"Mold grows because condensation is occurring as a result of high humidity and low surface temperatures," said Doug Walter, extension specialist in residential energy at Kansas State University.
Furniture, pictures, cabinets and other objects mounted on exterior walls can act as insulation. This causes the surfaces behind these objects to be cooler than exposed surfaces.
"If the humidity is high enough, the temperature of the walls behind these objects can be below the dew point, resulting in condensation," Walter said.
Mold grows when enough moisture is available to germinate bacteria on these surfaces.
This problem generally occurs only on poorly insulated exterior walls and in conditions of relatively high humidity.
"The immediate solution is to move furniture away from outside walls, remove pictures and open cabinet doors," Walter said. "You should operated your bathroom exhaust fan for about 30 minutes after you shower."
If the relative humidity in your house is very high, with levels above 60 percent, you should operate an exhaust fan continuously until the humidity drops below 50 percent. Eventually you should try to maintain humidity levels in the 30 to 40 percent range.
"The long-term solution to mold buildup is to improve the insulation in your exterior walls," Walter said. "If this is not feasible, humidity control and good air circulation should keep the problem from recurring."
Will setting back the thermostat at night save energy with an air source heat pump?
"If you are using a thermostat designed for air-souce heat pump use, then night settings will provide savings," said Gene Meyer, extension mechanical engineer at Kansas State Unviersity. "These special thermostats limit the use of resistance heat during morning warm-up."
If you use a conventional thermostat, the electric resistance heating elements of the back-up system often comes on.
"Then the cost of recovering from setback may exceed any savings achieved during the night because of the cost of electric resistance heating," Meyer said.
February 11, 1996
What water treatment should be used on cast iron section boilers?
"Cast iron sectional boilers are designed for use in closed steam or hot water systems," said Gene Meyer, extension mechanical engineer at Kansas State University.
A closed system is one in which little or no water makeup is required in the system. Whenever water is introduced into the boiler, minerals are also introduced.
If the boiler is used for hot water, then a corrosion inhibitor should be added. This prevents the build-up of rust in the water.
As long as there are no leaks, this is all that is required.
If the boiler is used in steam service, then the type and amount of water treatment depends on how tight the steam system is. Typically in a closed system, more than 95 percent of the water is returned to the boiler as condensate. Corrosion inhibitors as well as a small amout of sludge forming chemicals are added. The sludge forming chemicals combine with the magnesium and calcium in the water, form sludge, and settle to the bottom of the boiler. Most of this can be removed by "blowing down" the mud legs of the boiler.
If there are lots of leaks and a lot of make-up water is required, additonal chemicals must be added to control scale. This increases blowdown. Finding and fixing leaks is critical because cast iron boilers are not well suited to steam systems that have high make-up.
"Does Kansas have any air quality standards that prohibit or limit wood-burning stoves?
No such restrictions exist in Kansas," said Richard B. Hayter, director of Kansas State University's Engineering Extension, "nor are any being considered by the Kansas Department of Health and Environment or by the federal Environmental Protection Agency at this time."
February 18, 1996
I currently have six inches of insulation in my attic. Should I add more insulation or install a radiant barrier on top of what is already there?
"It is apparent that in Kansas radiant barriers are not a replacement for adequate insulation," said Bruce Snead, extension specialist in residential energy at Kansas State University.
"R-38 attic insulation would be recommended for Kansas homes to adequately address heating load requirements," Snead said. "In residences with adequate attic insulation, a radiant barrier might be cost effective if it was installed by the homeowner and material costs were held to 5 cents per square foot or less.
Is the condensate from a high-efficiency furnace harmful to a septic system?
"It's unlikely a healthy septic system will be affected by the water condensed from the flue gases of a high-efficiency furnace," said Doug Walter, extension specialist in residential energy at Kansas State University.
A 60,000-Btu furnace operating 50 percent of the time will produce about seven gallons of condensate a day. The condensate has a pH level of about four, which is about the same as a carbonated soft drink.
Furnace condensate is not safe to drink, however, because of trace toxic chemicals it contains.
February 25, 1996
Can I cover the openings in the boiler room to prevent the pipes from freezing?
No, you should not cover the openings you refer to.
"Those openings are probably the supply for the combustion air used in the boiler or furnace," said Dennis Matteson, extension specialist in small business energy at Kansas State University.
"Any device that burns fuel must also have an air supply for combustion," Matteson said.
In many homes, this supply is provided by air leakage through doors and windows. Therefore, additional air inlets are not needed.
"In most public buildings, however, the building codes require combustion air inlets to the boiler or furnace room," Matteson said.
The size of these inlets is determined by the size of the combustion device. Restricted inlets can cause incomplete combustion, which results in sooting and production of carbon monoxide.
"Before making any changes, consult with a professional engineer," Matteson said. "There may be another way to keep the pipes from freezing besides reducing the size of the opening."
Which is better for insulating attics, fiber glass or cellulose?
"Both products are excellent insulating materials," said Bruce Snead, extension specialist in residential energy at Kansas State University.
Each can be effectively installed in attics. Cellulose is easier to install in attics, and it is lower in cost.
"It also has a higher R-value per inch thickness, and it is more effective in reducing air leakage," Snead said.
Fiber glass, however, is less subject to settling.
"Fiber glass is much easier to work with in cathedral ceiling construction and in new wall construction," he said.