The Energy Efficiency and Conservation Authority (EECA), which oversees the grants, has a simple warning: buyer beware. Follow-up inspections by the EECA of newly fitted homes revealed about 10 per cent of work did not meet their standards.
EECA chief executive Mike Underhill said every job needed to be certified by the company which did the work, as well as meeting all installation requirements.
"EECA then randomly audits a percentage of homes to check quality and safety," he said. "By putting this selection and auditing process in place, we can ensure that people get a good and safe job under the New Zealand programme."
EECA spokeswoman Vicki Connor denied installers were hiking their prices. She said providers had to stay within a set dollar-per-square metre range. "We check it back when they claim from us."
A small proportion of people asked EECA to check their quotes to find out whether they were more expensive under the scheme. "Every time we have looked, they have not been comparing the same thing."
Shopping around was still the best way to get the best deal: "People should make sure they are comparing apples with apples and look at not just prices but the quality of the heat pumps and insulation materials as well," said Paul Halford, the authority's residential marketing account manager.
"People should also make sure they know exactly what is included in the price. For example, does the quote include full installation, or not?" he said.
"And if you are getting a quote from a retailer or supplier outside of Warm Up New Zealand Heat Smart, ask them if they offer any quality assurance such as a certificate of compliance from an electrician."
Counting the cost of warmth
Aucklanders Quentin and Tere Parsons want to warm up their weatherboard home with the help of the Government Warm Up NZ subsidy but they're confused by the options.
They've had four quotes ranging from $3742 to $6406 - on top of which the installer would invoice the Energy Efficiency and Conservation Authority (EECA) for thousands in taxpayer subsidies.
They've decided to get their home insulated but they won't get a heat pump installed; even with a subsidy, the price is just too high.
The Avondale couple called in four firms to quote on their three-bedroom bungalow, but the estimates left them confused.
"Some companies told us we could add the cost to our rates. One said they couldn't do that but offered us finance instead," Tere said. "What the best deal is, is anyone's guess. I'm bamboozled."
A 33 per cent subsidy (maximum $1300) is available for retro-fitting insulation. Community Service Card holders get an uncapped subsidy of 60 per cent, as well as a $1200 subsidy on a heat pump. The Parsons are instead opting for basic insulation to see them through winter.