NTI Trinity On-Demand High Efficiency Boiler

By Todd Fratzel on Air Conditioning, Energy Conservation


On-Demand High Efficiency Boilers

The new Energy Star certified home that we’re building at work for a client includes a NTI Trinity on-demand high efficiency gas (propane) boiler. This amazing on-demand high efficiency boiler provides all of the domestic hot water and hot water for the heating system. The heating system includes a combination of base board hot water and radiant floor heating.

The photo shows the entire heating system completely installed. The gray rectangular box in the center of the black plywood is the actual boiler. This boiler is producing all the hot water for a 2400 sq. ft. house on-demand!

The boiler is vented up through the roof using PVC pipe. The fresh air is also produced from a PVC pipe through the roof. The pipes to the right of the boiler are the manifolds that supply hot water to the radiant system. The piping to the left of the boiler is for all the zone pumps that supply the base board and radiant zones. The big difference here is the lack of a hot water storage tank.

On-demand boilers offer much higher overall efficiency because the hot water is made as it’s needed. In a traditional set up you’d have a boiler that generates hot water to be stored in a tank. The tank holds the hot water waiting to be used. Over time the hot water can lose heat when it’s not being used. With an on-demand boiler you only make the hot water you need.

We’ve installed this type of boiler in several houses and they work great. They are able to produce all the domestic hot water you could ever use while still providing hot water for your heating system.

In addition to being very energy efficient they are also extremely quiet and small in size. The units are so small you can easily install them in very small areas (as code will allow). You can be standing 5 or 6 feet away from these and not even know they are running. Venting through the roof is also a nice benefit because it keeps the steamy exhaust away from windows and vents.

About the author

Todd Fratzel

I'm full time builder for a large construction company in New Hampshire. I run their design-build division that specializes in custom homes, commercial design-build projects and sub-divisions. I'm also a licensed civil and structural engineer with extensive experience in civil and structural design and home construction. My hope is that I can share my experience in the home construction, home improvement and home renovation profession with other builders and home owners. I'm also the Editor-in-Chief and Founder of Tool Box Buzz. Please feel free to contact me if you have any questions, suggestions or you'd like to inquire about advertising on this site.

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  1. Peter Smith says:

    We bought this house that was just under a year old, in 2004, and it had a new NTI boiler system heating the house by way of (fan coil), in floor heating in the basement, and our hot water tank. In the first year the system continually shut down, and we spent more then $3000 during the next three years, hiring a plumber to continually repair the NTI boiler. The costs were mostly for the electronics of the system, none of which were covered under warranty, as we had no idea who installed the system. On Christmas Eve of 2004, the whole system shut down, and we had to heat our home with electric heaters. In the fall of 2007, the boiler failed and became irreparable due to water damage and rust throughout the boiler. This damage was also causing exhaust to leak into our home. Obviously, this could have been catastrophic for our family. I contacted NTI directly by way of letter requesting their assistance in replacing the unit, but they ignored me completely. Their area representative did show some interest at first in helping us, but quickly abandoned me when it was determined that the whole unit would have to be replaced. As such, I contacted a local plumbing company and requested a quote on replacing the boiler with a forced air system, and gas water heaters for the in-floor heating and hot water. Their owner came, and after looking everything over, told me that the NTI boiler system was a good system, that NTI had made significant changes to the boiler for the better, and that his company could replace it for $8000. However, he told me that he would get in touch with NTI and seek their financial help in paying for a new boiler, and led me to believe that the costs would be greatly reduced. He seemed sincere in that the bill would be much less then $8000. With winter coming on, I was anxious to ensure that we had heat in the house, and took this man at his word. We had the new NTI boiler system installed.
    Unfortunately, after the work was done, NTI refused to provide any sort of financial assistance for their new boiler. Even worse, the plumbing company did not include the cost of extra parts and some pumps that had to be replaced, and the final bill came to $9400.
    Within a few days of having it installed, I found a leaking pipe from a connection made by the installer. This had nothing to do with the boiler itself. I called the company to come and repair it, which he did. Over the next few days, I found four more leaks from joints, which I cut out and replaced myself. From that time until recently, the boiler has performed as it should. A few weeks ago, I noticed water dripping from the boiler. I determined that the leak was coming from the top of the unit, at a joint that was not sealed properly in the exhaust pipe. After two weeks of waiting for parts, the same plumbing company came today, and replaced the top of the NTI boiler. The cost of the boiler parts were covered under warranty, however, I had to pay almost $200 for the plastic vent pipes and the labor. Because I had not noticed the leak sooner, the interior of the boiler system is now rusted and water damaged, again…!
    In any case, although I am happy that NTI has covered the top of the boiler this time, the first time around we only received about four years of service from the boiler. In 2007 we spent $9400 on the same NTI boiler system, and now at just over two years, the boiler is in need of repairs and again starting to cost us money.
    In hindsight, I should have found another company, and simply replaced the boiler with a high efficiency forced air furnace, and be done with it. I will never again take a chance on installing any sort of boiler system, because there are just too many parts, pumps, joints and tubing, just waiting to fail. A forced air furnace is much less likely to break down, and if it does, it is never as serious nor expensive to repair, and you do not have to worry about the water damage.
    Finally, if you do consider buying a boiler, I would suggest you stay away from NTI, as in my experience and opinion, their products are not reliable, they do not stand by their equipment, and they have absolutely no concern for the fact that their product was directing exhaust into our home. They just ignored us.

