Boiler Size and Potential Downsizing

Brycewvu

I have a one pipe steam system run by an oil fired WM -SGO7. I did an EDR measurement of my house and came to 336 sq ft(183.25 on the 1st floor and 152.75 on the 2nd floor). If my math is correct, that equates to 80,640 total btus.

My boiler specs sticker shows an IBR capacity of 240,000 btus. I know you don't want to undersize a boiler to the system, but 3 times the necessary size seems crazy. Is my assessment of that correct?

With the price of oil where it is and the fact that my system drinks oil at a substantial rate(1.5-70 nozzle), is it an option for me to replace the main boiler body and jacket to a smaller series rather than replacing the whole boiler? Will I see noticable impacts to my system efficiency and reduced oil consumption being properly sized or would I be spending money/effort for little reward?

Mad Dog_2

"Main boiler body" ?? I think you mean the sectional block. You have two practical choices: 1) Have your oil burner company install the smallest nozzle your particular boiler can safely use and still heat the load. He must be proficient with the Combustion Analyser, pay attention to the key numbers....this is a process. 2) Replace the entire boiler with the proper-sized model.* Removing sections and purchasing a new jacket on a residental boiler like that is not worth it. Mad Dog

Jamie Hall

Don't think in terms of BTUh. Think in terms of the EDR. You have measured the EDR or your radiators, now compare that with the EDR rating of the boiler (sometimes shown as square feet of steam — same thing). Conversion into BTUh isn't necessary and gets slightly messy, as their are losses which are hard to figure in going from gross or net BTUh ratings for a boiler to EDR.

Second, you may save a little money with a smaller boiler — but not much.. The amount of fuel you burn is related to the heat loss of the house, not the size of the boiler, within rather broad limits. If you want to reduce your fuel burn, reduce the heat loss of the house. Insulation. Storm windows. Sealing up draughts.

Steamhead

@Brycewvu , there are a lot of other factors that can reduce efficiency, for example, lack of pipe insulation or missing or improper main vents.

Where are you located? We might know someone who can help.