As a manufacturer of whole-house humidifiers, we often get calls from home owners asking: How do I get more humidity out of my humidifier or Which setting offers more humidity? Numerous factors contribute to humidity levels in a home.
First, it’s important to know that every humidifier manufactured is designed for a finite, maximum humidity output. The humidifier that is initially selected for installation should be properly sized by a qualified technician, who will consider:
• The square feet of the home
• Ceiling height
• Number of fireplaces
• Age of home
• Type of widows
• Type of insulation
• Amount of woodwork and wooden items (artwork, musical instruments) in the home
• Future plans for home additions or installation of wood floors
• Climate at the given location
It is important to note that installing an evaporative or fan-powered humidifier with the hot water supply produces approximately 20% higher humidity output. If there is a manual humidistat, turn the dial towards the higher number for more humidity. With an automatic humidistat (with an outdoor sensor installed), select the desired percent humidity level and the humidity level will be maintained. Set to a higher number for more humidity.
To help with humidity, be sure to replace the Vapor Pad (also called humidifier pad, humidifier filter, water panel or water filter) at the start of each heating season. The homeowner may need to replace it more often depending on the water supply’s sediment content or the humidifier’s run time. Do not wash/clean the pad—it will remove the coating that holds water to the pad and the humidifier will produce zero humidity as a result.
It is important to perform other maintenance tasks while replacing the Vapor Pad, such as checking water lines and the solenoid valve for clogs, and removing scale build-up from the distributor trough and drain pan.
There are also a few simple things that can be forgotten, so be sure to check that:
• There is power to the unit (plugged in and turned on)
• The water supply is turned on
• The humidistat is set to the humidity level desired
• The damper is turned to “open” or “winter”
• The Vapor Pad is new/not clogged
• The solenoid valve is not blocked (it allows water to run to the humidifier)
• The temperature is correct—colder air cannot hold as much moisture as warmer air
• The furnace run time and plenum temperature support the humidity output needed
Has the home been remodeled since after the installation of the humidifier? Has the homeowner added on a room or installed hardwood floors or a new fireplace? These may increase the demand for humidity from the humidifier, and you just may need to replace the unit with a higher output humidifier. Another culprit could be water pressure. Has the water pressure changed in the home for some reason? Perhaps the water line is not fully open?
As you can see, there are numerous considerations in selecting the humidifier for a home. Understanding them prior to selection will set up the homeowner and technician for a positive humidifier experience. ICM
With a steamy summer climate in much of the U.S., the annual maintenance check on your customer’s air conditioning unit is also an ideal time to discuss reducing relative humidity (RH) in their homes. As you may know, the air conditioner is not the ideal humidity- reducing solution. A whole house dehumidifier solution is best. In addition to offering increased comfort, the addition of a whole-house dehumidifier can also help reduce your client’s monthly energy bills. By reducing a home’s indoor moisture while outdoor temperatures are high, occupants will feel cooler and turn the air conditioner down.
Warmer summer air is able to hold more moisture, which is indicated by dew point. Dew point is the atmospheric temperature below which water droplets begin to condense. It varies according to pressure and humidity. The relative humidity is the amount of water vapor present in the air, expressed as a ratio compared to saturation at the same temperature.
High summer temperatures combined with a higher dew point reduce the atmosphere’s ability to evaporate perspiration from the skin (necessary for cooling the body), correlating to a higher level of discomfort for your clients.
Although a home’s air conditioning system removes moisture while reducing the temperature, the system stops when the desired temperature is met. Humidity remains high in the cooled space and your client’s discomfort level remains relatively unchanged. If one were to run the air conditioning unit until desired humidity levels were reached, it would probably feel like they were living in an igloo instead of a home. Only a system such as a whole house dehumidifier dedicated to moisture removal can solve humidity problems.
Any region experiencing a summer dew point average above 55°F could benefit by a whole house dehumidification system at some point. For example, the average RH in Florida during summer months is 89. We normally think of Florida as more humid than most States, but even in Michigan the average RH during the summer is 88. Connecticut sees an average RH of 86.