    • Todd says:

      @ Peter – Really sorry to hear this story. We’ve built several homes with the NTI boiler with zero problems. It is a bit disheartening to hear they wouldn’t fix the boiler. I have a high efficiency propane boiler in my home and we love it. Again….really sorry to hear the bad experience.

      • Mary says:

        Hello Todd,

        I just bought a new home in August and the builder installed a high efficiency NTI heater. During home inspection recently I was told that there was no emergency switch installed for shut off.

        I wondered if this had just been left out or if the system doesn’t need this?

        can you advise as I am a new home owner and I want to be sure I know what I am facing with this new system.

        Thanks so much,


        • Todd says:

          Mary – Most local building codes require the installation an emergency shut off switch for the boiler. All it consists of is a regular “light” switch, installed with a red cover plate, designating it as the emergency shut off. Around here we typically install two of them, one right at the boiler so a service technician can shut down the boiler and one near the door to the utility room so you as a home owner can shut down power to the unit in case of an emergency. This is not very expensive, several hundred dollars at most. The builder really should have done this.

          • Susan says:

            Thank you all for sharing your nightmares! I WAS thinking of installing this heating system into my new house/renovation project. NOT NOW.

    • Bob says:

      Peter, I know exactly what you are talking about. I waited until the supply company here had sold NTI’s for a year and they told me they had no problems. I installed a few of them and started to hear about major problems with them. Some I installed wouldn’t even run right out of the box until I spent many hours working on them. They are utter trash! They have components that fail continually. A serviceman’s delight and a homeowner’s nightmare. Anyone who tells you these boilers are reliable and trouble free probably thinks Saddam Hussein was just a misunderstood dictator.
      If you have many backup sources of heat, love to have servicemen visit your home, and have lots of excess money to blow – buy one of these. Bob

    • John says:

      I hear you brother – The Trinity boiler is absolute crap. I have a trinity T200 I installed in 2005, and I’ve had switches fail any time we get cold air that condenses (had to buy the “upgrade” kit for that…. I had to buy new electronics, and a new blower fan.

      Now it’s rusted and leaking the radiant glycol through the condensate tube… I assume that the heat exchanger is cracked, so obviously unsafe (The plumber will be here tommorow, we have it completely shut down).

      Buy anything else… I regret not buying the Munchkin.

  2. jay says:

    I can relate to the problems you have experienced with your trinity boilers. I bought a new t200combi in 2004. Once installed and up and running, the boiler would just shut off randomly when there was a call for hot water. Sometimes it would work and sometimes not. At first i thought i was simply exceeding the capacity of the boiler because the water would come out warm, then hot , then cold. After checking the flow of my showerhead i realized that the boiler should produce twice what i was using therefore something must be wrong. I assumed it had something to do with my installation so i read and read and read. I studied every page of trinitys installation manual, their troubleshooting manual. I even downloaded a copy of their service manual for the service techs. I could find nothing wrong with the installation whatsoever. After about a year of dealing with occastional cold and lukewarm water, I talked to a factory rep who told me that their were a bunch of units that went out with faulty sentry controllers. there is a transistor inside the sentry that was bad. This would cause the unit to constantly shut down and reset causing hot cold water cycles for the domestic, and sometimes the heating cycle. Since it had been over a year NTI wouldnt help me with the cost of the part even though the thing was defective since the day i bought it. I bought a new sentry for around 300 dollars and installed it and then the boiler worked amazingly well. I had more hot water than i thought was possible. The unit worked fine until that winter. The temp reached 25 degrees one day and on that day, the boiler decided not to light. After much troubleshooting i found the fenwal controller to be bad. That cost around 250. I installed it and the unit fired right up and worked again. When replacing the fenwal i also noticed water leaking from the top of the boiler. It was coming from where the upper exhaust vent attatches to the combustion chamber. I replaced the gasket and have two more times since then. The gasket or maybe the design seems to be problematic.
    Other than that, I have replaced the flame probe once and the ignitor twice. Cant complain about that too much since they get alot of use in a boiler that cycles on and off all the time. Those you should expect to replace every couple years anyways.
    All in all the boiler works fantastic when it is up and running. I too feel that nti should have stepped up and replaced the defective components. Their reps knew that the sentry was defective from the factory on some units and it seems pretty cheap not to stand behind your product especially when you know that it was manufactured with defects. If NTI would have shown some class and at least covered the cost of the parts i would have been a customer for life. But as it stands, I will be replacing my t200Combi with another brand when the old girl eventually bites the dust.

