New HTP Combi Boilers EFTU-199WCN vs ELU-199WCN

[Ashwin]

Hello,

My plumber is recommending the HTP Combi Boilers line for our home to replace a non-functional water heater and 40 year old cast iron boiler. HTP has come out with two new systems where the difference seems to be in the heat exchanger material in use and design.

EFTU-199WCN
ELU-199WCN

Does anyone have any experience with the above products and a recommendation to go with one or the other? From what I have read so far the larger tubes in heat exchanger for the ELU line seem to be good thing to lean towards but I do not have enough knowledge to make a decision as of now. Thank you!

 

[Fitter30]

Have no experience with this brand. ELU horizontal burner 11/1 turn down enhanced stainless heat exchanger, wifi capable.
EFTU vertical burner 10/1 turn down burner design has been around for 20 years ( different brands)
What i would want to know what boiler your plumber is more comfortable with and any factory training. Supplier do they stock parts for both, do they have factory service trained person. Plumber replacing any pumps? Are they a ecm pump ( energy efficient pump motor). All condensing boilers 95% efficient return water has to be 130* or below. 86% if water temp is above.

 

[Sponsor]

 

[Ashwin]

Thank you, fitter30. Plumber seems to be Ok with both and says you cannot go wrong with either option. I am looking for a more technical reason to go/ not to go with one unit vs the other. The unit will be installed in Massachusetts. HTP's manufacturing plant is based in MA as well so plumber says getting parts is very easy for their products and supplier has parts readily available. Yes, they both come with a built in ECM pump. Plumber says he has had issues with Navien's he has installed and likes HTP better.

 

[Dana]

Is the system broken up into heating zones? What type of radiation (and how much) on each zone?

The total water volume of the EFTU-199WCN is 2.8gallons (~23lbs), the ELU-199WCN has 2.7 gallons (a half pound less) which isn't a whole lot of thermal mass to work with compared to a cast iron beastie when serving low-mass low-emittance radiation. If the place is micro-zoned to the nth degree with fin tube baseboard or similar it's possible to short cycle these combi-boilers into low efficiency and an early grave.

Since you have a heating history on the place, use the wintertime-only fuel use to ballpark the whole-house heat load, and measure up the radiation zone by zone to assess the short cycling potential at condensing temperatures. With the design load numbers and total radiation size in hand you'll have a starting point for setting up the outdoor reset curve for maximizing efficiency & comfort without short cycling.

Note, the ELU series has water tube heat exchangers, with a higher pumping head than the EFTU fire tube heat exchanger. As a drop in replacement for a (usually very low pumping head) cast iron boiler the EFTU will have fewer system design changes to attend to, but a competent designer can get good results with either.

Navien's fire tube boilers & combis don't have the same issues as their water-tube heat exchanger versions. The NFC200 is pretty similar to the EFTU-199 in most respects, and shouldn't be discounted despite the heat exchanger problems with their water tube wateer heaters/boilers/combis. The NFC heat exchangers have 4.5 gallons (37.5 lbs) of thermal mass to work with, and might perform better to the ELU/EFTU combis in low mass multi-zoned systems.