Automatic Controls for Electric Furnaces

The automatic controls used in an electric heating system are designed to ensure its safe and efficient operation. This section is primarily concerened with outlining the operating principles of the automatic controls used with an electric furnace. These controls include room thermostat, thermostat heat anticipator and timing sequences. In a central heating system, the wall-mounted room thermostat is the control that governs the normal operation of the furnace. The operating principle is simple. The temperature selector on the thermostat is set for the desired temperature. When the temperature in the room falls below this setting, the thermostat will call for heat and cause the first heating circuit in the furnace to be turned on. There is generally a delay of about 15 seconds before the furnace blower starts. This prevents the blower from circulating cool air in the winter. After about 30 seconds, the second heating circuit is turned on. The other circuits are turned on one by one in timed sequence.

Use a heat pump thermostat or a conventional thermostat containing an electric setting to operate an electric furnace.

When the temperature reaches the required level, the thermostat opens. After a short time, the first heating circuit is shut off. The others are shut off one by one in timed sequence. The blower will continue to operate until the air temperature in the furnace drops below a specified temperature.

A typical room thermostat will have a fan switch, a system switch and a temperature selector. The temperature selector on the thermostat is used to select the desired temperature. The actual operation of the heating system is governed by the position of the fan and system switches.

Most room thermostats contain a heat anticipator. This is a device designed to assist the thermostat in controlling closer to the to the desired temperature range.

When timing sequence are used the current flowing through the first time-delay sequencer must also flow trough the heat anticipator. In order to obtain satisfactory operation, the heat ainticipator setting must be equal to the current draw of the sequencer.

The furnace manufacturer will generally recommend the setting for the heat aniticipator adjustment for each size unit. For example, this setting recommended for a Trane Model EUADH 07 electric furnace is .45. This thermostat adjustment will vary depending upon the type of time-delay sequencer used, the furnace manufacturer, and the size of the furnace. This may be illustrated by the recommended heat-anticipator setting given by Coleman for its furnace models. All Coleman 25-kW, and 20-kW furnace models require a heat ainticipator setting of .60.

After you have adjusted the heat anticipator to the suggested setting, operate the furnace several hours and observe the results. If there is insufficient heat, it may be caused by short furnace cycles. This can be corrected by moving the heat-anticipator pointer to a slightly higher setting. If there is too much heat, the long furnace cycles are overheating the structure. This can be corrected by moving the heating-anticipator pointer to a slightly lower setting. After making these thermostat adjustments, allow the furnace to operate several hours to determine whether further adjustment is required.

Atlanta HVAC Guide: Green Your Home Ideas

Written By: triadmechanical.com
Energy costs and depleted supplies force us to consider alternatives to how we lived 20 and 30 years ago. This transformation of thinking is most prevalent in our homes.  Not only are the habits of our lifestyles under consideration, but the very structure of our homes as well.  From materials to furnishings, houses are being transformed.

Remodel versus New Construction

The amount of open land available for development is less than before, so creativity is being utilized to design more compact developments, concentrating homes into multi-family structures and creating communities with shared spaces.
If you need more square footage for a growing family, staying put by increasing the footprint or adding a second story is viewed as more green than starting fresh on a new plot of ground.  In either case, careful consideration to the materials and heating systems used can have a significant impact on the environment.

Changing Habits and Habitats

From acoutrements to the house design itself, each decision to change an appliance or upgrade the finishes has greener impacts, no matter the choice of color.  Something so simple as converting light bulbs from incandescent to longer-lasting and more efficient compact florescents (the twisty tube ones) is becoming required in many communities and saves serious dollars in utility costs.
Hot water heaters can be combined with the boiler to share the energy.  More energy efficient glass can bring in more solar heat and light and hold it there longer.  Bamboo flooring only takes five years to grow, but can last 60, allowing our supply of trees to replenish.  Getting an energy efficient air conditioner can lower you energy bills during the summer.

Greening Your Home

Transforming the colors on our walls with odorless zero VOC  paints makes the chore fun to do yourself (instead of smelly and causing a headache), satisfying a need to feel accomplished and useful.  Composting left-over food to nourish our vegetable garden contributes to the effort of awareness far more emphatically than just flushing waste out of mind down the garbage disposal.

3 Sounds You Need To Listen For

Written By: Westland Heating & Air Conditioning Westlake, OH 

Our homes in Westlake make weird noises from time to time. This is to be expected. But the furnace in your home might be a different story. If you start to hear certain noises it might be a good idea to call for furnace repair services. At Westland Heating and Air Conditioning, we’ve responded to countless calls for furnace repair service in Westlake. So that our customers can have a better understanding of their furnace, we put together a few of the most common furnace sounds that should cause trouble.

Squealing

If your furnace makes a squealing sound when you start it up, you should probably call for service. This isn’t a life-threatening problem, but it can be annoying. This happens when the blower’s belt or bearings have worn out. This can be easily fixed by a professional Westlake heating technician.

