Expensive Assumptions: The Deadly Sin of Pride
by GeoFease | April 1, 2025, 7 a.m.
The Setup
In the chilly expanse of a northern climate, a 100-unit seniors’ home relied on a heating and cooling system featuring water-source VRF (Variable Refrigerant Flow) heat pumps with a ground heat exchanger (GHX) and a backup electric boiler. Winters were particularly harsh on their wallets, with electricity bills soaring to frustrating heights.
In November 2024, they installed our Ensure® system. What followed was a cautionary tale that highlights one of the most pervasive sins in the GSHP industry: Pride.
The Problem: Prideful Assumptions
The VRF heat pump units in this system had two modes: ‘glycol’ and ‘water’. During commissioning, the mechanical contractor faced an issue: the VRF units would lock out if the fluid temperature dropped below 41°F (5°C). To sidestep this, they set the electric boiler to kick in when the ground heat exchanger (GHX) outlet temperature was at a balmy 48°F (8°C). This setting was evident in the GHX temperature data seen below, which fluctuated between 45°F and 50°F (7°C–10°C) during the winter months.
Here’s the kicker: the undisturbed ground temperature in this region is 45°F (7°C). In other words, the electric boiler was doing almost all the heating, operating at a COP of 1—turning every kilowatt of electricity into just one kilowatt of heat. Predictably, the electricity bills skyrocketed.
The Fix: A Simple Adjustment
When the Ensure® monitoring system came online, it flagged this inefficiency. Its analysis pointed to a surprisingly simple, yet critical oversight: the VRF heat pumps were still in ‘water’ mode, which automatically shut down if fluid temperatures dipped below 5°C (41°F).
With this insight, the building operator switched the VRF heat pump to ‘glycol’ mode, allowing the system to handle GHX temperatures as low as 27°F (-3°C). They also lowered the electric boiler set point to 30°F (0°C), guided by the Ensure® system’s predictive control capabilities.
The exact time of the control switch can be seen below, with an immediate drop in the GHX temperature—enabling the GHX to take over heating instead of relying on the inefficient electric boiler.
The result? Dramatic efficiency improvements—and no more sky-high bills.
The Lesson
This story isn’t just about a heating system—it’s a lesson in humility. Both the mechanical and controls contractor fell prey to pride, assuming they had all the answers without asking about the heat pump settings during commissioning.
Moreover, a gap in communication between the system’s mechanical engineer and the commissioning team compounded the issue.
The takeaway? Don’t let pride—or poor communication—stand in the way of optimal performance.
Closing Thoughts
This is just one example of how the "Seven Deadly Sins" of system design and implementation can lead to costly consequences. Stay tuned for more stories from the field, where we’ll uncover how sins like pride can sabotage even the best-intentioned projects—and how you can avoid these pitfalls.
Got questions or similar experiences? Let’s talk—your next success story might just start here.