How to choose a superior outdoor pizza oven suited to New Zealand conditions

How to choose a superior outdoor pizza oven suited to New Zealand conditions

Thinking of purchasing a pizza oven and you're uncertain how to distinguish a top-tier or high-quality pizza oven? You're not alone, it can be challenging to compare pizza ovens. There's an overwhelming array of options, each promising durability, heat retention, quality and longevity making the decision process complex.  

Years of experience go into building a superior pizza oven and it’s not something that can be mass-produced. While there are various options available on the market for every budget, we will discuss what defines a well-built pizza oven and what you should look out for.

When choosing a pizza oven it’s important to assess whether it’s durable to the New Zealand weather conditions and going to deliver exceptional quality pizzas. Factors that customers need to look into are materials, heat retention, insulation, size, ease of cleaning and more.

Why does the material matter?

The material your pizza oven is made from will determine the quality of pizza and the life of your pizza oven. 

Pizza ovens come in many shapes, sizes and materials such as stainless steel and refractory material pizza ovens. Stainless steel are known for their robustness but don’t do well at retaining heat. They need constant monitoring and can become a hindrance when trying to socialise at your event. Compared to refractory material pizza ovens which excel in heat retention and are traditional choices, providing an authentic taste to pizzas. These materials ensure your investment last. 

Typically cheaper ovens on the market are made from an array of materials, you will see separate components for the entrance, chimney, and outer shell, made from materials like mortar, bricks, plasters, ceramics, and steel for the smoke exhaust system. The mix of materials used can often result in a common issue known as “oven cracking” due to thermal expansion and it’s not uncommon to hear that pizza ovens are expected to crack. 

Thermal expansion is the tendency of matter to change in shape, volume, or dimension in response to changes in temperature. As substances heat up, their particles gain kinetic energy, leading them to move more vigorously and increase the space between each other.

Why does thermal expansion matter? 

Materials have different thermal expansions, if a range of different materials are used, this can lead to cracking and excess wear on the pizza oven. At Kiwi Pizza Oven we manage thermal expansion due to our unified structure that combines the entrance, chimney, and outer shell into one cohesive unit. All parts are crafted from the same materials, ensuring consistent responses to thermal expansion. The entire system is fortified with anti-cracking measures and protective coatings and membranes. 

It’s important to understand what your pizza oven is made of, if contradicting materials are used or cheap substitutes for quality materials, it can cause the oven to form cracks.

What materials are used at Kiwi Pizza Oven and why do they matter?

Outer Shell: 

The outer shell is constructed from one piece of reinforced shell. We use 100% ceramic fibre woven blankets for insulation. Ceramic fibre is durable and resistant to deterioration or sagging. It’s important to check what the outer shell is constructed from, other companies use a fabric cover which is not waterproof.

Clay floorboards:

Our floorboards are custom-made exactly for our pizza oven’s purpose. Comprising densely compressed fire bricks, called pizza oven floorboards because of their large size, each brick weighs over 20kg each. The large size has been designed to reduce the number of joints on the floor. Their high density enables them to retain significant heat for a long period.  Made from the same high-quality restaurant pizza ovens to ensure they can withstand intensive use and deliver quality pizzas every time.

Inner Dome: 

Our inner dome can withstand 1200°C. Made from high alumina cement constructed from four quarters, using top-quality refractory materials that are exceptionally dense, surpassing firebricks in heat capacity. The quarters fit together like a puzzle, thanks to the special recesses at their joints, and are tightly held in place with fibre strips. The flexibility and secure connection create expansion joints which significantly reduce the risk of cracking. Unlike other inner domes made of firebricks with hundreds of mortar joints, this gives an increased risk of cracking due to the inability to relieve stresses caused by thermal expansion.

Why do we build sandwich walls?

Our pizza ovens are constructed with sandwich walls of up to 10 different layers, enabling the selection of various layers to work together. The oven achieves exceptional thermal insulation, and weather resistance, minimises the risk of cracking and offers a truly unique oven to mass-produced or home-made ovens. This is why our pizza ovens take 100 hours to build.

Flue: 

A flue ventilates smoke, gases and combustion byproducts. A flue enables temperature regulation by controlling the airflow. Our pizza ovens use a traditional external front flue system. This works to perfectly suck up smoke with minimal heat loss. Ovens that contain the flue system inside the dome area of the pizza oven are not as effective at retaining heat as the heat escapes out the flue without transferring to the dome mass. 

What is thermal mass? 

Thermal mass is the oven's ability to absorb, store and distribute heat efficiently. An optimally balanced thermal mass is crucial for maintaining stable temperatures, enabling consistent and efficient cooking, key to achieving that sought-after crispy yet tender crust and thoroughly cooked toppings. 

Thermal mass needs to strike a balance and be matched to the oven’s intended use, which may vary between residential and commercial ovens. In some home projects, an overly thick mass results in extended heating times and excessive wood consumption. Cheap ovens tend to have a thin thermal mass, leading to temperature instability, quick overheating, an uneven cooking experience and rapid cooling. The key is to select oven parameters that deliver all the benefits of a traditional one, from perfectly baked pizza with crispy edges to slow cooking over 10-15 hours, with all advantages intact.

