Compass Records

How Much CO Can There Be?


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How Much CO Can There Be?

The BPI Standards list acceptable levels of CO.

Some Manufacturers provide a CO level that theirequipment must be operating at.

For example: The CO levels at the exhaust breachshould be 105-110 ppm on high fire on all units.(Munchkin Boilers)

Finally


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Finally

Dont get in over your head!

Know what you are doing. Get hands-on training. If you are lost, ask for help. (Its OK to ask for help.)


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I N V I S I B L E E N E R G Y / R I C H M O O R E

D E N V E R , C O

R G A L E N M O O R E 1 @ M S N . C O M

3 0 3 - 9 1 9 - 9 8 4 9

THANK YOU

caz pressure testing

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