Solving sick-house syndrome

Q: I have made my house more efficient and airtight, but I'm concerned about "sick-house syndrome." The air does seem stale sometimes. What is the most efficient method to bring in fresh outdoor air without driving up my electric bills? - T. S.

A: Your concern about sick-house syndrome is well taken and it can be a year-round problem. The Environmental Protection Agency has listed poor indoor air quality as one of the top five environmental issues. At a minimum, a house should have one complete air change every two to three hours.

A typical older house naturally had about one air change every hour. This was due to leaks, natural stack effect, and combustion air used for gas furnaces and water heaters. With the introduction of more electric heat and heat pumps, the latter air-change component was eliminated.

The problems of inadequate fresh air are many. If heated by gas, an airtight house can have carbon dioxide levels two to six times higher than outdoors. This can make one feel sluggish and sleepy. Other common pollutants come from household cleaners, gases from furniture and carpet, mold spores, cooking, even air fresheners. High indoor humidity levels in the summer increases mold and mildew and the cost of air-conditioning. High humidity forces you to set your thermostat lower to feel comfortable.

Installing a heat recovery ventilator (HRV) is the most efficient method to bring in fresh outdoor air year-round. There are many designs ranging from ducted whole-house models to small portable window-mounted units. The small air-circulation fans use only about 100 watts of electricity — about as much as a light bulb. This is much more efficient and controlled than just opening windows or relying on the wind.

HRVs incorporate one of several designs of heat exchanger cores. In the winter, cold incoming fresh outdoor air picks up heat from warm outgoing stale indoor air. The stale indoor and fresh outdoor air paths are sealed from one another so no pollutants are transferred. HRVs save from 65 to 80 percent (efficiency) of the energy from the outgoing stale air.

In the summer, the air flows through the same heat exchanger, but the heat flows in the opposite direction. The cool outgoing stale air precools the incoming fresh air. If you have allergies, select a model with a prefilter for the incoming air. Most filters are washable and reusable. Raydot offers an optional hospital-quality HEPA filter with a charcoal element.

In hot or humid climates, or to control mold and dust mites for year-round allergy relief, select a HRV with a enthalpy type of heat exchanger. Most enthalpy type units use a rotary honeycomb design, some with a desiccant coating for greater moisture removal. This rotating drum also picks up and transfers moisture along with the heat. Altech and Mitsubishi use an efficient fixed cross-flow heat exchanger made of special moisture permeable materials.

Small window units are the easiest to install. These lightweight units mount in windows just like an air conditioner and can be moved from room to room. Larger through-the-wall models also are easy to install. The fresh air gradually circulates throughout the entire house. These operate very quietly with many internal components attached by rubber mounts.

James Dulley is a mechanical engineer who writes on a wide variety of energy and utility topics. His column appears in a large number of daily newspapers.

Copyright 1996 James Dulley

18 ILLINOIS COUNTRY LIVING JULY 1997

Whole-house models can be ducted into your existing heat pump or furnace ducts. They also have their own duct systems if you have baseboard electric or hot water heat. The indoor stale-air intakes often are located in the bathrooms, kitchen and laundry. The fresh-air outlets are located in the living room, dining room and bedrooms. The entire unit weighs only 70 pounds and is about 31 inches long.

A variable-speed HRV provides the most precise control so you can fine tune it to changing conditions. For example, if you have a party with guests who smoke, you can quickly set it to a higher speed. Most HRVs can also be set for timed operation. In humid areas or for allergy control, choose one with a humidistat control.

All HRVs have separate inlet and exhaust fans. The inlet fan should be set to a slightly higher speed than the outlet fan. This creates a very slight positive air pressure inside the house to block unfiltered outdoor air, dust, pollen, and other pollutants from naturally migrating indoors through cracks. In areas prone to high levels of radon gas, this is a great advantage.

Write for Update Bulletin No. 559 — a buyer's guide of 21 whole-house and window HRVs listing airflow rates, heat exchanger types, efficiencies, warranties, prices and a size selector chart. Please include $2 (checks payable to Jim Dulley) and a business-size SASE, to Jim Dulley, Illinois Country Living, P.O. Box 3787, Springfield, IL 62708. To read 150 previous columns: http://www.dulley.com.

JULY1997 • ILLINOIS COUNTRY LIVING 19

Do you need a generator and double-throw switch?

Meteorologists tell us that there are some 2,000 thunderstorms taking place over the surface of the earth at any given moment, and it seems that we in Illinois get our fair share and then some. And they seem to be most prevalent this time of year.

While thunderstorms are scary, they often bring something even scarier with them—tornadoes. But whether one develops into a tornado or not, a thunderstorm can do a lot of damage. In short, they can flatten a large part of a cooperative's service area in minutes.

Throw in winter blizzards and ice storms, and many Illinoisans might be wise to invest in a standby electric generator. While you can easily cope with a two-hour summer outage with just a flashlight, some candles and maybe some bottled water, a long-term outage might cause serious disruption. Long winter outages can become life-threatening.

We encourage you to think how badly inconvenienced you'd be in the event of a two-day to two-week outage, and plan accordingly. Think about what you absolutely have to have operable, and plan from there. You may need just lights and a refrigerator, but most of us need more. Since everything doesn't need to run all the time, there are some things you can run alternately, reducing the need for generating capacity.

If you're thinking of getting a generator, now's the time to act. In the event of a widespread outage, generators become hard to find and the prices go up dramatically. During major storms in the past, hordes of fast-buck artists have descended on the afflicted area, selling generators out of the back of their trucks at greatly inflated prices. Some occasionally sell direct current generators, which are useless to run motors, unless you add a converter. Don't wait to buy a generator until you absolutely have to have one.

It would be a good idea to decide now, and how much power you will need in the event of a prolonged outage. And be sure to list the things you can run alternately. Take your list to your local electric cooperative and ask for advice. The people there are your friends and neighbors. They'll be glad to help.

You can get a feel for how big a generator you'll need if you know that the average refrigerator uses about 600 watts, and the average freezer uses about 800. But since they have motors, it takes both of them some four to six times the amount of wattage to start them than it takes to actually run them. Naturally, you'll want to start one, let it get running, then start the other. Unless you have a huge generator, you'll need to manage your usage carefully. Light bulbs, of course, use the amount of wattage stamped on them. Generally, lights are going to be the least of your problems. Water heaters use from 1,000 to 5,000 watts, while water pumps use from 800 to 2,500.

You need to be careful with a generator, and put it where gas won't be a problem and where fumes won't endanger you. You need to position it as close as possible to the largest load, because long distance adds up to large conductors or extension cords. Locate it where you can protect it from the weather, and keep your spare fuel and oil in a safe place.

If you're going to run your generator and just plug a few things into the receptacles provided, you'll be okay without any other preparations. If you're going to have it wired into your home's electrical system, you'll need a double-throw switch to protect your co-op's personnel and equipment, as well as your own equipment. Remember that a double-throw switch is as absolute necessity, not something you just add on as an afterthought!

Remember—a generator is not just for emergencies. Portable generators can be used on camping trips, at construction sites, and in many other ways. While they're nice to have in the event of trouble, they are useful in other ways, too.

A portable generator like this one can be a big help during an outage, and can be useful around the home, too. Note the receptacles to plug appliances into. If you connect the unit into your house's wiring, you'll need, a double-throw switch.

20 ILLINOIS COUNTRY LIVING JULY 1997