Choosing a Dehumidifier 

Moisture in house air can be a problem when there is either too little or too much. Air that is “too dry” can cause discomfort, dried and itchy skin and nasal passages, cracked or rickety furniture, and sparks when you reach for a doorknob or other person.  

Air that is “too damp” can cause itchy skin and nasal passages, ongoing condensation on windows, water damage to materials, mold growth and even rot of wood materials in your house.  

Note that both excessively dry and overly damp conditions can both lead to the same problem of dry and itchy skin and nasal passages. In the first case this is because the air is dry and in the second case it contains mold debris and spores that are toxic.  

You can adjust and control the relative humidity in your house. The following will suggest some ways of avoiding problems caused by air that is too damp and suggests ways to stop moisture.   

What is relative humidity? 

Relative humidity is a percentage. It tells you how much moisture is in the air relative to the maximum amount the air can hold at that temperature. For instance, when air at a given temperature contains all the water vapour it can hold at that temperature, the relative humidity is 100%. If the humidity is higher than 100%, moisture will begin to condense from the air. If the air contains only half the water it can hold at that temperature, the relative humidity is 50%.  

Warm air can hold more moisture than cool air. The relative humidity of a sample of air will change as the temperature changes, even though the actual amount of moisture in the sample air does not. For example, as a sample of air cools, the relative humidity rises.  

What is the “right” moisture level? 

Generally, the “right” moisture level-the relative humidity-in your house is less than 50%. At less than 50% relative humidity, it is unlikely that mold will grow indoors. 

There are cases when 50% relative humidity is too high. For instance, if there is condensation on your windows in cold weather, it’s a good idea to lower your relative humidity to as low as 30%.  

Another instance: if you, or someone in your family, is asthmatic, you should consider keeping the humidity level in the bedroom at 40% or less.  

Dust mites prefer relative humidity of 50% and higher. Dust mites leave debris in bedding, and the debris aggravates asthma. Keeping the relative humidity at 40% or less controls the dust mites and reduces their effect on asthmatics.  

Sometimes, reducing relative humidity won’t solve moisture problems. Defects in insulation or the air barrier in walls and ceilings can cause cold spots in your house. They show up as areas where there is always condensation, even if relative humidity is 50% or less. A dehumidifier won’t solve the problem. You will need help from a qualified builder, renovator, or insulation specialist.  

Where does moisture in air come from? 

Moisture can come into your home from many places. Outside sources include the soil around your house, surface water drainage and damp outdoor air. Breathing and perspiration by you, your family and your pets is a major source of indoor moisture. So are showering, bathing, drying clothes indoor, venting clothes dryers indoors, washing dishes and floors and humidifiers. 

Most houses have more than one source of moisture. Moisture can cause problems once in a while, or all the time. A little prevention can keep excess moisture out of your home’s air and prevent occasional and continual problems. 

Catastrophes-such as plumbing leaks or floods-can cause serious problems very quickly. You will need emergency repairs to deal with them. 

Checking the moisture level in your house 

A “hygrometer” measures relative humidity. A hygrometer is an inexpensive, easy-to-use instrument, sometimes called a humidity sensor or relative humidity indicator. There are mechanical and electronic hygrometers. A mechanical hygrometer usually costs $20 or less. Electronic hygrometers cost $35 to $80. 

Stopping moisture 

Preventing moisture from entering your hose is the best way to solve moisture problems.

If you have surface leaks you can fix them by grading the soil around your house. You can fix underground leaks by repairing basement or crawl space walls and floors.  

Easy preventive measures include shutting down humidifiers, drying clothes outdoors and venting the clothes dryer outside of the house. One of the best ways to reduce moisture is to use a good quality quiet bathroom fan. It vents moisture from showers and baths.  

In hot, muggy weather, ventilate your house as little as possible. Air out your house when there’s a dry spell and no chance of moisture problems. However, you can reduce relative humidity in dry, cold weather by increasing ventilation. A whole-house ventilation system, such as a heat recovery ventilator (HRV) or an exhaust fan coupled with fresh air intakes, will increase ventilation and dry out house air.  

In the summer you can use an air conditioner that removes water from incoming air instead of just cooling it. Look for an air conditioner with a high “latent heat” rating rather than a good “sensible heat” rating.  

In regions where there are months of cool, damp weather or hot, muggy weather, ventilation just adds more moisture to indoor air. A dehumidifier is an effective way of preventing moisture problems.  


(The comments contained on this site are for information purposes only and do not constitute legal advice.)

If you have any questions/suggestion or require more information, please do not hesitate to contact me and I will be happy to assist you.

Vijay Gandhi,
Sales Representative- REALTOR®,
RE/MAX Dynasty Realty Inc. Brokerage*
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