Ask Energenie

November 1998

Table of Contents

1. I am usually comfortable when I set my thermostat at 68 degrees. However, during recent cold spells, I have had to raise my thermostat setting to remain comfortable. Why is this?
2. I’ve noticed the fluorescent lights in my garage aren’t as bright since the weather got cooler. Is there anything I can do to improve light output in cold weather?
3. Can I insulate the ceiling of my business?
4. I'm building a new house with a basement. Because the basement will be heated, I plan to have the concrete wall framed and insulated. My builder says the insulation needs to extend only to the grade line, plus two feet. Is this correct, or should the insulation go to the floor? Is there any harm in insulating to the floor?
5. What should a homeowner do to a heat pump to make sure it is ready for winter?
6. How often should I check or clean my chimney?
7. I'm planning to replace my electric furnace with a gas furnace. My house was built without a chimney or flue. I've heard there are some furnaces today that don't require a conventional flue. Is this true? If so, how are the flue gases vented to the outside?
8. Now that winter is here, I’ve noticed drafts around our double-hung windows. They are the old style with sash cords. Is there any way to stop air from leaking around the sash pulley?
9. How can I weatherize the double doors on the entrance to my school?

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1. I am usually comfortable when I set my thermostat at 68 degrees. However, during recent cold spells, I have had to raise my thermostat setting to remain comfortable. Why is this?

"Your thermal sensation is a function of the temperature of the air and that of surrounding surfaces, such as walls, ceilings and windows," said Richard Hayter, director of Engineering Extension at Kansas State University.

"Surface temperatures affect your thermal comfort as much as the surrounding air does. This is true under low air velocities, which are typical in winter."

"During mild conditions, air and surface temperatures are about the same and a thermostat setting of 68 degrees is usually comfortable," Hayter said. "However, as the outdoor temperature drops, so does that of a room’s exterior surfaces. This is especially true if walls are uninsulated or if windows have only a single glazing and lack the insulation of drapes and blinds."

As surface temperatures drop, your body loses more heat to the surfaces by radiation. Then you must raise the room air temperature to compensate for the increase heat losses.

"Ceiling and wall insulation not only reduces heat loss from the room, but also keeps surface temperatures closer to the room’s air temperature. This allows you to maintain a lower thermostat setting and still provide comfort," Hayter said.

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2. I’ve noticed the fluorescent lights in my garage aren’t as bright since the weather got cooler. Is there anything I can do to improve light output in cold weather?

"Fluorescent lights are strongly affected by operating temperature," said Gene Meyer, extension mechanical engineer at Kansas State University. "Below about 60 degrees, the output begins to be affected."

There are special low temperature lamps that you can use, but they are often inefficient and expensive, he said.

Another approach is to use enclosed fixtures.

"Enclosed fixtures trap some of the heat from the tubes, thereby raising the temperature of the bulb," Meyer said.

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3. Can I insulate the ceiling of my business?

"Insulation at the ceiling level is one of the simpler and many times the most cost-effective approach to limit the heat gain and loss through the ceiling," said Gene Meyer, extension mechanical engineer at Kansas State University.

In most cases, you can add fiberglass batts or loss-fill insulation directly on top of the existing ceiling. You can also add more insulation on top of existing insulation.

"Avoid insulating over light fixtures," Meyer said. "If the attic contains domestic water lines, fire sprinkler lines or uninsulated heating and cooling ducts, these must be properly treated prior to insulating the ceiling."

Moisture condensation also may be a problem when you add insulation to your business’ ceiling. You should seal all penetrations from the occupied space and install a vapor barrier against the ceiling.

If your attic space has knob-and-tube wiring, you should not cover it with insulation.

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4. I'm building a new house with a basement. Because the basement will be heated, I plan to have the concrete wall framed and insulated. My builder says the insulation needs to extend only to the grade line, plus two feet. Is this correct, or should the insulation go to the floor? Is there any harm in insulating to the floor?

"Insulation should extend all the way to the floor," said Doug Walter, president of Kansas Building Science Institute, Manhattan. "A heated basement will always lose heat through its walls, no matter how deep they are."

Although heat loss to the soil near the bottom of the wall is not great, heat is conducted up the wall to colder soil near the surface. Insulating the entire wall reduces this "bypass" heat loss.

"Also keep in mind that the cost of the additional insulation is relatively small compared to the cost of framing and finishing the wall," Walter said.

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5. What should a homeowner do to a heat pump to make sure it is ready for winter?

"In addition to maintaining the blower, you should clean the outside condenser ," said Gene Meyer, extension mechanical engineer at Kansas State University.

Meyer recommends eight tasks homeowners can do to prepare heat pumps for winter. many modern units have sealed motors that cannot be oiled. If yours does not have oil ports, do not disassemble.

Before starting on those tasks, turn off the power to the unit.

Inside

1) Lubricate the blower motor with a few drops of lightweight oil.

2) Lubricate the blower bearings if not a direct drive.

3) Check any belt for cracks and proper tension.

4) Change the filter.

Outside

5) Inspect the outside coil for signs of oil.

6) Remove grass and other debris.