Finding the Right RH
For ideal health and comfort, the indoor relative humidity range should be somewhere between 40%–60%. Outside of that range (above or below), conditions can be adversely affected.
Leading literature on allergens recommends keeping RH to less than 51% to deter dust mites, since they can thrive at temperatures between 59°–95°F and an RH level between 55%–85%.
The Ideal Combination
From a human comfort perspective, the worst combination is a dew point above 65°F combined with a high RH of 70% or more. The most comfortable combination is reported to be a dew point of around 60 and an RH of between 40%–60%.
Some Other Reasons
Clearly summer season humidity is not the only reason to install a whole house dehumidifier. Folks living in humid places like Miami, New Orleans, Houston, Portland, Myrtle Beach or Charleston may feel humidity year-round and find great relief by installing a whole house unit. Otherwise, clothes and bedding might feel moist and sticky. Allergy and asthma triggers may intensify because mold and mildew growth may accelerate. The insect population may increase due to excess moisture that attracts moisture-loving spiders, ants and other pests. Low humidity can also extend the life of bug sprays!
Installing a dehumidifier can reduce musty smells, inhibit mold and mildew growth, prevent corrosion of metal and prevent wood from warping. A dehumidifier can also control excess moisture in a crawl space.
Why Whole House?
Room units generally treat only the space in which they are located, often require emptying, cleaning and other maintenance that whole house models do not. In addition, they take up valuable living space, are not always attractive and can be noisy. Even if they are in the basement, home owners may not wish to run up and down stairs to empty water bins.
Whole house units treat the whole house and often work faster to reach the desired comfort level in the home. With either choice, offering options that work to a homeowner means long-term satisfaction.
As a contractor, you have two goals: assisting a homeowner with their indoor air quality (IAQ) needs and generating income. Installing IAQ products can increase your income, not only through the installation, but also through ongoing maintenance. Offering IAQ products while servicing an air conditioner or furnace is the right thing to do for both your company and your customers. ICM
Most of us have seen images of outdoor pollution from vehicle exhaust, wild fires, pollen, industrial emissions, dust, etc. The adverse effects of such pollution on our environment and our health were brought to the forefront in the 1950s and 1960s, resulting in widespread public concern.
In response, the U.S. Environmental Protection Agency (EPA) was formed in 1970 to protect human and environmental health. Legislation introduced by the EPA over many years has worked to clean the environment and restrict the release of pollutants in our waters and the air.
Prior to the COVID-19 pandemic, indoor air quality was hardly a thought for many. Indoor air pollution is less obvious; however, pollution indoors can be up to five times higher than outdoors. How serious is the problem? Air pollution is estimated to have caused more than 6.7 million deaths globally in 2019.
Consider this—the average human drinks 0.5 to 0.8 gallons of water per day, and we expect the water we drink to be clean. The average human breathes 3,000 to 5,000 gallons of air each day, yet we rarely think about what we’re breathing.
Indoor air pollution
New homes are tightly sealed to save energy. Unlike Mother Nature outdoors, where the air is cleaned by sunshine, plants, wind and rain, pollutants get trapped inside. Since we spend most of our time indoors, we actually spend more time in spaces with higher levels of pollutants.
Air pollution exacerbates allergy and asthma symptoms, causes headaches, eye irritation, fatigue, coughing, dry skin and an inability to concentrate. Over time, people without allergies or asthma may actually develop these chronic health issues. Furthermore, poor indoor air quality exacerbates other health conditions such as diabetes, heart disease, cancer, depression, stroke, obesity, chronic lung ailments and more. Environmentally you may experience excess dust, mold, mildew, strange smells, hot or cold spots within your home.
The financial costs of poor indoor air quality (IAQ) are in the billions of dollars in the U.S. alone, and can include premature death, increased health care needs, absenteeism, building remediation, elevated hospital budgets, higher energy costs, reduced work productivity and increased criminal activity.
