Condensation on Your Windows?

Transcription

1 Condensation on Your Windows? Many new homeowners have concerns about condensation on their windows, especially when the temperatures begin to drop. Here is some advice as to how to manage this issue. Each home varies in the amount of condensation present because each person/household has their own preference regarding the humidity level in their home. Because of this, there is no single solution as to how to manage condensation, but several factors need to be taken into consideration. Condensation may appear on your windows at different times depending on the humidity (the amount of water vapour in the air) the temperature inside your home and at the surface of the window. Condensation usually appears on windows before any other surface because windows contain the least amount of insulation, are part of your home s exterior wall, and react quickly to temperature changes inside and outside. Some indications of surface condensation are: Frost on door handles and hinges, or door frozen shut Water or ice on windows Damp spots or mildew on walls and ceiling Damp spots or mildew on closet walls Moisture on light fixtures Moisture on water closets Moisture on cold water pipes, walls and doors Fresh air in a home is essential for a number of reasons. Human activity generates a tremendous amount of water vapour through cooking, bathing, and simply breathing, all of which affect your indoor air quality. In many new homes, it s a struggle to keep enough moisture inside the home to maintain an acceptable humidity level for the occupants. Homes built in the last 40 years in Canada are relatively airtight. Before that we generally relied on leaky un-insulated walls to provide fresh air, and they did that very well. Windows do not provide much resistance to heat loss and they are often the coldest component part of your entire home and can be an indicator of humidity issues. Because condensation occurs on inside window surfaces whenever the surface temperature falls below the dew point temperature of the room air, window condensation may signal a need to reduce the humidity level in your home.

2 What Can Affect the Performance of Windows? The following conditions may cause condensation to form on a window at lower humidity levels than given in Table 1 below: Air Circulation - a window may be in an area in which there is poor circulation of warm air. This means that the temperature of the inside glass surface is colder than in other parts of the home and this may cause condensation to form at humidity levels which are practical for the rest of the home. Drapes - the figures in Table 1 (below) are based on natural circulation of warm air on the inside surface of the window. By drawing heavy drapes or venetian blinds over a window or patio door the possibility of condensation can be increased because the flow of warm air is restricted. Varying Humidity Levels - remember that the humidity in some rooms, kitchens and bathrooms in particular, can be higher than in other areas of the home, thus encouraging condensation to form on the windows in these rooms. Orientation - if windows are exposed to prevailing winds, then they will be slightly colder than the other windows in the home and may cause condensation to form at humidity levels which are practical for the rest of the home. Exposure - some windows in the home may be protected by other buildings, trees, etc., which form a windbreak while others are totally exposed to the wind and, therefore, colder. Wind Chill Temperature - this is the method used to relate wind and temperature. Usually traditional temperature readings do not include a wind chill factor. For example, with an indoor temperature of 20ºC and an outside air temperature of -12ºC, Table 1 recommends a relative humidity of 30 percent. However, with an outside air temperature of -12ºC and a 20 kilometer per hour wind, the outdoor wind chill temperature is -26ºC and so the level of relative humidity should be reduced to 20 percent. Outside Air Temperature** -28 ºC (-18ºF) or below Not over 15% -28 ºC (-18ºF) to -23 ºC (-9ºF) Not over 20% -22 ºC (-8ºF) to -17 ºC (-2ºF) Not over 25% -16 ºC (-3ºF) to -12 ºC (10ºF) Not over 30% -11 ºC (-12ºF) to -6 ºC (21ºF) Not over 35% -5 ºC (23ºF) to 4 ºC (39.2ºF) Not over 40% **Outside Temperature Including Wind Chill Table 1 - (Inside Relative humidity of 21o C with Double Glazing) Indoor Relative Humidity It is very difficult to maintain indoor Relative Humidity below 30%, for this reason it is normal for condensation to develop when outside air temperature drops in the cold winter months. Although condensation cannot be eliminated due to the humidity in the air, there are productive ways to manage your humidity levels