How do you differentiate between an appropriate thermal mass vs an inappropriate thermal mass?

It can be difficult to determine the quality of the pizza oven by looking at it, some questions you may want to ask are: 

“How long does the pizza oven take to heat up” 

“What is the cooling period” 

A well-built pizza oven should have a cooling period of at least 10 hours. If this is less, it’s an indication the insulation and thermal mass may not be as good. In a pizza oven with good insulation it’s easier to light a fire, takes less time to heat up and there is no moisture from the environment, prolonging the life of the pizza oven. 

While these questions aren’t going to cover everything, it’s an indication as to whether the pizza oven has been constructed with thought and the starting point to determining the quality of the pizza oven.

Why is insulation important?

Wood-fired ovens are heated by setting wood on fire. The heat is stored in the walls and floor of the oven (thermal mass), the pizza is cooked from the heat stored in the thermal mass, not from the fire directly. If a wood-fired pizza oven isn’t well insulated it will cool down quickly, requiring more wood and attention when cooking pizzas. 

Temperature regulation: 

Entertaining can become challenging when you’re constantly darting in and out of the kitchen. If your wood-fired pizza oven lacks proper insulation, you’ll find yourself constantly monitoring it, tending to the fire, and hurriedly making pizzas to ensure it stays hot enough. 

At Kiwi Pizza Oven, the ovens are well insulated, once the dense mass is heated up, it takes a long time for the pizza oven to cool down, around 10-15 hours. This extends the variety of food that can be cooked in your pizza oven. To find out what can be cooked in a pizza oven check out this blog. 

A pizza oven equipped with a dense thermal mass and robust insulation not only minimises wood consumption for extensive cooking but also has a slower cooling time, distinguishing it from the cheaper options available. 

Not to mention, you won’t be required to constantly monitor the pizza oven and quickly churn out pizzas, you can take it at a leisurely pace and enjoy the company of your guests. 

Why does size matter? 

Size is a critical component when it comes to a pizza oven. In the past at Kiwi Pizza Oven we used to build large pizza ovens, the weight would exceed 1000 kg. After years of testing, it turned out the optimal size was between 450-500 kg. This combines high efficiency, short heating time and long cooling. 

Our pizza ovens require 2 hours to heat up and a 10-15, sometimes 20-hours to cool down, this allows for a range of food to be prepared such as cakes, breads, stews or dried fruit. The utilisation of the oven is excellent compared to cheaply built ovens which lose heat quickly and cool down. 

The next day your pizza oven will still be around 160+ degrees which is perfect for baking fresh bread.

Why is moisture and cracking important to consider?

Moisture:

Moisture is a critical consideration often overlooked by many wood-fired pizza oven manufacturers. When a pizza oven is exposed to moisture from external sources such as rain, dew, or water vapour, it can lead to detrimental consequences for the oven’s structural integrity. 

You may have heard the saying “Pizza ovens are expected to crack” however, in a well constructed pizza ovens the risk of cracking is very minimal. Technical expertise in managing thermal expansion during oven construction and using modern professional materials can reduce the risk of cracking. 

Our ovens are unified structures that combine the oven entrance, chimney, and outer shell into one cohesive unit. All components are constructed using the same materials, ensuring consistent responses to thermal expansion. 

Water will always find cracks, regardless of whether you can see these or not. The insulation is porous so it will absorb the water. Next time the oven is lit and the temperature increases, the water which would normally evaporate begins to boil due to heating up too quickly, this creates steam, which can lead to the formation of micro-cracks that compromise the overall structure and integrity of the pizza oven. In severe cases, the accumulation of steam can create pressure, potentially causing the oven to rupture from the back or sides, posing a risk of injury or harm.

It’s essential to ask the right questions and that’s whether the pizza oven is water proof. If it isn’t it will require you to bring the pizza oven inside, which may not be practical as they are extremely hot. Leaving it out overnight can cause water from dew and light rain to penetrate the pizza oven, compromising the structure. 

It’s essential to ensure the oven is equipped with a door and flue cap to safeguard against the rain entering. 

How Hot does it get on the outside?

Temperature serves as a critical indicator to how well the pizza oven has been built and the quality of insulation. During operation, despite the oven reaching 450-500°C inside, the oven will only be slightly warm on the outside, around 40-50°C. This also applies to the ovens underneath so they can be safely placed on any structure of material. This is for efficiency and safety. 

Why is buying an authentic wood-fired pizza oven the best choice? 

Kiwi Pizza Oven guarantees an authentic, traditional cooking encounter by employing top-notch materials that enhance heat retention and even distribution.

Crafted to endure rigorous outdoor conditions, it boasts superior craftsmanship, offering heightened performance, durability, and unwavering reliability. It can also serve as a captivating centerpiece in your backyard, perfect for hosting entertaining gatherings.

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