1

Key PointsAlthough radon fans have improved over the years, they can still be abused.• Locate fan in a location where all portions of fan and vent pipe

that is under positive pressure is not in a location where leakageof radon could enter living space.

Good Locations:• In unoccupied attics• Outside of the house• In garage with no living space above it

Bad Locations:• In crawl space beneath house• In basement• In occupied attic• In garage where there is living space above it.

• Locate fan where it can be accessed for maintenance.• Install fittings that allow for removal (don’t glue fan to pipe!)• Don’t bury fan below grade (even if you do use a box)

EPA Radon Mitigation Standards. Section 14.3.3Radon vent fans used in active soil depressurization or block wall depressurization systems shall notbe installed below ground nor in the conditioned (heated/cooled) space of a building, nor in anybasement, crawlspace, or other interior location directly beneath the conditioned spaces of abuilding. Acceptable locations for radon vent fans include attics not suitable for occupancy(including attics over living spaces and garages), garages that are not beneath conditioned spaces,or on the exterior of the building.

Fan outdoors mounted within a cosmetic enclosure

Fan in attic.

Note fittings for easy replacement

Operating Costs

Topic 3 - Audio 33

2

Key Points

• Discharge of system can have high levels of radon

• Terminate at a location where gases will not re-enter house or expose people in at grade level or inadjacent homes.

• Minimum of 10 feet above ground level

• Minimum of 10 feet away from any opening that is less than 2 feet below the discharge

• Minimum of 10 feet from any private or public access

• Minimum of 10 feet from any adjacent building

• Above eave of roof

• Keep away from swamp coolers and other powered intakes.

EPA Radon Mitigation Standards. Section 14.2.8

To prevent re-entrainment of radon, the point of discharge from vents of fan-powered soildepressurization and block wall depressurization systems shall meet all of the following requirements:(1) be above the eave of the roof, (2) be ten feet or more above ground level, (3) be ten feet or more fromany window, door, or other opening into conditioned spaces of the structure that is less than two feetbelow the exhaust point, and (4) be ten feet or more from any opening into an adjacent building. Thetotal required distance (ten feet) from the point of discharge to openings in the structure may bemeasured either directly between the two points or be the sum of measurements made around interveningobstacles. Whenever possible, the exhaust point should be positioned above the highest eave of thebuilding and as close to the roof ridge line as possible.

Discharge through roof

Discharge of exterior system.

Do not discharge under soffit.

Take around gutter.

Operating Costs

Topic 3 - Audio 34

3

Key PointsRadon Vent Piping:• Must be well sealed – prime and glue fittings• Must be able to able to withstand moisture (condensation)• Interior

• Plastic (PVC or ABS)• RMS allows thin wall (schedule 20) - code violation in some areas• Must be schedule 40 when routed through garages.

• Exterior• Plastic (PVC or ABS) must be at least schedule 40• Oversized commercial grade downspout often used above fan-seal joints.

• Size• Typically 4-inch – but based upon diagnostics and experience• The larger the diameter, the easier for air to flow as well as reduces noise.• See pipe sizing information in appendix.

Moisture• Air from soil will be humid. As pipe runs through cold space condensation can occur.• Condensation must be able to drain back to collection point• NO TRAPS and DO NOT Cut FLOOR JOISTS !!!!

Mount fan vertically so condensate can drain down

through casing.

Water condensate ordew may form inside of pipe. It must be allowed to flow back to suction point.

Cold air temperatureson outer surface of pipe

Air Flow

Condensate

NO!Traps will accumulatewater and cause systemto fail. Don’t cut the joistout of the way.

Slope Pipe: 1/8 inch per foot

Condensate should flowback to suction point

YES!Fan

Operating Costs

Topic 3 - Audio 35

4

Key PointsInterior Routing

Pros Cons

• Can allow system to be more hidden• Less problem with condensation

• Air noise can be heard if pipe diameter too small or pipe not insulated

• Can be more expensive to install• Can take up closet space

Exterior RoutingMay be most practical way for exterior foundation drain systems

Pros Cons

• Less expensive• Faster

• Can be unsightly• Can have more condensation problems if water

separators or insulated pipe not used in certain areas.• Neighbors may complain about noise o exposure

Interior Routing

• Can be hidden in closets

• Less noticeable

• Be careful of air noise

Exterior Routing

• Less expensive

• More noticeable

• Fan can be mounted in enclosure to improve looks.

• Take precautions against freezing in cold climates.