The pandemic & pollutants
There’s no mistaking it. Just like clean water, clean air is essential to good health, comfort and the health of our home. With the advent of COVID-19, healthy indoor air has been on the minds of business owners, hospital administrators, educators and home owners alike. While many of the COVID-19 safety guidelines focus on public places, people have taken great interest to ensure the air in their homes is safe as well.
COVID-19, however, is only one of many harmful airborne pollutants potentially present inside with us. The U.S. Centers for Disease Control & Prevention (CDC) identifies three categories of indoor pollutants: gases particulates (pollen, dust, smoke, pet dander, dust mites), and germs (viruses—like COVID-19, bacteria, pathogens, germs, fungi, allergens).
We also track pollutants into our houses on our shoes, clothes and packages. We bring it into our homes through hobbies, pets, cooking, cleaning, beauty supplies, new furniture, carpet and tobacco use. Opening doors and windows along a busy dirt road or highway lets pollutants inside.
People make many different choices about their self-care—the choice to exercise, visit a doctor, go to places of worship, enjoy the spa, eat healthy foods, go to counselors, get ample sleep, keep a clean house. We ask advice from family, friends and professionals about a whole plethora of health and well-being decisions. As such, breathing clean indoor air should be part of that entire comprehensive health plan.
Whole-house air treatment products, installed with an HVAC system, exist to keep indoor air fresh, clean, pure, comfortable and healthy. They include:
• Air Filtration: Quality Minimum Efficiency Reporting Values (MERV)-rated air filters remove the smallest airborne particulates from indoor air; these are pollutants that would normally reach your lungs. The EPA agrees: When used along with other best practices recommended by CDC and others, filtration can be part of a plan to reduce the potential for airborne transmission of COVID-19 indoors. (Consult your HVAC professional before upgrading to higher MERV-rated filters).
• UV Air Purifiers degrade pathogens (like COVID), germs, VOCs, odors, bacteria and fungi. From the EPA: When used properly, air purifiers can help reduce airborne contaminants, including viruses, in a home or confined space.
• Humidifiers: Maintaining 40–60% humidity ensures moist nasal passages prevent pollutants from reaching your lungs. Proper humidity levels also reduce the spread of pathogens indoors. From the Harvard T.H. Chan School of Public Health: Studies suggest that higher humidity can enhance the body’s ability to fight off infection; that the coronavirus decays faster at close to 60% relative humidity than at other levels; and that drier air can lead to greater numbers of tiny coronavirus particles that travel farther and penetrate deeper into the lungs.
As the globe reels on its axis in response to the COVID-19 pandemic, Americans are left wondering what the virus’ lasting social and economic impact will be.
In the absence of a crystal ball, we’re left to speculate. As the days spent social distancing drag on, it becomes increasingly clear that major change is inevitable. Society will alter its behavior much like it did in response to the attack on the World Trade Center in 2001 and the 2008 recession. These events—as dissimilar as they were—both prompted massive social and fiscal changes within society. There’s no reason to believe that a global, novel virus and resulting pandemic doesn’t have the same potential.
These changes will undoubtedly materialize organically and via new legislation. Aside from medical professionals, there’s not likely to be a sector of the U.S. population more heavily impacted by the fallout of COVID-19 than small business owners.
Where and how Americans spend time and money will change. The HVAC industry will change, too, as folks tighten purse strings. Jobs have been, and will be, lost. Financially, people will come out of this crisis behind the eight-ball. Even before this, the residential HVAC market was showing signs of softening.
As a result, there’s a distinct possibility that we’ll slip from the generous replacement market we’ve grown fond of into a service and repair market similar to that of the 2009 and 2010. Mechanical contractors will need to develop other revenue streams to offset their lagging replacement revenue.
Bob Miller has more than 30 years’ experience in the critical environments industry. He is a Partner and Director of Technology with Top Product Innovations, Inc.
