Duct Work and High Ceilings | HVAC Duct Work Systems
Duct Work and High Ceilings – 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?
Air Conditioning and Heating Sizing – 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.
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 wheelsto 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.
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Air Conditioner Condensate Problems – Possible Causes
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.
Air Conditioner Condensate Problems – Condensation Drain Plugged
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.
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Air Conditioning and Heating AHUs 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 AHU also conditions the air. The air handler heats air for heating and cools air for air conditioning.
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:
Trane Air Handler Making Dust | HVAC Troubleshooting
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.
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.
On the left is a pressure sensor to tell a maintenance technician if the HVAC Furnace Filters and the right control is a low static pressure switch to trip the unit if the mixing box drops below the set point pressure the switch is calibrated to. The low static pressure sensor protects the fan and the duct work including dampers from damage if the economizer damper and the return air damper would fail closed or another possible scenario that would cause the unit to pull negative pressure in the mixing box.
Pressure controls typically either protect the unit from a catastrophic failure or are used to control a fan or dampers. Pressure controls are either switches that trip at a calibrated pressure set point or transmitters that can transmit an analog signal back to the controls systems to control other components that control air flow. On this air handling unit there are four pressure sensors. The pressure sensors shown in the photo (Filter Pressure Sensor and Low Static Pressure) and two additional pressure sensors.
HVAC Ductwork delivers the conditioned air to the spaces. The Air Handling Duct channels this conditioned air to spaces where it is needed and then a return duct channels the air back to the air handling unit duct for re-conditioning. The return ductwork has a negative pressure while the supply ductwork has a positive pressure. In commercial systems and tight residential homes it is necessary to add fresh air to this conditioned air so the air remains fresh and healthy for the occupants of the structure. This is required by the mechanical code and often this air comes through ductwork from the outside.
Ductwork systems channel the air to the spaces where it is needed from the air handler. HVAC duct systems also pulls the air from the space and channels it back to the air handler where it needs to be conditioned. In some commercial applications the area above the ceiling is considered the return duct. All the return air is channeled back to the air handler through the plenum where it is conditioned in the air handler. Part of the conditioning process is the air being passed through a filter and then an exchanger like a coil or heat exchanger.
Installing duct smoke detectors or smoke detectors in air handlers are not ideal for protection of life and property in the event of a fire or smoke condition. The NFPA and mechanical codes cover smoke detectors. It is preferred that the occupied and non-occupied areas and spaces have smoke detectors simply because the fans in air handlers or that move air through duct work may not be operational at all times so having smoke detectors in the duct work will not offer the amount of protection that smoke detectors would offer in the spaces or area served whether those areas or spaces are occupied or not. Yes, if the fan is operational it would create a negative at the return and suck the smoke into the duct work where a smoke detector would trip and alarm people there was smoke in the building somewhere but ideally in most circumstances it is better to have smoke detectors in the spaces and areas of the building for better protection.
Most air conditioning and heating systems require some form of duct work to channel or direct the air to places in the dwelling where the conditioned air is needed. There are many types of ductwork available and often times the ductwork can make a big difference in your utility bills. For that reason, it is important that the ductwork is installed correctly by qualified installation technicians. A poor installation job will result in poor performance, bad air flow, leaky ductwork systems, and higher than usual utility bills. Another important factor in the installation process is to make sure the duct work is sized properly. Over sizing systems cost more and does not maintain the desired air flow and undersized ductwork causes the system to strain mechanically and can be noisy. It is important that you have qualified people design and install your system from start to finish so that you get the best and highest performing duct work system money can buy. It is also critical that the air conditioning ductwork system be designed for the air conditioning load.
This photo shows the air handler blower compartment. This is how the air handler is opened when the blower needs service or repair. The evaporator coil is on top of the blower which makes this an up-flow air handling unit. The supply air duct work will be above the AHU. Since this air handler is installed in a closet then the duct work is installed in the ceiling and makes this an ideal installation for AC since cool air falls.
Essential Guides and Manuals for the Advanced Residential HVAC Technician
There are many HVAC technical guides and manuals available to help HVAC technicians hone their skills on the job and become an even better and more knowledgeable HVAC technician. We can all use improvements in everything we do in life whether it is professionally or personally and always remember one can never know everything. If you think you know everything then it is time to quit because in reality no one knows everything and if someone claims to know everything then I run as far from that person as I can and recommend you do the same. Whenever I have someone ask me a question which I cannot answer because I do not know the answer I can confidently tell that person, “Sorry, I don’t know the answer but I know where I can find an answer”. And that is far better than trying not to look bad an guessing and being wrong about the answer that can possible have detrimental effects. That happens to Mr. or Mrs. Know-it-all described above and rarely to people who have my attitude and answer for questions we do not know. Going to a manual to look up the answer is not unprofessional and does not make one look ignorant or stupid. On the contrary, I would rather someone look up the bona fide answer rather than make an educated guess. When we push the button to bring the machine alive I want to have absolute confidence it will work and work properly. In that regard I am making some recommendations for a basic library of manuals and guides that every advanced residential HVAC technician will have in his library. This will include software along with the basic book formats because in modern times an HVAC technician should be computer savvy or working to become computer savvy.
So you are having a new HVAC system installed and you selected a system that is high efficiency and you want to get the most out of it. Have you looked at or has the HVAC contractor looked at the duct work and determined if it is good enough for the high efficiency system. A good HVAC contractor would look at the ductwork to make sure it is adequate and sized properly for the new system. This is often done as the HVAC contractor wants to ensure that the new system is properly matched to the HVAC ductwork lest the system not work as it should. Beyond that the most overlooked part of the ductwork is the ductwork integrity.
Quality HVAC Equipment Installation and Energy Savings
The average homeowner will buy from the lowest bidder and fully trust the HVAC contractor 100% to finish the work. Some homeowners will do their homework while many will not and while most of the HVAC contractors will do the right thing and give the homeowner what they pay for there are absolutely some unscrupulous contractors that will take advantage of the homeowner all without the homeowners knowledge. I have even seen some home improvement contractors who knew absolutely nothing about HVAC try to do HVAC work and they failed miserably. Regardless there is a responsibility upon all parties involved to do the right thing. The homeowner should research all the best opportunities and seek out the best contractor and the best equipment for the money being spent. The HVAC contractor has a responsibility to correctly install the equipment for a competitive price to the customer. The contractor should also offer some sort of guarantee their work for a specified period of time to prove they stand behind their work.