Air Duct Efficiency

Air ducts lose or gain heat whenever your hvac equipment is running. If the temperature inside your duct is different from the air outside, then a heat loss or gain will occur. This loss or gain is something that needs to be considered when designing ductwork in a home or office. This aspect of heat transmission will depend on some or all of the following factors:

•  Temperature of the air in the duct
• Air velocity in the duct
• Ambient temperature
• Air duct insulation

If the ducts are used to convey heat, excessive heat loss from the air ducts will reduce the efficiency of the heating system. This will result in a total loss of heating effect if the heat loss occurs in the ductwork passing through an unheated area but it can be considerably reduced with proper insulation.  This heat loss can also occur in heated spaces but run the risk of poor air distribution.  These same conditions exist when the ducts carry cool air.  When air passes through spaces subject to the cooling effect of air conditioning insulating the ducts will effectively reduce the amount of heat gain.

Air velocity will also influence the amount of heat gain in the ductwork. High air velocities are recommended when the ducts are carrying cool air because their effect is to reduce the amount of heat gain pickup in the ducts; however they need to be maintained consistent with the acoustic requirements of the installation.

Air Duct Leaks
Air leakage through ducts seams and holes will result in the loss of a portion of the air flowing through the duct and a proportionate reduction in the heating or cooling effectiveness of the system. Depending on the seriousness of the problem, the ductwork can lose up to 1/3 of the air supply in this manner. It is usually a matter of poor workmanship and can be corrected by sealing the seam cracks and holes by calking or soldering.  You can also contact an energy contractor in your area to help you seal your air ducts.

Hot Water Heaters

A water heater is an appliance designed to heat water for such purposes as cooking, washing and bathing. This water is generally referred to as domestic hot water or potable water

The most commonly used water heater is the vertical tank-type stand-alone unit used in residences and small commercial buildings. It is independent of the space heating system and is separately fired water heater. Other water heaters depend on an external heat source such as a boiler. The domestic hot water is heated when it circulates through a heat exchanger inserted in the hot-water or steam heating boiler. These heat exchangers are used only with boilers. In a warm-air heating system, domestic hot water is provided by an independent and separately fired water heater. Most water heaters are installed by a local HVAC company regardless if it is for a residential or commercial water heater.

Types of Water Heaters:

Water heaters can be divided into several groups or classes. The most common classifications are based on the following criteria:

1. Size and intended usage


2. Heating method


3. Heat-controlled method


4. Fuel type


5. Flue location and deisng


6. Recovery rate
   

Water heaters are classified as either residential or commercial water heaters based on their size and intended use. Residential water heaters are those with input rates up to 75,000 Btu per hour. Water heaters regarded as commercial types have input rates in excess of 75,000 Btu per hour. Temperature is another of the criteria used to distinguish between residential and commercial water heaters. For commercial use, hot-water temperatures of 180 degrees or more are generally a requirement from the unit. The hot water used in residences doe not normally nexceed 180 degrees. For residential use, 140 degrees is generally considered adequiate.

Another method of classifying water heaters is by how the heat is applied. Direct-fire water heaters are those in which the water is heated by the directo combustion of the fuel. In indirect water heaters, the service water obtains its heat from steam or hot water and not directly from the combustion process.

Natural gas or propane, oil, coal, electricity, steam or hot water can be used to heat the water in a water heater. Either steam or hot water can be used as the heat-conveying medium in indirect water heaters. Neither, of course is a fuel. The fuels used to heat the residential water supply are gas, oil and coal. Gas is by the far the most popular fuel. Oil is gaining some popularity but it still falls far short of gas. The use of coal as a fuel for heating water is now only found in rare cases. Although electricity is not a fuel, in strict sense of the word, it is generally used along with the three fosil fuels as an additional category for classification.

Quite often, water heaters are also classified on the basis of flue location and design. This is particularly useful creiterion for classifying the various automatic storage type water heaters.

Water heaters can also be classified on the basis of their recovery rate. Quick-recovery water heaters are capable of producing hot water at a more repaid recovery rate than the slow-recovery types. Quick-recovery heaters are often used in commercial structures where there is a constant demand for hot water.

If you need help with your water heater, count on a trust Denver HVAC company. We have helped hundreds of people with their water heaters. We work on both residential and commercial water heaters; repairs and new installations. Contact us today (303) 997-1774 or visit our website: HVAC Denver