Types of HVAC Systems

Found great article on HVAC Systems types and sizing. thought it was worth a repost.


Types of HVAC Systems

Split systems, mini-splits, furnaces and boilers are just a few of the choices for your home.
BY: Steven Castle and Jim Wheeler
Source: HGTV
Link: 
Heating Systems

According to the U.S. Department of Energy, modern conventional heating systems can achieve efficiencies as high as 97 percent, converting nearly all the fuel to useful heat for your home.
Heating units can be categorized into furnaces that provide heated air through ductwork, which is a popular type of heating system in the United States such as boilers that heat water for steam radiators or forced-water systems with baseboard radiators, electric heat and heat pumps. Furnaces generally use natural gas or propane for fuel, while boilers can use gas or oil.
Seek Annual Fuel Utilization Efficiency (AFUE) ratings (efficiency percentage) in the 80s and 90s. The national minimum for furnaces in the United States is 78 percent. Look for Energy Star-certified systems that are more energy-efficient, and consider sealed and combustion units that bring outside air directly into the burner and exhaust directly to the outside. These are the most efficient systems and do not pose a risk of backdrafting combustion gases.
All-electric furnaces have AFUE ratings of 95 percent to 100 percent, but they are not economical is many parts of the country. You can also consider electric heat pumps to heat or cool parts or all of your home. Some heat pumps can be added onto furnaces as well, to help use less gas or propane.
Radiant floors, or hydronic heating systems, often use piping under a floor. Flexible tubes are filled with water or a glycol solution to heat a concrete or other floor. These can be quite efficient and require either a boiler or heat pump. And they can be retrofitted, if carefully installed beneath wooden floor sheathing. Though radiant systems are much more effective if built into a concrete floor, which will retain the heat and release it slowly.

Cooling Systems

Air conditioning systems today come in several different sizes and types, and what you decide to add or upgrade in your home depends on the systems you already have, as well as the climate.

Quick Tip

An air conditioning system’s output is measured in tons, a term derived from the amount of heat needed to melt one ton of ice in 24 hours. One ton of refrigeration can remove 12,000 British thermal units (Btu) of heat in one hour. An average, 2,000-square-foot home requires about 3 tons of cooling.
Today's best air conditioners use 30 percent to 50 percent less energy to produce the same amount of cooling as air conditioners made in the mid-1970s. Even if your air conditioner is only 10 years old, you may save 20 percent to 40 percent of your cooling energy costs by replacing it with a newer, more efficient model.
The most generally known efficiency rating is Seasonal Energy Efficiency Rating (SEER). SEER 13 is the minimum efficiency you should consider, but higher efficiencies are likely to be cost effective. Some central air systems have SEERs of 16. In hot, dry climates you should look at the Energy Efficiency Rating (EER), which denotes how well the system will work at peak conditions. Also look for Energy Star-rated systems for the best energy efficiency.
Air conditioners have three important parts that include a compressor, a condenser, and an evaporator. The compressor and condenser are normally located on the outside part of the air conditioner while the evaporator is located on the inside. Most central air conditioning systems in homes are split systems.
Many today use for ductless mini-split systems, which can be installed by do-it-yourselfers, though it is a moderately difficult project, as interior and exterior units must be installed and both refrigerant and condensation lines must be run between the two elements. These systems can run $1,500 to $2,000 per ton, according to the U.S. Department of Energy.
Some in hot but non-humid climates like the southwest use evaporative coolers, also called swamp coolers, that cool outdoor air by passing it over water-saturated pads, causing the water to evaporate into it. The cooler air is then directed into the home, and pushes warmer air out through open windows.Room air conditioners that fit into windows or can be installed in walls are good options for cooling selected spaces.

