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I have an Ecobee 3 lite and PTAC heating/cooling unit. Heat is supplied from building hot water pipe. There is valve on the hot water supply that is connected via wires to the PTAC unit. AC controls worked fine all summer. Come winter heat is only working sometimes. When the Ecobee triggers the "Aux Stage 1 Heat" heat comes out. When it triggers "Heat/Cool" the compressor i believe comes on and cold air blows out. I've tried just leaving it in "heat mode" and this still happens. I can't figure out why sometimes "Heat/Cool" vs. ""Aux Stage 1 Heat" is triggered. Any ideas?
See https://ibb.co/imz6vw for screen shot of image of graph.