90% vs 80%

Steve Ebels_3

80 vs 90 goes like this.

The MINIMUM efficiency of a 90% boiler, even at high water temps, will be greater than the MAXIMUM efficiency of a standard boiler. Now add to that the fact that many 90% boilers feature modulating burners that track the load and adjust the firing rate accordingly and you pick up additional % points over the rated AFUE. Which, BTW does not tell the whole story on available energy savings. Many of the regulars here on the Wall report energy use reductions in the 35-40%+ range when the AFUE is only 5-10 points different.

As for life expectancy, there is no doubt that Cast Iron is usually more forgiving than some of the alloys found in the current crop of condensers. There is also no doubt that a condensing boiler, as with any high efficiency heating appliance, requires more maintenance as a rule. I would think that this is especially true in those boilers with aluminum blocks.

The one condensing boiler that truly stands apart from the crowd is the Vitodens from Viessmann. Totally different burner design, fully integrated control package and heavy gauge Stainless steel HX are the most pronounced differences. Given normal care, I would expect this boiler to last exceedingly well in field conditions.

PS: Go to the "On the Job" section on the left side of the page and read the Vitodens evaluation written by Mike T.
You can also check out the Viessmann vs Furnace story that I sent to Dan. The boilers I used for that particular job are not condensing but not really a "standard" boiler either. We dropped that particular customers usage by around 40% if I recall correctly. Also, for an example of the benefit of a modulating burner, pay attention to the run time hours on the two boilers we installed on that project. You RARELY need the full output of your system.

Jim_5

90% vs 80%

Do the 90% eff. boilers really save you money over 80% eff. models? I've heard unless your heating with low temperature water In the ceiling, or in the floor the savings aren't much, if any. In this area, with very few boilers. No one seems to be installing the high eff. models. What is the truth

Tony_23

90 %ers

are leaps and bounds above 80's.

That being said, proper installation is key, and installer comfort is also important.

Did you try "Find a Pro" ?

ryan_7

in the long run

How long with the condensing boilers last. The cast iron boilers I am putting into day I do not plan on replacing in my lifetime. (I am 43 years old) That said we sell warm air too, and I rarely install 80% efficient furnaces anymore.
I have sold quite a few of the Burnham Revolutions (87% efficient CAST IRON) I have noticed on low temp applications it makes condensate, but on high temperature applications I do not see much. Thats my two cents worth.
Ryan

hr

That Burnham Revolution

is not a condensing boiler. It is a basic cast iron with an on board mixing system. And actually I think they run fairly hot, around 210° to be able to mix and see 70° return temperatures.

It a good boiler for those that don't want to screw with mixing controls, and it makes DHW very well with that high block temperature.

I doubt it is much more efficient than any basic sealed combustion cast boiler. Certainly not near the efficiency of a condensing boiler seeing 70° return temperatures

hot rod

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Steve Ebels_3

Revolution condensate?

Where exactly are you seeing this condensate? That boiler is designed with an internal bypass circ and control to keep it from condensing. If you are getting condensation, you should get the situation corrected before it ruins the boiler.