RePower Humboldt: Blue Lake Elementary Heat Pump Study

Contractors installs one of the two heat pump units at Blue Lake Elementary school.

Contractors installs one of the two heat pump units at Blue Lake Elementary school.

In our last update we mentioned that SERC is working with the Redwood Coast Energy Authority to install and test heat pump systems at Blue Lake Elementary School. We hope to determine how well such systems work in our local climate and whether or not they can save money as well as reduce greenhouse gas emissions compared to conventional systems.

Completed installation of the outdoor unit on top of the covered walkway in front of the classroom.

Completed installation of the outdoor unit on top of the covered walkway in front of the classroom.

In July, the project moved out of the planning phase and into hands-on implementation when HVAC contractor Crystal Air of Weaverville installed two Daikin mini-split units at the school. These systems consist of an outdoor compressor unit connected via insulated refrigerant lines to an indoor, wall mounted head (or air handler) which distributes the conditioned air throughout the classroom.

Data loggers with a USB cable for downloading the data to a laptop.

Data loggers with a USB cable for downloading the data to a laptop.

SERC installed a battery of monitoring sensors and data loggers on each of the heat pumps, as well as on the existing natural gas furnaces in two other classrooms. The information collected by the test equipment is being used to determine the amount of heat energy delivered to each of the classrooms as well as the total energy consumed by each of the systems in the process. In the case of the heat pumps, this consists entirely of electricity, while the gas furnaces (as the name implies) rely mostly on natural gas, but also require a moderate amount of electricity for the fan and other electrical components.

Following a shakedown period in which various problems were discovered and rectified, the system is now reliably collecting data around the clock. Preliminary results show that the heat pump systems are consuming less electricity than the conventional furnaces. However, the weather has been so mild up until recently that none of the systems have been used extensively. In addition, the colder it is outside, the more difficult it is for heat pumps to absorb enough energy from the outdoors to heat a room. The true test will come when outdoor temperatures are much lower and heat demand is correspondingly higher.