Operating Costs

Topic 3 - Audio 36

5

Key PointsOccupancy Separations (Fire Walls)• Wall between the interior of the home and the garage is a fire resistant wall.• Ceilings can also be fire rated, especially where there are townhomes with common attics.• Floors separating stacked apartment units are also fire rated.• Routing plastic pipe through these walls can reduce their rating which is a severe code violation.

Use “Plastic Pipe Devices” to maintain integrity of fire wall.• Purchase approved assemblies.• Consist of metal collar that fits around pipe and contains a material that will swell and choke off

pipe and opening in the event of a fire.• Install per manufacturers recommendations and local code practices.• Internal knife gate styles with external fusible links not recommended because of potential

corrosion due to humidity of air stream.

(Drawing compliments of Professional Discount Supply)

Fire Collar

Specify pipe diameter and fire rating needed

Note some areas may require fire collars on both sides of wall.

Operating Costs

Topic 3 – Audio 37

6

Key PointsExterior Systems• In cold climates a significant amount of water can condense inside pipe.• Water can freeze in pipe.

• When it thaws, chunks can drop into fan and lock it up.• Locked fan will get hot thermal overload switched (in fan) will shut fan off, until it cools

and then start back up.• Cycling can cause bearing failure.

• Water separators on discharge can help remove condensation as well as prevent ice chunks fromdropping into fan.

If using downspout above fan• Additional condensation can occur if it is

metal.• Plastic downspout can be used.• Use water separator.• If using than one length of downspout

• Fit upper section into lower section sowater will drain back down rather thanleak out at joint (just like a regulardownspout)

• If you do it the opposite way, water willfreeze on outside of lower section andhas been known to pull system off walldue to weight of ice.

Interior Systems• Insulate pipe in cold areas

• Insulated flex duct slipped over pipe• Also useful in reducing noise in

portions of pipe in living spaces.• Pre-insulated pipe available from some

suppliers.Pipe

Cross Section of InsulatedFlex-Duct Slid Over Pipe

Plastic VaporBarrier

Fiberglass

Fan

PowerSupplyto Fan

Roof Flashing

Shingles

1” ThickFiberglassInsulation

6 x 4 RubberReducers

Screw Bracketsto Siding

Crimp End Down to Fit into Lower

Section and Screw Together

Adapter

CaulkCaulkCaulkCaulkCaulkCaulk

Caulk and ScrewJoint Together(Polyurethane)

Operating Costs

Topic 3 - Audio 38

7

Key Points• Active soil depressurization systems can have fairly high concentrations of radon in them.

• Keep away from openings to home.• Discharged air can be humid

• Avoid air striking building components where moisture can cause damage.• In cold climates don’t impact cold surfaces where ice can form.• Rain caps can force radon back towards house.

• A properly installed system will handle far more water from condensation of soilhumidity than the amount of rain that will fall down discharge.

• Use water separator at fan instead.• Discharge air is mean annual temperature, so in cold climates the air is nice and warm.

• Birds, squirrels, etc. like to fly down discharge.• Tough on birds and system!

Be sure you start up fan before installing screen on discharge to clear out debris. Otherwise, bits of attic insulation or PVC shavings will rise up, lodge against screen and shut off airflow.

Install ¼-inch screen in discharge. To keep critters out.

Pre-made fittings can be obtained, or put coupling on discharge with screen placed

between coupling and pipe.

Operating Costs

Topic 3 - Audio 39

8

Key PointsActive soil depressurization systems need appropriately sized fans to capture the radon laden soil gas beforeit enters the home. Here are some key characteristics of fans rated for radon service.• Must be able to draw air out from foundation at a faster rate than is supplied to it.• Have sufficient vacuum producing capability for the volume of air needed to be moved to not be

overcome by negative pressures in home.• Be capable of handling damp air and even condensate load.

• Mount vertically.• Most fans are inline centrifugal fans

• Wattages: 40-150• Some are packaged as low voltage systems that can be plugged into wall with class II wiring to

fan up to 100 feet away from combination power supply/indicator.• UL or CSA listed

• Comply with local codes with respect to wiring fans.• Must be rated for location they are installed.

EPA Radon Mitigation Standards:14.6.1 Wiring for all active radon mitigation systems shall conform to provisions of the National Electric

Code and any additional local regulations.14.6.2 Wiring may not be located in or chased through the mitigation installation ducting or any otherheating or cooling ductwork.14.6.3 Any plugged cord used to supply power to a radon vent fan shall be no more than 6 feet in length.14.6.4 No plugged cord may penetrate a wall or be concealed within a wall. 14.6.5Radon mitigation fansinstalled on the exterior of buildings shall be hard-wired into an electrical circuit. Plugged fans shall notbe used outdoors.14.6.6 If the rated electricity requirements of a radon mitigation system fan exceeds 50 percent of thecircuit capacity into which it will be connected, or if the total connected load on the circuit (including theradon vent fan) exceeds 80 percent of the circuit's rated capacity, a separate, dedicated circuit shall beinstalled to power the fan.14.6.7 An electrical disconnect switch or circuit breaker shall be installed in radon mitigation system fancircuits to permit deactivation of the fan for maintenance or repair by the building owner or servicingcontractor (Disconnect switches are not required with plugged fans).

