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Best practices for troubleshooting no-heat calls in older homes

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plumberingpro
plumberingpro
edited September 3 in Plumbing

Hi everyone,

I work in the plumbing/heating trade and often run into no-heat calls in older homes with outdated boiler or furnace systems. I wanted to get some input from experienced techs here:

  • What's your go-to first step when diagnosing a no-heat issue — checking the thermostat, pilot light, or something else first?
  • Any common mistakes you see newer techs make when troubleshooting these systems?
  • For older cast-iron boilers specifically, is there a checklist you follow before assuming it's a major component failure?

I'd love to hear how you all approach this, especially for homes with systems that are 20+ years old. Appreciate any tips!

Thanks in advance.

Comments

  • EBEBRATT-Ed
    EBEBRATT-Ed

    70% of Most hvac service calls including boilers are usually electrical related. So I would get a meter and an amp probe and learn how to use them and brush up on wiring controls and relays and transformers, zone valves and circulators.

    Don't rush in stay methodical. Spend a couple of min walking around and being observant.

    Does anything smell

    any fuel oil leaks

    If gas are the other gas appliances working

    any soot around the boiler or around the flue pipe

    water pressure in a HW boiler

    water level in a steam boiler

    pressure on a steam boiler

    switches on or off

    Boiler or furnace cold, hot or warm

    water leaking from boiler

    Like Yogi Berra said "you can observe a lot by looking"

    All the above you can do with nothing but a flashlight.

  • Jamie Hall
    Jamie Hall
    edited September 3

    Assuming we're talking steam or hot water here, if there isn't a big puddle on the floor, as @EBEBRATT-Ed said start with the electrics and the controls.

    Some systems have one or more manual reset safeties on them. If they are tripped, find out why they tripped before you do anything to try to restart the system!

    And one more thought. Figure out how the system — particularly the controls — is SUPPOSED to work before you touch anything.

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    mattmia2
  • HydronicMike
    HydronicMike

    Seems like an AI post.
    Seeing a lot of these on FB.

    Maybe I’m wrong

    GGrossmattmia2
  • hot_rod
    hot_rod

    For hydronic systems

    https://www.caleffi.com/sites/default/files/media/external-file/Idronics_32_NA_Troubleshooting%20hydronic%20systems.pdf

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Grallert
    Grallert

    First thing I always did was ask the customer what if anything they noticed. Smells, odd noises, if it's happened before etc. Check the electrical. Switches fuses thermal disconnects etc.

    Around here everyone has delivered fuel, oil or propane. I check that. Then I try to run the unit and go from there.

    Miss Hall's School service mechanic, greenhouse teacher, dog walker and designated driver

    HVACNUT
  • HomerJSmith
    HomerJSmith
    edited September 3

    I ask a lot of questions. My sequence is fuel first, electrical second. If electrical, I ask is there anything electrical in the house that has malfunctioned? If yes, I ask, has the power company been working on the power lines in the neighborhood? Twice the answer was , yes. The power company dropped the neutral and sent 240V thru the house circuits.

    Diagnostics relies upon experience and the collective experience of others that you were wise enough to incorporate.

    Like Mark Olson's Dad, I get great satisfaction fixing things and making them work again, because the last time I checked, I'm a Guy and that's what Guys do.

    I told my daughters, when you complain to your husband, tell them that you just want to talk about it and you don't need to fix it.

  • HVACNUT
    HVACNUT

    If the client is around, they get interrogated first. Every call is different. Don't fix it before you get there.

    PC7060mattmia2
  • EBEBRATT-Ed
    EBEBRATT-Ed

    Listen to the client but take it with a big grain of salt. Some know things some don't.

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