Beaches, palm trees and sunshine, things synonymous when one thinks of Florida. Sweaters, wool hats and snow, not so much, but they do exist there. An average temperature of 75°F is what South Floridians experience during the winter months1, while our friends to the north are typically experiencing gray skies, artic blasts and showers of rock salt. However, in 2010, the subtropical continental United States, or South Florida as it is commonly known, experienced an uncommonly extended cold snap over an approximate three-month period between January and March1. The monthly minimum temperatures of 51°F – 55°F were an average 7°F below the typical minimum temperatures from prior years (58°F – 62°F), with exterior relative humidity measurements ranging from 65 percent to 80 percent1. After the cold snap, homeowners and building owners complained of a patina of fungal growth on exterior walls and on various contents within the structures. The moisture source was unknown and no apparent water leaks were identified; however, in many cases the causes were misdiagnosed.
A patina of fungal growth on various surfaces can be characteristic of existing, previous high-humidity conditions; whether it be a hot and humid environment in the south or a cool and clammy environment in the north. Why the high-humidity conditions and fungal growth during this period of uncharacteristically cool weather? In most cases, dampness and moisture necessary to support fungal growth are the result of multiple factors, not just one, increasing the complexity of determining the source. A good understanding of building science went a long way in determining and supporting the cause and origin of the abnormal fungal growth.
Psychrometry is a good place to start. Fundamentally speaking, it is the study of moist air. For the purposes of this glimpse into the world of pyschrometrics, we need to understand three measurements: dry bulb temperature (actual temperature of the air), the wet bulb temperature (amount of water vapor in the air) and the relative humidity (amount of water vapor in the air compared to the total that could be held at a given temperature). With these three measurements we can use a psychometric chart to determine the dew-point temperature. Alternately, we can use our digital psychrometers, which give real time measurements including the dew point.
What is dew point? It’s the temperature at which moisture will begin to condense out of the air onto a surface. Why is that important? Because the fungal growth in question was a patina on the surface of materials where a water release was not known or proven to have occurred. The moisture had to come from somewhere and it was attributed to a phenomenon known as condensation.
Condensation is the physical change of a gas to liquid, in this case water vapor to water droplets. As water vapor cools, the molecules slow down and begin to join together, forming droplets of liquid. Think about a cold beverage pulled out the refrigerator and the moisture that appears on the surface. The cooled can is cooling the surrounding air below its dew point, encouraging moisture to form as a film on the surface of the can. A similar condition occurred on the inside surfaces of these residences.
The ability for moisture to condense within the built environment depends a lot on the relative humidity (i.e. water vapor) maintained within the space. Water vapor normally originates from the exterior, and it will migrate into the building until equilibrium is reached between both spaces. Additionally, latent moisture is a common source which is created within the space by the occupants. Examples of this include cooking, breathing and bathing. Even if the relative humidity is low outside, occupant activities within the residence can play an important part. In South Florida, it is common for multi- generational families to inhabit the same home, in many cases a small home with one or two bathrooms and a small kitchen. When latent moisture increases within the residence and is not properly evacuated, surface fungal growth problems often arise.
This can be further complicated by the absence of, or improperly operating, exhaust fans and dryer ducts.
How is this moisture controlled? Primarily via operation of the heating, ventilation and air conditioning (HVAC) system, specifically the air handler unit (AHU), which removes moisture out of the air as it passes over the evaporator coils. AHU operation is based on the thermostat set-point temperatures that will call for cooling when the interior temperature rises above the set point. From my experience, thermostat set-point temperatures typically vary from 75°F to 78°F; therefore, during this period of colder outdoor weather, dehumidification was relatively absent as the ambient air temperatures were below the thermostat set point. The absence of dehumidification allowed water vapor to increase within the residences, both from exterior and occupant use. The elevated water vapor inside the home increased the likelihood of moisture condensing on the interior side of exterior walls of the building as the dew point temperature of the interior air increased. The colder outside temperatures allowed the exterior walls to maintain cooler temperatures on the interior surfaces of the exterior walls, creating conditions for fungal growth to proliferate. The increased water vapor also encouraged fungal growth on the surfaces of various contents within the home.
