Many people want to know how much their humidity vent-free appliances add to the air. This is a concern because either too much or too little humidity in a living space is a problem. There have been research studies that address this question and offer valuable insight.

To have good air quality, a certain amount of humidity or moisture is necessary. If the humidity is too low, we will not be comfortable or healthy in our homes and workplaces. If the air is too dry, we may be uncomfortable or experience health problems. Symptoms caused by low humidity or dry air include: dry skin, dry noses, dry throats and dry cough. Low humidity poses problems for babies and children, and many parents resort to running humidifiers to compensate for dry air.

Overly dry homes are also more likely to cause damage to wood furniture, hardwood floors, and drywall. If you live in a cold climate, you are more likely to have low humidity in your living space because cold air holds less water that warm air. Also, old homes are typically less energy-efficient and have lower humidity.

On the other hand, too much humidity creates a host of other problems and can be particularly damaging to the home. Too much moister creates a breeding ground for pests such as: cockroaches termites, and other insects. Excess moisture is harmful to walls and can cause stained ceilings and walls, peeling paint and wall paper, rotting wood, etc. Structures that are highly energy-efficient or “tight,” are prone to high humidity because of lack of air circulation or less air exchange. This is why so many homes require a dehumidifier to lower moisture levels. It is important for home owners to run dehumidifiers in humid basements and other moist areas to avoid mold problems. Many people are allergic to mold. Mold and mildew are damaging to the structure of your building.

One study called “The GAMA Relative Humidity Research Study” analysised how much humidity vent-free appliances put into the air. Because different parts of the country (the US) have different relative humidity levels, results differed depending on the location. However, the study determined that vent-free heating appliances did not increase indoor relative humidity enough to, in most cases, cause mold or mildew growth. For example, some areas had an increase of only 4% in indoor humidity, while others had increases that ranged from the teens to the twenties. One region had an increase of 43%. But in all cases, the vent-free heating appliances did not add enough moisture or indoor humidity to promote mildew of mold growth.

The publication by G.K. Whitmyre and M.D. Pandian (2004), “Probabilistic assessment of the potential impacts of vent-free gas products on indoor relative humidity” in Building and Environment, vol. 39: pp. 1179-118, states: “Vent-free heating appliances did not add enough indoor relative humidity to encourage mold growth in most cases. A beneficial and comfortable level of humidity is provided by vent-free gas appliances.”

Vent-free appliances are an excellent source of supplemental heat. These heaters, fireplaces and stoves are easily installed in any home because they do not require a vent to the outside. They are 99% efficient and do not add significant amounts of moisture to the air in most cases.

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