Just had a tech out today. Gas pressure was up way higher than it should have been so he reduced it (he said it was a 7 something and it should've been 3.4?). CO detectors not going off but they are the ones that only detect above 30ppm.

Oddities: Noticed that the burners will ignite fine and run until goal temp is reached. Then the flames go off but the fan etc still runs. It does this for another 5 or so minutes before the flames turn back on and the furnace continues to run for an additional few minutes. Then everything shuts off. By this time it has reached 1 degree above goal temp.

After tech left I noticed a humming sound coming from it when the furnace is not running. Called back and they said it sounds like the transformer but it was otherwise quiet before tech was out.

Is it okay to leave it as is and monitor or should I be looking to replace ASAP?I really wanted to get through 1 more winter before replacing it as I have other structural home repairs that need addressed as well.

If it's okay to monitor - what temp should I set it to to try and slow down further cracking? (If that's even possible)

furnace crack

  • I don't know what parts you were focusing on, there seems a quite wide crack. I would call another company for inspection. Do you remember to replace your CO2 monitor? It could be outdated.
    – r13
    Commented Nov 24, 2021 at 3:17
  • 2
    Do you mean "CO monitor"? Commented Nov 24, 2021 at 3:30
  • I've revised your post title to ask something more objective. Otherwise it's a risk tolerance poll, which is off topic.
    – isherwood
    Commented Nov 24, 2021 at 16:00
  • No matter what you decide to do, change the CO monitor to ensure you will get ample warning.
    – r13
    Commented Nov 24, 2021 at 20:35
  • If you keep it like that I'd add a CO monitor into each room the furnace is blowing air. Commented Nov 24, 2021 at 23:19

1 Answer 1


I'd replace it. Don't mess with CO and your life. I doubt any tech will tell you that it is safe. Even if the crack is small now the chance of it changing and the result of the risk of that change is too great.

  • Ah so conflicted. Had another tech from the company out and he said that it's okay to run as there's no carbon monoxide leaking (he tested it). He seemed to think it was just superficial on the panel and that it would probably take time (like years) before the crack got big enough to create a problem. He said to obviously keep the CO monitors. But I'll make preparations to replace it sooner than I wanted to. @isherwood Sorry about title! New to posting here, thanks for changing it.
    – abeighc
    Commented Nov 25, 2021 at 6:05

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