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Steam Boiler with Indirect Heating House during Warmer weather

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TSanson7
TSanson7 Member Posts: 1
I have a customer with a gas fired steam boiler with a 40 gallon indirect ran off of it. System works fine all winter but customer has complaints with the radiators getting hot during the warmer months when they are using the hot water. Im wondering what the proper way is to handle this. I have installed an aquastat on boiler to keep boiler temp around 140⁰ for a call for DHW but customer says the radiators are still getting hot. Thank you in advance for any info on the subject.
Tim Sanson
HVAC Technician 
10+ years experience 

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 23,303
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    If the aquastat really is shutting the boiler off at 140, there should be no heat getting to the radiators at all. Check the wiring.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • ethicalpaul
    ethicalpaul Member Posts: 5,702
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    The proper way to handle it is to have a separate water heater. Then they won't have to heat up all that iron and boiler water every time they do the dishes
    NJ Steam Homeowner. See my sight glass boiler videos: https://bit.ly/3sZW1el
  • STEAM DOCTOR
    STEAM DOCTOR Member Posts: 1,972
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    Bad wiring, bad aquastat, bad aquastat placement.... Is this a new problem or an old problem? Did things ever work properly?
  • Jamie Hall
    Jamie Hall Member Posts: 23,303
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    The proper way to handle it is to have a separate water heater. Then they won't have to heat up all that iron and boiler water every time they do the dishes

    Aye, well... but if a low dollar service visit to find and fix the problem does it, would you shell out for a whole new installation?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    EdTheHeaterManbburd
  • The Steam Whisperer
    The Steam Whisperer Member Posts: 1,215
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    The proper way to handle it is to have a separate water heater. Then they won't have to heat up all that iron and boiler water every time they do the dishes

    Yes this is true, but a standard residential water heater is only about 55% efficient year round anyway. However, the indirect running in the winter pushes up the efficiency of the steam boiler by loading it heavier and the boiler could be running 75 to 80% efficiency. Indirects have almost no stand by loss from the tank. Stand by loss is what kills the efficiency of standard residential tank water heaters. I usually install indirects in 6 flats and tell them the average year round efficiency is probably similiar to a commercial tank heater ( with stack damper), but you'll probably get 2 or 3 times the life and it usually allows the gas service to be downsized, which saves about $1300.00 per year in base charges in Chicago. it also helps keep the boiler clean and dry over the humid summer months.
    To learn more about this professional, click here to visit their ad in Find A Contractor.
    EdTheHeaterMan
  • ethicalpaul
    ethicalpaul Member Posts: 5,702
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    The proper way to handle it is to have a separate water heater. Then they won't have to heat up all that iron and boiler water every time they do the dishes

    Aye, well... but if a low dollar service visit to find and fix the problem does it, would you shell out for a whole new installation?
    Yes I would :smile:
    NJ Steam Homeowner. See my sight glass boiler videos: https://bit.ly/3sZW1el
  • Jamie Hall
    Jamie Hall Member Posts: 23,303
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    The proper way to handle it is to have a separate water heater. Then they won't have to heat up all that iron and boiler water every time they do the dishes

    Aye, well... but if a low dollar service visit to find and fix the problem does it, would you shell out for a whole new installation?
    Yes I would :smile:
    That's sort of like buying a new car if you get a flat? Of course, some cars... !
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    EdTheHeaterManethicalpaul
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,838
    edited May 2022
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    @Jamie Hall ...You need to remember that @ethicalpaul is independently wealthy. If he loosed a hub cap, time for new electric car. (Just kidding Paul)

    But this banter does not help the OP with the problem. I am just wondering if the OP has a water boiler or a steam boiler. because a steam radiator can't get hot if the boiler is shutting off at 140°F. A hot water radiator, however, can get heated with 140° water.

    @TSanson7, since you are new to the forum, sorry for this question but enquiring minds want to know. Is this really a steam boiler or are there circulator pumps on the pipes?

    Pictures of the boiler will be conclusive evidence!
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • ethicalpaul
    ethicalpaul Member Posts: 5,702
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    I wondered that about the water vs steam also, Ed. If @TSanson7 provides some photos we can tell him which pipe to grab onto to see if it gets steam in it :smirk:
    NJ Steam Homeowner. See my sight glass boiler videos: https://bit.ly/3sZW1el
  • WMno57
    WMno57 Member Posts: 1,266
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    @TSanson7, are you sure this is a steam system? Could it be either Gravity Hot Water, or Steam with a few hot water radiators that are fed off the water side of the boiler?
    I DIY.
  • bburd
    bburd Member Posts: 918
    edited May 2022
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    I have seen this problem in a steam boiler with an auxiliary hot water zone from a tankless coil installed on one side of the boiler. The aquastat was set at 180°, and inserted into the tankless coil. Before the hot water zone was  satisfied, the boiler would sometimes be steaming on the other side.

    Could be a bad aquastat, or poor contact between the aquastat sensor and the thermowell in the boiler.

    Bburd