Heater Noise

[Jennys planted tank]

I noticed a high pitched whistling coming from my tank this morning. I figured it was a leak in an air hose but it turns out it was my heater. I immediately unplugged it and threw in my spare. Has anybody had this happen? I assume it is broken and will need to be replaced but I would like to understand what the issue is.

[Biotope Biologist]

I can’t tell you how many times I have been zapped by a faulty heater. 
 

Its better to be safe than sorry! And it can be a number of things. Most common is that whatever grommet they use to seal the cord to the top of the heater fails and moisture gets in the housing. Water touching coil boils rapidly and steams out the top.

[dasaltemelosguy]

@Jennys planted tank, that's most likely the internal thermostat beginning to fail. They have a mechanical connection that connects the power to the heating coils. This connection makes and breaks with temperature changes. When they corrode enough that the connection is tenuous, they can vibrate as they try to connect & reconnect (turn the heater on) and sometimes that vibration is fast enough to hear as a squeal. In the dark you often can see small blue sparks. 

Or as @Biotope Biologist said, if you see condensation inside, it could even be steam escaping.  But unfortunately, either one is an indicator that it may be unreliable (getting stuck in the 'on' or 'off' position) and that it will fail soon. 

[Jennys planted tank]

Thanks! I’m very surprised this happened already. The heater is only a month old and as it’s warm in the house hasn’t even been kicking on that often. Oh well, that’s why we have backup heaters! I’m just grateful my animals weren’t hurt.