Does the Ensbury LT power flame boiler require shunt pumps and is there a minimum flow rate required? Hamworthy Heating June 11, 2018 10:08 Updated Follow The Ensbury boilers do not require back end protection pumps. There is no minimum flow rate required with these boilers. Related articles What is the seasonal efficiency of the Wessex ModuMax mk3 boiler? Comments 0 comments Please sign in to leave a comment.