The Navien NFC (Navien Firetube Combi) boiler is one heck of a performer for a combi-boiler. I have made a list of details I would recommend changing, I’ll list them below. This is the only combi that I have exeperience with that will handle any typical three bathroom home. The DHW production is very impressive.
This model combi has a modular piping arrangement that is removable for service if needed which is a huge improvement over the previous model NCB boiler (they’re going that route with the new NPE and NCB in 2020).
Navien designed and manufacturers the all stainless steel heat exchanger in house, this isn’t common of most boiler manufacturers. Having complete control over all aspects of the boiler is what tends to set companies apart from others. In this case its too early to tell if they’ve got an advantage here since the new boiler and Combi have only been on the market for less than two years.
The control for the NFC [and NFB] boiler is the first we have seen from Navien with a plain English line-by-line display. A huge step forward when compared to previous code display models.
Navien decided to go a new route with the NFC, something we haven’t seen from them in the past. Included with the NFC is a laundry list of additional components. First and foremost would be the stainless steel low-loss header designed specifically for the NFC [and NFB], its manufactured in house by Navien.
Additional components in the box include a “Naviclean” magnetic filter made by Adey and a universal temperature sensor that can be used on the supply or return system piping; parameters within the control allow for the choice of placement and control function if installed. Add to this you’ll find the usual parts like a pressure relief valve, outdoor sensor and even a 1″ iso valve kit with unions for the heating supply & return. An impressive accessory package to say the least.
Of course all these accessories add to the cost of the Combi. When added up individually the additional components would likely cost more than $1300, you can expect the contractor cost of a NFC 175 to price out about $1K more than the previous Combi (NCB), of course every market is different and discounts vary so your best bet would be to contact your supplier for current pricing.
The Navien Firetube Combi (NFC) is available in two sizes, NFC 175 & NFC 200, the differentiating factor is the space heating capacity.
NFC 175 – 18,000-175,000 Btu heating, 18,000-199,900 Btu DHW
NFC 200- 18,000-199,900 Btu heating, 18,000-199,900 Btu DHW
Both Combi units offer control and power of en external DHW circulator and up to 3 zones of heating control [pumps or zone valves] built in to the internal control and control board. This is a smart move by Navien in my opinion that will save contractors working in single or [up to] three zone systems to save on additional component costs. Outdoor reset is standard.
Now the wish list:
1: Include a tankless service valve kit. This is a premium combi at a premium price, the cost for the add by navien would be about $25-35 and when passed thru the channels probably an add on of $50-60 for us. Having to order or stock a separate item for install is higher cost and can delay projects. Just include it in the box, I don’t want to deal with this, I have too many other parts and pieces I need to worry about.
2: Package the accessory box separate or attach the outer box to the skid because the straps don’t hold the outter box secure and you definitely DO NOT want to unpackage anything until it’s in the room you’re installing it.
3: Add a 1/2” tapping on the front of the LLH that is included with the boiler. A low point drain is needed and that header is already long, add adapters to size down from 1-1/2” connections. I would use this 1/2” tapping for a drain, could be used for a tridicator gauge. Either way it would save me about $20 and time. This add on would not effect the LLH packaging.
4: Get rid of the dip switches. Integrate those settings into the control. They’re annoying and I’m nearly certain most installers don’t touch them.
5: Put a wire diagram, large print, on the inside of the boiler cover. The labeling at each terminal is extremely small, numbers would be better, but a large print schematic would be best.
I want to go on record by saying my wishlist is not a dig on Navien or their engineers. The quality and functionality of the NFC places it in the premium boiler category in my opinion but like any other equipment I have installed throughout the years I will find ways I think it could be improved. I wouldn’t focus on the list, my intention is Navien may consider it as feedback, none of the items on that list will keep me from buying another unit and installing it in my costomer’s home because I certainly will install more in the future. To me, that’s a true testament to the product’s design. Hope this helps.