Converting Fitzgibbons Oil Eighty from Heating Oil to Natural Gas

KeddyLad · April 2020

Hello there,

I recently purchased a house built in 1926 which is heated by a Fitzgibbons Oil Eighty oil-fired boiler (circa 1930s/1940s). At some point, the original burner was replaced with a Beckett AFG MP1192 oil burner (3 GPH), and the unit vents to an adjacent chimney stack. The draft control regulator was modernized as well. The water temp in the hydronic system is set for around 170 F. The previous owner would burn about 260 gallons of heating oil a month to keep the house warm during the winter months.

I am in the process of having natural gas service installed to the house, and will be doing away with the heating oil system altogether. However, perhaps for sentimental/historic reasons, I would like to try and preserve the old Fitzgibbons and integrate it into the heating system. Before settling down I worked on steam ships and shipboard incinerators, so it would be a fun project not too out of my depth.

The existing burner is bolted to a custom skid, and is inserted into the firebox at the base of the unit. It appears that physical removal and installation of a new burner wouldn't be too technically involved, hence why they had updated it previously. My experience with natural gas burners is limited, hence why I pose the following questions to you top minds:

1) Plain and simple, is a conversion of this sort feasible or just plain ridiculous?
2) What infrastructure would need to be updated as well? I already anticipate needing to run a chimney liner/B-vent down the length of the stack. What considerations for drafting and backdraft need to be taken with natural gas burners?
3) How would one calculate the appropriate size of a natural gas burner in terms of BTU output? What are the dangers/problems of oversizing/undersizing a natural gas burner?

Thanks much for your advice and opinions on this project. Let me know if there is any other information I can provide.

Robert O'Brien · April 2020

pecmsg · April 2020

I like the old as well it really?

Replace the boiler with a properly sized and 85 + or - % efficient unit. Of course depending on your home you could even go higher.

EBEBRATT-Ed · April 2020

Perfectly reasonable. You mentioned the oil burner at 3gph, I think that is the burners maximum capacity. How much is it actually firing? You would have to know the existing nozzle size and oil pump pressure to calculate this. oil is 140,000 btu/ gallon. Gas is about 1000btu/cfh so 3gph (if that is the actual firing rate)=3x140,000=420,000btu/hr=420cfh of gas. That is one approach.

You didn't mention steam or hot water. With steam you calculate the radiation load in BTU/hr x 1.2 x 1.33= firing rate of your burner.

For hot water you would do a heat loss of the house and get btu/hr x 1.2x 1.15=firing rate.

The problem withe the second method (which is the correct way) is you have to be careful to keep the boiler stack temp up above 300 deg to prevent condensation. This isn't an issue with a correctly sized boiler but if your boiler is oversized this could be an issue

HVACNUT · April 2020

A boiler from that era is almost certainly oversized. Probably double. Especially if insulation, window upgrades have been done or will be done.

The first step is a heat loss calculation. Slant/Fin has a free app and you can do it yourself.

Many prefer mod con boilers but I would opt for a cast iron 3 pass oil boiler with a gas conversion burner or an Energy Kinetics System 2000 EK-1 Frontier Gas.
IMO, either is more reliable and repair parts cheaper and available right off the techs service truck. No "We can order it. It'll be here next Tuesday."

Can you post some pics of the boiler? It would be cool to see an oldie still in action.

Edit: Is the burner rated for 3 GPH or is that the actual firing rate? If it's actual and the heat loss calculation is still high, then the EK-2 would be better suited. But do the calculation.

Jamie Hall · April 2020

There is another question here. Is this house in sufficiently intact shape to qualify as historic, and a candidate for restoration, at least in part?

If so, there is something to be said for keeping the old boiler as is -- just not using it. Modern gas boilers are much smaller for a given capacity, and it might well be possible to install a correctly sized modern, mod/con boiler -- even a wall hung -- somewhere out of the way and pipe it into the existing system.

Mind you, this is a very different discussion -- and question -- with very different considerations from just "can I convert the old boiler to gas" (yes, you probably can, but it may not be all that simple -- and almost certainly wouldn't be all that efficient).

EdTheHeaterMan · April 2020

@KeddyLad said "... I am in the process of having natural gas service installed to the house, and will be doing away with the heating oil system altogether. However, perhaps for sentimental/historic reasons, I would like to try and preserve the old Fitzgibbons and integrate it into the heating system.

By this statement, may I make an assumption that your intention is to install a new more efficient gas boiler system while leaving the old historic system in place? That old Fitz... Oil Eighty also was available in Coal eighty and Stoker Eighty. Since your emblem says Oil Eighty the original installer uses an oil burner of his choice. there were over 100 oil burners to choose from in the 1940s and 1950s

If space allows, and the boiler is set up for hot water heating (Not Steam) then you can set up the new boiler and add some isolation valves to keep the old boiler connected while using the more efficient new heating boiler.

