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AIR CONDITIONING & HEAT PUMP SYSTEMS
A/C - HEAT PUMP CONTROLS & SWITCHES
AIR CONDITIONER BTU CHART
AIR CONDITIONER COMPONENT PARTS
AIR CONDITIONER TYPES, ENERGY SOURCES
AIR CONDITIONER NOT WORKING
AIR FILTER EFFICIENCY
AIR FILTERS, FIBERGLASS PARTICLES
AIR FILTERS for HVAC SYSTEMS
AIR FLOW MEASUREMENT CFM
AIR HANDLER / BLOWER UNITS
ADDING A/C: RETROFIT SIZING
BLOWER FAN CONTINUOUS OPERATION
BLOWER FAN OPERATION & TESTING
BLOWER LEAKS, RUST & MOLD
COOLING COIL or EVAPORATOR COIL
DIRTY A/C BLOWERS
Leaks, Rodents In Air Handlers
Mold Growth in Air Handlers
BACKUP HEAT for HEAT PUMPS
BLOWER DOORS & AIR INFILTRATION
BLOWER FAN CONTINUOUS OPERATION
BLOWER FAN OPERATION & TESTING
BOOKSTORE - Air Conditioning "How To" Books
CAPACITORS for HARD STARTING MOTORS
CLEANING & Legionella BACTERIA
CHINESE DRYWALL HAZARDS
COMBUSTION GASES & PARTICLE HAZARDS
COMPRESSOR & CONDENSING COIL, A/C
CONDENSATE HANDLING, A/C
CONTROLS & SWITCHES, A/C - HEAT PUMP
COOL OFF HEAT Thermostat Switch
COOLING CAPACITY, RATED
COOLING COIL or EVAPORATOR COIL
DATA TAGS on AIR CONDITIONERS
DEFINITION of Heating & Cooling Terms
DEW POINT CALCULATION for WALLS
DEW POINT TABLE - CONDENSATION POINT GUIDE
DIAGNOSTIC GUIDES A/C / HEAT PUMP
DIAGNOSE & FIX HEATING PROBLEMS-BOILER
DIAGNOSE & FIX HEATING PROBLEMS-FURNACE
DUCT SYSTEM & DUCT DEFECTS
DUCTS - Asbestos
DUCT INSULATION, Asbestos Paper
DUCT INSULATION for SOUNDPROOFING
DUCT SYSTEM & DUCT DEFECTS
DUCT SYSTEM NOISES
DUCTS, Asbestos Transite Pipe
DUST, HVAC CONTAMINATION STUDY
DUST SAMPLING PROCEDURE
EDUCATION, HVAC SCHOOLS
ELECTRIC MOTOR DIAGNOSTIC GUIDE
ELECTRIC MOTOR OVERLOAD RESET SWITCH
ELECTRICAL POWER SWITCH FOR HEAT
EVAPORATOR COIL or COOLING COIL
EVAPORATIVE COOLING SYSTEMS
EXPANSION VALVES, REFRIGERANT
FAN, AIR HANDLER BLOWER UNIT
FAN AUTO ON Thermostat Switch
FAN CONVECTOR HEATERS - HYDRONIC COILS
FAN LIMIT SWITCH
FURNACES WARM AIR HEATING SYSTEMS
GAS EXPOSURE EFFECTS, TOXIC
GAS DETECTION INSTRUMENTS
GAUGE, REFRIGERATION PRESSURE TEST
HEAT LOSS (or GAIN) in buildings
HEAT LOSS (or GAIN) INDICATORS
HEAT LOSS R U & K VALUE CALCULATION
HEATING SMALL LOADS
HOUSEWRAP AIR & VAPOR BARRIERS
HUMIDITY LEVEL TARGET
INDOOR AIR QUALITY IMPROVEMENT GUIDE
INSPECTION CHECKLIST - OUTDOOR UNIT
INSPECTION LIMITATIONS, A/C SYSTEMS
LEED GREEN BUILDING CERTIFICATION
LIGHT, GUIDE to FORENSIC USE
LOST COOLING CAPACITY
LOW VOLTAGE TRANSFORMER TEST
MANUALS & PARTS GUIDES - HVAC
MOTOR OVERLOAD RESET SWITCH
MOLD in AIR HANDLERS & DUCT WORK
MOLD INFORMATION CENTER
NOISE AIR CONDITIONER / HEAT PUMP
NOISE / SOUND DIAGNOSIS & CURE
ODORS in AIR HANDLERS & DUCT WORK
OPERATING COST, AIR CONDITIONER
OPERATING DEFECTS, AIR CONDITIONING
OPERATING TEMPERATURES, AIR CONDITIONER
PORTABLE ROOM AIR CONDITIONERS
PRESSURE READINGS, REFRIGERANT
REPAIR GUIDES A/C / HEAT PUMP
REPAIR & DIAGNOSTIC FAQs for A/C
REFRIGERANTS & PIPING
RETROFIT SIZING for A/C or HEAT PUMPS
SEER RATINGS & OTHER DEFINITIONS
SPLIT SYSTEM AIR CONDITIONERS & HEAT PUMPS
THERMOSTATS, HEATING / COOLING
THERMOSTATIC EXPANSION VALVES
WATER COOLED AIR CONDITIONERS
WINDOW / WALL AIR CONDITIONERS
WINDOW / WALL A/C SUPPORTS
Tests for mold in HVAC air ducts: this article explains how to assess the level of mold contamination in heating or cooling air ducts, and the aggressiveness of mold testing (do we agitate the ducts) that can form sources of error when testing HVAC systems for mold contamination. This document is a brief tutorial which provides information about the accuracy of and sources of errors in tests for the level of allergenic and toxic mold in residential buildings:Are spore counts valid? Are cultures and swab tests valid?
