Our Hot Water Cylinder Installation Process
Explained start to finish so you know what to expect before you accept a quote.
Step 1 — Work Out Which Cylinder Type You Need
There are six main cylinder types sold in NZ, and the right one depends on your existing plumbing, power supply, and what you’re trying to achieve:
- Mains pressure — strong, even flow to multiple outlets at once; the standard choice for a modern home.
- Low pressure — the cost-effective option when you’re replacing an existing low-pressure system and reusing the pipework.
- Heat pump — uses up to 70% less power than standard electric; the highest upfront cost but the lowest running cost.
- Gas continuous flow — heats water on demand rather than storing it, good where space or hot water demand is high.
- Solar-compatible — mains-pressure cylinders, outlets available for solar or heat pump.
- Wetback — compatible with a wood burner as a secondary heat source to the element.
Step 2 — Choose the Right Size
Undersizing is the single biggest cause of “we ran out of hot water” complaints. Size is mainly driven by how many people are in the house and your hot-water habits (long showers, spa baths, etc. push you up a size):
Not sure where you sit? This is exactly what we confirm as part of your free quote — we won’t just take an order for whatever size you ask for if it doesn’t match your household.
Step 3 — Get a Price
The prices below are supply only prices — installation is quoted separately once we know your site (existing pipework, access, whether you’re changing cylinder type, and any electrical or gas work needed). This is also why “how much does installation cost” doesn’t have one honest answer online — it genuinely depends on your setup, which is why we quote it properly rather than guessing a number.
Step 4 — Book a Site Assessment
Before our work commences, we check:
- Cylinder type, age, and location (indoor cupboard, garage, roof space, outdoor)
- Existing pipework condition and whether it needs upgrading for the new cylinder type
- Power supply suitability (e.g reconnect or new switch)
- Access — will the new cylinder physically fit through doorways/into the space
- What NZ Building Code compliance applies (Acceptable Solution G12/AS1) and whether the job will meet building consent
Step 5 — Isolate Power and Water
Safety comes first during any hot water cylinder installation. Before disconnected fittings or draining begins, the existing system is fully isolated from all utilities. The main power supply (or gas feed) is safely disconnected, and the cold water incoming valve is shut tight.
Skipping or rushing isolation is where DIY projects typically derail. Pressurised cylinders store significant thermal energy and water pressure under load. Properly isolating the system protects your home from accidental flooding and eliminates electrical risks before replacement begins.
Step 6 — Drain and Remove the Old Cylinder
The old cylinder is drained through its discharge line, disconnected from water and power/gas, and removed and disposed of responsibly.
You can keep your old cylinder, just let one of our team know.
Step 7 — Prepare the Site and Pipework
Once the area is clear, a certified plumber prepares the site and adapts the existing plumbing to suit the new system. Because every installation varies, whether upgrading from low to mains pressure, converting to gas, or installing a heat pump—the pipework is carefully aligned, resized, or upgraded to match the new specifications.
If the cylinder is being relocated outside, weatherproofing and proper pipe insulation are added to ensure maximum efficiency. This setup phase ensures all connections, fittings, and surrounding plumbing are fully prepared before the final installation and securing begin.
Step 8 — Fit the Valves
Every new cylinder installation requires a specific valve set to regulate temperature, control pressure, and comply with the NZ Building Code.
Tempering Valve: Installed on almost all systems to mix cold water with hot, ensuring water at the tap does not exceed safe scalding limits.
Mains Pressure Valve Packs: For mains pressure systems, an all-in-one valve kit such as the Apex CP20 Combi Pack is fitted. This contains all the essential valves required for a compliant installation, including the pressure limiting stop valve, cold water expansion valve, and non-return valve.
Low Pressure Systems: Low pressure cylinders use a different, dedicated valve set tailored specifically to open-vented or low-pressure requirements. Apex low pressure valve kit is one example.
Temperature & Pressure Relief (TPR) Valve: Releases water automatically if the system ever overheats or over-pressurises.
Step 9 — Seismic Restraints
New Zealand’s Building Code (G12/AS1) strictly mandates that all hot water cylinders are secured against seismic movement to prevent them from toppling or shearing pipework during an earthquake.
To meet compliance, heavy-duty galvanised steel straps are anchored directly into the wall’s structural framing. Tanks up to 200 litres typically require two straps, while larger cylinders (or those with specific layout constraints) require three or more straps to keep the system rock-solid. We fit fully compliant seismic restraint kits on every installation, correctly sized and tensioned to protect your home from major earthquake and water damage.
Step 10 — Connect Pipework, Utilities, and Position the Cylinder
With the cylinder secured in place, final plumbing and utility connections are made. All hot and cold pipework is joined to the new valve setup, ensuring every fitting is tightened to the correct torque and properly sealed to maintain watertight integrity.
Next, the power (element/heat pump unit) or gas line is reconnected. It is vital during this stage that the power remains safely switched off at the main board—an electric element must never be energised while the tank is empty, as this will instantly burn out the heating element. Once all gas, electrical, and water connections are verified and sealed tight, the unit is ready for filling and testing.
Step 11 — Refill and Test
Once all connections are secured, the system is re-filled with water and bled of trapped air. Before switching on the power, water pressure and flow rates are checked across household taps to ensure smooth distribution.
During the final sign-off, a thorough inspection is carried out to verify:
Thermostat Configuration: Ensuring the tank’s thermostat is set directly on the unit to maintain a cylinder temperature above 60°C.
System Pressure & Initial Flow: Testing flow rates at taps and outlets to ensure proper water distribution throughout the home.
Valve Operation & Leak Checks: Inspecting every join, fitting, and valve (including the TPR, expansion, and tempering valves) under line pressure to guarantee a 100% leak-free installation before leaving the site.
Step 12 — Compliance Paperwork and Certification
Where required, official compliance documentation is completed so your installation is fully certified and on record. Having correct certification is essential, it protects your home insurance coverage and ensures smooth property transactions if you ever choose to sell, as non-compliant work can void insurance claims.
Once the job is wrapped up, key documentation is issued and provided to you directly in person or sent via email:
Electrical Safety Certificate (ESC / Certificate of Compliance): Verifies that all electrical wiring, isolation switches, and element connections meet official safety standards.
Gas Certification: If gas work or a gas hot water system was installed, a Gas Fitting Certificate (CoC/SDoC) is issued to certify safe operation.
Step 13 — Warranty and Aftercare
If anything comes up afterward, you’re contacting one company, not chasing down separate plumbers, electricians, and the retailer.
Workmanship Warranty: Every installation includes our 1-year installation warranty covering all trade labor, connections, and fitting work.
- Element/Thermostat: 1-year for parts and labour and can be replaced with an Electrician
Manufacturer Tank & Unit Warranty: The cylinder or heat pump itself is covered under the manufacturer’s warranty. While specific coverage depends on the model, standard warranties typically include:
Copper Cylinders: 5-year tank warranty
Vitreous Enamel & Stainless Steel Cylinders: 10-year tank warranty
Heat Pump Water Heaters: 5 to 7-year manufacturer warranty (depending on the brand and model)
Why book the whole process through us
Cylinder selection, sizing, pricing, removal, seismic fixing, valves, compliance, and warranty — all thirteen steps above are handled by us as one job, not thirteen things you have to coordinate. You get one quote, one appointment, and one point of contact if anything needs following up afterward.
Frequently Asked Questions
Supply prices range from roughly $900 for a basic mains pressure cylinder up to $6,500+ for a heat pump system — installation is quoted on top once we’ve seen your site, because it depends on your existing pipework, access, and whether you’re changing cylinder type.