Listed lines company Horizon Energy Distribution says Mainzeal owes its Aquaheat subsidiary $4 million.
Mainzeal, the country's third largest building company, went into receivership on 6 February.
Horizon says its bottom line will be lowered by $500,000 as a consequence of the debt, pushing down its anticipated full year profit to just under $3 million.
The company says it is discussing options to recover as much as possible of the debt, as well as resuming work on 37 stalled projects.
