37. Replacement of open-vented water storage heater connected to supplementary heat exchanger

Open-vented water storage heater

A building consent is usually not required to replace an open-vented water-storage heater connected to a solid-fuel heater (or other supplementary heat exchanger), if it is carried out by an authorised person.

What the law says

Schedule 1 of the Building Act 2004 states the following:

The replacement of any water-storage heater connected to a solid-fuel heater or other supplementary heat exchanger if the replacement:

(a) is a comparable open-vented water storage heater; and
(b) is fixed in the same position, and uses the same pipework, as the replaced water storage heater.

Guidance on the exemption

This exemption enables an authorised person (refer to the glossary) to replace open-vented water storage heaters associated with existing supplementary heat exchangers (eg wetbacks or solar collection panels). The replacement water storage heater must be comparable and in the same position.

Examples where this exemption could apply

Open-vented water storage heater with solar collection

Replacing an open-vented water storage heater with an open-vented water storage heater (eg electric to electric, gas to gas, electric to gas, or gas to electric) in the same position, using the same pipe work and connected to solar collectors.
Open-vented water storage heater with wetback

Replacing an open-vented water storage heater with another open-vented water storage heater in the same position, using the same pipe work and connected to a solid-fuel heater wetback.
Open-vented water storage heater with heat pump

Replacing an external water storage heater with a heat pump water storage heater (eg replacing an open-vented water storage heater with another open-vented storage heater) in the same position, using the same pipe work and connected to a heat pump.

Examples where building consent is required

Replacing an open-vented water storage heater with a valve-vented water storage heater. As the water-storage heaters are not comparable, a building consent will be required.
Replacing and relocating an open-vented water storage heater and reconnecting it to the existing wood burner with a wetback. As the replaced water storage heater will not be fixed in the same position, a building consent is required.
Replacing an open-vented water storage heater and adding a wetback where there was no wetback before.
Adding a roof-mounted solar collection panel which will be connected to an existing open-vented water storage heater.

This information is published by the Ministry of Business, Innovation and Employment’s Chief Executive. It is a general guide only and, if used, does not relieve any person of the obligation to consider any matter to which the information relates according to the circumstances of the particular case. Expert advice may be required in specific circumstances. Where this information relates to assisting people: