  We investigate heat circulators where a phase coherent region is contacted by
three leads that are either normal- or superconducting. A magnetic field, and
potentially the superconducting phases, allow to control the preferential
direction of the heat flow between the three-different temperature-biased
contacts. The main goal of this study is to analyze the requirements for heat
circulation in non-ideal devices, in particular focusing on sample-to-sample
variations. Quite generally, we find that the circulation performance of the
devices is good as long as only a few transport channels are involved. We
compare the performance of circulators with normalconducting contacts to those
with superconducting contacts and find that the circulation coefficient are
essentially unchanged.
