Burnham ESC vs. Combi Wall Hung

rennie179

I'm looking at a renovation where the homer owner is removing the existing chimney to make way for a kitchen renovation. Here is the question, I'm proposing a pairing a Burnham ESC boiler with a Super Store SSU-45 indirect storage tank for domestic. On the heat side I need 140,000 input / 120,000 output . Two full baths, washing machine, dishwasher, laundry sink, and a proposed 3rd full bath in the future. I'm also looking at the Navien NCB 240 combination condensing wall hung boiler. 120,000 net for the heat and a max of 4.5 G.P.M. at a 77 degree rise for domestic. I'm also toying with the idea of using two separate Navien's, one for heat only and one for domestic  I'm looking for all opinions on this post. I'm somewhat of a traditional old timer and if it were not for the removal of the chimney, the existing Weil-Mclain CG boiler and 50 gallon gas water heater I installed seven years ago are working flawlessly. What would you do? Regards, and thanks Bob.



P.S.- Family consist of a Mom and two teenagers, one boy / one girl.

Ironman

Heat loss?

What's the heat loss of the house? Has a load calc been done?



We always recommend doing one and sizing the boiler to that, especially a mod/con. Otherwise, you'll have a short cycling problem. Just a simple calc of the entire envelope is sufficient for sizing the boiler. Modern boilers are low to medium mass and over/sizing will greatly shorten the boiler's life as well as efficiency.



Don't size it based it based on domestic, unless it's a combi like the NCB.



Also, the NCB can be twinned with an NR, but I seriously doubt that's needed for the load you've described.



On other caveat: depending upon the type of emitters and the water temp required, you may not get the full 120k for space heating as the on board pump will only deliver 4.5 gal. for space heating also. (4.5x500)x20* delta T= 45,000 btu's.



120k btu's would be enough to heat a 4000 sq. ft. house that's not well insulated. Is the house anywhere near that size?

CMadatMe

Agree With Iron

But may I add one thing....What's in those 2 full baths? Human car washes or just regular shower heads? I also never understood why one would add another energy user when one piece of equipment could do the job.



Could the Navien provided 120,000 btu/hr for heating? Yup sure can but at what what water temp? The on board circ can only move 5gpm across the HX. so that heat loss Iron was talking about is critical and so is measuring and calculating emitter capability..