Navien Combi Boiler Review

Navien Combi Boiler Review


A good boiler is the heart of any home. During the cold winter months, having a good system in place for heating your house and providing hot water is absolutely essential.

Navien is a Japanese company that has found a large market in both America and the UK with their range of household boilers.

A combi boiler is one of the most common types of hot water systems found in many households across the world. Since they don’t require a storage tank like more traditional boilers, they take up very little space and cost significantly less to maintain.

They are also very easy to install in your home and can provide enough hot water for the taps, showers, and radiators in a small house.

This review will be looking at Navien’s top two combi boiler models, the NCB-E and the NCF. We will also provide some insight into Navien as a company to see why they are one of the most popular boiler manufacturers in the United States.

Who Is Navien?

Navien is a Japanese company founded in 1978 that was originally known as KyungDong Navien (or KDNavien for short). They were one of the first companies to produce, energy-efficient and environmentally friendly condensing boilers for use in residential buildings.

Over the years they expanded their business to include ventilation and zone control systems, as well as many more products designed to heat people’s homes. In 2006 they broke through into the American market and have been selling high-quality tankless boilers ever since.

What Makes Their Boilers Special?

Navien specializes in tankless boiler models, which take up far less space in the home than more traditional alternatives. Their units use condensing technology, which means it takes the exhaust gases from the fuel it burns and recycles them to preheat the water for your radiators and showers.

The method of heating water is considerably more efficient, not to mention more eco-friendly.

They also remove many of the harmful byproducts created by burning propane gas through their stainless steel heat exchangers.

Navien’s condenser boilers have an average efficiency rating of 90% which will help to reduce the carbon footprint of any home, as well as save money on your gas bills.

They can even be connected to Wifi so you can control their heat output from your smartphone. This makes them much easier to use than other traditional heating systems.


The NCF Navien Combi Boiler Review

The NCB-E was one of the first condenser, combi boilers sold by Navien, and to this day it remains one of their most successful products. These compact units can easily fit into any home and are highly efficient with an Annual Fuel Utilization Efficiency( AFUE) of 95%.

Despite their small size, the NCB-E’s are more than capable of providing enough heat and hot water for large houses and families.

There are four available combi boilers in this range with the largest, called the NCB-240E, having an HTG(heating) value of 120,000BTU/h and a DHW (domestic hot water) value of 199,000 BTU/h.

In layman’s terms, this boiler is capable of providing enough heat and hot water for all but the largest family homes.

For fast installation, these boilers come with all the necessary manifold kits. These are the copper piping pieces that are needed to connect your heater to a house’s gas line. All Navien products use standard ½ inch gas lines so they can be easily retrofitted into older homes.

The NCB-E can be cascaded, or linked, to Navien’s NCP units for providing extra hot water when necessary. This means even if you have an especially large house, this boiler will still be able to meet all your heating needs by working together with other units.

Dual stainless steel heat exchangers help to reduce corrosion of the metallic parts in your boiler. The sleek, touchscreen, control panel on the front can be used to regulate your heating and hot water output.

This boiler has a turndown ratio of 6:1 for heating and 11:1 for hot water meaning that you can precisely adjust it to save on energy when you don’t need it running at full power.


This model of combi boiler has many of the same features as the NCB-E models. The main difference is that the largest of the two models in this range can produce 199,000 BTU/h for both heating and hot water. This model has an even greater potential for cascading and linking up with other units.

If you need a lot of hot water, for heating a swimming pool for example, then up to 8 NFC boilers can be hooked up to the same vent.

Just as with the NCB-E, this boiler can be connected to the standard ½ inch gas pipes found in most homes. It has a turndown ratio of 11:1 for both heating and hot water which means that on its lowest setting you will be running the boiler at 11% of its maximum output.

The benefit of this is that your heating system will be much easier to control and you can save even more energy when you don’t need to use its full potential.

The NCF is an upgrade over the NCB in almost every way, with the patented stainless steel fire tube heat exchanger being extremely durable as well as resistant to corrosion.

It is also considerably quieter, so you can have a nice warm house without having to tune out an annoying rumbling sound from your heating system.

Buyers have the option of fitting the NCF with a NaviClean magnetic boiler filter which removes iron oxide, and other debris before it can clog up the rest of your pipes.


Overview Navien Combi Boiler Review

Navien is a company that has had a lot of practice when it comes to making high-quality condenser combi boilers. Both the NCB-E and NCF models are great options for heating large family homes, while simultaneously providing plenty of hot water.

Navien’s products use state-of-the-art technology to create boilers that are both highly energy-efficient and environmentally friendly.

One thing that does bear mentioning is that the 7-year extended warranty offered on both the NCB-E and NCF won’t apply if you buy your unit online and install it yourself.

If you want to make use of this warranty, then you will need to hire a professional for the installation.

So if you are looking for a new boiler to heat your home, and don’t have the space for a hot water tank, then consider buying a combi-boiler to save on space and energy bills.

There are other options available but if you want a heating system from a reputable company that is the leader of their field, then Navien may be the brand for you.


  • Energy-efficient to save on gas bills.
  • All models have high turndown ratios for better control over your boiler’s output.
  • Stainless steel heat exchangers for removing harmful byproducts of gas combustion.
  • Compact and easy to fit anywhere in your home.
  • You can cascade several units and link them to the same vent for even more hot water and heat.


  • Warranty voided if you install your boiler yourself.
  • May be harder to maintain without calling a professional.

Frequently Asked Questions

What Does BTU Stand For?

BTU stands for British Thermal Units and represents the amount of energy required to heat 1 gallon of water by one degree Fahrenheit. In most heating systems it refers to the amount of energy your unit needs to cool down or heat up a room.

It is quite a confusing metric, but all you need to remember is that the higher the BTU value, the better a boiler will be at raising the temperature of your house and water.

Are Navien’s Boilers Energy Star Certified?

Yes, all of Naviens boiler units are Energy Star certified and boast an AFUE of 95%.

AFUE stands for annual fuel utilization efficiency, and the higher this value is, the more efficient a unit will be. High efficiency is very important, especially in a heating system that you will be running very frequently in winter.

With Navien’s boilers, you can rest assured that your boiler will heat your house without unnecessarily running up your gas bills.

What Is The Turndown Ratio?

One thing you will see frequently advertised on Navien’s boilers is their high turndown ratio. This is the ratio between a boiler’s highest and lowest fire settings.

Smaller ratios mean that even on their lowest setting, a boiler will still use a fair percentage of its maximum output, which isn’t good for efficiency.

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