Eric I was thinking about the pipe insulation and suggest an experiment to see if it makes a difference, or what difference it makes? Initially, I suggested a before and after test of recording the temps coming in and exiting. However thought of another way. Suppose you boost the thermo 3 degrees and time the length the boiler runs to complete the demand. Measure your temps 5 minutes into the cycle. Then insulate the pipes let the thermo settle to near where you had previously started. Boost it again 3 degrees, record the time to meet the demand and 5 minutes in record the exiting temp of the water, same as before. It would be interesting to see the results. From the data conclusions could be arrived at.