Rattling

If you hear a rattling sound when you turn on your furnace this a very serious problem. While it might be that some screws are loose on one of the covers, it can also indicate a problem with your heat exchanger. The heat exchanger in your furnace has two jobs: first, to heat the air going into your home and second, to exhaust the harmful combustion fumes out of your house. When the heat exchanger cracks, those dangerous combustion fumes, that can include carbon monoxide, are blown into your home. Call your local heating contractor immediately.

Rumbling

If you have a fuel oil furnace and you hear or feel a rumbling when you start it up, this could be another critical problem. The cause of this is unburned oil in the combustion chamber continuing to burn after the unit is turned off. This could also leak carbon monoxide into your Westlake  house.

Roaring

If your furnace erupts with a loud roaring sound, like when you fire up a welding torch, this is a very bad sign. It means that there is an uneven mixture of fuel and air.

Furnace Fixes for the Handy Homeowner

Next time your furnace shuts down, check these five fixes before calling your Denver HVAC company . This trouble shooting guide will help you to repair your furnace yourself. Troubleshooting your furnace problems is worth considering before making a call for furnace repairs. These steps will show you and explain how you can diagnose and fix common furnace problems. Only you know just how handy you are consider your abilities before performing these steps safely and properly.
Proper furnace maintenance is the best way you can prevent common furnace malfunctions from happening. Furnace servicing should be carried out at least once a year. Even if your furnace was was installed professionally there are times when it will cease providing heat. The reason for the furnace failure could be anything from an airlock in the fuel pipe, blocked fuel inlet, or a problem with the controls. The following explains some of the most common issues you can fix on your own.

1. Check for leaky or blocked ducts that diminish airflow
If your furnace is running but there are cold rooms in the house, check to see if the registers are open. Next take a look at the ductwork you can access without trouble. Look for space between sections of the ducts and branching areas. If you find gaps seal the sections with foil tape. Finally check for handles, these are dampers, coming from the ductwork if you find any make sure they are open.

2. Change filters
Old dirtied filters are a common cause of furnace issues. Dust and grim hamper airflow and if the filter is too dirty is clogs and the heat exchanger will overheat and shut off causing your house to remain cold. A dirty filter can lower the efficiency and lifespan of your furnace. When the heater is running but heat is not going into any of the rooms in your house it's time to replace the filter.

Your owner's manual will show where the filter is located and what it will take to remove it. Changing flat filters monthly will help increase efficiency. All filters should be checked monthly. Checking the filter should be done by holding it to a light source. If you can see the light clearly it is time to replace the furnace. Most pleated filters will be OK to use for up to three months however you should change them more frequently if you have pets.

Insulating Materials: Building Construction and Location

Insulating materials are specifically designed to reduce the rate of heat transmission through ordinary construction materials to an acceptable level. A dry material of low density is considered a good insulator; however, in addition to this characteristic, it must also have a conductivity value of less than 0.5.

The conductivity value of a material is a purely arbitrary one determined by the amount of heat that flows in 1 hour through a 1 inch thickness of a material 1 square foot in area with the temperature exactly 1 degree F higher on one side of the material than on the other.

Air spaces, or air spaces bounded by either ordinary building materials or aluminum foil, also provide some insulation, but not to the degree formerly thought possible. Dead air spaces in building walls were once considered capable of preventing heat transmission in a manner similar to the space between the walls of a thermos bottle. Later research proved this to be a somewhat false analogy because the air in such spaces often circulates and transmits heat by convection.

Air circulation can be checked by filling the hollow space with an insulating material that contains a great number of small confined air spaces per unit volume. This stoppage of air circulation is what produces the insulating effect, and not merely the existence of the air space. Under these circumstances, it is obvious that the most practical method of insulation is to fill the area in the walls with a material containing these minute air spaces.

Several manufacturers produce insulating materials in a variety of shapes and forms for insulation in houses and other buildings. Frequently, instructions for the installation of the products will also be provided by the manufacturer. Local building supply outlets and lumber yards will often be very helpful, too, and will usually recommend the best way to install the insulation material.

Construction and Location
A masonry, common in many older homes, is a particularly poor thermal barrier. A typical masonry cavity wall has a thermal resistance equal to approximately 1in of ridged insulation. Exterior opaque masonry walls should have maximum U-value of 0.11, requiring insulation rated at R-7 or greater.

A new building (particularly a residence should be located so that the large windows in the main rooms face south to receive the maximum sunlight during the winter months. If possible, the building should be built in a location that offers some natural protection from the prevailing winter winds. Tight, well-insulated construction should be incorporated in the design of the building from the beginning. Although the initial costs will be somewhat higher, they will be effectively offset by the reduction in heating and cooling costs.

If a new Denver heating and air system is planned for an older structure, the existing insulation should be checked and, if necessary, repaired or replaces before the new system is installed. 