Operating CostsTopic 3 - Audio 40

Low voltage Class II package avoids need for electrician in

certain code jurisdictions.

Picture: Compliments of Professional Discount Supply

9

Key Points

• Fan selection is based on permeability of aggregate which is a function of building practices in different areas. Radon fans can typically deliver 0.5 to 1-inch of water column at air flows of 70-80 CFM.

• Static pressure is the pressure that a fan can overcome for a specific air flow.

• Resistance to be overcome is a function of resistance of subgrade materials and vent piping.

• As air flow goes up, ability to produce vacuum goes down (Air flow and differential pressure are inversely related).

• 3-inch pipe is considered minimum size.

• In difficult to mitigate houses, it may be better to add more suction points than to increase fan size.

Radon Fan Characteristics:

• Balanced motor and impeller

• Ability to handle moist air streams and condensation

• Sealed bearings

• Install vertically

• Life expectancy: 10 years continuous service

• Thermal overloads to protect motor

• As long as fan still runs the radon will continue to be controlled unlessthe home is added onto.

Failures:

• Moisture in bearings (run all the time)

• Water in terminal box - secure gasketon lid.

HP Series Fans

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

2.2

2.4

2.6

0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340Flow Rate (cfm)

Sta

tic

Pre

ssu

re (

in H

2O

)

HP2133HP190HP220FR150

Operating Costs

Topic 3 - Audio 41

10

Key PointsPipe Supports• Horizontal Supports

• 1 every 6 feet• Plumbers tape (plastic or metal)• Specialty hooks

• Vertical Supports• 1 every 8 feet• Plumbers tape fastened to wood block anchored to wall• Metal clamps for high traffic areas• Metal straps for downspout

Label Pipe

• At every floor it is visible (including the attic)

• Label should read Radon Reduction System

• It would be good to include other information see sample below

• Breaker for circuit that powers fan to be labeled in panel

EPA Radon Mitigation Standards, 16.4

A system description label shall be placed on the mitigation system, the electric service entrance panel, orother prominent location. This label shall be legible from a distance of at least three feet and include thefollowing information: "Radon Reduction System," the installer's name, phone number, and RCPIdentification Number, the date of installation, and an advisory that the building should be tested forradon at least every two years or as required or recommended by state or local agencies. In addition, allexposed and visible interior radon mitigation system vent pipe sections shall be identified with at least onelabel on each floor level. The label shall read, "Radon Reduction System."

RADON Reduction SystemDO NOT CUT OR DAMAGE

A fan is attached to this pipe and is located ___________.

If this pipe must be removed for maintenance purposes, turn off the fan. Disconnect for the fan is located _______ ____________, and is connected to circuit #______ in the electrical breaker panel. After repairs have been made turn fan back on.

*U.S. EPA recommends bi-annual testing.

Operating Costs

Topic 3 - Audio 42

11

Key PointsA system performance indicator is required when installing active soil depressurization systems• Indicate system failure

• Typically do not measure radon• Indicate pressure or air flow of system when it was installed

• Change in vacuum or air flow could indicate failure.• Indicator to be labeled as to what measured variable was at time of installation• Guidance should be given on interpretation.

EPA Radon Mitigation Standards

16.1 All active soil depressurization and block wall depressurization radon mitigation systems shallinclude a mechanism to monitor system performance and warn of system failure. The mechanism shall besimple to read or interpret and be located where it is easily seen or heard by building occupants andprotected from damage or destruction.

16.2 Electrical radon mitigation system monitors (whether visual or audible) shall be installed on non-switched circuits and be designed to reset automatically when power is restored after service or powersupply failure. Battery operated monitoring devices shall not be used unless they are equipped with a lowpower warning feature.

16.3 Mechanical radon mitigation system monitors, such as manometer type pressure gauges, shall beclearly marked to indicate the range or zone of pressure readings that existed when the system wasinitially activated.