Pictures of your old system would help in the design process. there are so many piping options. you may want to remove the oil tank and oil burner. maybe there are some old antique burners in a Wearhouse somewhere. If my son did not toss it, I have an antique that will match that system. It has a really cool "Space Age" removable cover to hide the Webster fuel pump and Webster Electric cast iron motor.

Steamhead · April 2020

@KeddyLad , the "Oil-Eighty" was a horizontal steel fire-tube boiler- kind of a shrunken version of Kewanee, Pacific and similar boilers we find in larger buildings. So it's going to be a bear to remove.

This type of boiler typically had a lot of heat-transfer surface, so it would run very efficiently if properly sized and installed. ISTR it was one of the better boilers you could get in its day.

An ad in the 1947 ASHVE Guide shows what appear to be spiral baffles in the tubes. These slowed down the escaping hot flue gases and contributed to the boiler's efficiency. If I had any money, I'd take a bet these baffles are no longer there. Unscrupulous oil techs are notorious for removing such baffles, since doing so helps their employers sell more oil. We see a lot of this on more-modern units. AFAIK you can still get replacement baffles.

Assuming the boiler is in good shape, it might just make sense to convert it. We'd need a lot more information, such as the house's heat loss from which we could determine the water temperature needed. And we'd need to make sure we didn't reduce the boiler's flue gas temperature enough to cause condensation.

Where are you located?

KeddyLad · April 2020

Good morning gang,

Thank you for the replies, seems like there is wide range of expertise and opinions. I'll try and answer all the inquiries you have:

I live in Northern Nevada, which has winters more similar to Idaho rather than Las Vegas in the south, probably around 6,500 heating degree days. We usually dip below -15 F in December/January. The woman I bought the house from had hardly modified the house in her lifetime, save for some carpet, paint, and wallpaper, so much of the house is constructed way it was 1926. This also means the windows are single-pane and the interior walls are lathe and plaster. At some point the owners updated the insulation in the overhead, because it is all white fiberglass. It will take me a while to run the heat loss numbers on the house, but I will try and get those posted later.

I toured and inspected this house several times in the winter, and the house was toasty. I checked the thermostat and boiler as it was operating, and the thing was a workhorse. That is part of the reason I would like to preserve it; to maintain the historic character of the house and because it works like a champ. It is currently out of operation because we are entering spring here, and I felt that the $1000 I would spend refilling a 500 gal. oil tank might be better served in a burner conversion kit.

It is a hot water system, and as Steamhead pointed out it is horizontal-firetube construction. I'll post some photos of its design as well as the tubes. The spiral baffles are indeed missing. The water temp for the system is set for around 165. The Beckett oil burner currently installed is running either a 1.00/60 degree "A" or a 1.00/60 degree "B" tip. I do not have the figures on the oil pump pressure. The Becket burner currently installed supposedly has a BTUH of between 56,000-420,000.

The firetubes and box need cleaning, and the refractory insulation needs to be redone as well (which is a process I am familiar with). This is in addition to running a liner down the chimney.

I see that Beckett and Carlin make oil-gas conversion burners, are these worth looking into?

Thanks again, for your advice.

Jamie Hall · April 2020

Oh lovely! You are going to have a wonderful time! Do keep the old boiler -- either refit it for gas and use it, or refit it for gas and stick a higher efficiency one in too, so you can use either one.

Lathe and plaster walls. Don't, whatever else you do, replace those with drywall if you can possibly help it. If they are damaged in places, they can be repaired. You may not have that expertise immediately available in northern Nevada, but it's not magic and there's no reason on earth why you can't learn to do it if need be.

Reason being: they are much quieter than dry wall, they last longer, the insulate much better, they look better.

Insulation. You can blow fiberglass insulation into a plaster stud wall, if you want. Do NOT however, use dense pack cellulose or similar, and certainly not foam in place. Either one can break the plater keys, and then you do have a problem.

Windows. Again., like the plater, don't replace them. With a modicum of work (and again, something you can learn to do in short order, unless you are a complete and hopeless klutz, which it doesn't sound like you are) they can be made remarkably tight and yet smooth working. To add insulation -- probably not a bad idea -- you can either use high quality triple track windows on the outside (which have the advantage of having screens built in) or there are several companies which make excellent inside storm windows. Unless you spend many big bucks no modern window is going to equal that.

mattmia2 · April 2020

@EdTheHeaterMan I'd like to see some pictures of those antique burners.

EdTheHeaterMan · April 2020

I'll ask my son if he still has them. @mattmia2

Converting Fitzgibbons Oil Eighty from Heating Oil to Natural Gas

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