Important Air Duct Maintenance

The air ducts used in HVAC systems require very little maintenance other than periodic cleaning.  Most air ducts accumulate dust and dirt which can be dangerous as mold, fungi and dirt mites can grow in the warm dirty air ducts. Built up dirt can also become a fire hazard as it combustible materials accumulate in the ducts.  Air duct cleaning should be scheduled periodically to prevent these accumulations, especially if you live in a climate where you run heat and air conditioning.

Proper doors should be placed throughout your duct system to allow access for cleaning.  New access doors can be installed by a local HVAC company to allow you to clean your air ducts regularly.

You will want to check your ductwork for cracks, holes or other damaged areas causing leaks.  If you find cracks or holes in the return ducts you can be sure you're spending more on energy bills than necessary. If you try and patch up the cracks or holes yourself, you can almost be sure you will create a pressure imbalance in your system.  If you find cracks or holes, find a heating and air conditioning company that has experience fixing ductwork.

The last thing you want to check is the proper balance of air supply and return in your system.  You want to make sure the amount of air supplied to an area by the air ducts is equal to the amount of air returned to your furnace air handler.  An imbalance can draw allergens, dust mites, mold and other contaminants from your basement or attic into the rooms you are heating or cooling.

Rethinking Your Home Furnace

Posted on November 2, 2012 by Tracy Burleson

Guest Blogger: Valerie Hanneken, Social Media/Communications Specialist, Lennox Industries, Inc.


Advances in technology are not limited to new cell phones, computers and tablets. Innovation has changed the products of the heating and cooling industry as well. In the past, homeowners relied on a furnace to heat their homes as temperatures dropped. The furnaces of today can provide comfort while significantly reducing consumer’s monthly utility bills.


The Dave Lennox Signature Collection SLP98V furnace uses the latest industry-leading technology to improve efficiency and sound pressure levels. Recognized as aMost Efficient ENERY STAR Qualified Product, the SLP98V furnace meets or exceeds the U.S. Environmental Protection Agencyguidelines for energy efficiency, with more than a 98 percent conversion of fuel to energy.


The SLP98V also incorporates Precise ComfortTM technology, which automatically adjusts fan speed, heat and airflow to give the homeowner ultimate temperature control. AirFlexTMtechnology provides unique custom settings that allow the furnace to meet the specific year-round comfort requirements of any home.


When installed with the easy-to-use programmable Lennox icomfort Wi-Fi thermostat, the SLP98V furnace can exchange information with the device through “cloud” connectivity and make adjustments to optimize performance and efficiency. This means, consumers can control their furnace wirelessly from any Smart phone, tablet or computer.


Technology has changed the way heating and cooling equipment operates, and as a leader in the market, the Lennox SLP98V will certainly cause consumers to rethink the home furnace.


The Dave Lennox Signature Collection SLP98V furnace will be on display as part of the American Natural Gas and Propane Industries exhibit at the National Association of Home Builders’International Builders’ Show on January 22 through 24 in Las Vegas, NV. Make sure to stop by to learn about the SLP98V furnace, as well as other leading-edge natural gas and propane appliances.

What Makes an Efficient Furnace so Efficient

By Mike Meincke

With today's rising energy demands, volatile financial & housing markets and a constant potential of increased living costs looming over our shoulders, catching a financial break anywhere we can as a consumer should be of keen interest to everybody. 90%+ Annual Fuel Utilization Efficiency (AFUE) furnaces may easily provide the solution and can easily off set a household bill or two with all of the energy being saved by this furnace in contrast to the conventional 60-80% AFUE furnace that is more than likely currently in your home even as you read this article. 90%+ AFUE furnaces have a 2 heat exchanger design to avoid wasting heat, in the past the product was problematic when it was first developed in the 90's, but has since been improved to near perfection today by most manufacturers to be a very reliable product and if sized properly and installed properly will save an incredible amount of money on the utility bill that you can capitalize on year in and year out.

The two heat exchanger design is the key feature that allows a 90%+ AFUE furnace to operate so efficiently. A primary heat exchanger handles the ignition of the furnace and the natural gas fire (propane, kerosene, heating oil or what ever the furnace burns) of the furnace burners. As the burners are engaged inside of the heat exchanger, the heat exchanger gets hot so that when the furnace blower turns on, forced air travels over the hot heat exchanger to allow for heat transfer to occur, sending warm air through your air ducts and to ultimately heat the air in your home. With a conventional 60-80% AFUE furnace that is all that is present for a heat exchanger, but through brilliant engineering furnace manufacturers realized that flue gases always creates hot moisture that is typically wasted out of the flue pipe and so they decided to capture this free energy by designing a better product. So engineers went to work to produce the two heat exchanger furnace and incorporated a secondary heat exchanger that looks like a coil to capture the hot flue gas moisture to re use this heat in a more efficient appliance, rather than wasting this heat out of the flue pipe.

Remarkably after 70 years of relatively little change in the heating market in terms of how a gas furnace basically operated, a vastly more efficient appliance emerged on the market.