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Heat Source Selection help

silverlex Member Posts: 5
edited February 2019 in Radiant Heating
HI all - I am in the process of building a new home and i'm under the gun to select a heat source for the in-floor radiant (Basement slab and garage) as well as DHW. We laid 2700ft of 1/2 pex in the slabs (9 in the basement and 3 in the garage), each is a separate zone. We have 2" XPS foam under all of it. We're located in the Midwest (Kansas City area). I have done a heat loss calc and come up with around 30-33k BTU requirements for the basement and garage. The house is a reverse 1/2 story (4k sqft ranch style with finished basement) and will have a 93% forced Nat Gas furnace for primary heat (the radiant is to make sure our basement is nice and usable in the winter, and my wife and I like to use the garage for various projects). We have 3 people in the family (myself/wife and daughter).

I started this project with the intent of being cheap and picking up a quality tankless water heater and plumbing it in for boiler duty, i know plumbers hate that (and for good reason) however it does seem to be successful to a degree, and the cost to replace tankless units is fairly cheap compared to a boiler. Especially with DYI installs/maintenance. I decided i might as well heat our DHW with this unit and started down the rabbit hole of Combi/Indirect/heat exchanges and so on.. and made the decision to start looking at boilers to do it right. After reading about how many mod/con and combi's fail after 3-4years I may just go back to a cheap tankless with heat exchanger and call it a day :pensive:

I'm looking at 50-80K range (with ideally a 10:1 turn down so i wont short cycle and blow through fuel) and premature wear and tear of the machine. That should give me plenty of power for the radiant and DHW.

Here's what I'm looking at - the HTP/Westinghouse being a clone (although i cant find the HTP readily available online at the moment). I have a heat only option (using a closed loop setup, i assume this should be fairly reliable and minimal maintenance since I plan on using distilled water in it. I'm not opposed to doing the annual maintenance on the combi's.

Heat Only (with 30-40g indirect)
HTP - UFT-80W (10:1) 8-80k BTU Direct plumbing recommended with easy indirect tank option.
Westinghouse - WBRUNG080W (10:1) 8-80k BTU Direct plumbing recommended with easy indirect tank option.
Laars - MFTHW-80 (5:1) 16-80k BTU Primary & Secondary plumbing recommended
Navien - NHB-80 (10:1) 8-80k BTU Primary & Secondary plumbing recommended
Navien - NHB-55 (10:1) 8-55k BTU Primary & Secondary plumbing recommended

Combi (Heat & on-demand dhw)
Laars - MFTCW199
Navien - NCB-240E (heating 18-120k btu) (dhw 18-199k).
Noritz - NRCB199 (heating 18-120k btu) (dhw 18-199k).

Traditional Tank option
AO Smith - GPHE-50 (50 gallon with 75k BTU input)
Laars - LCH-75T10BN (75 gallon with heat exchanger and 75k BTU input)

I've read many things about how people hate navien.. and also how so many of the issues are maintenance and install issues.. I've also read poor reviews on just about everything :smiley: so what should i do?



  • SuperTech
    SuperTech Member Posts: 1,854
    edited February 2019
    If you want something that will last longer than a mod con I would look into an Energy Kinetics boiler with a gas burner. Near 90% AFUE. No need for primary secondary piping (but I would anyway), efficient DHW production, easy to service. They seem to chug along forever even when they are neglected.

    Whatever you do please don't put in one of those open loop Takagi systems.

    I've read bad reviews on every boiler, what matters most is ease of service, availability of parts and the warranty. Don't buy something that your local suppliers don't carry parts for if you are buying something with model specific parts that may fail.

    Im not a big fan of combi boilers in general, I'd rather see the use of an indirect tank. I've worked on plenty of Navien boilers and I haven't had too much trouble with them. Not sure about longevity, but people buy these because usually they are the least expensive option.
  • silverlex
    silverlex Member Posts: 5
    No open systems :P Takagi or otherwise :)
  • Jamie Hall
    Jamie Hall Member Posts: 20,401
    I'm going to climb out on a limb here and say not to worry about what you read about mod-cons having a short and unhappy life. Some do, granted. The better ones don't -- with one major caveat: maintain it. If you don't maintain your boiler, it's going to be unhappy. If you do, 10 to 20 years is not unreasonable to hope for.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • pecmsg
    pecmsg Member Posts: 3,526
    Like everything else the instillation is Key. Over-sized, bad piping, not looking at the pictures = short life.

