What old boiler(s) left this floor imprint?

D107

I've learned as much as I can about my 1924 house. The floor imprint has me curious. (see photo). I know first boiler was coal, probably changed in the early 50s to oil. The circular pattern has me guessing oil burner. Large imprint coal boiler, rectangular imprint oil boiler? WM was put in 1981. Possible to discern any particular boiler companies?

Jon_blaney

What does the ceiling look like above the imprints. Any sign there was any grating or grillwork?

D107

See attached photo. Can't say I see any signs of that. What would the purpose of grating/grillwork be? I know this was an old gravity system re-piped in 1981.

ratio

It looks like the footprint of an old gravity air furnace. If there are signs of ductwork, it could have been one of the air/water combos, I think we saw pics of one here in the last few months

JUGHNE

Ducted gravity air furnace would leave a lot of holes in the floor.
Not necessarily directly above the furnace.
Supply air usually came out of inside walls.
Return air usually were around perimeter under windows and sometimes were boxed down to tunnel under basement poured floors. The tunnel then came up directly under the furnace.
The supplies would have been huge by todays standards; 12-14" round pipe. Though the hole in the floor may have only been 3.5 x 14" between the studs of an inside wall.

They may had upgraded to gravity hot water as some point or had the combo for maybe 2nd floor rads or DHW as Ratio mentioned.

Steamhead

Looks like the imprint of an old round coal-fired boiler, also known as a "snowman". The small round imprint was the base of an oil burner that was used to convert the coal boiler to oil. That setup was probably no more than 40% efficient on oil, according to one of my Dead Man's Books.

D107

Steamhead's boiler idea seems right--no signs of hot air heating here. All rads are old US Radiator Co. 3-column Triton. But not sure if all 'snowmen' are hot water or steam. No sign of steam heat here either. All risers are embedded in wall--though Dan's book says Tritons can handle steam or HW. Don't know how well steam mains can be converted to gravity fed system. Also used to be an expansion tank up in the attic. I suppose it could have been steam originally but then why change it--folks who lived here back in the day didn't have alot of money.

Steamhead

It's always been hot-water. They made snowmen for both.

D107

@Steamhead Thanks, just so I understand:
There are three imprints shown in my photo in the first post of this thread. The large outline (52" wide, 58" deep) seems way too large for a boiler for my small house. The circular, as you say, is the oil burner converting coal boiler to oil; the rectangular imprint--just behind the circular pattern––that curves towards the rear and is about 27" wide and 23" deep--would seem to be the 'snowman' I've attached a photo I found online--ironically from one of your old jobs--shows pretty much the exact same shape of snowman base as is on my floor. So I'm wondering that is that really large outline? Hard to believe there would have been another larger boiler there before the snowman. There may have been another oil boiler there added in 60's or 70s but that probably would not have left an imprint.

Fred

The largest outline was probably the original coal gravity hot air furnace that had just one large central register to the first floor. I suspect the round outline could have been the cast iron fire pot in the gravity furnace. Those old furnaces were sheet metal on the exterior and the ash box and fire pot was about a 300 to 500 pound cast iron 2 section (bottom and top half) pot that sat in the middle of the furnace and on the concrete floor. Two doors, lower one to shovel out ash, the top one to load fuel.

D107

@Fred I thought it had been established that the house was heated from the start in 1924 by hot water. There's no evidence of a furnace on the first floor or in the basement ceiling, and the CI rads are all very old. I guess anything is possible but I can't imagine in those days any resident of this house--a railroad man--would have the wherewithal to add a gravity hot water boiler and all the associated big piping and rads.

JUGHNE

That floor register would have left a large cut in floor joists that was usually not repaired very well. The ones I have seen anyway.

Fred

JUGHNE said:

That floor register would have left a large cut in floor joists that was usually not repaired very well. The ones I have seen anyway.

Yes but the home I owned, before the one I'm in now had a old coal gravity hot air furnace in it. It was a 2 story brick home. The furnace was converted to gas, probably in the 50's. I am the one that tore it out and replaced it with a new furnace and central air in about 1980. All the asbestos wrapped duct work, returns and supplies to each room was about 10" pipe in the basement and changed over to square duct where it entered the interior walls. All registers were wall mounted, in each room. It was truly an octopus. I'm not saying that was the case here but, based on that footprint, I wouldn't rule out a gravity hot air until I looked at all the sub floor above/around each joist.