    • Art says:

      I installed my T150 in 2004, and the Sentry controller failed just after a year, it was fall and I was heading out of town on a Saturday and was able to pick up a unit locally. I wrote to the factory and indicated that there must have been a problem with the design of the original as I had to install a grounding kit for the replacement. I said I did not want a refund but a replacement unit for future emergencies. They responded by sending me a replacement unit. I have yet to need it. I have replaced ignitors and flame sensors several times, instruction for new flame sensor required it to be bent diferrently than the first, telling me they are constantly trying to deal with the problems. I have not had the problems that others on this forum have had, but I do have a constant problem of hot water supply, especially in the shower, a liile bit of seepage at threaded joints, but my old boiler had those same issues.

      Has anyone tried to run a chemical cleaner through the domestic hot water heat exchanger, the manual says it should be done if the water is not soft enough. I did install a water softner a couple of years ago, has helped some what. I hate cold showers!!!

  3. Ray says:

    I had a Trinity NTI boiler installed in a century home in 2003 to feed the old radiator heaters and provide water-on-demand. Bad installation meant I had to replace the condensate lines and the venting since it leaked water since day one, but of course that was not NTI’s fault. However, there were also problems with the boiler unit itself. In 2008, it leaked water at the top of the boiler unit where the vent pipe joins the boiler. It seems that many other people have had this problem after reading several blogs on NTI’s boilers. I had to install rubber washers around the screws that hold the plastic vent pipe to the top of the boiler. That seems to have fixed the problem for now. I think a gasket ultimately needs replacing there. A faulty connection on a flow sensor had to be replaced in 2009. Occasionally, the water turns cold momentarily in the shower. Other than that, the units worked OK. But after all the water leaking problems, I’ve learned to distrust it. I inspect it for leaks once a week. Keep spare ignition and flame probes on-hand as these will fail eventually (mine did in the dead of winter). This is inevitable. I’m not sure I’d buy this unit again.

    • Jay says:

      There is a revised version of the vent hood available with a better gasket and connection that doesn’t leak. I would recommend doing this update ASAP if you have condensation leaking. Your local NTI rep should be able to get the parts for you. If water drips onto the Sentry or Fenwal controllers you will have some expensive repairs to make. The water will also destroy the fiberglass/aluminum insulation on the heat exchanger and rust the insides of the boiler itself. Don’t ask me how i know… ;)

  4. bluelady says:

    I am sooooo disappointed in having a high-efficiency Trinity boiler system installed in my home. I have a 1912 3 storey home that ypgraded my old boiler for a new Trinity high efficiency boiler. Boy what a mistake. I was told that the new boiler would be worry free and maintenance free for many years. Since installation it has been a real headache! I now rent my property, and tenants won’t stay because of the frequency of boiler/hot water failure. I have to provide electric heaters for emergency heat during the winter months. I have spent enough money in repairs/labour that I have almost bought the furnace twice. Don’t know when I should stop and just replace this boiler, but I am a senior lady (62) and only live on cpp. So I can’t afford to replace it. Can’t afford to keep fixing it either. Ive had a ventor motor, and a new flow diversion and many other things fixed. Now i have constant water spillage from the safety relief valve. I need to empty containers of water several times a day. WHAT TO DO????
    i can’t take this anymore! Who do I call to complain, that cares? I lose sleep at night because of this “monster”.

  5. jason says:

    I have a trinity NTI 100 boiler and have noticed that it relitivly quite with the exception while heating the domestic water and runing through its cycle from 160 degrees F to 180 degrees F it hums/vibrates pretty loud compared to all the other heating cycles. Any ideas? thanks

    • Matt says:

      We have run into some instances with some rumbling or vibrating in certain areas of the cycle on a trinity. Dealing with our rep. from the supplier that handles these, he has had us tweak the configurations on them from the gas input value’s to 1 or 2 other things. Haven’t run into this problem in awhile so i don’t exactly remember what he had us do. It is fixable though!!!

