Are the AFUE ratings outdated for hydronics? Help, I'm confused!
While researching quotes and info for a new natural gas-fired boiler for my 1700 sq. foot home; I was referred to the Brookhaven Study which was done by NORA, the National Oil Research Association. According to this study, also funded by the New York State Energy Research and Development Council, the reality is that in hydronic heating and hot water systems, the AFUE number does not reflect the true energy efficiency. According to these guys, standby, jacket and draft losses can account for as much as 20-30 % efficiency losses which is not accurately reflected in AFUE ratings. If you google Brookhaven Study you can read the findings. Anyone out there want to comment?
I would like to use this information to make an educated decision about purchasing a new natural gas boiler. According to the study, I should shy away from an atmospheric vented cast iron boiler which will only really truly achieve an efficiency of about 68 %. The mod/con boiler with outdoor reset and indirect water can expect a drop in efficiency of 12% bringing the true AFUE to about 84%.
The study also advocates beginning a new system of labeling efficiencies by taking into account both water heating and space heating and combinging the numbers for a single efficiency. This new info would assist both contractors and consumers in making decisions about purchasing.
My conflict is that the atmospheric cast iron boiler with indirect (Buderus) will cost me about $5K installed and the Buderus wall-hung mod/con will be about $8500. If you try to figure a true R.O.I for the high-efficiency boiler, the payback is too long! My cheap husband wants to go atmospheric! Help, please, anyone! Thank you!