Jonathan
I don't think we are in disagreement at all . My point
was that FWH's produce better thermal efficiency. That
does translate into fuel and water saving, but it also
means for a given size boiler you get more out. Thus
for hard service, be it harder grades, bigger loads or
faster trains, it can do the job.
One thing you are leaving out of your well reasoned
piece, is that most of the class O-3's had exhaust
steam injectors (sometimes called "poor men's" FWH).
In fact, Elesco sold their exhaust system injectors as
"open feedwater heaters".
As a futher note, the Mechanical Dept. performed many
tests and studied the various alternatives of design
in making these decisions. This is one the things for
which the dynometer car was used.
Another factor in all of this, was the state of the
art. Reliable FHW's became available in the early
20's. So many engines were retrofitted.
John D. Mitchell, Jr.
--- jonathanharris@e... wrote:
> John and Scott,
>
> Many thanks for your postings. It sounds like you
> both know a lot more
> about steam engines than I do. I apologize for
> taking so long to respond
> and even more for the monstrous length of what
> follows (anyone who just
> wants "the bottom line," please scroll down to the
> last 2 paragraphs; those
> of you who love plumbing, grab a lunch and read on).
>
> After thinking about it, I still am not persuaded
> that the most important
> benefit of feedwater heaters was fuel or water
> savings. I do get what you
> are saying. I'm sure it's the majority view; in fact
> I think it's exactly
> the conventional wisdom against which I was arguing
> in my last posting.
> Don't misunderstand me; I agree with all your facts.
> The increased thermal
> efficiency FWHs provide is undeniable; and as you
> rightly point out, that
> translates into savings of fuel and to some extent
> water -- which then
> allows trains to operate with fewer servicing stops,
> thus faster and more
> efficiently. But I suspect that's not the whole
> story, or maybe even the
> most interesting part of it.
>
> If you were to ask me, for example, why I flipped on
> the light switch in a
> room at 3:00 a.m., I wouldn't say it was because an
> incandescent bulb can
> illuminate the dark space at low cost. Factually
> true though that may be,
> it wouldn't tell you anything very useful about my
> motives. Somewhat the
> same problem with citing themal efficiency or fuel
> savings as the reason
> for using feedwater heaters. It begs the question of
> WHY the Burlington or
> any railroad used them as they did (when, where, and
> on which
> locomotives?).
>
> John anticipates this objection when he cautions
> that the expected savings
> had to be greater than the capital cost of
> installing, plus the ongoing
> cost of maintaining the FWH system. And
> theoretically he is right, but that
> raises the tricky question of how to measure
> savings. In reality, a lot of
> considerations probably came into play when deciding
> when to use this or
> any improved technology on new or existing engines.
> Some important costs
> and benefits may have been perfectly real but less
> tangible and
> quantifiable than, say, the price of coal consumed.
> If the addition of FWHs
> helped reduce the need for double-heading, for
> instance, or of purchasing
> new power, or if they just helped trains keep to
> faster, more competitive
> schedules, they might be considered worthwhile even
> when they cost more to
> install and maintain than they saved in fuel.
>
> It's often the case that people (and companies) make
> economic decisions for
> reasons other than the obvious, stated ones
> (economists worry about such
> questions all the time, and some even have won Nobel
> Prizes for figuring
> out the "reasons behind the reasons" for people's
> economic behavior). In
> the case of steam technology, the choice of which
> extra appliances to add
> to new or existing engines, like any management
> decision, undoubtedly took
> into consideration information that was coming in
> from all over the
> corporate structure -- from the accounting
> department at one end to the
> shop foremen and engine crews at the other. Only by
> looking at the overall
> pattern of how the railroad actually used -- or did
> not use -- feedwater
> heaters can we get a fair sense of what they really
> thought were their most
> important benefits.
>
> The 1935 List of Assignments in Corbin and Kerka
> (Steam Locomotives of the
> Burlington Route, p. 292) gives us the chance to do
> just that. As Scott
> notes, Corbin and Kerka's 1935 list has a wealth of
> information on how
> engines were equipped with various steam
> technologies, and geographically
> where those engines were used. It thus provides a
> snapshot of the
> Burlington's decision-making process at one point in
> time -- a very useful
> snapshot, too, since it was a time when steam power
> was used in almost
> every "niche" all over the system.
>
> So which engines had feedwater heaters? Well, most
> obviously, newer, larger
> engines -- just what you would expect. Big engines
> used the most fuel and
> water, and they probably ran up the most miles too,
> so the savings would be
> greatest, right? True, but bear in mind that
> feedwater heaters were not
> included on new engines until the mid-1920s (the T-2
> mallets are a special
> case; they were built in 1910 with a split boiler,
> which provided a kind of
> internal feedwater heating system). None of the
> mikados or Santa Fe types
> built before 1925 had FWHs when delivered. None of
> the Pacifics did, nor
> did the original B-1s. I think the B-1As (1925) may
> have been the first to
> have them included by the manufacturer, and
> everything built afterwards --
> the M-4s S-4s and O-5s -- had them as standard
> equipment. On all other
> classes, however, they were retrofitted during the
> 1920s and 1930s.
>
> Or not -- raising the question of which engines were
> upgraded with
> feedwater heaters, and why?
>
> Again, as you would predict, larger engines tended
> to be upgraded, smaller
> engines not. The cut-off point for freight engines
> was about the 2-8-2.
> Most mikados had received feedwater heaters by the
> time of the 1935 list,
> but a significant number (almost one third, in fact)
> had not, and what is
> more interesting, many never would. Almost
> everything larger than a 2-8-2
> was FWH-equipped by that time, though there were a
> few outstanding M1s or
> M2s still using injectors only (interestingly, most
> of those are listed as
> stored unserviceable, which tells me they were
> awaiting major shopping and
> were about to have FWHs added; or they were about to
> be retired). No
> smaller freight engines are listed as having FWHs.
> No consolidations,
> prairies, ten wheelers or moguls. And no switchers.
>
> For passenger engines, the cut-off point was the
> Pacific. Smaller passenger
> engines -- e.g., Atlantics, ten wheelers, and
> prairies -- used only
> injectors (I have seen at least one photo of a
> prairie with a Worthington,
> and there may have been a few other exceptions, but
> this was the broad
> pattern). The overwhelming majority of Pacifics
> (over 90%) were equipped
> with FWHs by 1935. All heavy Pacifics, Mountains and
> Hudsons had them.
>
> What does this pattern tell us? That more fuel is to
> be saved with larger
> engines? Yes, but it's far from a perfect
> correlation. Does an O-3 drag
> freight engine working tonnage at a tractive effort
> of 60,000 lbs really
> use less fuel and water than a light passenger
> engine like an S-1A
> (tractive effort 31,000 lbs.) pulling a 5-car train?
> I'd doubt it. Yet all
> the S-1As were equipped with feedwater heaters,
> while a large number of O3s
> (as well as some O2s and many O1s) weren't. Indeed,
> if we include the
> "out-of-service" engines, the percentage of all
> 4-6-2s without feedwater
> heaters (8%) was lower than the percentage of 2-8-2s
> (30%) or even 2-10-2s
> (13%) equipped with only injectors.
>
> Let's think about this from a different angle for a
> moment. As John and
> Scott have explained, feedwater heaters save energy
> and thus fuel by using
> waste heat (e.g., in the smokebox) to preheat water
> before
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