Minn. Stat. § 326B.197: BOND REQUIRED FOR CERTAIN CONTRACTORS.

(a) A person contracting to do gas, heating, ventilation, cooling, air conditioning, fuel burning, or refrigeration work must give and maintain bond to the state in the amount of $25,000 for all work entered into within the state. The bond must be for the benefit of persons suffering financial loss by reason of the contractor's failure to comply with the requirements of the State Mechanical Code. A bond given to the state must be filed with the commissioner of labor and industry and is in lieu of all other bonds to any political subdivision required for work covered by this section. The bond must be written by a corporate surety licensed to do business in the state.

(b) The commissioner of labor and industry may charge each person giving bond under this section a biennial bond filing fee of $100.