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Heating and Cooling

Attic Vents and Winter Heating

Will additional attic vents cut winter heating bills?

Attic ventilation will not necessarily decrease heating bills. But additional venting still may be a good idea. Attic ventilation helps keep the attic free of moisture that leaks in with warm air from the living area of older homes in the winter. It will reduce the likelihood of ice dams by keeping the roof deck cooler and it will keep the attic and the house cooler in the summer.

Cold Hot Water Radiators

The radiators in some of our rooms don’t get very warm what could be the problem?

In a hot water heating system water flows through pipes from a boiler to radiators in various rooms. The water fills the radiator and then flows out the other end and back to the boiler to be reheated. However, air gets into the pipes and then into the radiators where it builds up. The air keeps water from filling the radiator and so the radiator does not heat up very well. Most radiators have a bleeder valve on the outlet end of the radiator. The valve is usually square and set inside of a small opening on the end of the radiator. There should be a bleeder key some place in the home, perhaps hanging by the boiler. If you don’t have one you should be able to purchase one from a hardware store or heating supply contractor. Fit the key on the valve and turn counter clockwise until you hear the hissing of air escaping. Have a pan or can handy to collect the water that will eventually follow the air. When water starts flowing close the valve immediately. For most systems it is a good idea to bleed your radiators each fall.

Corn as Fuel

Is shelled corn an economical fuel?

Assume about 60 million BTUs will be needed to heat the house for the year. This is usable heat, which takes into account that fuel-burning systems don’t convert all the fuel you put into them into usable heat. Part of it goes up the chimney in the form of steam.

Corn at $90 a ton burned in a 50-percent efficient system will cost about $15 per million BTUs. LP gas at 84 cents a gallon in a 90-percent efficient system will cost about $9.25 per million BTUs. Electricity at seven and a quarter cents per Kilowatt hour in a 100-percent efficient system will cost about $21.30 per million BTUs.

Given these figures and my assumption about your annual heating needs, corn would cost about $900 per year, compared with $555 for LP gas and $1,278 for electricity.

Energy Efficient Furnaces

Are furnaces with ECM blowers worth the extra costs?

The independent evaluators working with the Wisconsin Focus on Energy program have estimated that furnaces using what is referred to as electrically commutated motors or as ECM furnaces could save a typical home owner about 1,020 kWh of electricity and about 20 therms of gas per year. At $.08 per kWh and $.80 per therm, this amounts to about $97.60 per year. If the blower is left on all the time this will increase savings. Savings will also increase if the blower is used in the summer with a central air conditioning system. The additional cost for this new generation of furnaces is estimated to be about $500 over that of an older high efficiency furnace. That means that it would pay for itself in about 5 years. Looked at another way, you would be earning just under 20% a year on your investment 

Will a new furnace cut your heating bills?

A high efficiency model is defined as one that has an Annual Fuel Utilization Efficiency or AFUE of at least 90. AFUE is a measure of the amount of the fuel that a furnace uses that is turned into useful heat. If you have a furnace with the combustion products going up a chimney instead of out of side of the house through a white plastic pipe chances are you have a furnace with an AFUE of 65% or lower. That means that 35 % of the fuel you pay for literally goes up in smoke. In 90% AFUE models only 10% is wasted. If you have a heating bill of $1,000 with your current furnace, assuming it has an AFUE of 65% and you purchased a 90% AFUE model your bill could drop to about $722 assuming natural gas prices were at 80 cents a therm. Since gas price are expected to rise your savings would likely be higher.

Frost Blocked Furnace Exhaust

Why is frost blocking my furnace exhaust?

This can happen in very cold weather if the exhaust pipe for the furnace discharges too close to the inlet pipe. The exhaust contains large amounts of moisture that will freeze quickly. Your heating technician should be able to add elbows to the end of both pipes or otherwise separate the exhaust and intake openings to prevent this.

Furnace Filters

Do furnace filters need to be changed every month?

Conventional furnace filters keep dust from accumulating in your furnace and contribute to keeping dust levels down in your home. Dirty filters make the furnace work harder so it is a good idea to check your filter every month. If it is dirty, change it. You may find that this is less often than once a month. Traditional fiberglass filters are cheap but not very effective. Their main purpose is to protect the furnace. If your household has health problems related to dust and pollen you may want to investigate other types of filters. However, the choice of filter will effect how often you need to change filters. Some of the newer filters may clog more quickly and more completely so changing them or cleaning them before they are clogged becomes much more important to the effective operation of the filter and the heating system.

Missing Mortar on Chimney

What needs to be done if mortar is missing from a chimney?

If only mortar is missing, that usually doesn’t require rebuilding the chimney. Tuck pointing, replacing the missing mortar, is typically all that is needed. However, if you have a chimney that only vents a hot water heater, you need to be sure that the flue inside the chimney is the correct size. It is possible that your flue is too big. If this is the case, combustion gases going up the chimney may be condensing while still in the chimney. This could be causing serious deterioration inside the chimney. Check with your heating contractor to make sure the flue is of the proper size. If not, have the contractor install a properly sized new liner. If the chimney is used for wood burning appliances you should check the inside of the chimney carefully to be sure that it is not damaged.

Oil vs. LP Furnace

How can fuel costs for an oil furnace be compared with an LP furnace?

You need to convert both fuels to their heat equivalent in British thermal units or BTUs. A gallon of heating oil equals 140,000 BTUs and a gallon of LP equals 92,000 BTUs. The other thing you have to consider is the efficiency of your current oil furnace and your replacement options. Most old furnaces only turn about 60% of the fuel they burn into usable heat. The rest goes up the chimney. New oil furnaces are typically about 85% efficient while new LP furnaces are typically over 90% efficient. Your dealer can give you the efficiencies, called AFUEs, for the furnaces your are considering.