If tubing runs through cold space, condensation can occur in tube creating strange readings

3

210

InclineManometer

HIGH LOW

To Fan

Tubing

3

210

InclineManometer

HIGH LOW

To Fan

Tubing

Inclined Manometer

Can mount device on wall and run tubing to suction piping several feet away

U-Tube

Mounts directly on suction pipe with small

hole drilled for tube

Operating Costs

Topic 3 - Audio 43

12

Key PointsCaulking Slab Improves System Performance• Joints closest to suction points are the most critical• Placing suction point in unfinished area allows access to this joint.• In most cases it is not necessary to remove carpet or walls to access joints

• Exception: where slab is not reinforced and a huge crack appears.• Dirt lines on carpet may show over time as air continues to be drawn down through carpet.• Use a polyurethane caulkFloor-to-Wall Joints• Expansion joints

• Cut expansion joint flush with floor, brush and caulk over• Up on wall and out on floor about 3/8-inch• Tool in with back of caulk tube• One 11 ounce tube/8 feet

• Cold joints• Brush and caulk• Tool caulk into joint with backside of spent tube or piece of cardboard• One 11 ounce tube per 12 feet

• Canal Drains• Serve as canal for collection and diversion of water to sump• Place backer rod halfway down canal

• Allows for water passage both above and below baker rod• Caulk over rod• MAINTAIN ABILITY FOR CANAL TO DIVERT SURFACE WATER

Floor Cracks• Typically are not a major opening

• Where no re-wire is used, slabs may have very large cracks and may require carpet removal and sealing(very rare).

• If you caulk floor cracks• Grind out crack and use a gun grade caulk• Flowable caulk may drain into subgrade

Use smoke bottle to determine where sealing is needed

Operating Costs

Topic 3 - Audio 44

13

Key Points

Floor Drains:

• If suction impacts utility trench, air could be pulled down drain (via slip joint).

• Verify need with smoke bottle with system both On and Off.

Reading Assignment:US EPA Radon Mitigation Standards - Section 14.5

Existing Grate

Dranjer® Trap

Existing Grate

Dranjer® Trap

Special traps can be places within floor drains that stop air but let water drain properly.

Same drains can also be used on sump lids, if surface water needs to drain into sump.

Block Walls (See earlier discussion)

Triple expanding foam Caulk at edge of full sill plate Wall Penetrations

Posts on sub-grade pads(drill and foam)

Tub & ToiletUse silicon

Permanent Seal: Use Polyurethane

Non-Permanent: Use Silicon

• Toilet

• Tub

• Sump lid

Operating Costs

Topic 3 - Audio 45

14

Key Points

Large leaks in system could cause combustion appliances to backdraft.

• Good sealing reduces potential

• Check draft of combustion appliances

• Especially with marginal flues

EPA Radon Mitigation Standards Section 11.3

1. Close all windows and doors, both external and internal.

2. Open all HVAC supply and return air duct vents/registers.

3. Close fireplace and wood stove dampers.

4. Turn on all exhaust and air distribution fans and combustion appliances EXCEPT the appliancebeing tested for backdrafting.

5. Wait 5 minutes.

6. Test to determine the indoor-outdoor pressure differential in the room where the appliance beingtested is located. If the pressure differential is a negative 5 Pascals or more, assume that apotential for backdrafting exists.

7. To begin a test for actual spillage of flue gases, turn on the appliance being tested. (If theappliance is a forced air furnace, ensure that the blower starts to run before proceeding.)

8. Wait 5 minutes.

9. Using either a smoke tube or a carbon dioxide gas analyzer, check for flue gas spillage near thevent hood.

10. Repeat steps (4) through (9) for each natural draft combustion appliance being tested forbackdrafting. Seasonal and extreme weather conditions should be considered when evaluatingpressure differentials and the potential for backdrafting.

17.3 Immediately after installation and activation of any active (fan-powered) sub-slabdepressurization or block wall depressurization system in buildings containing natural draftcombustion appliances, the building shall be tested for backdrafting of those appliances. Anybackdrafting condition that results from

Suggestion:

• Backdrafting can occur after installation when system is breached

• Verify existence of CO monitors

• Offer CO monitors

Operating Costs

Topic 3 - Audio 46

15

Key Points• Performance indicator provides information (suction pressure or amp style gauge)• The ability to measure air flow is very helpful• Having noted post-mitigation values of suction and air flow provides a valuable reference.• Check for obvious

• Fan off or on switched or GFI tripped circuit

Vac Air Flow

Amp Reason Explanation

↓ ↓ ↓ Blocked Discharge

Blockage or restriction in discharge creates backpressure. This increases pressure in suction piping (i.e., lose vacuum) and decreases air flow.

Check for: ice, birds, nest, debris behind screen

↑ ↓ ↓ Blocked Suction

A blocked or restricted suction (assumes restriction is below point of where vacuum measurement is made) reduces available air to suction side of fan. This causes fan to create higher vacuum in pipe between fan and restriction.

