thinking about replacing my oil-fired steam boiler

Tim Gardner

I'm thinking about replacing my oil-fired steam boiler. It's a GM Delco 4S. According to http://www.heatinghelp.com/pdfs/186.pdf, this boiler is "505" and has minimum firing rate of 1.6 gallons per hour, though I believe the current burner is set for 1.25. I have about 400 ft of radiation. I burned 1600 gallons of oil in 2005. The house has no insulation though I have plans to insulate soon.



The Delco boiler heats DHW with a big coil. My wife complains about not getting enough hot water for a good shower, but if you keep the volume low enough you can take an endless hot shower. The boiler keeps the basement warm in the winter and relatively dry in the summer.



I'm thinking of replacing the Delco with a new boiler (probably Burnham) and an indirect for hot water.



The Delco looks like it would have a lot of years left in it and I hate to replace something that is working well, but I am guessing that it is much less efficient than the 85% or so rating on a new one I would get. But I'm still on the fence because I'm worried that my overall costs won't go down for several reasons:




1. I'll need to heat the basement in the winter

2. I'll need to dehumidify the basement in the summer

3. Family will use more hot water since the indirect will be "better".




I would appreciate any comments.

Joe Brix

Set the indirect

down to only 100°, see how fast they get out when they run out of hot water! But seriously, don't blame the new system if your family takes advantage of it. Your basement can't be that damp if just the heat of the boiler keeps it dry. With the indirect, the boiler wil still need to cycle several times a day for hot water use. I'd much rather run a dehumidifier a few weeks each summer and throw on a zone of Baseboard just when I'm down there rather then heating the space 365 days a year.

I suggest finishing the insulation work first so you'll properly size the boiler for the BTU loss of the house. Your biggest savings comes from right-sizing the boiler. And at 1600 gal/year, sounds like you can realy cut that number down with insualtion and the right system.

Tim Gardner

why would btu loss matter for steam?

Thanks for the reply. Good idea about the 100 degrees! Maybe I could just fill the indirect half full!

But seriously, I thought that boiler sizing was supposed to be based on the radiation not on the heat loss. At least that's what I thought I understood from Lost Art.

Thanks,

Joe Brix

sorry tim

I missed that important word "steam". But I'm sure you can still find a smaller boiler to feed that much sq ft of radiator. Maybe some BB off the loop going to the indirect for the basement heat. I'd rather try to downsize the boiler I needed with insulation on the house and steam piping. Any plans to downsize radiators or pull some out?

Tim Gardner

boiler sizing

I was contemplatin the Burnham V84S which would give me 396 ft of steam, according to their website. That is about 1 gallon per hour of oil, if I'm reading it right.

I have no plans to remove radiators.

Thanks for your ideas.

Unknown

The Burnham is an amazing steam boiler

Plenty of tappings for an indirect tank or a zone of heat , and has a coil port . A few days ago we changed out a Delco for a V83 and used the coil for a zone of heat . The new boiler was easily 1/2 the size of the old one . Typical fuel savings are in the 30 percent range .

Tim Gardner

That looks like great work! Good to hear you like the Burnham. The old Delco looks very similar to mine. Thirty percent sounds very good. Thanks.