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Lochinvar Noble Fire Tube - Run with radiant heat drained?

OregonKiwi
OregonKiwi Member Posts: 3
in Domestic Hot Water

Hello!


I have a Noble Fire Tube Combi boiler. So far it has been rock solid and reliable.


Currently our radiant floor has a leak, and we have depressurised the system to minimise damage and water loss, turned off the floor heating at the wall thermostat and shut off the water supply to the top-up pressure valve. The system has been like this fora couple of days while we wait for contractors to chisel our floor up…


This morning, the system was not supplying hot water for my morning shower. It was clearly not happy that the heating water for the radiant wasn't present (I guess it took some time to fully depressurise). After half an hour of messing about, I partly repressurised the radiant system, and hey presto, the domestic hot water was fine again.


So, my question is, is there a user level way to have the domestic hot water work when the radiant/heating system is drained? Or is the design of the unit not conducive to this? Is this a menu option? Surely I'm not the first person with this issue!

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 24,984

    It's designed that way. You can severely damage (like… destroy) the boiler if it's run without water and circulation. Do you have a bypass or is it piped primary/secondary?

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • hot_rod
    hot_rod Member Posts: 23,507

    I think is locks off around 8 psi. Can you valve off the radiant and pressurize it back to 12 psi?

    Then the DHW function will work. The safety relief and expansion tank cannot be valved off. The relief valve should be on or in the boiler. Expansion tank location needs to be determined if you valve off the heating side

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • OregonKiwi
    OregonKiwi Member Posts: 3

    hot_rod, that sounds like a plan. I’ll see if I can pressurize the boiler circuit without pressurizing the floor.


    I’m off to give the valving a closer inspection, but the system was built in 1965, so hopefully there’s some way I can achieve this.


    Jamie Hall, thanks for the advice too! I definitely don’t want to damage the boiler, so I will err on the side of caution. I don’t know if it’s primary or secondary. Presumably, the unit is smart enough to keep itself from going thermonuclear, hence it shut down when it saw low pressure on the radiant heating side.


    I will take a look at the floor valves and see if there’s a way to do this.


    Thanks for your help!

  • OregonKiwi
    OregonKiwi Member Posts: 3

    Well, that was easy!

    Job done!!!

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