As we enter November and the beginning of the winter season Jack Frost is definitely nipping at our noses. Although the weather is mild compared to the subzero temperatures of December, January, and the better part of February, extra layers are being donned and people are seeing their breath most mornings.
Early sunsets and extra blankets mean different maintenance tasks are required of homeowners. While we have already discussed fall maintenance items and winterizing your home, we have yet to discuss caring for everyone’s favorite seasonal appliance: the furnace.
Furnaces aren’t known for being fickle, but there are certain protective measures homeowners should implement to ensure their homes are warm and comfortable this winter.
It is important to be aware of:
- Furnace Filters
- Furnace Humidifer
- Furnace Efficiency
Your furnace filter should be checked monthly to determine if it needs cleaning or changing. Typically located in the air return duct adjacent to the furnace, making sure your furnace filter is in good condition can help improve both comfort and heating costs. You will need to see if you should purchase a cleanable or disposable furnace filter – most homeowners choose to have a disposable filter, for convenience, but both are good choices. Furnace filters generally range from $5 to $30 depending on the type of filter you select.
Helpful tip: Note the size of your filter before heading out to buy a new one.
While ideal humidity for homes can be as low as 5%, people feel the most comfortable in environments with 60% humidity. Unfortunately, houses can have a hard time coping with this in cold weather. Too little humidity makes people feel uncomfortable. Too much can cause condensation, mold, mildew, and rot in homes as the warm moist air hits cool surfaces. Contrary to popular belief, homeowners actually have to lower the humidistat setting as the weather outside gets colder. The colder is it outside, the easier it is for condensation to form on cool surfaces, like windows. Homeowners can reduce condensation and the risk of mold by lowering the interior humidity level. The recommended house humidity levels are:
|Outside Temperature||Recommended House Humidity|
|-20 °F to -10°F (-28 to -23°C)||20%|
|-10 ° F to 0°F (-23°C to -18°C)||25%|
|0°F to +10°F (-18°C to -12°C)||35%|
|10+° F and above (-12°C and above)||40%|
Watching for condensation on your windows is another great way to gauge your house humidity level. Lower the humidity when you see condensation. In addition, room temperature and humidity monitors, available at hardware and building supply stores, can help you manage your humidity.
If your home is new, you may not have a furnace humidifier. Most new homes do not need one because the foundation and wood framing in newer homes take time to dry out, and release moisture into the air as they dry. In addition, new homes are “tight”, which means the air within them hangs around for a while before being replaced by dry exterior air. The air is around long enough to pick up moisture from things like showers, cooking, drying clothes and breathing. By comparison, older houses are drafty. Cold, dry air is creeping in all the time, replacing the warm, moist air that is flushed out.
If there is a small box hanging from the furnace or ductwork beside the furnace with a small electrical wire and a small water supply pipe attached, you have a furnace humidifier. You may also see a humidistat, a dial that looks like a thermostat but is used to control the humidity level, and is often mounted to the basement ductwork.
The two most common types of furnace humidifiers are: drum type humidifiers and trickle (cascade) type humidifiers. A drum type humidifier has a tray of water with a sponge on a barrel or drum rotating through it. The tray is kept full of water with a float switch, which adds water from the plumbing system when the water level drops. When the humidistat is turned up, or the humidity level drops, a small electric motor rotates the sponge drum through the tray, absorbing water. Some of the air moving through the ductwork blows across the sponge, picking up moisture. This moist air moves through the ducts and into the rooms of the home.
A trickle or cascade type humidifier has no tray of water. A small electric valve at the top controls the water supply to the humidifier. When the humidistat calls for water, the valve opens, trickling water down a honeycomb-like metal pad. Air blows across the pad, picking up moisture. Excess water is drained through a hose to a floor drain, laundry tub, or condensate pump.
Maintenance for a drum type humidifier focuses on the tray of sitting water. Ponding water can cause scale build-up and bacterial growth. Every spring, the water supply pipe valve should be turned off, the tray and sponge should be cleaned, and the humidistat should be set to OFF. In the fall, turn on the water valve, and set the humidistat to 35%. We recommend a mid-winter cleaning as well.
To maintain a trickle or cascade type humidifier, turn off the water supply and turn the humidistat to OFF in the spring. Before use in the fall, remove and soak the pad in a de-scaling solution. If it’s damaged or too clogged to clean, the pad can be replaced. Once the pad is back in place, the water supply pipe valve can be turned back on, and the humidistat set to 35%. This unit will not need cleaning again until next year.
There are two efficiency measurements with respect to furnace efficiency: steady state and seasonal. Steady state efficiency refers to how much usable heat is created when a furnace is running as a percent of the energy produced by burning the fuel. For example: conventional gas and oil furnaces have steady state efficiencies of roughly 80%. When the furnace is on, 20% of the heat generated goes up the chimney and outside. The remaining 80% is transferred through the heat exchanger into the house air, which moves through the ductwork to the registers in each room.
Seasonal efficiency addresses the off-cycle losses as well as the steady state losses. It is an overall efficiency measurement. Furnaces aren’t on all the time – not even in the dead of winter. They turn on as the thermostat calls for heat, and turn off when the thermostat is satisfied.
When the furnace isn’t on, the heat from your house escapes up the chimney flue the same way that heat would escape from an unused fireplace if the damper was left open. This is an off-cycle loss. If you add these off-cycle losses to the steady state losses you end up with the seasonal efficiency. Season efficiencies for conventional gas and oil furnaces are typically about 60-65%.
High efficiency furnaces are complex, and as a result they’re often more expensive than conventional furnaces. High efficiency furnaces on average cost about $1,000 - $1,500 more than a conventional furnace. In some areas, conventional furnaces are no longer available. When you buy a furnace, you have to buy high-efficiency. If you spend $1,000 per year heating your house with a conventional furnace, you can save close to $350 with a high efficiency furnace. A high efficiency furnace may pay for itself in 3 years.
If you’re considering a high efficiency furnace for your home, speak with a reliable heating or HVAC contractor to discuss the pros and con of various models and any estimated increase in furnace maintenance costs.
If you have homeownership questions, comment below or Tweet us @carsondunlop and we’ll do our best to help.