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Hot water radiator not working well

Rob22 Member Posts: 2
Hello, I've had a new cast iron boiler installed to heat my home with the original cast iron radiators. I had an extra one from a small renovation upstairs in a rental so decided to have it installed in my basement. It was a wall mounted one with the supply line on the top and the return line on the bottom. The plumber installed this basement radiator with PEX tubing. First run of the furnace this year resulted in all the radiators working well except the basement one. It only got warm at the top and the furnace shut off before all of the basement radiator was hot with the return line to the furnace remaining cold. I bled the radiator to remove air but wondering if this basement radiator did not heat up because there is a lack of gravity for the return to function properly? I assumed the pressure from the boiler and hot water would push the water back to the boiler through the return line. Any help would be appreciated. 


    JUGHNE Member Posts: 10,909
    Do you have a pump on the boiler?
    Could you show pictures of boiler, pump and all piping floor to ceiling?
    Also show new rad and where it is connected to system.
  • Zman
    Zman Member Posts: 7,496
    It's probably an issue with how it is piped to the old system. Do you know if yours is converted gravity, monoflow, or conventionally piped?
    Pictures would help.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Rob22
    Rob22 Member Posts: 2
    There is a pump on the boiler and I think it's conventionally piped. Here are some pictures. The last two you can see the smaller supply and return pipes going into the boiler. 
  • Jamie Hall
    Jamie Hall Member Posts: 22,162
    That's cute. Remember that water is lazy. Very lazy. It will always take the easiest possible route. My guess is that you have a much more restricted flow to that new radiator -- smaller diameter pipe, angle stop, various fittings... And the water just want to go there much.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Ironman
    Ironman Member Posts: 7,224
    As Jamie said, water takes the path of least resistance. In your case, that’s the old large iron piping, not the smaller pex.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • mattmia2
    mattmia2 Member Posts: 8,874
    It looks like that radiator with the small piping is in parallel with the much larger converted gravity piping so you would need to restrict the flow in the gravity piping to balance the flow between the 2. It might make more sense to make that is own zone with a separate thermostat and circulator. Short cycling could be a problem but I think the boiler has enough mass to keep that from being a problem.