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Replacement Boiler

goodguy Member Posts: 12
1930 Tudor 2-1/2 story house, 3500 sq ft, Cast iron radiators, 2 pipe system converted from original steam. One zone. One pump. Conversion did not change any of the "loop" piping to radiators, just the near boiler piping. Current boiler Utica MGB250 HD, 16 years old. 250 input, 205 out, Remodeling bathrooms and kitchen, would like to have in floor radiant in those areas. I realize that changes will need to be made to present system to accommodate that, so my thought is to replace boiler while we are at it. I have read lots of posts on this site. My thinking runs along the line of constant circulation with trvs on every radiator, with outdoor reset. I know current boiler is over sized but I don't know by how much. I am putting an hour meter on it so that I can see run time for rest of winter. I will also do my own heat loss study. Questions:
1) I am concerned about the maintenance and reliability of a mod-con boiler. Is that a valid concern? I would trade some efficiency for less hassle. Also I have read that my system with large pipes will have more water than modern systems and this affects the boiler.
2) Local hvac guys don't have lots of experience, and most of their experience is the of the infloor heat type. Is there a design source that could then be handed off to my local plumber for the work?

I know lots of this has been discussed on this site and I have read a ton of it but some info is older and contradictory. So sorry in advance for repeat.


  • Steamhead
    Steamhead Member Posts: 16,893
    Was it actually a steam system originally, or a hot-water system that circulated by gravity without a pump?
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • goodguy
    goodguy Member Posts: 12
    Steamhead, it was an actual steam system, converted by a previous owner.
  • nicholas bonham-carter
    You would have smaller pipes with a converted steam system, than with an old gravity system, built originally for hot water.
    Check your heat loss room by room, radiator EDR, and pipe sizes, and then see if you can take advantage of the lower temperatures supplied through outdoor reset.
    Steam radiators are sized smaller (for each room) to take advantage of higher steam temperatures, so with hot water, they may be radiating 3/5's of the heat required for the room. This means that you need higher water temperatures to compensate. This may rule out the Mod Con.
    How about turning back into steam?--NBC