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Question: After dealing with a moldy washing machine and even a mold remediation we are focusing on our ductwork: what is the best way to test for mold in the heating/AC system
Thanks for your website - it is truly a public service. My husband and I are both very ill - my husband has recently been diagnosed with metastasizing melanoma in his eye, which has spread to his liver and spine - his prognosis is not good.
I have been sick with sinusitis for over a year now and am known to have severe allergies to mold (causing recurrent bronchitis and sinusitis). After many scans and tests, my doctors feel the most likely reason not responding to treatment (many courses of antibiotics and sinus irrigations) is because of an environmental allergy.
Because of my known allergy, and because of a small area of what looked like black mold (and smelled unbelievably vile) discovered during the renovation, we had two different mold remediation companies as well as an air quality testing company come in.
They felt the black mold was removed completely (under negative pressure and other precautions) and then they did a fair amount of preventive work - since there were a few tiny areas of green mold in the basement and attic. Air quality testing afterwards supposedly showed no mold anywhere.
We recently discovered our front-loading washing machine is one of the brands known to have major mold problems and there are now several class action suits against them. We had several puzzling episodes of moldy sheets, which weren't recognized until our son came home to visit (my sense of smell has been wiped out by the sinusitis and my husband never had a good sense of smell).
We couldn't figure out how this was happening since we are very careful not to leave wet clothes/linens lying around or in the washer. According to our son, the mold smell permeated the master bedroom. We then moved to the other bedroom and the same thing happened again, discovered when our son was visiting again, and again the smell permeated the room. The washer is in the master bath.
I first got sick in our old house (which was a house that, up until then, had been a very healthy environment for me) after we bought the washing machine. We had a couple of episodes of moldy-smells in our wash in the old house, but I was still able to smell and threw things out right away, but was puzzled as to why they were occurring.
We have replaced the washer, aired out the rooms, bought air filters, have an HEPA filter on the return heating duct, but I am not feeling better (after having rewashed all our clothes and bedding.
We're concerned that mold could be in the heating/AC duct system.
We've thrown out all our linens twice now (after our son discovered the mold) but before we learned about the washer. We're also wondering if we need to throw out everything again.
My basic question is what is the best way to test for mold in the heating/AC system and is there a company/person you could recommend to do this work?
Thanks for your time and any advice you can give us. - K.J., New Jersey
Reply: A combination of Steps can Help Assess Mold Contamination in an HVAC System
We have sometimes found that thick absorbent furnishings such as carpets, upholstered couches and chairs, and mattresses that suffer prolonged exposure to a moldy environment may be smelly from MVOCs even if there was no observable actual mold spore or mold growth contamination on those items.
