Sunday, October 25, 2009
Plumbing & HVAC Maintenance : How to Operate a Gas Furnace
When attempting to operate a gas furnace, the first step is to make sure the furnace is getting power, after which the gas supply should be checked through the gas valve. Discover methods of telling whether or not a gas valve is on with help from a plumber and HVAC tech in this free video on gas furnaces.
Looking for more HVAC supply, visit HVAC supply in bidformaterials.com
Thursday, October 22, 2009
HVAC Static Pressure
Air Balancing Tips
Most people don't realize that residential heating and cooling systems are very complex. This is true for both forced air systems as well as hot water or steam heating systems.
There are many calculations that must be made to insure that the proper sized equipment is selected. There are many controls on the equipment which must be properly adjusted to assure a well balanced system. Duct work must be properly designed and sized. It is by far the most technical aspect of residential construction.
Deciding On A Furnace
When you decide to install a forced air furnace or air conditioning system, you need to make various calculations. Each room of your house, depending on its size, location, compass orientation, amount of glass, etc., requires a certain volume of air to enter it to properly maintain the desired temperature. As you can imagine, each room depending upon the variables mentioned above, will probably demand a different volume of air. A larger room will require more air than a smaller room. A corner room may have two outside walls, while an interior room may have no exterior walls. You or your HVAC person must think and quantify all of these things to provide for a comfortable interior climate.
Interior Climate Control
Interior climate control is the primary function of a heating and cooling system. A properly installed system will insure that each room of the house is adequately heated or cooled. An inferior system will result in widely different temperatures from room to room, hot and cold spots, excessive noise, etc. The trick is to make sure that the proper amount of air enters and leaves each room.
The calculations that are made to insure the proper amount of air enters the room tell the HVAC person a very important number. It tells that person how many cubic feet per minute of air each room requires. This in turn tells the HVAC person how powerful of a blower to install with the furnace. Common sense would tell you that if the calculations indicated that the entire house required 1,750 cubic feet per minute and the blower could only produce 1,200 feet per minute, there would be a problem. Let's assume that the HVAC person gets the right sized blower.
Flow of Air
Now, the challenge is to get the proper amount of air into each room at the same time. This is where things begin to get complicated. Here is the problem. The furnace blower fan only creates a certain amount of energy at any given instant. This energy is constant. If one room gets too much air (energy), there won't be enough for the remaining rooms. Remember, different amounts of air (energy) are going to each room.
To achieve the goal of getting the proper amount of air (energy) into each room at the same time is to have equalized static pressure throughout the entire duct system. Static pressure in a HVAC system is the same thing as blood pressure in your body. It's a time tested principle that works. It is not that difficult to achieve in your HVAC system.
The principle is very easy to apply. Remember the initial calculation that indicates the total number of cubic feet per minute of air that your house requires? It is vitally important that you or your HVAC person correctly calculates this number. If you decide to do this calculation, you must obtain heating and air conditioning books which tell you how to do it. It is not that difficult, it just takes time. Your local library probably has the books that you need. Once you have this number, and you have the separate number for each room, you are ready to design your Duct work.
Duct Work Installation
Duct work is like any other piping device. You can only get so much air through a duct at a given pressure. It makes sense. You must not forget this concept. We also know that the furnace blower fan can only produce so much energy. This energy translates to pressure, because it is pushing the air out of the furnace. The pressure at the blower will not be equal to the pressure at the air supply register in each room. This is because the total pressure of the blower becomes divided by the number of air supply registers. However, the pressure at each register must be the same regardless of the size of the room or register.
Here is how it works. Once the air (energy) leaves the furnace blower it begins to travel down the main supply duct. This duct has a certain cross sectional area. An example would be a duct 8" high by 22" wide. Before the blower turns on, this duct as well as all of the other ducts are full of air. The blower is going to have to push this air out of the way in order to get the hot or cold air into the rooms. It takes energy to push things. Remember, the furnace blower only creates a constant amount of energy at any given moment. When the furnace blower turns on, it begins to push all of the air down the ducts. Every time a branch duct turns off the main duct there is less energy to push the remainder of the air. If the main duct does not reduce in size after several branches are taken off, the remaining air (energy) begins pushing extra air that it shouldn't have to push. If this happens, this wasted energy results in lower energy (air) at the remaining supply air registers. The pressure of the air coming out of these registers will be lower than the pressure at the registers closer to the furnace. As you can see, the main air duct must continue to get smaller and smaller as more branches go off to each room. This is exactly how your blood supply system is designed. The arteries close to your heart are much larger than the arteries in your hands or feet.
