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Tag Archives: duct work

Duct Work and High Ceilings | HVAC Duct Work Systems


Duct Work and High Ceilings

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?


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Air Conditioning and Heating Sizing | HVAC Technical


Air Conditioning and Heating Sizing – How many tons of air conditioning and heating do I need per square foot?

Air Conditioning and Heating Sizing

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.


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Outside Air Dampers with Energy Recovery | Energy Efficiency


Outside Air Dampers with Energy Recovery

Outside Air Dampers with Energy Recovery

The dampers straight across are outside air dampers or make-up air coming from an energy recovery unit. According to the mechanical code commercial buildings require a certain amount of fresh air from the outside to maintain good IAQ for the occupants. An energy recovery unit allows it to be conditioned before being introduced into the building. Other methods include using enthalpy calculations to open economizer dampers and/or CO2 control of the dampers. The dampers at the bottom of the photo are the return air dampers. The return air will mix with the fresh air or outside air and go through the filters where the air is further conditioned based on what the control is calling for based on conditions inside the building, inside the duct work, and outside ambient air temperature. In HVAC using outside air can also be used for free cooling.


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Air Handler Water Coil Freeze Stat | Freezing Protection Control


Air Handler Water Coil Freeze Stat - Freezing Protection ControlAir Handler Water Coil Freeze Stat

Air Handler Water Coil Freeze Stat – The HVAC Air Handler Freeze Stat is a low temperature limit control and it is used mainly in commercial systems in the duct work on economizers or in air handlers just before any coil especially water coils. It is a safety and protection control to prevent extremely cold air from reaching the hot water or chilled water coils inside the air handler where the air enters from the economizer. Under ideal control set up if the freeze stat trips the economizer dampers close and the blower fan stops. This prevents coils from freezing. A frozen coil can bust open and will need to be replaced if it freezes thus the purpose of the freeze stat in HVAC air handler applications which utilize economizers for free cooling.


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Chilled Water Pipe Vibration Isolators | HVAC Piping


Chilled Water Pipe Vibration IsolatorsChilled Water Pipe Vibration Isolators

Chilled Water Pipe Vibration Isolators – Vibration isolators protect the chilled water piping from receiving vibrations transmitted through the piping when the chillers are running. The vibrations can create problems not only for the chilled water piping but also for the buildings structure. The vibration isolators reduce or eliminate the vibrations that can be transmitted by the chillers. Other equipment normally specified with vibration isolators includes air handlers, pumps, condensing units, generators and most types of equipment with motors. Not only are vibration isolators required in the piping but vibration elimination springs or spring isolators are required are required on chillers, pumps, air handlers, and the other types of equipment named above which can produce vibrations when running. Vibration isolators are usually rated according to the static deflection the vibration isolator provides for the equipment. HVAC piping whether it is for hot water or chilled water usually is also specified with springs in the pipe hangers to avoid further issues that can be caused by vibration. Depending on the location vibration isolators will also be rated for seismic activity with further specifications calling for seismic restraints on the equipment and associated piping.


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TUESDAY, July 07, 2015

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HVAC Tips: Helping You Learn

Air Conditioner & Heat Pump Tips: Additional Helpful Hints:
  • Always change your air filter on a monthly basis
  • Make sure all your supply vents are open and unobstructed
  • Keep area clean around indoor unit especially the return grills
  • Keep outdoor units free of leaves, grass, and debris including trash cans and/or children's toys or playthings like small plastic pools or playhouses.
  • Additionally your service technician will appreciate you not planting holly bushes near the outside unit
  • Lastly have system serviced every six months - once for heating and once for cooling before the season starts

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