In South Florida, homes are likely to be constructed with concrete block with insulation (when used) on the interior sides of the exterior walls. There is little need for heating, just keep the cool, conditioned air inside the residence. One of concrete’s many unique properties is its thermal mass. Thermal mass is the ability of a material to absorb and store heat energy. The denser a material is, the higher the thermal mass. Concrete is dense, therefore it takes a lot of energy to change the temperature. The uncharacteristically cooler exterior temperatures that occurred over the three-month period allowed the concrete walls to remain cool for longer periods of time, which transferred to the interior surfaces; promoting condensation on these surfaces. Think of the interior surfaces of a building’s exterior wall as the outside surface of a beverage removed from the cooler.
Thermal bridging is another phenomenon that can play a big role in determining why condensation and fungal growth occur on and near exterior walls. As a bridge allows us to cross a body of water or large void in the earth, poorly insulating building materials—including wood, metal, and concrete—provide a pathway for heat energy to travel from the outside of the building to the inside. Wall studs, whether metal or wood, concrete walls, and concrete porches/patios in buildings are prime examples of thermal bridges.
Take, for instance, a framed wall assembly: Insulation is typically located between the studs, leaving the studs in direct contact with the interior and exterior surfaces. This provides a pathway for energy to transfer from the outside to the inside. We saw deposition on the interior surfaces of exterior walls (both debris and fungal growth) that coincided with the location of the wall framing, a condition known as ghosting. The cooled surface encouraged condensation and also attracted debris out of the air. This was a strong indicator that thermal bridging had occurred, which supported our conclusion the fungal growth was the result of condensation, and the uncharacteristically cooler temperatures.
We have discussed why the moisture was occurring during this period, now let’s focus on the fungal growth. Simply put, moisture is the limiting factor for fungal growth to occur2. No moisture, no mold. Most fungi have varying moisture requirements known as water activity. Using these requirements, fungi have been classified as primary, secondary and tertiary colonizers3. Primary colonizers have the lowest moisture requirements and are commonly identified in environments experiencing periods of elevated relative humidity. In my experience, if you pulled spore traps or took surface samples in a home experiencing a patina of fungal growth on most surfaces, your laboratory analysis is likely to identify Aspergillus or Penicillium fungal structures. Many species of these fungi are considered primary colonizers, are xerophilic (i.e. dry-loving) in nature and are easily transported making them the principal fungi identified in a high humidity environment.
Why was the fungal growth on the surfaces of contents such as a mirror or metal surfaces? In essence, the porous materials and surfaces of non-porous materials served as reservoirs that collected organic materials such as dust and debris, as well as microorganisms (i.e., spores), two of the three primary elements needed for fungal growth to occur. The accumulation of organic matter provided the food source, add the spores and add the moisture from the water vapor and condensation, and over time the spores in these reservoirs began to germinate, grow and proliferate.
These conditions occurred over time and in many instances were discovered well after the conditions that caused them were no longer present. This created a scenario where a forensic approach was necessary. As experts, our interpretive skills for determining the sources of damage or fungal growth must be keen. Complex causes require a heightened awareness of both building science and the factors limiting fungal growth.
This will provide the knowledge needed to recognize and opine on the cause of the fungal growth. In this case study, it was the result of conditions that were abnormal and the result of multiple, compounding factors. ICM
National Oceanic and Atmospheric Association, Climatic Data Center.
Yang, C. S. and Heinsohn, P. “A Retrospective and Forensic Approach to Assessment of Fungal Growth in the Indoor Environment.”. Ecology of Fungi in the Indoor Environment, Hoboken, N.J.: John Wiley & Sons, Inc., 2007.
Grant, C., Hunter, C.A., Flannigan, B., & Bravery, A.F. “The Moisture Requirements of Moulds Isolated from Domestic Dwellings.” International Biodeterioration 25 (1989) 259-284.
About the Author:
Jeremy D. Beagle is a Certified Microbial Consultant, Certified Moisture Control Consultant, and a Florida Licensed Mold Assessor with 12 progressive years in the consulting industry. His primary responsibilities involve providing forensic cause-and- origin assessments concerning water loss and IAQ concerns, generating remediation protocols, and expert witness testimony. He earned his Bachelor of Science from East Stroudsburg University in Pennsylvania and is currently attending Tulane University where he is completing industrial hygiene coursework.