7) Clean the outside coil with water, or preferably a coil-cleaning solvent.

8) Lubricate the outside fan with a few drops of lightweight oil.

Restore power to the unit and check its operation.

"If you find anything unusual, call a service technician," Meyer said.

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6. How often should I check or clean my chimney?

"Your cleaning schedule will depend on how frequently you use the stove or fireplace, the type of wood you are burning and the efficiency of your unit," said Bruce Snead, extension specialist in residential energy at Kansas State University.

Old, drafty fireplaces used only occasionally may need to be check once a year and cleaned every few years. United used regularly or that have higher efficiencies should be inspected more often and cleaned at least twice a year.

"If a high efficiency wood-burning stove is your primary heat source, you should have the flue inspected and cleaned monthly," Snead said.

Proper wood burning practices will decrease creosote buildup in you chimney, but there is no substitute for regular inspection and maintenance.

"Set up a schedule and stick to it," Snead said. "And have smoke alarms and fire extinguishers properly located in your home."

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7. I'm planning to replace my electric furnace with a gas furnace. My house was built without a chimney or flue. I've heard there are some furnaces today that don't require a conventional flue. Is this true? If so, how are the flue gases vented to the outside?

"Yes, it's true," said Doug Walter, president of Kansas Building Science Institute, Manhattan. "Today most high-efficiency furnaces use a small fan to exhaust flue gases to the outside.

"The fan eliminates the need for a conventional chimney," he said. "The higher efficiency of the furnace reduces the temperature of the flue gases, lowering the surface temperature of the flue pipe."

Furnaces that are 80 to 85 percent efficient typically are vented through a small, stainless steel pipe that can be run horizontally to an outside wall, Walter said. Super high-efficiency furnaces, those over 90 percent, often are vented through two-inch-diameter plastic pipe.

"These types of furnaces are ideal for electric to gas conversions because their higher cost can be offset by not having to install a conventional flue," Walter said.

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8. Now that winter is here, I’ve noticed drafts around our double-hung windows. They are the old style with sash cords. Is there any way to stop air from leaking around the sash pulley?

"You can choose between two methods that will stop air from leaking around your sash pulleys," said Gene Meyer, extension mechanical engineer at Kansas State University.

"The first and easiest method involves the use of pulley seals," Meyer said. Pulley seals are plastic covers that fit over the pulley opening while still allowing the ropes to move. They are temporarily attached with double-sided tape and then secured with screws or tacks.

"The second approach involves permanently removing the sash, rope and pulley and filling the hole where the pulley used to be," Meyer said. "I suggest you use plastic wood to fill the hole. Then install v-form brass weatherstripping to provide enough friction to hold the window open." Even with the brass weatherstripping, there might not be enough friction to hold the window.

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9. How can I weatherize the double doors on the entrance to my school?

Entrances that have a pair of doors that close against each another may allow significant air infiltration. The doors should be properly weather-stripped, particularly if the entrance does not have a vestibule.

"Doors with a common mullion, which is the vertical bar between the double doors against which both doors close, can be weather-stripped much like a standard single door," said Richard B. Hayter director of Engineering Extension at Kansas State University.

Typically, weatherstripping is attached to the door frame, including the header, using such materials as spring bronze, stainless steel, or aluminum; vinyl gasket; or fabric, rubber or plastic sponge. The doorsill usually is sealed by attaching weatherstripping to the door bottom. Again, you can use spring metal materials as well as neoprene or felt strips.

"Also available are mechanical sill closures which are spring-mounted so they snap closed when the door is closed and spring free when the door is opened," Hayter said.

Thresholds also are available which contain a neoprene insert that seals against the door bottom upon closing.

Doors without a common mullion must be treated differently.

"Vertical molding, called an astragal, is attached to the meeting edge of one or both doors," Hayter said.

An overlapping astragal is a vertical rigid molding attached to the meeting edge of one door that overlaps the other door when they are closed.

"Although this type of molding can provide an excellent seal, the doors must close in the proper sequence or they will stand ajar," Hayter said.

Mechanical overlapping astragals are available which are spring-loaded to allow either door to close first.

"An alternative to overlapping astragals is the split astragal," Hayter said.

These devices are similar to the standard weatherstripping. Spring metal, neoprene gasket or other weatherstripping material is attached to the meeting edge of one door and seals against the other.

Hardware is also available which uses a vinyl molding attached to the surface of the door and extends beyond the edge, mating with a similar molding on the adjacent door.

"These moldings may contain a magnetic insert, creating an even tighter seal," Hayter said.

Regardless of the weatherstripping used, you must install it properly. If the seal is not tight, the weatherstripping will not provide adequate protection.

"Most weatherstripping will wear with time and must be replaced," Hayter said. "Routine preventive maintenance should include inspection of the weatherstripping."

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Ask Energenie is produced by the Kansas Energy Extension Service through Kansas State University. This material was prepared with the support of the U.S. Department of Energy (DOE) Grant No. DE-FG47-92-CE60210. However, any opinions, findings, conclusions, or recommendations expressed herein are those of the author(s) and do not necessarily reflect the view of DOE.