2 better than 1?

Steamhead

you need to measure up the radiation. This will tell you what size boiler is needed. For a nearly comprehensive collection of radiator ratings, order a copy of Dan's book "E.D.R." on the Books and More page of this site.

Don't go by the ratings of the current boilers- they may be oversized.

One other thing to consider is if you stick with two boilers, if one quits the other will still work.

Frank_34

2 or 1 boiler

I own 2 sides of a double block home that I'm converting into a single. Both sides are oil/steam with separate boilers. I would like to replace them with single boiler. My local plumber stated that there are no residential boilers (coal or oil) that could supply enough steam for both sides(approx 4000 sq ft.)and I should stick with 2 separate boilers. Any input would be appreciated.

Steamhead

Is that 4000 square feet of radiation

or 4000 square feet of house? If the former, you're definitely into commercial sizes.

Frank_34

clarification

That's 4000 sq ft house.

Frank_34

radiation sq footage

I did some calculations last evening and I'm looking at approximately 700 sq feet of radiation. Is this too much for a single residential coal or oil boiler?

The 2 boilers have some advantages especially in the summer when only 1 is needed for hot water, but my biggest concern is fuel consumption. Would 2 Weil-Mclains SGO-4's consume more oil than a single SGO-7 and if so, would you consider the amount significant?

Mike T., Swampeast MO

700 square feet EDR @ 240 btu/hr (for steam) = 168 mbh.

Add a 15% "pickup factor" and you get 193 mbh.

While this would be a rather large residential steam boiler, you should find appropriate models by every manufacturer.

I'd suggest finding a good steam man to find if one versus two boilers will be the "best". Since this was originally two separate systems, it may or may not be practical to "bring it together" into one. I would suggest that the piping layout will be a significant determining factor.