If you used 1,000 gallons of fuel oil last year with your old furnace with an efficiency of 60% you would have needed only 600 gallons if your furnace had been 100% efficient. A new LP furnace at 92% efficiency would have required 652 gallons of LP. A new 85% efficient oil furnace would have required 706 gallons of fuel oil to provide the same amount of heat. Multiply the amount of fuel you would use by the local cost of fuel to compare annual costs. Information on the heat value of various types of fuel is available in Extension Bulletin A 1844 “How to Figure Heat Loss and Fuel Cost.”

Radiant Heating

What are the advantages and disadvantages of radiant heating?

Radiant heating systems use air, electricity or, most often water to heat surfaces, which then radiate heat into the adjacent room. Most of the systems are designed to heat floors. Radiant heat warms objects including people rather than warming the air. Comfort is a frequently mentioned advantage. You can have warm floors in the midst of winter. You also avoid cool drafts that are common with forced air or baseboard radiator units. There are a number of potential energy savings. There is likely to be less wasted heat as warm air leaks out through cracks and other openings. Radiant systems are often zoned room by room so that heat can be saved by only heating rooms where needed. Because of the low temperature hot water needed, radiant heating works well with solar energy systems allowing additional energy savings. Other advantages include quieter operation. There are no noisy furnace blowers or clanking and gurgling radiators. Without radiators or registers there is much more flexibility in furniture placement. Indoor air quality may be improved, since there is less dust flowing around and dust particles are not heated to the point that they can produce possibly toxic gases.

On the other hand, a radiant heating system may be twice as expensive as a conventional heating system according to an article in the January 2002 edition of “Environmental Building News.” Most radiant heating systems have a long lag time before the floor is warm; similarly, it takes a long time to cool. This means the control system must be much more sophisticated and other heat sources such as extended use of an oven or solar gains can cause over heating. At this point radiant heating systems provide heat only. Separate systems are required to provide cooling, air cleaning and ventilation. A forced air system can do all four. Radiant systems can provide cooling but this is not recommended in climates with high summer humidity since condensation and mold can occur.

Reducing Air Conditioning Costs

How can I reduce the cost of running my central air conditioning system?

Start by minimizing the amount of work the air conditioner has to do. This means close storm windows and lower drapes and blinds. It also means keeping your blower filter clean to maximize air flow. Also keep the thermostat set as high as you can tolerate. Consider setting it higher during the day if you are gone. The air conditioner can make your home more comfortable when humidity levels are high by reducing the humidity level as well as reducing the temperature. Also minimize the amount of humidity you generate in the house. Operate exhaust fans after showers. Be sure the clothes dryer vents outside and even better dry clothes outside. Finally you can increase your ability to tolerate higher temperatures by using ceiling fans or other fans to circulate air.

Room Air Conditioner Performance

My room air conditioner doesn’t seem to be cooling my room, what can I do?

Check the fan and temperature setting. You will get more comfort over a larger area with higher fan speed. Use the directional fins to avoid uncomfortable breezes. Clean the filter and evaporator. When these are dirty, it decreases air flow and reduces temperature transfer. The use and care manual for the unit should have cleaning instructions. Use an extension cord rated for the current flow the unit requires or, better yet, have an electrician install an outlet next to the air conditioner. If you are using a long extension cord, the unit may not be getting the voltage it needs. You should also check the seal around the unit to be sure warm air isn’t leaking in around the air conditioner. Make sure the unit is an appropriate size to cool the room. A unit that provides cool air up close but leaves the rest of the area warm may be too small for the space you are trying to cool. Consider shutting doors to reduce the area to be cooled. If the unit shuts off frequently and the room feels cold and clammy, then your unit may be too large. The unit is cooling without dehumidifying adequately, meaning you should cool a larger area or buy a smaller air conditioner.

Space Heater

Is an electric space heater a good idea for supplementary heat?

Portable space heaters are fairly expensive to operate. At an electric rate of 7.2 cents per kilowatt hour, it would cost about 11 cents an hour to operate a 1,500-watt heater. Most funaces produce heat more efficiently if you are trying to heat a whole house. However, if you want to warm your living room for a few hours in the evening, a portable heater will provide heat where you need it quickly. There are some safety issues to keep in mind, however. A 1,500-watt heater uses most of the capacity of a typical 15-amp electrical circuit. If the circuit has numerous lights or other applicances on it, the heater may overload the circuit. Also, avoid using extension cords with space heaters. Most are not designed to carry the electrical load required by a space heater. Finally, do not leave a space heater on while you are sleeping. Curtains, clothing or other flammable materials may come into contact with hot surfaces, which could start a fire.

If you plan to use a space heater extensively, you might consider having a permanent one installed by an electrician.

An alternative to space heaters might be covering windows with plastic film. This may have as much effect on comfort as a portable heater. Kits are available that can be removed easily in spring without damaging woodwork. Window coverings can stop drafts and reduce heat lost through window glass.

 Stains on Chimney

What causes brown stains on the outside of our chimney where it passes through an unheated attic?

This is most likely when a medium efficiency furnace vents through the chimney or a furnace is removed and only a hot water heater vents through the chimney. The exhaust temperature of these appliances is not hot enough to carry the moisture in the exhaust up and out of the chimney. Instead it condenses in the chimney. When it condenses against the chimney walls it can carry creosote from previous wood burning through the chimney to cause the stains. The solution is to install a flue liner in the chimney properly sized for the water heater. In addition to stopping the staining and possible damage to the chimney it will reduce the danger of back drafting of combustion products into the house.

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