Navien or Takagi Flash T-H1 Tankless Gas Water Heater?

Wayne Reibold
May 1, 2009

I'm looking for a high efficiency gas tankless hot water heater. I've come across Navien which makes 98% efficient and the Takagi Flash T-H1 which is 92% efficient but I'm totally new to tankless water heaters and am curious if anyone has experience with either of these and can share some opinions.

I'm wondering how reliable tankless water heaters of these types I mention are.

Any reviews, feedback or tips would be greatly appreciated.

Comments (20)

  • jake2007

    To begin with, use the energy factor as your guide rather than the manufacturer's "efficiency rating".

    Heaters with an EF of 0.82 or better qualify for the federal tax credit. That's a floor that I would use.

    Once you get closer to an EF of about 0.9 you are looking at a condensing unit. These are more expensive for the heater itself than the .82 heaters - but they can vent with plastic pipe rather than Stainless Steel. Venting with plastic pipe (PVC) can be a huge savings if you don't have a short flue run. The difference in energy factor alone doesn't ever pay back the additional cost of the condensing unit over the .82 unit - but the savings in venting can.

    Takagi has a good reputation. It would not be a bad choice. Navien is a little bit newer to the market and more innovative. Some of their units include a buffer tank and a circulating pump. Apples-Apples, I think they also cost less than most other condensing tankless heaters. The problem is that they don't have the reputation... it's not that they have a bad rep, it's that they are too new to have a good rep.

    I would like to see Navien take off and do well-- but I don't have any feedback from people who have used them.

    If you have a short flue run, consider a 0.82 unit from a reputable company (not Bosch). I have the Rheem unit and have been very happy with it both in quality and value.

  • zl700

    Something you should know-

    The Navien vents with PVC/ABS

    The Takagi TH1 although it is over 90%, still only has approvals as a Cat III venting appliance thus requires special 4" Stainless Steel pipe. Because of this, and the unit itself costing almost a $1,000 bill more could add $1,200 to $2000 in install costs over a Navien.

  • jake2007

    Thanks zl700, I didn't look at the TH1 to see what pipe it used. In general, the condensing units that are above 0.9 EF use PVC/ABS to vent. It's still important to verify that.

    zl700, do you know anyone using the Navien? Have you seen pricing for them?

  • zl700


    I am familiar with countless tankless installs, including dozens of Naviens.

    The differences with the other heaters at or above 90%, are that they are still flash heaters with high temp operating heat exchangers and then a bypass with cooler water mixed back in with inlet water going through the secondary heat exchanger. Thus the flash type heaters are still susceptible to liming. On the Navien, 100% of the water travels through two SS heat exchangers with no downstream mixing.


  • Wayne Reibold

    bump! Anyone have any reliability info on Navien? I just got a quote on a tankless, was leaning toward a Noritz but the person was pushing Navien very hard and saying his company has installed tons of them over the past 3 years and no problems, just a couple of problems with Noritz which he also said is good.

  • zl700

    Either you misheard or the salesman exaggerates

    The Navien has been in the US for about 16 months, 7 years + in Europe & Asia.

    Which Noritz Model?

    Navien has features the Noritz unit hasn't.

  • Wayne Reibold

    Didn't mishear, he said that, he was a big B.S.er though.

    I'm looking at the Noritz 751 or 841 (likely the 751 as the 841 seems to be a huge increase in cost for unit and accessories -- e.g., triple the cost for the outside vent cover of the 841 vs. 751).

  • alanlucero

    Here's another aspect to consider before purchasing Navien. The PVC elbow (water feed) inside the case of our CR-180A sprung a pinhole leak, spraying fine mist and soaking all components for weeks or more before the system board failed (puddles of rust left on bottom of case). Local tech could *not* get the Navien support engineer in Calif to agree to a unit return. They shipped a new board, despite my protest that all electrical components and contacts had been soaked. A few weeks later, the system is now failing multiple times a day. Navien tech support in Calif refuses to send the local rep anything more than a replacement transformer as their next attempt at hit-or-mis diagnostics at our expense. Dealing with these people feels like dealing with the gate keeper of some insurance company. Based on their utter lack of consideration of customer service, coupled with an apparent problem with compentence of the tech support line in California in trouble-shooting, I strongly recommend avoiding them.

  • walkrcharm_gmail_com

    I am in the middle of trying to find a tankless unit that will do both my domestic HW, but also my heat which is Baserae iron baaeboard.I was just told I could not use the Navien tankless condensing 199,000 btu unit because of the size and distance of my baseboard. Appox 160' of baseboard with the furtherest baseboard appox 60' from the tankless unit. Any ideas on what to do? My boiler is a 10yr old V15 160,000btu, Tom

  • Wayne Reibold

    Lots of negative reviews of Navien. I bought a Noritz 2 years ago and absolutely love it, could not be happier.

