Why my heating system makes noise after it is shut off? - (2)?

I have fixed the problem. It turns out it the Expansion Tank is too old and not working. I replaced it and the heating system doesn't make noise any more. Just want to share this with everyone:

- Check the Expansion Tank by knocking at the expansion tank while the heat is not running. If you feel the tank is empty, it is working fine. If you feel the tank is full of water, it is time to replace it. A expansion tank usually lasts 5-8 years.

- Order a Extrol Expension Tank on internet. I did some search and found https://www.pexuniverse.com/ offers the best price and the shipping is quick.

- It is not difficult to replace the tank. Read the instruction before you do anything. It took me 15 minutes to replace it.

- To fix the fan running too long after the heat is shut down, I turned the fan/limit thermostat switch in the attic to a higher temperature, the fan stops 5 minutes after the heat is shut down. You can try turning up the temperature a little by little.

fyi: this is the original question I posted:

After my heating system is shut off, (let's say after 10 PM), my fan is still running for a while (about 15 - 20 minutes). Meanwhile, it makes some noise. 1. Why is my fan is still running for quite a while after the heating system is shut off? 2. Why it makes noise? 3. How to fix it?

2 weeks ago

Additional Details

Thank you all, for your answers.

The noise is definitely NOT from the fan. I went up to the attic when it made noise.

These two points sound more like the reason:

Confiort Climate Service - Three: Duct expansion/heat exchanger expansion and contraction due to rapid temperature change, ( install thicker gauge duct)

emgee - The blower operates until the reverse thermostat in the plenum is cool. The noise is the ductwork expanding and contracting of the metal.

Can you provide more information about the solution?

Additionally, my "fan/limit switch" has only one dial, I set it to 115. It was 110 and it made noise more often. I set it to 115 and it gets better. It still makes noise, but, it less often. Any advise?


My house is in USA and it was built 1990.

1 Answer

  • 8 years ago
    Favourite answer

    yep that is why we don't use that kind of heat in the USA

    Source(s): old timer
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