Tank Heaters left on with empty tanks

[XLR29HFS]

Okay, it was only a matter of time.
I left my tank heaters turned on for over 2 weeks after I emptied all my tanks. I was plugged in to shore power so I wasn't saved by dead batteries.

Will the heaters survive this sort of abuse (stupidity) or will they have burned out, how can I tell?
Will the tanks have suffered any damage or deterioration and again what is the best way to tell?
Bottom of trailer is fully enclosed and insulated so it is not as simple as putting my hand on the heater or looking at the tank.

Thanks for any feedback.

[Mr. Dan]

How cold was it?
As I understand them, tank heaters have thermostats that only turn on around 40°F. Someone will quickly correct me if I'm wrong.

[aeblank]

I doubt very much any damage. They're small wattage, obviously only to put enough heat to not freeze.
Any pad heater I've dealt with has been self regulating (even if it's just heat causing the resistance to go up, thus causing the current to go down).

[XLR29HFS]

I checked weather history and there were a few nights where it dropped below 40F.
Is this just a wait and see what happens after de-winterizing?
I could live without tank heaters(short term) but I wouldn't want to be using weakened tanks.

[old40ford]

They should be fine. They still heated the tank itself so they really should have suffered no damage.

[jimmoore13]

Most electric heaters are just resistive wire. Perhaps you could use a multi-meter to test continuity through the element - downstream of the thermostatic switch.

It's also reasonable to presume that there is a thermostatic switch...similar to that on a plumbing "heat tape." So the heater only ran while it was below the set temp...as others suggested, perhaps 40 degrees F.

If you see no physical melting damage to the pad and/or holding tank, then the heater very likely did not overheat. Even the cheap plumbing heat tapes can withstand this kind of "abuse" You plug them in in the fall and pull the plug after all threat of freeze is over in the spring.

If you have continuity through the wire in the heat pad, it will likely show some modest resistance...not sure how much, but something on the order of 10 to 20 ohms (rather than zero ohms for regular wire). If you have a continuous circuit, even with significant resistance (e.g. 200 ohms), the heater is probably just fine. This will be a "yes or no" answer - it works or it doesn't. To test it later, wait for a very cold day (e.g. 20 degrees), and plug it in for a few hours and see if you can feel heat. It will probably be subtle on the underside of the pad, but you should be able to feel "something".

[UT_Grandpa]

Easy way to test the heaters. Unplug your converter from house power, put a volt meter across the battery or an amp meter in series with the battery cable. Measure the volts/amps. Turn on one heater and see if the voltage drops or the current increases. Do the same for the other tank. My bet is everything is OK.

[bend302]

While the heaters turn on at 40 deg, they don't shut off until a warmer temp like 50 or 60 deg. My Artic Pak system includes heat tape around the grey tank drain elbow. That might be an access point.

That said, while the instructions say not to use on dry tanks, I still doubt you have damaged anything.

Bill

[Witch Doctor]

Key question, you said the temp dropped to 40 outside, I doubt it dropped to 40 in your underbelly. They measure the tank temp not the ambient air. You can only tell if they are working with a 12v amp probe when they are on, even when the light is lit, it just showing you have potential. I wouldn't worry about it. Add 5 gals of water to each tank, and let it go. IMO I think you will be okay.

[card16]

I am not sure what type of tank heaters you have, but for my 2016 Cardinal 3450, the manual says that once you have turned on the switch to the heaters that:
"The thermostat on the heater will turn ON the tank heater as soon as the tank temperature drops to 44 F (7 C). The tank heater immediately starts protecting your holding tank. When the temperature in the holding tank rises to 64 F (18 C), the tank heater will automatically turn OFF."

Again, not sure how yours are set up, but this is what the Forest River Owners manual has to say about their "Ultra-Heat" tank heaters operation.

[XLR29HFS]

Thanks for all of the replies to my questions.
General consensus is that I have not likely done any damage to heaters or tanks, but I will confirm all of this when the weather warms up in 6 or 7 months.
I did notice that nobody said "oh yeah, I did that too" so now I feel special.

Thanks again,

[rockfordroo]

Originally Posted by XLR29HFS

Thanks for all of the replies to my questions.
General consensus is that I have not likely done any damage to heaters or tanks, but I will confirm all of this when the weather warms up in 6 or 7 months.
I did notice that nobody said "oh yeah, I did that too" so now I feel special.

Thanks again,

If you can access the wiring somewhere, put an ammeter in series with one of the wires. If you have current (below 40 deg F), you're good.