A COP of zero in all cases
You are showing a lack of understanding about COP. It does not go zero. A resistor gives a COP of 1 (out/in) if the calorimeter is perfect.
The engineer said they might have gotten 1.3 sometimes but gave no estimate of the error bars. If the error bars were say 15% then you could expect to see 1.3 levels about 5 % of the time (1 sigma is about 68%"sure", 2 about 94%, 3 sigma about 99.7%)
10 to 20% accuracy on such a large system with multiple pumps and outlets and uncertain pressures and temp would not be unreasonable.