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Small Multifamily Boiler Piping Help

Ylli Member, Email Confirmation Posts: 3
edited October 2021 in Radiant Heating
Based on layout (see attached diagram) what would you suggest for near boiler piping changes to allow for addition of ODR control and to protect boiler from cold water return?

Also, would TRVs at each rad be the best bet to help balance heat to the apartments? Other suggestions?

My goal is to keep it simple and affordable.

Existing system info:

-100 year old building with new windows and doors.
-20year old Weil McLain CI hot water boiler 180k BTU input, single circulator on the return side. Runs well, no problems, has been inspected and heat exchanger looks clean.
-5 apartments all with cast iron rads (total of 22 rads).
-Converted gravity piping system.
-Most of the large original piping is still in place except for the near boiler piping (shown in the diagram).
-No ODR.
-Uses one interior thermostat in the apartment closest to the boiler to call for heat.

See attached for diagram.
-Each of the 5 branches go to different areas of the building and are not dedicated to any one apartment.
-Radiation to each branch is also shown.

Thank you for any suggestions.


    EBEBRATT-Ed Member Posts: 13,848
    TRVs on the radiators that overheat. Pressure differential valve piped off a tee on the boiler supply to the circulator inlet. This valve will allow flow through the boiler when the trvs choke down. No TRVs where the thermostat is located.

    Keep the TRVs to a minimum on the rads that over heat
  • Ylli
    Ylli Member, Email Confirmation Posts: 3
    EBEBRATT - Thanks for the suggestion. I like the idea of putting TRVs in the lower apartments which are the shortest distance to the boiler. Less than half of the 22 rads will get TRVs. Do you feel an overpressure situation could happen in that case?

    Any suggestion on what piping changes to make for using ODR and also protecting the boiler from cold water return?

    Thanks for your help.

  • Ylli
    Ylli Member, Email Confirmation Posts: 3
    Bumping for anyone else's help, thank you.