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Piping diameter on a hot water system.

Hi I am looking into a new home in the neighborhood. The home has a converted steam into hot water system. To make a long story short. During the super frigid temperatures earlier this month the boiler ran out of oil in the vacant house, you guessed it, frozen pipes. There was what I would consider a catistrophic failure in two radiators, catisrophic in that they blew chunks off in their freeze. The radiators that froze were newer style square 3 and 4. Column radiators and both blew apart at the top. There are two other radiators that the owner believed to have been cracked but I think tHt the may have just forced out water from an area near the shutoff valve as that area looks to have drip marks around it.
At any rate my questions are the following:
Can the old piping be abandoned and can I run new pex to the radiators or do I need the volume supplied by what I believe are repurposed steam pipes?
Can I eliminate the broken radiators and put in radiant floor heating in the effected rooms.
If I can run new pipes should I put in second floor and first floor zones. In the future I want to add a tv room of about 204 sq ft with radiant floor heating on another zone.
I am a steam guy not but would have to change my thinking for this new system.


    EBEBRATT-Ed Member Posts: 15,510
    ??? need a clearer description on what you want to do
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,576
    It would be wise to check the heatloss of the rooms, and compare that to the hot-water EDR of the radiators to see how effective the system could be. Steam radiators are capable of greater radiant output, than hot water, and unless the radiators had been oversized originally, (not uncommon), the system may not have the Moxie required at design temperatures, and below.
    I presume the water pipes are toast as well, so a challenging project to say the least, but maybe worthwhile.—NBC
  • hot_rod
    hot_rod Member Posts: 22,103
    Yes you could run a manifold system with a pex supply and return to the radiators. Each could be controlled with a TRV.

    For radiant you may need another low temperature circuit which would include a mixing device of some sort.

    A room by room load calculation would be a good first step.

    The determine how much heat is needed in each room and if the heat emitters you have or will add will handle the load.

    Plenty of options when you start from scratch, they should all follow a load calc and system design for best results and bang for your $$.

    You can try a load calc on your own, find a local knowledgable hydronics expert, or contact one of the designers on this site for the first step.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • jumper
    jumper Member Posts: 2,245
    With no heat how did plumbing survive? Did interior walls weather the temperature okay?