Symptoms
- Audible buzz or hum from the small transformer box, often near the furnace
- Doorbell chime sounds weak, delayed, or doesn't ring at all
- Buzzing gets louder or the transformer feels warm
Likely causes
- CommonA doorbell load too high for the transformer's ratingSmart doorbells often need more current than the small transformer originally installed for a basic wired chime.
- CommonA short or stuck button held downA doorbell button stuck closed keeps the transformer under constant load, causing it to buzz and overheat.
- PossibleA failing transformerTransformers hum more as their internal components degrade.
- PossibleIncorrect voltage transformer for the installed chime or smart doorbellMismatched voltage or VA rating can cause continuous strain.
What to do
- Check whether the doorbell button is stuck or stuck pressed, which would explain constant buzzing.
- If you recently installed a smart doorbell, check its power requirements against the existing transformer's rating.
- Feel the transformer for excessive warmth, and note if the buzzing has been getting worse.
- Avoid leaving a buzzing, warm transformer connected long term.
- Have an electrician check whether the transformer needs to be upsized for a smart doorbell.
- Replace an old, failing transformer rather than letting it continue to run hot.
- Confirm all doorbell wiring connections are tight, since a loose connection can also cause buzzing.
Tools and parts
Doorbell transformer rated for smart doorbellsSearch: “16v 30va doorbell transformer smart doorbell”
When to call a pro
Call an electrician to replace or upsize a doorbell transformer, especially when installing a smart doorbell that draws more power.
Safety
Use caution
The transformer connects to your home's line voltage. Don't open or replace it yourself unless you're experienced; have an electrician handle it if it's warm or buzzing loudly.