Oversize steam boiler

RonWHC

I believe his boiler is the 19. The predecessor to the 19A. About a gallon less per hour. Below the rated 702 input.

If so, it came w/ the older 301 CRD Carlin, w/o the pressure augmenter. 100# to the nozzle.

If memory serves, this job is screwed. High stack temp w/ 50% input. He needs a pro.

Steve Garson_2

Oversize steam boiler

Our building had a Smith Model 19 6-section boiler. The EDR calculations indicate that it just needs a 3-section. Replacing this boiler is an expensive proposition.

Today, everything works fine, with the exception of our oil bills: 5500 gallons/year.

Is there any way of estimating the savings we will gain with a properly sized boiler so we can make a better decision on what the return on investment might be?

Thanks,

Steve

nicholas bonham-carter

revenge of the giant boiler

i wonder if any steamies here would consider the posibility of using a modulating burner in this situation to even out the disparity between boiler size and the edr of the rest of the system.
when in doubt--modulate!!--nbc

Steve Garson_2

My thinking is that there is an additions 28 gallons of water that is not needed, in addition to all the extra iron. All this needs to be heated for every steam cycle. But what does this really mean in energy consumption.

The firing rate is 2.5 gph.

Brad White_185

Cycle Losses of Excess Water

Your "extra" 28 gallons of water (233.25 call it 233 lbs.) would require 33,550 BTU's to raise it from 68 degree room temperature to 212F, the boiling point.

The oil required would be about 0.3 gallons worth but at your firing rate of 2.5 GPH, that temperature rise would occur in about seven minutes if my math is correct.

Consider that during a colder spell, the water will not go back to 68 degrees (artificial basis point), but may well start from 180 degrees or more, especially if domestic HW comes off the boiler maintained at that temperature. Thus your cumulative expense will be less over a given season.

I suppose you could "bin-method" calculate the annual energy used; so many hours at certain outside temperatures, each with an assumed baseline water temperature. (Hotter in cold weather and cooler in mild weather because the time between cycles is longer.)

Your steam output is not affected, meaning that what leaves the boiler is what has that additional 970 or so BTU's per pound. The water remaining in the boiler is just bubbling away, maintained at temperature but is not changing state.

Steve Garson_2

Brad:

There is no domestic HW on the boiler. Is the long and short of it that I should just keep the boiler as it is, that the inefficiency of the oversized boiler is not enough to warrant replacing it the right size boiler?

Steamhead (in transit)

Steve, check with Smith

not sure what burner you have now, but the 19A-6 has the Carlin 702CRD available as a factory option. IIRC, this burner offers lo-hi-lo firing, so if the combustion numbers look good you could really drop the firing rate after the system has warmed up and pressure builds past a couple of ounces. This would save a lot of oil.

That boiler is rated to fire at 6.5 GPH, so I'll bet it's heating up very slowly at 2.5 GPH. Lo-hi-lo would help get around this.

Also- have you checked the pump pressure being supplied to the nozzle? Many burner specs go beyond the old 100-PSI standard- some to 300 PSI and more. So that 2.5-GPH-rated nozzle might be firing over 4 GPH.

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Steamhead (in transit)

Which

is why I said to check with Smith. They'd be able to say for sure what Steve's options are.

If he has the original 19 and that boiler is pressure-fired, as the current 19A is, the burner's firing capability is decreased since it can't move as much air. On the 702CRD, according to the Carlin manual, the maximum rate for high fire at .1 positive draft drops from 12 GPH (at zero pressure) to 11.6 or so. So it might be able to squeak by.

But with lo-hi-lo burners coming out in smaller capacities (Carlin just released a residential model, can't wait to get my hands on one) if the 702CRD turns out to be too big for this boiler, we shouldn't have long to wait for a good lo-hi-lo burner that will work in it.

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RonWHC

The new

lo-hi-lo residential Carlin only goes to 1.5 GPH. Turndown 2:1 or less. Air controlled by varying motor speed. Atomization is enhanced by heating the oil. And. The heater is not your everyday oil pre-heater. If you're going to get your hands on one - you'll have to buy the boiler, furnace, or water heater. No retrofits. This is not just a smaller cousin to the 701,702,801 CRD, etc. A different animal indeed.

Carlin had a 450 FFD lo-hi-lo (4-9 gph) in the 70's. No one bought them. Too expensive. Maybe higher priced fuels will get burner manufacturers off the snide. Then again, it took 25 years for Carlin to take Len Fisher's 801 Gas-Oil off the back shelf, & push the new 702GO thru UL.

Did I say UL? There is one of the biggest road blocks to innovation we face. A huge reason the Euros are so far ahead of us.

Steamhead (in transit)

I've told our Carlin rep

that I could sell these lo-hi-lo burners right off the truck to our steam customers. With the burner, a Vaporstat and some wiring, and proper setup to get the combustion parameters and turndown just right, it would save a lot. Those systems would just simmer along on low fire after the pickup factor was satisfied, just like they did on coal. We have a customer with a large Broomell system who has documented 40% fuel savings after we hooked up a lo-hi-lo setup that the original installer ignored.

Carlin is really missing a HUGE business opportunity if they don't make the new burner available as a retrofit. But if they blow it, someone else would likely step in.

I'll have to ask about the 450FFD next time I talk to him- never seen one, maybe fuel wasn't expensive enough then. That's no longer true!

Also, I think in Europe there actually is a standard-setting body, something like UL- I think it's called TUV but am not sure.

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Peter Zelchenko_2

I have the Carlin 301 burner. I called an engineer at Smith and he told me that the old 19 is the same as the newer 19A.

I read with interest your comment about a hi-low-hi burner. There is a gas version available today that has the correct capacity. Would this be beneficial for our installation? The total replacement of what today is a working boiler appears prohibitive based on the first quotation that I received. I just want to figure out how to somehow reduce our 5500 gallon annual oil usage. The gas meter is fifteen feet from the boiler.

RonWHC

Converting to

gas will take care of the oil usage. Won't do much, if anything, for boiler efficiency. Bottm line. Get a new boiler w/ whatever fuel you want.

When talking to factory reps, ask them to dig out the pertinent books, not just dial up the 'puter. That is - if they have any books.

Peter Zelchenko_2

I think this thread has diverted from the original question: what kind of additional efficiencies can I roughly expect by downsizing to the correct size boiler with 28 gallons less water. It will be essentially the same style boiler, just three less sections?

For instance, if I use 5500 gallons this season, would I use 20% less, i.e. 1100 gallons less equal to $3,500. Then if it cost $25K to replace, I have a better sense of the pay-off.

I need a sense to determine whether it is worth the investment.

Paul_11

just remove 3 sections and replace the burner

If the boiler is not very old and in good shape you could just remove three middle sections and you have a 19-3.
You wouldn't have to buy a new boiler.
You would have to replace the burner with a smaller one.

In terms of the savings, I don't have the math worked out, but your talking about a boiler half the size of the old one. The savings will be huge and definitely worth it.
This is especially true if you are doing the work in your own building as you imply.

paul

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mark ransley

What is run time on the coldest days.

Steve Garson_2

Mark:

I haven't a clue what the run-time is on the coldest days since I haven't been there for the occasion. The K-Factor is 1.13. Based on the oil usage, for the period 2-28-08 and 3-18-08 it used 491 gallons which is an average of 1.01 gallons per degree day.