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Tim McElwain, I have a question for you

jdb Member Posts: 22
Hi, you responded to one of my posts in the past, and I can't find it. 

It doesn't matter. I have an old coal boiler converted to oil, that you looked up, and you said it had to be run at a minimum of 100k btus

I asked an oil burner tech to downsize the nozzle from 1 gph to .75 gph, and he said he would have to see what I have. 

Calculations indicate .75 gph would be about 102 btus. So my thought is, it not really down-firing per se.

I want to paste my post (long) below, to refresh your memory. In addition, I want to ask you to give me something to say that will help the service tech feel at ease with the .75 gph nozzle. 

Post below:

@ April 13, 2008

8:23 PM in Oil to Gas boiler


I need some help. I

asked on the Wall about changing out my old cast iron coal conversion boiler to

a new gas boiler, but I did not get much of a response. I notice you're pretty

detailed, so I'll try to be detailed as well. Weil-McLain originally a coal

boiler, size 5-W-19, Series-D. I need to know the size of this boiler in BTUs,

or would like to. Converted to oil in????????? We've lived here since 1984, and

 everything is still the same, no circulator, gravity hot water system, with radiators. (Ed.--cast iron radiators)

The oil gun is a Beckett Models "A", "AF", may be suffixed

MP, 1192 Series burners, 0.4-3.0 gph. A date of 1968 is on it, which is either

the year of manufacture, or the year the model first came out. The nozzle is

rated for 1.0 gph, which computes to 140,000 BTUs/hr. Our house is all brick

masonry, except a small 40 sq. ft. addition to the back, which is framed but

not insulated, 2 stories plus attic, no insulation anywhere. Total living space

 with rads is about 700 sq. ft. (Ed.--actually about 750) The attic is additional and is not heated, but

it stays in the low 50 degrees most of the time, a result of heat loss through

the ceiling, and up through the attic door. It has been converted to living

space, so that heat loss is ok. Problem is, we use 600-650 gallons of heating

oil every year, regardless of any attempts to use supplemental space heating or

any other measures. However, I've been reading up on tightening the envelope,

etc., so have been working on that. I've concluded that the culprit must be the

boiler, and its inefficient gravity system. I've tried to do the heat loss

calcs and EDR, the heat loss seems to be consistent at about 58K BTUs/hr. Allentown,

PA, which has a design day of either 6 or 9 degrees Fahrenheit, depending on

the source, is my location. We rarely have single digits, and the heat loss

calc was done with a 10-degree design day. EDR X 170 gives 41,310 BTUs/hr. The

problem is, the burner nozzle is rated for 1.0 gph, which is 140,000 BTUs/hr.

Not knowing the efficiency of the boiler, BTUs may be hard to determine.

Knowing the size of the boiler would help, if that info is available. Burner

efficiency was listed as 79% in 2003. We don't get it tuned every year, it's

never made a difference. 650 gals./yr., 600 with a mild winter. I asked on the

Wall about swapping out the old boiler with a new gas boiler, and keeping the

inch-and-a-half steel pipes. But I got 1 response, and not a direct one. We may

move in the forseeable future, and want to keep the change as non-invasive and

cost-effective as possible. With oil at $3.669, a comparable amount of ng is

$2.114, approximately. My other alternative was derating the nozzle, insulating

the pipes, installing a vent damper or barometric flue damper. Supposedly the

last item would cost only about $100. I could go for a new flame retention

burner or gas burner, but if I go that far, I might benefit more from a

replacement boiler. Also, a new burner might not work for various reasons (age

of boiler being the most obvious. It could be 75 years old, according to a page

I found online with this exact boiler.) My original question had to do with

choosing a gas boiler that would involve the least amount of retrofitting. An

opinion on derating, insulating (the pipes, that is), dampers, the envelope,

etc. would also be appreciated. I have aluminum replacement sashes with storms,

and just installed door sweeps on the door bottoms. The heat loss calc was done

with the free version from, and was pretty thorough, I think. I'm

thinking, with 41,000 BTUs of radiation, and 58K heat loss, why do I need a 1.0

gph nozzle? Also, the boiler itself and steel vent/flue pipe leading to the

chimney seem pretty leaky. If I were staying here forever, a replacement boiler

would be a no-brainer, and a Biasi with dual-fuel possibilities would be an

option. I apologize for the length of this. Any insight you would be willing to

offer would be appreciated very much. I guess I just need an objective

viewpoint after focusing on this for so long.

I just need to know what it would take to keep this going until we can sell the house. Was also wondering if I have tightened the house up too far. Is this even possible on an old brick house, built around 1900-1920? Boiler is probably the first and only one this house has had.


  • Empire_2
    Empire_2 Member Posts: 2,343

    With all due respect, If your post were any longer, I would need a day off just to answer the question.  It's not only Tim that reads this but all members try to help.  Is there any way to condense you Q? in say a paragraph or so?  We never charge for our advice and are happy to help where ever possible, but the question itself requires much time to honestly give you the answer you seek.  Hopefully, someone can help you out.


    Mike T.
  • jdb
    jdb Member Posts: 22
    Thanks, Peace Man; my bad :)

    Weil-McLain, originally a coal boiler, size 5-W-19, Series-D. It’s “round”. Converted to oil prior to 1984, the year we purchased the house.  

    The oil gun is a Beckett Models "A", "AF", may be suffixed 

    MP, 1192 Series burners, 0.4-3.0 gph. A date of 1968 is on it, which is either

    the year of manufacture, or the year the model first came out. The nozzle is

    rated for 1.0 gph, which computes to 140,000 BTUs/hr.

    750 sq. ft. living space, 2 floors, 7 rooms total, each w/ a cast iron radiator. EDR X 170 gives 41,310 BTUs/hr. Has an unheated attic. Boiler is in basement, and keeps it warm in winter. 

    The heat loss seems to be consistent at about 58K BTUs/hr. Located Allentown, 

    PA, which has a design day of 9 degrees Fahrenheit.

    Tim McElwain said this model needs to run at 100k btus, or 140 with domestic hot water. It does not have a domestic hot water coil.   

    Would like to downsize the nozzle to .75 gph (104k btus), not de-rate or down-fire the boiler. Or maybe compromise, and go with .85 gph 

    Goals—run as clean as possible, meaning less soot, and/or, as one poster described it, kibbles-and-bits. Seems to have k and b’s right now. 

    Burning less fuel would be a bonus.

    So anything a service tech would have to look out for here? The 1 gph nozzle was arbitrary way back when. Since then, aluminum replacement windows were installed, and I have tried to seal drafts, and caulk where possible. 

    Last year, a new energy efficient window was installed in place of the old drafty attic door.The thermostat was kept low, and a space heater was used on the 2nd floor. 

    In sum, 1 gph just seems like too much.
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