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what happened to all the old coal fired furnaces and boilers during power outages?

luketheplumber Member Posts: 149
edited January 2021 in Strictly Steam
Last night my family lost power for a couple hours. that got me thinking about a question that I've had for some quite time now and that is, What happened to all the coal fired boilers and furnaces when they lost power if they were running?
I know that a lot of the systems like all the gravity octopus Furnaces, gravity how water systems and Steam Systems didn't power. I'm pretty sure that my 1935 house's original coal fired furnace was Forced air and not Gravity. I think that there were hot water systems that always had a circulator pump even when they were coal fired.
What about all the Two Pipe Systems that needed Condensate and Boiler feed pumps?
I've heard about some coal fired Steam Boilers having motorized dampers.
So what happed to these systems?
Did someone have to be there to refill the boilers to prevent them from Dry firing.
Did some boilers just blow their pressure relief valve?
I assume that the old style coal Furnaces were built to tolerate the heat that would build up if the blower went out.
There's now way that the deadmen didn't consider this as Power outages were much more common and longer lasting back then.
I just earned my GED and am looking for a apprenticeship with one of these steam gurus on this site!


  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,567
    edited January 2021
    If the system was installed in the 1800s then there is a possibility the house was not electrified. Some homes were Gas powered. Gas lamps, Gas cooking, and Coal gravity heating.

    There are even Gas Appliances the use a Thermopile or Pilot Generator to create enough electricity (750 millivolts) to operate an automated gas valve by way of a thermostat. So electric outages did not effect these homes.

    Rarely was a coal-fired boiler fitted with a circulator pump. The coal fire was not an off and on type of burn as was gas or oil burners. The coal was an always-on, always flowing contraption. as the water got too hot, a pulley & chain attached to a thermometer actuated lever would close a damper to reduce the combustion air making the fire lower. As the temperature dropped the damper would open increasing the flame. No electricity needed with that design.

    Any home that was designed after the 1930s would have included electricity and the heating system would be designed with smaller ductwork or radiator piping accounting for the forced circulation of pumps and fans. Those furnaces and boilers would not usually be designed for hand firing. There was no market for that. Only a small percentage of modern hand-fired appliances are in use when compared to the overall heating appliance used in residential applications.

    So to answer your original Query regarding "What did they do?" The 1% of those residences that needed a fan or pump to push the coal heat thru the system did what everyone else did. They waited for the electricity to come back on. In the meantime, they depended on the lesser gravity heat that kept the pipes from freezing.

    Yours Truly,
    Mr. Ed
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • mattmia2
    mattmia2 Member Posts: 9,429
    They continued to circulate via gravity. Most coal boilers and furnaces weres set up for gravity circulation. Sometimes they got a circulator or blower later on to help but they were fundamentally designed to work with gravity circulation only. The gas furnace that was in my house when i bought it that had been installed in about 1950 was designed as a gravity furnace but installed with a separate blower cabinet and had an aga label that said "approved for gravity use only". It and a lot of older furnaces and boilers had a knob on the bottom of the gas valve that you could use to turn the burner on without electricity. I think there are instructions for a bryant conversion burner somewhere i the library that explain how to use that manual knob.

    Coal boilers had larger water content and needed feed pumps in far fewer applications than modern boilers. Large, complicated systems usually had a caretaker that lived in the building and were only in commercial or very large residential buildings.
  • LS123
    LS123 Member Posts: 466
    my neighbor has a wood stove and a generator.. last time we lost nearly 5 days of power ... some of the generators powered by gas and propane, with electric and remote start....some sort of power source is needed to keep the heat going at 1 F today and windy... hope to get one just enough to run the fridge and oil burner....
    Thank you!
  • retiredguy
    retiredguy Member Posts: 883
    If this happened in a commercial building without an emergency generator to provide electricity until the main power came back on, it was up to the man on watch to decide what to do. If the boiler was a steam boiler,high or low pressure, the combustion air would stop and the coal fire would go almost dormant. If the boiler water level got to low, the boiler operator could hand feed the boiler with water from the manual feed valve or it the pressure was too high would rely on an injector if the boiler was so equipped. If the boiler was hot water and the dormant fire still heated the water too much, the boiler operator would take one of the firing tools, open the access doors and pull the coal out of the fire box and onto the floor. (I have done this a few times and it is not a job anyone likes to do). Most of the time in a residence the systems were gravity flow, the coal fire would go dormant or be forced to go dormant by the home owner, and every thing was OK. For hot air, I don't know since I never worked on any.
    JUGHNE Member Posts: 11,021
    If you had a "Power pile generator/pilot light/gas valve" and lost power the burner would still work. If it was gravity flow water or air you still had heat.
    If burner was in the basement and you had fairly large heating pipes you might get some heat flow if you manually opened your "flow checks" if you had them.
    The high limit should shut off the fire when the unit overheated.

    I just came from repairs on an old boiler that has a power pile burner and a 120v circ pump.
    The owner told me that one power failure the burner kept heating until the relief valve opened. His boiler is on the same floor as the BB heaters are. Consequently there was no gravity flow at all thru his 3/4" loop and boiler overheated eventually opening the relief valve. His failed exp tank was also not doing what it should either.