Watch Video 


* Proper sizing of a home's heating and cooling systems is a key calculation.* Proper sizing is very important for efficient air conditioning. A bigger unit is not necessarily better because a unit that is too large will not cool an area uniformly. A small unit running for an extended period operates more efficiently and is more effective at dehumidifying than a large unit that cycles on and off too frequently.* Based on size alone, an air conditioner generally needs 20 British thermal units (Btu) for each square foot of living space. Other important factors to consider when selecting an air conditioner are room height, local climate, shading, and window size. Also look for a filter that slides out easily for regular cleaning, logically arranged controls, a digital readout for the thermostat setting, a built-in timer, and an Energy Star-rating for efficiency. Replacing an older unit with an EER rating.


10 Key Features of HVAC Systems

The following is a checklist of the most important features of an HVAC system for a new home. If it saves you even one callback, it's be worth the time to read it and remember its points:

(1)  The design and type of ductwork. If the ducts aren’t sized and balanced properly, the home will never be comfortable. Externally insulated round ducts are the most efficient; long runs of flexible duct are the worst.
(2)  The refrigerant. Federal law requires R-22 to be phased out in 2015; what little that remains available for servicing after that will be very expensive. I recommend systems that use the environmentally friendly R-410A.
(3)  Balance dampers in the ductwork. The worst and noisiest place to adjust the amount of heating and cooling coming into a room is at the diffuser grille. Balance dampers should be installed some distance from the diffusers and be balanced by a qualified technician with the proper tools.
(4)  Location of the indoor unit. Attic-mounted furnaces will eventually leak and cause ceiling damage, unless you take special design precautions, such as a secondary condensate pan and drain line to the exterior. Furnaces mounted in closets at floor level are less prone to cause leaks and water damage, and they are much easier to service.
(5)  Location of the outdoor unit. The worst places to locate outdoor (condensing) units are where they can be seen and heard, such as outside a bedroom window; where they can be easily damaged; or under the edge of an un-guttered roof.
(6)  Efficiency. As of January 2006, the minimum allowable efficiency for new air conditioners will be 13-SEER. (The minimum limit in 2005 is 10-SEER.) Think of it as miles per gallon: the higher the SEER, the lower the utility bill. In fact, some air conditioners (those rated close to 20-SEER) can cost half as much to run as those with the current minimum limits.
(7)  A filter dryer. Installing a filter-dryer in an air-conditioner liquid line (the smaller one) always extends the compressor life by removing damaging moisture and any grit.
(8)  The condenser (outside) coil type. Coils that are made of a single metal (such as aluminum coil and aluminum fins or a copper coil and copper fins) last longer and hold their efficiency better. This becomes especially critical in mildly corrosive environments; specially coated coils should be used where salt spray is encountered.
(9)  Return-air considerations. Remember that in order for conditioned air to enter a room, an equal amount of air must be able to leave the room. Otherwise, there'd be no space for the conditioned air to occupy. The ideal condition here is for each room to have an entering-air diffuser and a return-air diffuser. However, this extra expense can be eliminated if you add transfer grilles or jump ducts sized at 300-400 fpm.
(10) Air-filter location. Air filters should be located where they are easy for the homeowner to reach. Since the filters should be replaced about every three to four months, the homeowner should be able to find the location and replace the filter with minimum effort and searching.


If you need assistance in sizing your HVAC sysytem or need Mechanical Designs for CalGreeen compliance, please call us 209-538-2879.  

Jump Ducts Increase Efficiency


Why Use Jump Ducts?

The standard practice for homes with central returns is to undercut doors to allow for air flow, but undercutting alone doesn't provide enough room for air to move; the best practice is to use transfer grilles or jump ducts, so air can easily reach the central return grille.

California Living and Energy recommends the use of jump ducts on most of our mechanical ACCA Manual D designs, due to their undeniable effect on overall system efficiency.


Jump Ducts Increase Efficiency.

By Dave Wolkowitz

Source: HGTV

Link: Original Article

Jump ducts are an increasingly popular method for improving the energy efficiency of homes with forced-air heating and cooling systems. They address the critical issues of equalizing air pressure in various parts of the home and of handling return air.

