I did not see any reference to my question and would appreciate a response as soon as possible, as due to medical situation, have to make a decision soon. We own an OLD house with 13′ ceilings in a large part of the home and 11″ ceilings in the LV/DR and BR. We are oscillating on where to place the ducts….Floor or ceiling. It appears to be counterproductive to me to put the duct work in the ceiling since it will have so far to go. We are looking for the most cost effective, not upfront cost but operating cost, solution. In addition, we are considering DF heat pumps. The house will need 2 or 3 to be zoned correctly. Please let me know about the duct placement and thank you for your help? Continue reading “Duct Work and High Ceilings” »
How many tons of air conditioning and heating do I need per square foot?
Rules of Thumb
It is not uncommon for HVAC estimators or HVAC contractors to use various rudimentary techniques which are generally referred to as rules of thumb. Some will say on the low end you need 1 ton of cooling for every 500 square feet. On the high end you will need 1 ton of cooling for every 700 square feet. These rules of thumb will also generally take into account a basic heat gain calculation for the kitchen and the number of people who will occupy the structure. At best these rules of thumb are educated guesses and may not give you an accurate calculation of what you really need. Unless the contractor used software based on the above mentioned manuals it would be to your advantage to actually do a proper load calculation for the structure based on Manual “J” or Manual “N” whichever is appropriate for your HVAC application.
Air Conditioner and Heating Ductwork
Manual “D” is used for sizing residential ductwork for the appropriate amount of airflow. For each ton of air conditioning you will need 400 cubic feet per minute (CFM) of airflow. It is imperative that this amount of airflow (400 CFM) be provided to the air conditioner evaporator coil of the air conditioning system. If the ductwork is too small it will restrict the amount of airflow crossing the air conditioner evaporator coil and this will likely cause big problems. If the ductwork is too big the system may have a problem generating enough static pressure to maintain designed airflow across the coil. The proper design and construction of the air conditioning and heating duct work is important for the proper functioning of the system. Using the proper techniques, software, and skilled personal will ensure that the HVAC job is accomplished correctly and will provide many years of reliable and efficient comfort to you.
Using good and time tested methods to size air conditioning and heating systems for your home or business is a smart thing to do. Using an HVAC estimator who is going to employ a rule of thumb for something that will be attached to your home and provide you with comfort for 15 to 20 years is not so smart. Use proper HVAC sizing methods and you will be better off and comfortable in the future.
Air Conditioning and Heating Sizing
As the cost of energy rises engineers are looking for ways to improve and increase energy efficiency. Aside from HVAC equipment with higher energy efficiency rates, improving structures for less heat loss and heat gain, and building automation systems giving the equipment precision control for better efficiency of the equipment, there are other ways to increase energy efficiency inside buildings. One of the ways to increase energy efficiency inside buildings is to add energy recovery wheels to the economizer systems. A US Department of Energy study concluded energy recovery wheels can save over 15% of the energy used in commercial HVAC applications.
A good consideration when replacing the air conditioning system is the duct work. Duct work seems to be the most ignored part of an HVAC system but is a very important consideration in this age of new technology and higher energy efficient equipment being developed and manufactured. You can have the most energy efficient engine but if its in an old 60 or 70’s model car your efficiency is going to suffer. The same is true with HVAC systems. You can have the most energy efficient compressor available on the market but if your duct work is leaky or your house or business is not properly insulated that high efficient system you just spent big dollars on is wasted money. For more insight on HVAC ductwork see the High Performance HVAC Ductwork Page. Continue reading “Air Conditioner Ductwork Leaks” »
Labor time (approximate): 1 hour in some cases, several hours in others
It is important for preventive maintenance to be performed on your system to avoid problems. Condensation water leaking near the air handling unit can be avoided with proper air conditioning repair and preventive maintenance. Normally this is a very simple problem that can be fixed in less than 30 minutes. Here is a list of what can cause water around the outside of the air conditioning air handler unit.
- The black insulation (called Rubatex) has a tear in it or doesn’t cover the entire suction line. This line normally (in Air Conditioning air condition mode) operates below the dew point and will sweat if it is not insulated. It must have a sealed vapor barrier to be effective.
- The insulation surrounding the air handler supply transition or ductwork is torn. The supply transition and duct can operate (under the right conditions) below the dew point and sweat. It is important that the transition have a vapor barrier around it. This scenario is especially true for those that have over sized units.
Air Conditioning and Heating Air Handling Units provide air flow throughout the duct systems providing conditioned air throughout the spaces served by the duct work. Air conditioning and heating systems rely on air handlers to move the air throughout the system. The HVAC air handler unit also conditions the air. The air handler heats air for heating and cools air for air conditioning. Continue reading “AHU – HVAC Air Handler Unit Construction Phase” »
Air Handling Unit Components: Air Handling Unit Heat
There are many different types and arrangements of heating systems for air handling units and these types of heating systems and arrangements of heating systems vary from commercial to residential. Some air handling units do not have any heat source inside them at all but have remote heat for zoning. The air handling unit provides the air flow and the remote heaters provide heat for zoning. Sometimes the air handling unit is a VAV air handling unit and other times it is just to provide air for a duct heater whether the duct heater is gas fired or electric. For air handling units which some have heating systems inside the five main ways of providing heat for air handling units are:
I would appreciate from some one in Trane organization that would please tell me why since installment and still 5 years later my house is nothing to a dust pit. I am not exaggerating. You can wipe dust blankets DAILY off my walls, floors, furniture. I have been since installation for someone to help me. My original installer put a filtering system “like used in coal mines” – did not help. I have had independent HVAC inspectors who cannot understand nor have any reasoning for the dust. One thing was that the original TRANE installer did not put sufficient air return duct in my house.
CAN SOMEONE HELP OR AT LEAST GIVE ME AN ADDRESS/TELEPHONE NUMBER WHERE I CAN CONTACT THE MAKER/OWNER OF TRANE?
The magnehelic measures duct pressure inside of ductwork. It is important, for many reasons, to know the pressure inside of ductwork. This magnehelic measures the supply side pressure of the blower inside the air handler. The static pressure in this system is actually controlled by a static pressure transducer which is directly hooked up to a DDC controller that controls a variable frequency drive based on static pressure. The static pressure transducer is a solid state magnehelic and works in much the same way a magnehelic works except the transducer is digital and sends out a signal that registers the pressure it is reading. The magnehelic pictured is simply for visual display and reading the static pressure inside the air handler. It does not send out any signals. Continue reading “Magnehelic Duct Pressure Sensor – Magnehelic Duct Static Pressure” »
This article will take different types of air handlers and disassemble them part by part to give you a good description of each part and hopefully a better understand of the air handler in general. Most of the components associated with the air handler are in the air handler. However, there are a few components which are not in the air handler but associated with the air handler. There are some hot water and cold water coils which are not fixed into the air handler but downstream in the ductwork. There are also some gas and electric duct heaters which are mounted in the ductwork and completely reliant on the air handler for air flow. These systems will also be covered and hopefully this article will offer you a comprehensive look at the air handler, all its parts, and how it functions.