  • wisehvac

    The very first thing you would want to do is get a heat loss calculation for the home, that way you know exctly how many btu's you need. That will also give you pipe and pump sizes. I dont recomend a water heater for a boiler. Id rather see you use a triangler tube, WEIL-McLain or a peerless high effiecncy pice or equipment.

  • brita_iverson_yahoo_com

    I am looking at a Navien N-210 and the sales person claims that in order to keep the warantee alive. it must be serviced every year. Their service contract is 9 dollars/month or 108 dollars which I think blows any savings on the unit. Anyone, anyone?

  • robglass2_mchsi_com

    I have used two Paloma gas tankless water heaters for 35 years. One for hot water and the second for baseboard heat for a 2000 sq ft home. I recently replaced both with one Navien CH-240 to provide both functions. We are extremely pleased. We now have flawless contol of the home temperature and more hot water than ever before. My warranty does not require annual service as someone reported. It is 5 yr on parts and 10 yr on heat exchanger and one year free labor. This is one well built heater.

  • beth4

    As I type this my 14 year old tanked water heater is being replaced with a Navien 240. My warranty is 15 years on heat exchanger, 5 years on parts and 1 year free labor. No requirement for an annual service. Additionally, the company installing the Navien has a policy that guarantees if, during the first year I have the Navien, I'm unhappy with it, they'll remove it, and fully refund my money. They said they've never had a customer claim that benefit. All of their customers are happy. Last year, when the state tax credit was in effect, they were installing 2-3 Navien units each week. Install rates have fallen off a bit since the state tax credit has been dropped. Interestingly, they're installing Naviens only in existing homes.

    They were also candid that, like other new technologies, there were some hiccups a few years ago that needed to be worked out. In their opinion, all problems have been resolved, and today the best, most reliable tankless units on the market are Navien and Eternal.

    I chose the Navien because the heat exchanger is stainless steel, not copper, eliminating the need for the periodic de-scaling required of other makes. And because it appears easy to operate...more so than the Eternal.

    I'm nervous at the change. And I'll post back here after I've lived with the Navien for a month. I've got house guests coming later this month, and it'll be interesting to see how it performs with lots of showers, laundry, dish drawer use, etc.

    I'm so pleased to hear that Rob is delighted with his new Navien.

  • rjbbicoast_aol_com

    We installed Navien tankless heaters last year, and they have continuously performed poorly even after numerous servicing and consultations with the Navien service rep. The problem has been that even with moderate use the water turns from hot to warm after a minute or two. Our plumber is recommending removing them and the rep has offered to refund the full price of the units. The recommendation is for a traditional Phoenix hot water heater. Is the problem tankless heaters or is the problem just Navien? They rarely show up in lists of top ten manufacturers. Are they just new or bad?

  • davidrt28 (zone 7)

    I know of 4 Takagi installs that have been trouble free for about 5-7 years and my own Rinnai install has been trouble free for 4 years. I think your problem is the brand!

  • beth4

    Rjb--- I've lived with the Navien tankless since May 11th -- 2 months. Have had lots of house guests for several days, and have entertained quite a bit in the past 2 months. So...lots of water use, lots of showers, laundry, etc. I've not had a single problem with the Navien tankless system. In all candor, the hot water from the Navien reaches my master bath fixtures more quickly than the water did from the hot water tank. The water temperature is maintained from the beginning. I was quite nervous about this purchase, but my fears were groundless. Everything is working well.

    The plumber who did my installation did caution that I might find changes to the hot water in the shower, and this would be an indication that the cartridge needed to be replaced with a new cartridge, so the water level, heat setting of the faucet would hold (those are my lay-woman's words, not his -- but you get the drift). This is not a big job, should it be required. For the past 2 months, I've not had any problems, so I'm leaving the current cartridge in there.

    I'm wondering if your Navien was properly sized for your house and the length of run of your plumbing pipes? Or, perhaps you needed to install the recirculating feature? I did install the recirculating pump model, and it does the job getting hot water to the outlets more quickly.

    Hope this info helps.

  • gdpark

    My Navien was just fired up for the first time today- Had lived with a Renaii previously and had no issues, plumber pushed Navien as the recirculating function is within the unit rather than being outside the unit. Not in house yet but shower walls went up today and may try it out tomorrow! Just hope it is as dependable as the Renaii... ill keep you posted!

  • cclmnts6

    How has the Navien240A held up? Higher energy costs for the recirculating feature?

  • cclmnts6

    Decided to get the timer for the recirculating feature.

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