Hot Dawg hum

[Group B]

Moved into a house with a Modine Hot Dawg in the garage. There is a noticeable transformer hum when the unit is off but plugged in. It's not super loud, but I can hear it from the far end of the garage. Sounds like an old fluorescent light humming. Is this normal for these or is something on its way out? Thanks.

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[The Cobbler]

I had a door bell transformer that hummed real bad out of the box. replaced it with another & it was silent by comparison. not sure that it's bad, just a loose core was what someone said to me. you could probably live with it, or replace it if you wanted.
Just my Internet $0.02 , so take it for what it's worth

 

[Showkey]

My vote it’s ( the hum) normal. Pull the side cover and touch or wedge the transformer to see if you can change the volume.

 

[D45]

When mine has power to the unit, there is no noise when the tstat is off

 

[jlv03]

My electric boiler has a contactor that is normally held in if no overtemp conditions exist. This means it hums all the time. Not annoying, but you can hear it if you think of it. In the summer I just kill the power to the whole thing, just to not occasionally hear it.

 

[csp]

No hum on either Hot Dawg that I have, and they are powered 24/7/365. Both are 45k units

 

[Group B]

Thanks for the input everyone. It is indeed the transformer. I pulled the cover off and checked everything. Looks like it's about $50 to replace it so I'll probably just hold off unless it gets a lot worse. Unit seems to function fine otherwise. Glad I checked the exhaust pipe (horizontal) it was full of mouse house.

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[HarrisFD]

Thanks for the input everyone. It is indeed the transformer. I pulled the cover off and checked everything. Looks like it's about $50 to replace it so I'll probably just hold off unless it gets a lot worse. Unit seems to function fine otherwise. Glad I checked the exhaust pipe (horizontal) it was full of mouse house.

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Apparently this is not that uncommon with this unit. Mine is humming too, partially vibration, partially cabinet panels buzzing from vibration. Naturally their $52 replacement part is actually made by someone else, Hartland controls in this case, see pic below.



You can use just about any 120vac input, 24vac output transformer . Needs to be 40 or 50 VA. This one would work and it’s $16 on Amazon:

Endurance Pro 90-T40F3 Class 2 Transformers Thermostat Energy Limiting with Foot Mount, 24V Replacement for White Rodgers Emerson https://www.amazon.com/dp/B07RS5C41J/?tag=atomicindus08-20

 

[Dave Carney]

Mine (75k) hums if the power to it is on. I have it on a switch though and it's mostly kept off.

 

[D45]

I've had two HD heaters, both were quiet