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
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
so what should i do?