Logic Masters Deutschland e.V.

This is the fourth puzzle in a loop series that uses thermometer clues. Estimated difficulty is somewhere between 3 and 4 stars. Links to the previous puzzles in the series is given below.
Heated Whisper Loop
Heated Dutch Loop
Heated Entropic Loop

Rules:

Normal Sudoku rules apply: Place the digits 1 to 9 in every row, column, and 3x3 box.

Along thermometers, digits must strictly increase from the bulb to the tip.

Draw a one-cell-wide loop of orthogonally connected cells. The loop may not touch itself, not even diagonally.

-- All thermometer bulbs must be on the loop.

-- The digit in a thermometer bulb gives the total number of loop cells in the 3x3 Sudoku box containing the bulb.

-- The loop acts as a region sum line. The sum of digits along the loop is the same in each 3x3 box the loop enters. If the loop enters a box multiple times, the sum is counted separately for each segment.