3 Controlling Humidity In Your Home Ventilation is the most effective means to remove moisture from your home. By exchanging some of the drier outdoor winter air for warm humid interior air, the moisture level inside the house will be reduced. Try these practical ways to reduce your moisture level.. Open a door or window for short periods to allow moisture to escape. Gas appliances produce moisture from combustion. Cooking adds even more moisture so be sure to run your kitchen fan while cooking. Vent the kitchen fan directly to the outside to achieve the desired effect. (See table 2 for examples of how household activities add moisture to the air) Showers are a high source of moisture. Keep bathroom doors shut and run the exhaust fan to eliminate moisture. Leave bathroom and also bedroom doors open when not in use. Table 2 Moisture from Household Activities Moisture Sources Litres Added to Air (per week) 4 People / occupants Showers (8 per week) Baths (8 per week) 3 Drying Clothes 12 Cooking 9 Gas Stove 9 Refrigerator 9 Washing Dishes 3 Large Plant 3 Laundry 2 Clothes dryers should be vented to the outside. Hanging up wet clothes to dry inside your home can add significant moisture to your home. Humidifying devices - Shut off the furnace humidifier and any other humidifying device in the home. Free air circulation is important. Do not cover hot or cold air registers with furniture or appliances. Room temperature - Keep the temperature of all rooms at a minimum of 10ºC (50ºF), even if unoccupied. Condensation will occur in an unheated room. Snow & wet floors - Wipe up tracked in snow before it melts. Floors wet from mopping can add large amounts of moisture. Run exhaust fans (bathroom and kitchens) while floors are wet. Avoid washing floors on extremely cold days. Drapes and blinds should be left open during the daytime. At night, raise blinds at least 4 up off the frame to allow air to flow against the glass. Certain fabric blinds that are designed to fit snugly from jamb to jamb must be left partially open to ventilate the window cavity. Failure to do this can cause extreme temperatures between the blinds and the glass. Built up of ice - Ensure that the exterior HRV intake is free of debris and ice.

4 Optimizing the Efficiency & Use of Your Furnace & Hrv Systems Mechanical ventilation systems are known as heat exchangers, HVACs (Heating, Ventilation and Air Conditioning) or HRVs (Heat Recovery Ventilators). The point of these systems is to remove moisture and provide fresh air to your home while limiting heat loss. Indoor air quality is important for the following reasons: Prevents moisture issues such as rot and mold Prevents damage to windows from condensation Prevents respiratory illnesses caused by interior contaminants Reduces heating costs by not heating excess water vapour Maintenance The essentials!! It is very important that you properly maintain both your furnace & HRV systems. L & L Cooling and Heating emphasize the importance of keeping a clean furnace filter running at all times, and recommend that the furnace filter be changed every 6 to 8 weeks. This is a 5 minute job and will save you time and money in the long run! The supplier of your furnace should also have contact information displayed on the furnace if you may have any other questions, or emergencies. A full service of the furnace is recommended every 2 years. It is recommended that the 2 foam filters on your HRV unit are removed and cleaned every 3 months with a vacuum then rinsed in lukewarm water with a mild soap solution. This is a 5 minute job and will save you time and money in the long run! The core unit should be removed once a year (after summer) and soaked in warm water with a mild soap for 3 hours. After it has soaked for 3 hours, it should be rinsed off, air dried and reinstalled. Remember, to unplug the unit every time the filters or core are removed. (Consult your operation manual for clearer maintenance specifications. Manuals are usually left by the supplier on the HRV or on the Furnace.) It is also important to ensure that all outside exhaust and intake piping is clear of debris and ice...these simple tasks will ensure your systems are functioning optimally

5 What setting should you be running your HRV at? L & L Cooling and Heating recommends running your HRV intermittently at 20 minutes on/ 40 minutes off (Vent setting at 20 m/h). It should be known also that anytime one of the timer buttons is pushed (bathroom fan or kitchen fan which are on a 10 minute timer) the HRV will jump up to high speed for that period of time pressed on the button. After that it will return to the intermittent cycle. Min cycle - On the Min (minimal) cycle, the unit will exchange air with the outside continuously at a slow speed (this is also the speed for 20m/h, 30m/h and 40m/h). An example of a time to run this setting is when you are entertaining a house full of guests and it feels stuffy. This setting will give continuous air exchange and fresh air. Max cycle** - On max (maximum) cycle, the unit will exchange air with outside on high speed. An example of a time to use this setting would be: if there was a smell of burnt food, prevailing odors, excessive water boiling during cooking (to control the high humidity level). ** It is not recommended to run your HRV on Max for an extended period of time (30m/h +) during extremely cold temperatures because the constant intake of cold air can cause the intake piping to develop condensation and ice (due to the interior room air being significantly warmer than the exterior air which is constantly flowing through the piping into the HRV.) If you happen to see condensation on your HRV piping during very cold temperatures (-15ºC to - 50ºC), reduce the speed and time which it is running at. Smart Mode - (only on some models)- SMART mode uses indoor relative humidity level and minimum and maximum outside temperature values to manage the air exchange with the outside temperature, in order to enhance comfort in the house. (In order for Smart mode to function properly you must set your Venmar to your current climate (this is how you set your time and date as well) by referring to pages 7-8 of the owners guide. Smart mode is good if humidity is an issue. It is the only mode with the Altitude control that takes the outdoor temperature in consideration when trying to maintain the indoor relative humidity level. Checking Relative Humidity in the House You can get a rough idea of the relative humidity within your house by holding the up arrow on your Venmar control panel for 8 seconds.