Hi and welcome - how large is your product system, i.e. do you connect to a supply chain for the heat? You could e.g. not have a provider in the line you show, and then create the product system with "only use providers", then you will have no supply chain and thus no impacts from the supply chain. If you get inventory results e.g. for CO2 emissions but no impacts in Climate Change in the LCIA calculation, then "something is wrong" with your method (you are not using a method from us or ecoinvent for ecoinvent, e.g.).
I hope this helps, best wishes, Andreas