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Posted by Joe on February 16, 2004 at 20:43:45:
In Reply to: Re: efficient oil furnace posted by keith on February 16, 2004 at 17:44:46:
Keith: Heatwise makes a residential hi/low firing burner, but I think the Monitor FCX is the only boiler maker using it. Problem is if designed oil boiler is built to put out X BTU's for the highest efficency, downfiring it only risks condensation which will soot up the boiler. There are a few steel boilers that are up-sized with just a larger firing burner, but usually performance suffers. So radiant systems, are always set up with mixing or injection to reduce the water temp. Not realy a bad thing. Hopefully the boiler will just cycle less as the BTU's are sucked out of the hot water. But K1 cost more and gives you less BTU/gal so you're killing off the price advantage for oil. I don't think manufacturers want AFUE ratings for modulating gas boilers since they would probably have to be tested at 180 degrees where they are not at their peak efficency. As Harold said, the difference between 87 and 92 is very small when compared to the install cost. That's what will take years to recoup before the cost of fuel comes into play at only a 5% eff. difference. If a $2.5K wall hung combo unit will out perform a high end oil boiler, indirect tank, and mixing controls at double the hardware costs alone, it will be a while before you can compare the extra $.020/gal difference for the LP.
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