    Issues with the water quality then address them don't mask them!
  • SuperTech
    SuperTech Member Posts: 1,854
    edited February 2019
    > @pecmsg said:
    > Like everything else the instillation is Key. Over-sized, bad piping, not looking at the pictures = short life.
    > Issues with the water quality then address them don't mask them!

    I have no doubt that with a quality mod con, if it's sized correctly and installed properly and then serviced properly annually will have no trouble going 20+ years.
    Water quality is often disregarded and we put up with whatever is available. I'm hoping this will change and filling the systems with distilled water will become more common. I'm hoping that installation of dirtmags increase more as ECM pumps become standard as well. I have yet to see a dirtmag or ECM pump in the field. Of course I have mine..😉
  • DZoro
    DZoro Member Posts: 1,048
    Lochinvar Noble is a great boiler, 10:1, fire tube, ODR, Install it properly and it will serve you well.
  • Gordy
    Gordy Member Posts: 9,537
    Out of your listings an HTP uft would be mine. Also you won’t find the HTP online. The westing house rebranding is at Menards, but they only carry the combi version.

    As others have said a mod/cons short life is due to neglect. You must follow the installation instructions, and pay close attention to the system water chemistry in that it falls with in the manufacturers guidelines. It’s really that simple. The manual even has pretty venting, and piping pictures.

    Which is why they get a bad rap. Those that fail early were always from someone not following instructions.

    Will they out last a CI boiler? Maybe. CI boilers are not as heavy as they use to be. Use to be they could last 40 years, or more. Now 30 is about it.
  • silverlex
    silverlex Member Posts: 5
    edited February 2019
    Thanks all - I guess i have to remind myself that only the people with negative things to say generally write reviews, I'm sure there are plenty of satisfied customers out there. I absolutely understand following manufacture piping recommendations (plumbing and venting). I also understand the maintenance needs (you cant ignore these like most do with a traditional tank water heater).

    Any thoughts on Mod/Con with indirect vs combi vs the tank? I like the HTP/Westinghouse because of the easy indirect tank (and low head of the firetube hx), plenty of standing water for DHW too. Downside i guess is I have to buy an indirect tank which adds about 1k. Anyone have a good indirect tank they recommend?

    Combi looks attractive since its essentially an all in one, but the complexity and potential repair issues cause me to hesitate. I'm not too worried about the hot water sandwich issues - I could always add a 6Gal tank if front if its a problem. We also arent a heavy DHW user but we do have a large master tub which is about the extent of it.

    The vertex tank looks interesting, 75-100k BTU, easy standing 50-75G DHW and fairly simple radiant via side port HX.

    I know you dont talk $ but it looks like cost wise the cheapest is the Combi --> Vertex --> Mod/Con + Indirect. probably in the order of reliability too :smiley: thoughts?
  • Gordy
    Gordy Member Posts: 9,537
    Well you can look at it this way. If something happens to the boiler a tank of hot water will get you a little farther than none at all. As far as combi verses indirect.

    A combi will be oversized compared to the heat loss to give good output for hot water production.

  • SuperTech
    SuperTech Member Posts: 1,854
    The over sizing, reliability and high maintenance issues make the combi the least attractive option. I'd definitely consider the indirect tank as the best option.
  • DZoro
    DZoro Member Posts: 1,048
    The nice part of a Lochinvar Noble is that you can Take a 150,000 on demand water heater, and turn it into a 15,000 btu boiler.
    40 gallons of hot water in a tank doesn't go far when the heater is broke either.
    Yes any and all appliances should have a annual cleaning, IMO.
    Just some food for thought
  • Gordy
    Gordy Member Posts: 9,537
    No the tank doesn’t go far depending, on tank size, and storage temp, but it’s something verses nothing.

    Murphy’s law it will happen right around shower time in the morning. At least someone will be happy :)
  • silverlex
    silverlex Member Posts: 5
    Does anyone have an indirect tank they would recommend? Here's some I've found, no personal experience with them, any thoughts?

    HTP SSU-45
    Crown MT040GBR
    Williamson GL-42-W
    Heat-Flo HF-40
    Triangle Tube SMART40