Q: During winter when we heat or summer when we air-condition, the indoor air becomes stale. How can we get fresh air into the house without losing a lot of heat or letting in hot, sticky, humid air?
A: The unpleasantness of stale indoor air might be the least of the problems. It’s not uncommon for indoor air in an energy-efficient house to be more polluted and unhealthy than outdoor air. Household cleaners and synthetic materials emit unhealthy chemicals, many which have never been tested for safety.
Although it sounds inefficient, opening a couple of windows on opposite sides of the house for a few minutes during winter doesn’t lose much energy. House-building materials don’t lose heat that quickly. During summer, this isn’t as effective, because it allows humid air to come in along with allergens: pollen and mold spores.
If you choose to try this low-cost fresh-air technique in summer, run a room-size dehumidifier in the room where the outdoor air comes in. The specific room might change based on wind direction. The dehumidifier pulls more moisture out of the moisture-laden air. The air conditioner will circulate the fresh air throughout the house.
The most effective method for year-round fresh indoor air is an automatic heat-recovery ventilation system. It can save more than 70 percent of the energy. Incoming cold, fresh outdoor air captures heat from the outgoing warm, stale air during winter. During summer, incoming hot, fresh outdoor air is precooled by the outgoing air-conditioned stale air.
Two blowers running in opposite directions are ducted from indoors to outdoors. The air flows through a heat exchanger, where heat from the warmer air is transferred to the cooler air without mixing. Stale air is drawn from bathrooms or the kitchen, and fresh air is ducted to a living room or hall.
This system works well in many climates; however, in very dry or humid climates, the fresh indoor air becomes uncomfortably dry or humid. Even though the HRV system has an effective air filter, extremely dry or humid indoor air can exacerbate allergies and skin problems.
In these areas an energy recovery ventilation system is better. An ERV is similar to an HRV, except the heat exchanger also transfers moisture. This is effective year-round, but it’s most effective during summer because outgoing cool stale air dehumidifies the incoming fresh humid air.
The most commonly used automatic control method is a humidity sensor. Stale indoor air tends to be more humid. This sensor determines how long and how fast the blowers run. There is a manual sensor override to run it for extra fresh air.
The following companies offer HRVs and ERVs:
Q: Our sliding glass door is getting more difficult to open. I found a small metal cylinder in the track. Did this cause the problem and how can I fix it?
A: The small metal piece probably was a roller from the gliding assembly. It is important to fix it so that your door is aligned properly for an airtight, efficient fit.
Although most home center stores have sliding door replacement parts, in most cases it is best to have it professionally repaired and adjusted. The door panel is heavy and difficult to handle.
Send inquiries to James Dulley, Lexington Herald-Leader, 6906 Royalgreen Drive, Cincinnati, Ohio 45244 or go to Dulley.com.