The downsizing of the main duct depends upon the amount of energy which is left after each branch duct leaves the main duct. Many factors come into play as to when this duct begins its downsizing. However, if for some reason your main duct does not get smaller as branch runs are taken off, ask your HVAC supply person why. I hope they have a good explanation.
Other Air Balancing Tips
There are some other important points you should consider when installing a new furnace or replacing an existing one. Try to locate the furnace in the center of the structure. Did you ever stop to wonder why your heart isn't in your head or your feet? By placing the furnace in the middle of the structure, you minimize the distance to the farthest room. This means less air has to be pushed. Make sure that the HVAC person installs a damper control in each branch duct going to each room. This damper control is very similar to a water faucet. You can limit the amount of air going to each room by adjusting this damper. This extra control will also help you to balance the system. Ask to see the calculations that your HVAC person used to enable him or her to properly balance your system. These calculations will show each room and the amount of air each room needs. The air volume will be expressed in cubic feet per minute (CFM). Ask questions so that you fully understand the calculations. Spend a few minutes at the library or local bookstore. Believe me, you can't know enough about your heating and cooling system.
Most people don't realize that residential heating and cooling systems are very complex. This is true for both forced air systems as well as hot water or steam heating systems.
There are many calculations that must be made to insure that the proper sized equipment is selected. There are many controls on the equipment which must be properly adjusted to assure a well balanced system. Duct work must be properly designed and sized. It is by far the most technical aspect of residential construction.
Deciding On A Furnace
When you decide to install a forced air furnace or air conditioning system, you need to make various calculations. Each room of your house, depending on its size, location, compass orientation, amount of glass, etc., requires a certain volume of air to enter it to properly maintain the desired temperature. As you can imagine, each room depending upon the variables mentioned above, will probably demand a different volume of air. A larger room will require more air than a smaller room. A corner room may have two outside walls, while an interior room may have no exterior walls. You or your HVAC person must think and quantify all of these things to provide for a comfortable interior climate.
Interior Climate Control
Interior climate control is the primary function of a heating and cooling system. A properly installed system will insure that each room of the house is adequately heated or cooled. An inferior system will result in widely different temperatures from room to room, hot and cold spots, excessive noise, etc. The trick is to make sure that the proper amount of air enters and leaves each room.
The calculations that are made to insure the proper amount of air enters the room tell the HVAC person a very important number. It tells that person how many cubic feet per minute of air each room requires. This in turn tells the HVAC person how powerful of a blower to install with the furnace. Common sense would tell you that if the calculations indicated that the entire house required 1,750 cubic feet per minute and the blower could only produce 1,200 feet per minute, there would be a problem. Let's assume that the HVAC person gets the right sized blower.
Flow of Air
Now, the challenge is to get the proper amount of air into each room at the same time. This is where things begin to get complicated. Here is the problem. The furnace blower fan only creates a certain amount of energy at any given instant. This energy is constant. If one room gets too much air (energy), there won't be enough for the remaining rooms. Remember, different amounts of air (energy) are going to each room.
To achieve the goal of getting the proper amount of air (energy) into each room at the same time is to have equalized static pressure throughout the entire duct system. Static pressure in a HVAC system is the same thing as blood pressure in your body. It's a time tested principle that works. It is not that difficult to achieve in your HVAC system.
The principle is very easy to apply. Remember the initial calculation that indicates the total number of cubic feet per minute of air that your house requires? It is vitally important that you or your HVAC person correctly calculates this number. If you decide to do this calculation, you must obtain heating and air conditioning books which tell you how to do it. It is not that difficult, it just takes time. Your local library probably has the books that you need. Once you have this number, and you have the separate number for each room, you are ready to design your Duct work.
Duct Work Installation
Duct work is like any other piping device. You can only get so much air through a duct at a given pressure. It makes sense. You must not forget this concept. We also know that the furnace blower fan can only produce so much energy. This energy translates to pressure, because it is pushing the air out of the furnace. The pressure at the blower will not be equal to the pressure at the air supply register in each room. This is because the total pressure of the blower becomes divided by the number of air supply registers. However, the pressure at each register must be the same regardless of the size of the room or register.