When managing the heating and cooling flow within any building, it is challenging to ensure that air moving into rooms equals the air moving out of rooms and back space-conditioning system. If more air enters than exits the room, the air pressure in the room increases and exceeds the pressure outside it. Without balanced air pressure, energy efficiency decreases as conditioned air escapes through the building envelope, through unplanned routes such as leaky windows or around electric outlets.


Houses have traditionally used a very distributed means of handling return air, according to Duncan Prahl, an architect and research manager with architecture and engineering consulting firm IBACOS, which conducts research for the U.S. Department of Energy's "Building America" program.

"Historically contractors would try to take return air from every room," Duncan says. "They would use wall cavities or floor cavities and connect them in a convoluted way to the return air system of a building. Research has found that is a very inefficient way of handling return air. It's leaky, and it draws in outside air because cavities are typically connected to the outside."

Jump ducts are a way to avoid the highly distributed, leak-plagued traditional means of handling return air. Duncan explains that one central return in the main body of the house reduces the cost of HVAC and provides effective air flow. Jump ducts handle return air from rooms that can be isolated by closing doors; the jump ducts move air from the room to the hallway and ultimately to the central return air duct. "Jump ducts are a best practice," he adds.

Keeping it simple
With comparable initial costs, jump ducts are relatively simple and more efficient than the traditional method of using building cavities for return air. A grille on the ceiling of the room is connected through ductwork to a grill in the hallway's ceiling. Air exits the room through the jump duct into the hallway, and then moves through the hallway to the main return duct. The simplicity of the system makes leaks less likely.

But what about noise and light following the same pathway in and out of a room? Duncan recommends the use of insulated flexible duct, which muffles sound. And although a jump duct can be as short as three feet, Duncan recommends a length of six to eight feet to help prevent light pollution, as well as to further dampen noise moving between a room and the hallway. Low-cost stamped-metal grilles are typically used to provide a finished look on the ceiling. Duncan adds that those with a net free area of greater than 80% may increase the ease with which air passes through the jump duct.

Duncan says that while builders should use jump ducts in any new home with a forced-air HVAC system, retrofitting existing homes may not be cost-effective. However, if a home's occupants experience problems related to return air, such as extreme inefficiency, dampness or other comfort problems, jump ducts are worth considering. It is relatively straightforward to gain access to the space above the bedrooms and hall, and a central return can be accommodated in the main space of the house.

Dave Wolkowitz is a Chicago-based freelance writer.

Source: RSS Feed from HGTV.com



Update: Perfect Balance now has a product:

Tamarack Technology's new Perfect Balance door RAP(return air pathway)

To modify doors to provide return airflow and acoustic baffling, as an alternative to undercut doors, which require usually 1.5 inches or more reduce pressure in closed rooms to less than 4 Pascal.



What is ACCA Manual D?

Why are duct design calculations important?
Achieving occupant satisfaction is the principal goal of any HVAC design. For residential air duct designs ACCA’s Manual D is the procedure recognized by the American National Standards Institute (ANSI) and specifically required by residential building codes. Air is the first word in air conditioning. If the network of ducts carrying the air is not properly designed then the health and safety of the occupant are at risk, the equipment could fail more quickly, the energy costs could rise, and occupant comfort might be sacrificed.

For more information, check out the ACCA Manual D checklist.

If you are in need of a reliable and trustworthy firm to design your ductwork for new or existing homes, please contact California Living and Energy for your Modesto ACCA Manual D services. We have been providing high quality engineered duct designs throughout all of California for many years.

