The Government's Energy Efficiency and Conservation Authority has capped the number of houses businesses can fit out under the new state-funded home heating and insulation scheme.
Firms who found the Government's tap suddenly turned on in midwinter are now finding limits being imposed on how many houses they can work on.
Under the Warm Up New Zealand Scheme, the Government is aiming to insulate or heat 27,500 homes in the year to July 2010.
A spokeswoman for EECA said this week the Government's energy campaign was being fine-tuned and companies were being offered new deals.
Contracts with a group of selected approved providers - the only ones consumers are allowed to use to get the state subsidy - were being renegotiated.
Interim contracts were signed in July but, from October 1, new contracts will be in force. Some had already been finalised, but she could not say how many houses firms were limited to.
"There's been an allocation on the numbers of houses to ensure national spread. We have a finite amount of funding spread over four years," she said, referring to constraints on the scheme, which has proved far more popular than expected.
