Technology Tuesdays: Residential Measures, a Personal Experience with Heat Pump HVAC
In recent months, the industry (SJVCEO included) has talked extensively about heat pump technology. We have dedicated many social media posts, blog entries, Fund-it Fast Chats, and other promotional products to making people aware of its existence and how it may be applied to bolster efficient electrification. Heat pump technology applies to both space and water heating and is a huge step in our transition from fossil fuels to renewable energy.
I would like to take this opportunity to pivot away from theoretical discussions about heat pump technology and share my experience owning one.
Background
A few months ago, the rooftop package unit on my home gave out. Unbeknownst to me, it was undersized for the square footage of my house and died a slow and labored death. As a family, we knew something had to be done quickly before the San Joaquin Valley cooling season began. For those unfamiliar with San Joaquin Valley weather, winter is generally tolerable without a furnace. However, the summer months pose a health and safety risk if one cannot access air conditioning.
After receiving quotes from nearly every reputable contractor in the area, we decided who we wanted to work with and the equipment we would purchase. Our choice? An all-electric, Bosch heat pump system. The Bosch unit was not the least expensive of the available options by any means, however we wanted to feel confident that we would not have to revisit this type of home repair for a long while. Due to the efficiency with which the unit operates and being sized adequately for the job, there would be less wear and tear on its components over time. Therefore, we expect to get the full useful life of the unit and then some, if we are lucky.
Heat Pump vs. Traditional Package Unit
A traditional package unit typically has a single speed. Some newer and more efficient traditional models have two speeds; however, those are not as common. This means, for a traditional unit, each time it turns on, it is going full speed. Think about driving a car. If you floor the accelerator everywhere you go, your car will not last very long. You would cause extreme wear and tear on your brakes, transmission, and tires, just to name a few. Additionally, traditional package units are designed to “chase” the desired temperature, meaning there will likely be more frequent and sizable temperature swings. This translates to your unit having to work harder overall.
The Bosch package unit operates much differently than a traditional package unit. One of the most notable differences is that it is variable speed. This means each time it turns on, the motor is running at the most efficient speed required to achieve the set point. Think back to my car example, you do not need to drive at full speed in a parking lot, when coasting at 5-10 miles per hour will do the trick. This is how the Bosch package unit “maintains” the desired temperature range rather than “chasing” it.
Operation and Project Scope
Taking this information into consideration, the most efficient way to operate a variable-speed heat pump package unit is to “set it and forget it.” No, really! Once our unit was installed, I set the thermostat to “Auto Heat/Cool” mode, and haven’t touched it since! If our home becomes cooler than the desired preset temperature, the furnace will turn on. If the temperature rises above the desired preset temperature, the air conditioner will turn on.
As part of the project, we also replaced the air distribution system and added an attic fan. This will increase the efficiency of the newly installed unit. The attic fan will keep the temperature and humidity inside the attic at a desirable level. Also, the new ductwork is well insulated, so it will ensure the air stays cooler while it travels to its destination as well as minimize leakage.
I have to say that it is only May, which means we have not reached peak cooling season. The hottest temperatures generally arrive in August. However, my home has remained very comfortable with little to no management. We installed solar panels a year ago and chose this technology to take advantage of the electricity we are now generating. However, we have not detected any significant increase in our energy usage. Of course, we will make a full assessment of the meter impacts once the new unit has been operating for a full calendar year.
Final Thoughts
There are significant differences in the experience between the new Bosch unit compared to our old traditional package unit. Most notably is how quietly the Bosch unit operates. I set a notification on my phone so that I would have an idea of when it turns on, because I simply cannot hear it. I would only notice it has come on if I were standing near a vent and happened to feel a wonderful gust of cool air on a warm afternoon. My old unit was very loud and seemed to announce to the entire household that it had come on. Another noticeable item is the size of the unit. The Bosch unit is much larger than the old unit. It is larger because it is a different size from the old unit. However, if the two units were the same tonnage, there would still be a size difference. This is due to the heat pump technology requiring more surface area to do its job.
This was a significant purchase for our family, and the decision was not made lightly. We did extensive research before making the final decision. The experience has been such that we feel it was worth the price. This is not meant to be an endorsement of Bosch. Many manufacturers make heat pump HVAC products. We will follow up on this after our first complete cycle of seasons with the Bosch unit.