  6. RD says:

    I have a BAXI unit similar to this and I love the thing. I installed it myself and have no problems, zero for four years. It saves me a fortune. My bill is as low as 20 bucks for the summer. We have a family home with dishwasher, washing machine, two showers, three sinks, $20 bucks! In the winter, dead of long island winter, $120 through cast iron. It rocks. I can’t believe the story about all the leaks? So many bad plumbers out there with licenses. Like bad drivers with licenses. it almost means nothing to have one. Im a contractor in nyc and long island. I cant trust anyone anymore from experience. I do most of my own plumbing and use a licensed plumber like a secretary. Just for the paperwork. The BAXi units are great.

  7. Matt says:

    I stumbeled across this site after looking to see what people put on the net for reviews. I literally just got done working on one and got home to relax on the couch. I love my job and helping people out with their heating and a.c problems. I work for a heating and a.c company in wisconsin. We install a handful of Trinity’s each year and have been for roughly the last 4-5 years. It’s terrible to hear of all the problems some people have had with these boilers. Im 24 years old and have a very good handle on installing and servicing these boilers. I have installed the Trinity Ti100’s up to the Lx400. From what i’m gathering it sounds like a lot of these people have the Trinity Combi design installed in there homes….Almost everyone of these boilers that the company and I have installed have been used for domesticated water use as well as for home heat. Each one has never been a Combi design. It’s always the trinity with a indirect tank piped in. We have had very few service calls related to this type of set-up and work closely with our supplier to make sure everything is done correctly.

    Don’t know the extent of the problems with these other problems. Maybe they were not installed correctly?? I don’t know, but i am curious to hear if the other installations were the Trinity combi or the set-up like i explained.

    *you always hear from the un-satisfied customers, but never from the satisfied.

    • Blake says:

      I have a T150 boiler that just stopped working the board won’t light up nor will it turn on when heat is called for. Matt where in WI are you located? I’m in twin cities and would be interested in having you come out if your anywhere close.

  8. John says:

    We have a T150 Combi. We get hot warm then cold water. This has been happening since we moved in the newly built home. Any chance any one knows what this is.

    • Jay says:

      See my comment above posted in 2010.
      I would bet your sentry controller is bad. On a brand new T-200 I had the exact same problem you have and tried everything. Then on the recommendation of my local NTI rep I replaced the sentry controller and it fixed it completely. Be warned though, from my experience the sentry controllers seem to last about 5-6 years. Thats it. After 5 1/2 years of perfect operation my boiler started doing the same thing again. Just replaced the Sentry yesterday for the second time and it is running perfectly again,

      Its disappointing that the parts don’t last longer but when the boiler is working it does an amazing job.


  9. Cornel says:

    I have a trinity t200 2001 boiler and I been having problems since day one. I repipe the hole thing again 2 years ago, work good for 6 months then it’s making noise like a whistle and it shuts off . Can anybody give me a hand ? thanks. please reply to my email address.

  10. Deep says:

    January 17, 2013

    I recently moved into a house near Guelph, Ont that had NTI T150 boiler installed for the domestic hot water and heating the house using hot water.

    In less than a year. I’ve had 3-4 service calls from the local Plumbing company. They’ve replaced the ignitor few times along with few other parts.

    Last week the boiler stopped producing heat. I could hear the water draining through the Y pipe into the drain. I suspected it would be the condensation as it is normal for these boilers to produce some water.

    Finally the same blumbing company came back that had replaced the ignitor 2 months ago. I was hoping it was the ignitor as it would be under the warranty. But once he opened up the boiler. One of the heating coil was leaking water, and the heat exchanger needed to be replaced.

    I contacted NTI in NB. So far they have been great. They are replacing the heat exchanger under warranty since it was installed in 2005.

    Now I’m looking for a blumbing company that can help me install this heat exchanger.

    Stay tuned for an update.

  11. Edward says:

    Inherited ti200 in house we bought in 2013. Have replaced multiple igniters, and just replaced flame rod at 4am this morning. Thank god I had spare parts.

    Does anyone know why these things eat ignitors?

    • Todd Fratzel says:

      We have used dozens of these boilers in houses we’ve built….never had issues. Sounds like something else is causing the problem and hasn’t been diagnosed.

  12. Brian Impey says:

    all the same problems. Constantly replacing parts.

  13. hello says:

    Wondering if there is anyone that would recommend a NTI in a 3 unit apartment ?

  14. Arthur says:

    Hi ,I have nti150 last winter I notice that from exhaust pipe steam is coming out call a plumber he came and he didint have an idea what’s wrong no codes show up,boiler working but for me there is nothing related with efficiency I put my hand against exhaust pipe and couldn’t hold.does anyone knows what’s going on?

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