A few weeks ago, we were in Greensboro, NC providing a dual-certification training (BPI Analyst + BPI Heat Pump Professional) to a group of HVAC contractors. We spent the first part of the week covering many core building science principles (heat flow, moisture flow, air flow), while spending the latter half of the week covering performance testing using tools like the “door-fan” (commonly referred to as a blower door), flow plates, ballometers (flow hoods), manometers (pressure testing devices), combustion analyzers (used to measure the contents of combustion appliance flue gasses), refrigerant gauges (used to verify the amount of refrigerant in heat pumps or air conditioners, and various temperature/humidity measuring devices.
By combining the use of all of these testing possibilities at the training house, the contractors learned how to diagnose comfort/efficiency/air quality/safety issues, utilizing the BPI testing protocol:
- By assessing the leakage locations of a house, they can determine the relative connectivity of the house to spaces like garages, attics, and crawlspaces. This helps to identify air quality issues that may be a result of these “bad-air” leaking air into the house from these various locations.
- By assessing the leakage rate of a house, they are able to determine whether or not the ventilation rates required by ASHRAE are being met or not. A big part of a typical retrofit project is to tighten the building. This allows one to decrease uncontrolled air leakage that leads to high energy bills and comfort issues. But, we want to have the proper exchange of air required to support good air quality. We teach them how to assess the building’s “leakage” and how to compare that to ventilation standards.
- Pressures measurements are used to assess a variety of things during the home assessment. One of the main ways this is used is to assess the “balance” of the HVAC system’s airflow throughout the house. This easily identifies rooms with poor airflow and/or circulation issues.
- Flow hoods (ballometers) are used to quantify the amount (cubic feet per minute) of air entering a return grille or exiting a supply register. These tools are used to compare “actual” airflow to airflow required by the Manual-J load calculation. By installing and adjusting balancing dampers, these airflow rates can be adjusted to achieve the correct airflow and increase comfort.
- Flow plates are used to quantify how much air is moving across the heat exchanger of the HVAC air handler. Proper airflow is critical in order to achieve optimum system performance. If there is too little airflow, system performance will suffer.
- Proper charge is also a critical component of an optimized heat pump or air conditioning system. We use refrigerant gauges to measure the pressures and saturation temperatures of the system to determine the superheat and/or subcooling of the system. Studies show that ~90% of systems have an improper charge (too much or too little refrigerant). By correcting refrigerant charge, systems deliver more heating/cooling, run more efficiently, require less maintenance, and provide better dehumidification in the cooling season.
- The combustion analyzer is used to measure the exhaust byproducts of all combustion appliances in the house, including water heaters, boilers, furnaces, fireplaces, ovens, and ranges. We’re concerned about the presence of carbon monoxide in these gasses, as well as the relationship of CO to Oxygen, as this relationship provides us with an understanding of how efficiently the gas is being converted to heat.
The participants were generally excited about their new understanding of a building’s systems, how these systems interact with each other, and how their performance affects the comfort of their clients. Most of the contractors are planning on incorporating this new diagnostic methodology into their existing businesses, while a couple were considering the concept of a separate auditing branch.