I'd like to know more about the clothes washer you had trouble with and what authoritative references you have on that matter.
At MOLD & ENVIRONMENTAL INSPECTORS we list some inspectors/testers specializing in mold and indoor contaminants. But there may be other well qualified people in your area. Talk with anyone you are considering hiring. Don't tell them the "right answer" (besides they are likely to have other good ideas). But name your concerns and ask how they will approach the job - stay away from superficial experts who dash in, collect a mold sample, charge you, and leave. [InspectAPedia.com has no financial nor business relationship with products or services discussed at our website
How much variation in airborne mold or dust level do we see inside heating and air conditioning ducts and air handlers?: The left hand photograph shows a one liter airborne particle trace collected inside of a heating furnace return air plenum using a Burkard Personal Air Sampler.
The right hand photograph shows a second particle trace collected in the same location, with the same volume of air, with one difference: we tapped lightly on the side of the air plenum during the sampling process.
Even before counting the number airborne particles of any type per liter of air it is obvious that even modestly aggressive sampling (rapping on the plenum to stir up local dust) can make a large difference in the level of particles seen in the sample result.
We conducted this test during a post mold remediation clearance inspection of a previously mold-contaminated air conditioning system. The remediation contractor vehemently disagreed with the procedure of tapping on the ductwork during testing, informing us that "... his hygienist never did such a thing".
We agree that consistency in test methods is important in order to be able to compare one mold test with another. However if we're looking for the presence or absence of a significant mold or allergenic dust reservoir that should have been removed, a little aggressiveness in sampling can be useful and in fact more accurate as well.
In sum, do not rely on the accuracy of airborne particle counts alone: Since air samples do not capture a representative picture of the indoor environment an indoor air quality investigator should not rely simply on conventional airborne particle quantitative analysis (particle counts per cubic meter).
Readers concerned with mold contamination in heating and air conditioning air handlers and ductwork should see BLOWER LEAKS, RUST & MOLD and PARTICLE & MOLD LEVELS in DUCTWORK where we describe how to test HVAC systems and ductwork for mold.
Mold in HVAC ductwork is also discussed at WHY DOES MOLD GROW in INSULATION?. See SLAB DUCTWORK for the role of in-slab placement of air ducts in the formation of mold contamination in HVAC systems. These critical mold testing accuracy questions are discussed in this paper.
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Frequently Asked Questions (FAQs)
Question: how can I arrange a test to identify the mold in the flex duct on my HVAC system?
Reply: focus on removing the mold (replace the flex duct) and fixing the cause of its growth
A competent onsite inspection by an expert usually finds additional clues that help accurately diagnose a problem - in this case, why the flex duct in your photos is moldy, how much moldy material is present, and thus not just how to correct the problem but how to prevent its recurrence. That said, here are some things to consider:
Testing your HVAC duct mold is easy following the procedure we describe using clear adhesive tape - see MOLD TEST KITS for DIY MOLD TESTS and use any qualified mold test lab or look into the list of labs and experts we provider at InspectApedia.
BUT I'm not sure I would bother in this case. There are sometimes reasons to test mold or dust samples, (see MOLD TEST REASONS ) but in this case you'd be best off spending your money on replacing the moldy ductwork and fixing the cause of its growth in the first place.
Replace the moldy flex duct, inspect the whole system for cleanliness, clean components that can be cleaned (air handler blowers, metal ductwork interiors), and fix the cause of mold growth.
See MOLD EXPERT, WHEN TO HIRE for help in deciding if it's appropriate to bring in an expert.
Questions & answers or comments about how to measure the level of mold contamination in HVAC air ducts and blower units.
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Technical Reviewers & References
Related Topics, found near the top of this page suggest articles closely related to this one.
Mold Contamination Testing, Cleanup, Prevention: references & products
OTHER IAQ ISSUES: How To Find and Address Other Indoor Air or Indoor Environment Contaminants Besides Mold
Mold or allergens may not be the only or even the main indoor environmental contaminant. Don't let media attention to mold cause so much enviro-scare fear that other, possibly more urgent hazards go un-addressed.