Here is how it works. Once the air (energy) leaves the furnace blower it begins to travel down the main supply duct. This duct has a certain cross sectional area. An example would be a duct 8" high by 22" wide. Before the blower turns on, this duct as well as all of the other ducts are full of air. The blower is going to have to push this air out of the way in order to get the hot or cold air into the rooms. It takes energy to push things. Remember, the furnace blower only creates a constant amount of energy at any given moment. When the furnace blower turns on, it begins to push all of the air down the ducts. Every time a branch duct turns off the main duct there is less energy to push the remainder of the air. If the main duct does not reduce in size after several branches are taken off, the remaining air (energy) begins pushing extra air that it shouldn't have to push. If this happens, this wasted energy results in lower energy (air) at the remaining supply air registers. The pressure of the air coming out of these registers will be lower than the pressure at the registers closer to the furnace. As you can see, the main air duct must continue to get smaller and smaller as more branches go off to each room. This is exactly how your blood supply system is designed. The arteries close to your heart are much larger than the arteries in your hands or feet.
The downsizing of the main duct depends upon the amount of energy which is left after each branch duct leaves the main duct. Many factors come into play as to when this duct begins its downsizing. However, if for some reason your main duct does not get smaller as branch runs are taken off, ask your HVAC supply person why. I hope they have a good explanation.
Other Air Balancing Tips
There are some other important points you should consider when installing a new furnace or replacing an existing one. Try to locate the furnace in the center of the structure. Did you ever stop to wonder why your heart isn't in your head or your feet? By placing the furnace in the middle of the structure, you minimize the distance to the farthest room. This means less air has to be pushed. Make sure that the HVAC person installs a damper control in each branch duct going to each room. This damper control is very similar to a water faucet. You can limit the amount of air going to each room by adjusting this damper. This extra control will also help you to balance the system. Ask to see the calculations that your HVAC person used to enable him or her to properly balance your system. These calculations will show each room and the amount of air each room needs. The air volume will be expressed in cubic feet per minute (CFM). Ask questions so that you fully understand the calculations. Spend a few minutes at the library or local bookstore. Believe me, you can't know enough about your heating and cooling system.
Wednesday, October 21, 2009
HVAC Common Repair Parts
Replaces: 69M08, 69M0801, 97L48, 97L4801,12L96, 12L6901, 24L85, 24L8501.
The Surelight Ignition Board replacement kit wasmade to consolidate the many different versions of the singlestage surelight ignition control board into one universal board. Thiskit replaces most single stage surelight ignition controlboards.
This Kit Includes:
- 1 - Surelight ignition control board
- 1 - Wiring harness (9-pin to 12-pin)
- 1 - Wiring harness (6-pin to 4-pin)
- 1 - Mounting panel
- 4 - Stand-offs
- 1 - Cicuit breaker
- 1 - Wire (Extends low voltage primary if required)
- 2 - Wiring diagrams
The 48K98 is the latest BCC (blower control) circuit board. This circuit board can be used to replace all BCC1, BCC2, and BCC3 circuit boards. Replaces 65K29, 65K2901, LB-90089A ,48K98, 48K9801, 45K48, 45K4801,LB-89859, 78J61, 78J6001, LB-65126A.
BCC21 through BCC32 Blower Control
The BCC is a printed circuit board which controls the blower and monitors primary limit and gas valve operation. The control has a nonadjustable, factory preset on"fan timing. Fan off timings are adjustable. The board is divided into two sections, 120 and 24VAC. Line voltage comes into the board on the120VAC side "CAB" and "XFMR " send 120VAC to the damper motor or combustion motor and transformer, respectively. The active cooling and heating blower speed terminals and three dummy "D" terminals are located on the 120VAC side of the BCC. Also located on the 120VAC side of the control are neutral terminals and a terminal for accessories such as an electronic air cleaner. The "HSI" terminal is not used. 24VAC comes from the transformer into terminal "24V" on the 24VAC side of the BCC. Thermostat connections and safety circuit terminals are also located on the 24VAC side of the control. Fan off timings may be adjusted by changing the position of a jumper across terminal pins. Thermostat terminal strips on early model BCC boards are removable. Late model boards have permanent thermostat strips.
Blower Speed TapsBlower speed tap changes are made on the BCC blower control board at the upper right corner. Unused speed taps must be secured to the dummy "D" terminals on the BCC. The active heating tap is connected to the "H" terminal and the active cooling tap is connected to the "A" terminal. To change a heating speed tap, turn off power, remove existing speed tap from the "H" terminal and place on "D" terminal. Next select new speed wire and place on "H" terminal of the blower control and restore power. Blower speed tap information can be found on the G20 unit wiring diagram.
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