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The Design of Your HVAC System in St. Louis

November 6, 2015

Throughout this blog series we are going to take you through the process of what it takes to design, construct and install a custom HVAC system in St. Louis to provide the highest standards in comfort and efficiency.  We will show you how the tools and strategies used in Energy Star rated, luxury new construction homes, like those built by our friends at R.E.A. Homes, can add benefit to your own heating and cooling project.

Taking you through each phase, we hope to educate so you can better understand what important steps go into making your home as comfortable and efficient as possible, and ultimately how the design of the system affects the health of your home. A heating, ventilation and air conditioning system is worth investing into and as with any investment one must to do some homework to make sure you are getting the most in return.

Phase 1: Design

The most important aspect of a HVAC system begins with thoughtful design. Some may think when hiring a HVAC company that all heating and cooling equipment and ductwork installation is standard and if you hire business A over business B, there would be no difference in the system with the exception of pricing.  Maybe a family just purchased a new construction home and they assume the system installed will work correctly because it is new.  Unfortunately, this is where homeowners are unaware of the many differences between companies and therefore can make a hasty decision when choosing the HVAC system to be installed.

How can some businesses get away with a poorly constructed system? Homeowners assume if it is built to the standards set by the local code, it is a good system. It’s important to keep in mind that local building codes are actually MINIMUM required standards.  The way building codes are written, there is much concern over life safety issues but not a lot of scrutiny to how well a system is designed. It is not until the home owner has comfort or performance issues that they realize the importance. This is why it is so important to not just build to code but to build & design beyond the code. This is why we look to sources like the Energy Star Program when looking at the best installation for comfort and efficiency in every room of the house.

The biggest problem we hear from home owners is that their home is not consistently comfortable. Maybe the second floor is always hotter than the first, or one room is always colder or hotter than the rest of the house. We have home owners coming to us in hopes to fix these issues on a daily basis.  We believe homeowners do deserve to have better.  Whether you paid $100K or $2mil for your home, there is no reason you should have to experience discomfort in your home.

For the new homes and retrofits in existing homes that SmartHouse gets involved in; we always take a more studied and engineered approach to the design. There are plenty of tools for all HVAC companies to use to make your home performance is high quality, however because it is not required most companies do not take the time or effort and that is where problems eventually occur. The systems SmartHouse installs on luxury new construction projects with R.E.A. Homes require a smart engineered system to optimize comfort and efficiency, and many of these principles can be applied to any project.

Let’s break down how we design a home with a smart and efficient system. There are many components necessary to proper design:

  • Manual J Load Calculation –First to consider is the load: (measured in BTU’s). This is a measure of how much heating and cooling is required to condition the air of the home based on how the home is used.

The load is determined by many factors, including the number of occupants, the size of the house, and the direction the house sits, and location of each individual room.  So, your vaulted living room is going to require more output than the small laundry room down the hall. Is there an area of the house that gets a lot of sun? Is there a room that has a lot of windows, or just one? How many people will be living in the house?  Do the homeowners plan to do a lot of entertaining?

  • Manual S System Selection – This step helps to determine the proper equipment needed to satisfy the load of the house in the most energy efficient means.

With so many choices in technology of equipment today such as single or 2 stage equipment, variable speed motor capabilities and system zoning options, this is where you rely on the expertise of your heating and cooling contractor to help choose the proper equipment best suited to match and give you the correct load and performance. Properly chosen equipment will lead to higher efficiency, better air quality, and more even temperatures throughout the home.

  • Manual D Ductwork Design– This is the ductwork design tool for correct sizing and quantity of supply and return ducts needed in order to provide the right amount of air for each room to heat or cool properly in the right amount of time.

Why is the ductwork so important? Simply put, properly designed ductwork is what distributes the right amount of air needed where and when it is needed.  We are sure you are familiar with what this looks like – it is that silver tube or sheet metal box the air flows across your basement ceiling and behind your walls. Typically, there are one or more large plenums running down  the middle of the home and then they have smaller ducts running off the main plenum to each room.  A properly designed system will typically have a plenum that gets smaller as it runs further from the furnace.  Also, there will be varied sizes of duct running off the plenum depending on the need of the room it is serving.  One tell-tale sign of a poorly engineered system is that each run from the plenum will be the same size. In this type of design, the problem lies that there is no thought put into how much air will be distributed, or each area of the home’s individual needs. It’s easy to imagine that your large living room should not receive the same amount of air flow as the small room down the hall and this is where home owners experience rooms that don’t seem to correctly heat or cool.

If the system is not designed with thought then the location of the thermostat in your house can be another contributing factor to inconsistent heating and cooling. Most thermostats are located somewhere close to the center of the home (not near outside walls). The thermostat is essentially your sensor to know if your home needs to be adjusted in temperature.  Since the location of a thermostat int the center core of a house, it does not let it feel what you feel in rooms around the perimeter, the system needs to be smartly designed.  What does this mean? It means that when the thermostat turns a system on, the ductwork system must deliver varied amounts of air to each room (using larger or smaller – or more or fewer ducts) according to their specific need in order for all rooms to reach comfort at the same time when the thermostat shuts off in order to provide an ideal point of comfort.

It’s easy to see when building a new home how these extra steps upfront can make a big difference in the ongoing comfort, and costs of the operation of a new system. There are still opportunities to address these issues when dealing with a retrofit on an existing home. Even though the duct system is already designed and installed, many of these principles can still apply, such as proper system sizing and best equipment options to meet your needs.  The duct system cannot necessarily be fully redesigned without extensive remodeling and opening walls but in most cases it can be substantially improved.  For example, when replacing your existing system it may be the right time to consider addressing potential duct improvements such as adding a return to improve air flow, or additional supply ducts in newly renovated areas of the home.  Maybe a zoning system would help control comfort in areas of the house you use the most, or simply converting to a wireless thermostat in another location of your home will provide better system control.  In many cases, these changes can also be made without replacing your furnace or air conditioner.

Unfortunately, all of this extra work is rarely done by most HVAC companies because it takes more time and may stretch their building science knowledge.  The truth is that most homes can achieve greater comfort and better energy efficiency.  Whether building a new home, doing an extensive remodel or even just a simple replacement of your existing system, make sure to choose a company who will take the extra time needed to ensure your new system is designed for your individual needs.   It will take extra work upfront but in the end, you will be glad you did!

In the next issue of this series we will discuss the importance of how ductwork the ductwork is fabricated and installed is essential to your home’s HVAC working efficiently.

Contact Smarthouse today if you want to learn more on how you can choose the right HVAC system in St. Louis for you!

 
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