Key Item Check Questions to Ask
Information
from load calculation
CFM for each
room
Does each room have a heating and cooling CFM assigned?
(Proportioned air supply based on Manual J8 room-by-room
load calculations)
Manufacturer’s
Data
Manufacturer’s
External Static
Pressure (ESP)
According to the manufacturer’s data will the fan produce the
specified airflow at the specified static pressure? (Manufacturers
produce a graph that relates air flow and static pressure)
Accessory and
device pressure
losses
Did the contractor submit the manufacturer’s data specifying the
pressure drop for any item in the air stream like a high efficiency
filter or a hot water coil?
Manual D Friction
Worksheet
Available Static
Pressure (ASP)
Are supply outlets, return grilles, and balancing dampers listed
at a standard 0.03?
Are the pressure drops listed for other external devices: filters,
coils, etc...?
Total Effective
Length (TEL)
Did the contractor calculate the TEL by adding the longest Supply
Total Effective Length and the longest Return Total Effective
Length? (Total Effective Length = the length of the duct
from outlet back to unit + the effective length for all fittings,
i.e., elbows, reducers, take-offs, etc…)
Friction Rate
design value
Did the contractor use the Friction Rate Chart or calculate Friction
Rate [FR = ASP x 100 / TEL]
Air Distribution
System Design
Branch Lead
Size
Did the contractor size the ducts based on the design CFM, friction
rate, and the duct material used?
Trunk Size Did the contractor select a supply trunk duct large enough to
accommodate all the supply branch leads?
Return Trunk
Duct Velocities
Did the contractor select the return trunk duct large enough to
meet the lower return air velocity requirements?
Return air path
Verify each occupied room has an open air path (ACCA recommends
a ducted return for each bedroom, den,
library, etc…)
Manual T
Register and
Grille Face Velocities
Does the air velocity across the register or grille exceed the
Recommended Velocity Chart? (Grille manufacturers list the
face velocity for grilles and registers at a given CFM, e.g., 12 x
4 - Model XYZ, 500fpm at 120cfm

MEP Design Services

MEP Design Services

Accurate designs are a must in any manufacturing project. But many a time accuracy is compromised by several factors such as unavailability of skilled talent, cost overruns, high investments in software and infrastructural costs. Outsourcing MEP design to a professional third party can give you a powerful tool against your competition by way of faster designs, accessibility to specialized skill sets and improved productivity. It also frees you of the time and money needed for drafting and enables you to focus on growing your business.

California Living and Energy has worked with Mechanical, Electrical and Plumbing engineering companies with their design requirements. We employ the latest in design software with a highly qualified team to produce accurate designs within a fast turnaround time. The features of our MEP drafting services include:

  • ACCA Manual J Load Calculation Services
  • ACCA Manual D HVAC Design Documentation Services
  • ACCA Manual S HVAC Sizing Calculation Services
  • With a wide industry experience, our engineers will conform to your requirements and standards.
  • Expertise in preparing co-ordination drawings with horizontal and vertical dimensions to avoid interference with frames, ceilings, mechanical, electrical, plumbing systems, partitions etc. All co-ordination drawings are checked for collisions.
  • Specific fabrication methods are employed for each drawing.

We serve a wide range of cities, including but not limited to:

  • Sacramento
  • San Ramon
  • Walnut Creek
  • San Jose
  • San Francisco
  • Fresno

California Living and Energy’s technical expertise as well as a decade of experience has helped us build strong customer relationships. Our MEP design team consists of engineers, draftsmen, subject matter experts and quality analysts. Along with a structured process we are able to produce accurate designs, which are perfect to the smallest detail.

Our MEP design services are spread across three specific categories:

·         Mechanical Systems (ACCA Manual J, ACCA Manual D, ACCA Manual S)

·         Electrical Systems

·         Plumbing Systems

To outsource MEP design & MEP drafting services with a reliable and trustworthy company, contact California Living and Energy today at (209) 538-2879. If you need assistance understanding the ACCA Manual J, ACCA Manual D, ACCA Manual S requirements of the new CalGreen Code, please don't hesitate to ask us.

More Articles...

  1. Manual J Checklist

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