Very Interesting site!!!

leo g_13

http://www.aceee.org/consumerguide/topboil.htm

Leo G

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Robert O'Connor_6

Interesting

to note the estimated elctrical consumption!!

I wonder what other criteria besides afue goes into getting a spot on their most efficient list? Ha Ha

thanks for the link

Robert

ME

Paul Pollets

Snake Oil

AFUE ratings are hogwash. Strip off the boiler insulation and efficiencies are increased, by their testing methods. Richard Trethewey wrote the best piece I've read concerning this very matter. Check it out:

http://www.rstreps.com/pdf/efficiency.pdf

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jerry scharf_2

efficiency vs. effectiveness

I vote we stop talking about efficiency and start talking about effectiveness. Getting the heat where you need it in the way that provides the best comfort, that's an effective heating system.

I've seen my fill of efficiency work, and so often it involves segmentation of the problem. You can improve a device X%, but what does it do for the overall system effectiveness?

IMO, how carefully you place and insulate your pipes should count as much as the boiler AFUE. LOL!

jerry

Constantin

Not completely familiar with AFUE,

...however, to call it pure snake oil is probably a bit of an overstatement. As with any standard, manufacturers can twist the results by designing their products to the standard, not to what they know is the better for consumer and environment alike.

The AFUE standard may be just good enough to simply give consumers a relative yardstick. For example, condensing boilers/furnaces have higher scores than comparable-capacity non-condensing units, an efficiency difference which seems to be borne out in real life in terms of operating costs.

Furthermore, when I look at some of the top-rated stuff, it doesn't strike me as chintzy hardware designed for the test. The Opus oil boiler is a beast to move and install, has a very high thermal mass, yet is regarded highly by everyone I have read accounts from. While non-condensing, it offers AFUE efficiencies at least 3 points above that of a V8 or other "run-of-the-mill" non-condensing oil boiler. Yet, when I looked at it, it did not seem to suffer from a lack of insulation.

Where I agree with you however is the actual testing methodology. As you and others have pointed out, it is rare indeed for boilers to be running at steady-state, full bore. This is one of the reasons I hope that even crude modulation will also come to the oil side, not to increase combustion efficiency (which it won't) but to reduce the thermal cycling. Granted, you can work around cycling somewhat by adding a lot of thermal mass (water or iron) to the jacket but then standby losses will also increase.

So yes, the AFUE standard is not perfect. Both electrical consumption and standby losses should be measured and factored in. Furthermore, the boilers/furnaces should be evaluated over the course of a "typical" heating season, not the steady-state system in employ now that makes lab checks easy and "real life" efficiency comparison more difficult.

The sooner the DoE AFUE testing methodology replicates real life conditions, probably the better. However, if my experience in the washer, AC, and water heater industry are anything to go by, then changing AFUE is going to be difficult indeed... The added steps towards "realism" outlined above will squeeze the smaller manufacturers in particular. All manufacturers would most probably trim down their scope of product in response to higher non-recurring-engineering/testing costs... and is that what we want?

Unknown

AFUE

This might help fill in some of the blanks

http://www.eere.energy.gov/buildings/appliance_standards/residential/pdfs/furnrbod.pdf

Noel