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Old radiant system, needs new boiler

I have a 55 year old copper radiant system in slab of a single floor large ranch house. The present boiler is a CI sectional with one pump and a mixing valve - 238,000 btu input but  needs to be replaced. I have been advised to use a Burnham Alpine condensing boiler with outdoor re-set, primary-secondary loops, etc. The owner presently changes the water temperature manually according to the season. The system will also have a indirect water heater. The boiler has been sized according to heat loss. The owner nor I do not know if the copper loops in the floor have ever been insulated. The system has always worked well for him and although in installation is not difficult, I wonder, since a lot of money is at stake for him, if there is anything about this plan that someone out there might notice to be 'out of whack'.  I also have made a previous post on this subject but obviously did something wrong in sending it as it hasn't appeared on the 'wall'. Thanks.


  • Ironman
    Ironman Member Posts: 7,181

    Any properly sized mod/con should work fine in this application. Remove the mixing valve and let the boiler control the water temp through its reset curve. Just make sure it's adjusted properly for your radiant floor.

    Also, do the math to select the correct pump / speed for the secondary and assuming everything else is done with good hydronic practices, you should have a good system.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • NRT_Rob
    NRT_Rob Member Posts: 1,013
    55 year old copper in slab

    has its days numbered. beware. Many such systems have developed leaks by now.

    I would begin eyeballing the "exit strategy" early so it doesn't catch you by surprise. Not to be a predictor of doom and gloom...but you should proceed cautiously.
    Rob Brown
    Designer for Rockport Mechanical
    in beautiful Rockport Maine.
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