But it turns out that this person finally decided not to rent because of a disagreement over the heating system.
Is the disagreement specifically about the charges or monetary payments over the use of heating? I see that on one side the tenant insisted on minimizing his charges, while on the other side, the owner became angry about this issue.
I would look only at the first hexagram, because
(1) that was raised earlier
(2) Parent line (document) is in void, and cannot produce Self line, so Self (the querent) does not obtain a contract. Moreover, Parent line is afflicted by Day Break. In contrast, Parent line in hexagram #2 is not void and suffers no breakage.
Further note (2): Parent line + Gou Chen indicates a contract or document pertaining land/property/house.
Note that Others line comes with Zhu Que, which represents heat,and the Sixth line means "wall". The other party's issue in mind is the heating.