Check for water in pit or sub-grade, suction pipe has fallen into bottom of pit.

↓↑ ↑ ↑Broken discharge pipe

A broken discharge pipe makes it easier for fan to exhaust air, so air flow rate increases. Vacuum can go up or down, but most likely will go up due to lower back pressure.

↓ ↑ ↑ Excess inlet air

A broken suction pipe allows additional air into suction of system (air flow increases) making it harder for fan to draw vacuum (vacuum decreases). Check for broken suction pipe, excess air under slab (permeable soils-wind), SMD plastic pulled up.

0 0 0 Dead fanWith fan off or burned out, no air will be moving and therefore no vacuum, no air flow and no power draw.

0 0 MaxLocked impeller

Because impeller is not turning no air will be flowing and no vacuum created. However, power will be at maximum.

Operating Costs

Topic 3 - Audio 47

16

Key PointsSub-Membrane SystemsToo much air:• Plastic is not sealed at foundation walls or riser• Air is being drawn through a void in foundation• Find excess air sources with smoke gun and seal them before increasing fan sizeToo little air:• A blockage has occurred in pipe. Debris left in pipe, or icing has occurred in discharge - Find

blockage and repair.

Sub-Slab SystemsToo much air:• Fan has insufficient capacity, or there is too much leakage from the outside grade or open areas

inside the foundation - Try to find excess air sources with smoke gun and seal them beforechanging fan.

Too little air:• A blockage has occurred in pipe. Debris left in pipe, or icing has occurred in discharge - Find

blockage and repair.Low or no sub-slab vacuums:• Fan is too small either from an air or vacuum standpoint.• An additional suction point is needed.• A large opening for air entry is between the suction point and the measurement location.• Pit was not dug out well enough.• HVAC system is over powering building.

Sump and Drain Depressurization SystemsToo much air:• Sump has not been sealed or removed for maintenance - Install lid with bold warning label• A soak-away is open to the air - Inspect check valve or look for additional soak-away• There are other pipes connected to drain such as downspouts - Locate and isolate –• Drains are connected to a large storm drain - Install check valve or abandon approach

Block Wall DepressurizationToo much air:• Large leakage areas at block tops, wall penetrations, or even wall surfaces - Locate and sealPoor communication to some walls:• Obstructions to air flow such as pilasters, bond beams, lintels - Add additional suction points or

jumpers

Operating Costs

Topic 3 - Audio 48

17

Key PointsIf a forced air system exists in the building always check to see if ductwork is buried in sub-grade.Supply Ducts Under Slab:• Supply is the positive pressure side of Forced Air Unit (FAU)• When FAU OFF, leaks in ductwork provide a pathway.• When FAU is ON leakage will be into subgrade.Return Ducts Under Slab: Watch out for this!• The return duct is air being returned back to FAU.• Very large negative pressure inside duct• When FAU is OFF, leaks in ductwork provide pathway.• When FAU is ON, soil gas is sucked into ductwork and distributed into building.• Vacuum may be so large that ASD systems cannot overcome negative pressure.Remedies:• Your ASD system may still work if duct effect is small• Fresh air make-up may provide dilutions and reduction of negative pressure in duct.• Attempt sealing near FAU cabinet• Conduct radon decay product measurement to determine if air circulation is reducing radon decay

products to acceptable level.• Consider high efficiency filters in return duct to reduce radon decay products • Abandon buried ductwork and re-duct the HVAC system

Cabinet door removed to view return duct View of return duct under slab

Operating Costs

Topic 3 - Audio 49

Always inspect return and supply ducts. This is an alligator that can bite you!

18

Key PointsElectrical Cost• Based upon either:

• Wattage of fan (conservative)• Actual measurements

• Watts = current (amps) x Line voltage (volts)

Heating/Cooling penalty due to loss of conditioned air• If air from within home is drawn into ASD system, that lost air is replaced by outdoor air.

• Puts additional load on HVAC system• Can be reduced by caulking and sealing

• Fairly complex equation (see additional explanation in appendix)

• Maintenance• Fans typically have sealed bearings, so lubrication is not needed• Life expectancy of fan is around 10+years if properly installed• Maintenance costs is minimal for system• Need to retest every two-years is to be advised.

See Appendix for more explanation

Example: What is the annual operating cost for a 90 watt fan operating continuously, if electricity costs $0.07 per kilowatt hour?

90 watts x 24 hr x 365 days x 1 KW x $0.07 = $55.19 per yearDay year 1000 Watts KW hr

Operating Costs

Topic 3 - Audio 50