Experience CAD Operator (HVAC)

As an HVAC (Heating, Ventilation & Air Conditioning) CAD operator, my job was to make sure that all drawings left my office were prepared properly. I designed, edited and proofed plumbing, sanitation, heating, and ventilation systems; utilizing accepted standards, CAD (Computer Aided Drafting) and construction codes. Other duties included (but were not limited to) communicating and troubleshooting with contractors and/or other consultants.

Plumbing and Sanitation

Plumbing System
Plumbing System Schematic

Plumbing and sanitation are usually the first set of drawings a mechanical consultant will complete. The water and sewer connections are made during the first stage of a building and are very important, as they will be under the building and much more difficult to change once concrete goes in. They are sized by the amount of water and discharge a particular building will require, also keeping in mind future uses. Once sized you can determine the required slope needed to make sure your pipes are under the frost line, using the building codes and common sense.

Plumbing CAD Pic
Plumbing CAD Example

You must plan the route your plumbing and sanitation lines take, remembering that you're sharing the space in a building with all the inner workings and must consider the layout with all consultants in mind. You must also be aware of the 3D implications your route can have i.e. ceiling height, and room purposes. Next you must calculate how much cold and hot water will be used. Keeping a detail record at this point helps. I use a hidden layer on the plumbing/sanitation drawing where I put the this information. With this information in hand, the size of the pipes and slope is calculated. Since the smaller the pipe the larger the slope it may be necessary to size your pipes larger to take advantage of the lower slope angle.

Heating/Air Conditioning

How a Heat Pump works
How A Heat Pump Works

Heating/Air Conditioning is a very interesting component in mechanical design, with many ways to implement efficiencies. Depending on the client’s constraints and building style you can choose from many money/environment saving systems. An increasingly popular choice is heat pumps; they operate by taking or giving the heat from one medium to another. For example the Purdy's Wharf building in downtown Halifax uses harbor water to cool the air. This works by pumping the cold harbor water into the building. Here the warm air comes in close contact to the cool water and a heat transfer takes place. The newly cooled air is then pumped into the towers, cooling the occupants.

Heating Duct System
Heating Duct System

You can of course use other methods, like water-to-water transfer, air-to-air transfer, solar etc. The heat or cool has to be distributed through the building; similar to the plumbing/sanitation, the route is very important. If the building uses forced air for heating and cooling the duct sizes and path must be considered carefully, producing a working set of heating/cooling drawings

Ventilation

Venting System with Flow
Venting System with Flow

Ventilation is important in any building. The building code, quite rightly, specifies air change requirements. This means that in any building you should be getting some fresh air. The fresh air is much more pleasant to breath, with pollutants getting out and oxygen getting in to you. It seems simple enough, however there are many things to keep in mind when designing ventilation; you must consider how many people the room is designed for as well as what that room does. Washrooms are a great example. If built to code, a proper bathroom will have a fan, ventilation system or a window to help keep it vented. Our homes are another great example; each bathroom has either a fan or an operable window to achieve proper venting, where other rooms have an undercutting on the doors for venting.

Office Venting System
Office Venting System

When you go into an office, have you ever noticed around air diffuser or a grate in the ceiling? Those are places air can get in and out. You must make sure the air intake and vent are not too close or your fresh air will go strait out the vent. Similarly if you have your heat coming in next to a vent, you will loose most of that heat. Again you must be very mindful of what space you are putting ventilation in. They are bulky and other consultants share the same space as you. A considerate design means all a building systems work well.

Communication

Excellent Communication
Excellent Communication

Communication is a big part of engineering consultation, not just with co-workers on the same project, but also with owners, architects, other consultants and contractors. If you run into issues with space in a design and consult with the architect you may find a resolution though communication. I often picked up the phone for clarification by the architect resulting in design changes to meet mechanical needs. As well communication is important in order to change mechanical drawings to suit architectural changes.

Collaborative Design
Collaborative Design

When working with designs, you need to consider other consultants. Design consultants, for example, may have a water cooler that needs plumbing considerations.

For contractors you must have open communication lines. Some things work on paper, but not in practice. If a problem arises and a contractor’s installation does not work in real life, you need to work together to solve it. One example of good communication with contractors is when approval is needed on equipment. On a drawing the mechanical designer will usually specify a piece of equipment by the specifications required or a list of equipment that can be used. The contractor is often in charge of purchasing the equipment and the mechanical contractor must review the planned equipment purchase from a submittal by said contractor. If the communication lines are open this process will be quick and painless.

Communicating Through Drawing
Communicating Through Drawing

Communication is not just done directly to a contractor or consultant; a big part of communicating is through a design standard. In this case when a mechanical consultant is creating their drawings they need to work to a standard. This is an accepted meaning of what colors or symbols, ect. mean. If you design to a standard the person reading your drawings will understand immediately and not have to interpret your work. Communication in the engineering world is a whole other language.