Wiring question/Freshwater tank

[medora]

You may remember me as the lucky 2012 17B Escape owner whose undertrailer freshwater tank heating pad shorted out and burned a hole in the tank. Months later and sadly for us, the saga continues. We were able to patch the tank, and now, finally, after excavating under the foam insulation (egads) and trying to dig everything out, we have been trying to install a replacement heating pad.

Here's where it gets confusing -- again.

There are FIVE wires in TWO pairs under the camper. The first pair is two thicker wires and a thin green ground; Dustin at Escape has confirmed these are 120V wires. The second is smaller 12V wiring in red and black.

When I tested the two wire pairs and the heater's on-off switch with a multimeter, I get continuity in all lines/switch, and current through the 12V -- but not the 120 V.

Dustin tells me that the 120V wires are not used -- that Escape has always wired the pads using the 12V, and the 120v wires are just there in the event an owner wanted to hook a heating pad up at 120v.

BUT .... I thought for the life of me that the BLACK wires were what was connected to the original pad. Maybe I messed this up because, well, because it WAS such a mess under there when this happened? But I also distinctly remember being told that the heating pad only worked on shore power (thus we only counted on using it when we were plugged in).

When I connect the new heating pad to the 12v wires and turn the switch on, the pad does not work. I know there's power there because of the multimeter reading.

I suppose it could be just ANOTHER bad pad? What are the chances?
And why was I told that the pad only worked on shore power? Have I been off my rocker all this time?

Any thoughts on this? Am I making another idiot mistake and missing something?

[alanmalk]

Originally Posted by medora

...
Here's where it gets confusing -- again.

When I connect the new heating pad to the 12v wires and turn the switch on, the pad does not work. I know there's power there because of the multimeter reading.

I suppose it could be just ANOTHER bad pad? What are the chances?
And why was I told that the pad only worked on shore power? Have I been off my rocker all this time?

Any thoughts on this? Am I making another idiot mistake and missing something?

To confirm that the pads are functional before installation: Use your multi-meter on the OHMs setting and take a reading across the 2 wires coming from the pad. Since the pads - assuming Escape original models - are 100 watts, the OHM reading you should get is anywhere around 1 to 10 ohms. The wide range is specified because it is not too important what the exact number is. But if you instead get a reading of 1000 to millions, or above, then the pad is not functional. Do not do this with power hooked up. You can also practice on a car tail light bulb for roughly the same readings. - just to get the feel of the numbers.

"Working on shore power": This may be a mis-interpretation. Pads come in pairs, and Escape used two 100 watt pads for a total of 200 watts. This is a lot of power to run overnight on batteries alone so the usual recommendation is to be connected to shore power to keep the batteries charged while running the pads. You might get away with one night, pads on and no charging, but a second night will be pushing your luck. Remember, if it is cold enough for heating pads is is cold enough to need the furnace. That's the reason for the "shore power" recommendation.

--
Alan

[medora]

Thanks so much for that response.

I did test as you described - I am attaching photos just to confirm I’m getting this right. And it looks like indeed, this is a bad pad ... ?? Is our luck really that rotten?

With regard to there originally being two 100V pads ... In our case, there was only one pad, which is what shorted out and burned/melted a hole in the tank. I’m sure about that, and Dustin confirmed that’s what was being installed at that point. What you say with regard to shore power makes sense if we would be draining 200V, but 100?

In any event, I wish someone would have explained this more fully to us, as there were times we could have used the pads with 12V (even during the day for brief periods) and had no idea it was even possible. And I’m still mystified as to why those AC wires would be there.

Hmmmmmmmm.

[Brian B-P]

Originally Posted by medora

With regard to there originally being two 100V pads ... In our case, there was only one pad, which is what shorted out and burned/melted a hole in the tank. I’m sure about that, and Dustin confirmed that’s what was being installed at that point. What you say with regard to shore power makes sense if we would be draining 200V, but 100?

That was two pads at 100 watts (W) each of power, not 100 volts (V).

There are two pads because one is on the bottom of the fresh water tank, and the other is on the bottom of the grey waste tank. The two heating pads are presumably both turned on by the same switch, but are wired in parallel so they operate independently (whether or not one is working doesn't affect the other).

[rubicon327]

Originally Posted by medora

When I connect the new heating pad to the 12v wires and turn the switch on, the pad does not work. I know there's power there because of the multimeter reading.

The pad you show has a built-in thermostat. Think of it as simply a temperature activated switch. It is not going to make and allow current flow to warm the pad until it is registering 45F or less. Did you consider this in your troubleshooting?

[medora]

Again, thanks for your responses.

Sorry about the V/W confusion. Long day.

When I hooked up the new pad it was -4C/25F and I put a water bottle on it to test. That’s plenty cold, but I didn’t feel any change in the bottle temp, even after an hour.

Just to be clear:
The multimeter test of the new pad (which I documented above) shows an open loop. So the fact that the new pad isn’t working may simply be a bad pad coupled with a case of incredibly bad luck. Can anyone confirm that I tested this correctly and that the pad appears to be bad?

It’s weird that in all the convos I’d had about this I still never realized there was a second pad on the grey water tank. Makes sense. IF the new pad is functional and should be working — would some unknown issue with the parallel wiring have anything to do with it not working?

Finally, I’m still wondering why there’s AC wiring there that’s basically a road to nowhere.

Thanks again, all.

[tdf-texas]

Originally Posted by medora

Finally, I’m still wondering why there’s AC wiring there that’s basically a road to nowhere.

My advise is to not try to figure out why Escape wires the way they do but to just fix it. If the 120v wiring shouldn't be there, remove it. Having unterminated 120v wiring under the trailer is not a good thing.

Or use the wiring for drain pipe heating.

https://www.amazon.com/HEATIT-30-fee.../dp/B01GZJJAQO

We don't have cold enough weather here to able to test a pad so - I would attach a pair of small gauge wires to the pad, throw it in the freezer running the wires outside the freezer door, and test for continuity the next day. If it still showed open, in the trash.

They don't cost enough to worry too much about.

https://www.amazon.com/Facon-Holding.../dp/B01MT9EUG9

[Brian B-P]

Originally Posted by medora

Finally, I’m still wondering why there’s AC wiring there that’s basically a road to nowhere.

Was the unused AC wiring only he wires which come out of heater , or is there also unused AC wiring on the trailer side? My guess is that these are just the wires attached to the heater which Escape does not use, and they were there because they bought AC/DC heaters and only wanted the DC feature. It's hard to imagine Escape running AC wiring to the heaters and not using it.

[medora]

Originally Posted by Brian B-P

Was the unused AC wiring only he wires which come out of heater , or is there also unused AC wiring on the trailer side?

From Justin at Escape:
In your photos you can see the green and two blacks at the front which are not used for anything and are just in the foam, this for the 120v. Further back I can see the black and red that are used for the 12v.

When I asked why those two wires were there if they are not being used, he responded:

The 120v wires would be if you hooked up the heating pad to 120v power as well which Escape does not.

To be clear, the pad that shorted out and burned a hole in our tank did NOT have 120v capability and was NOT hooked up. So those wires ... ? Who knows why. I'll just tape them off and tuck them in (there's no way to remove them without pulling out more spray foam which I am definitely NOT in the mood to do; I have been dealing with this since September and I'm done rooting around under the camper). Those two 120v wires don't have live current coming through, so they should be fine. Honestly I'm not sure how I'd control current to them if I wanted to.

Meanwhile, and sadly, I still don't have a working heating pad on the freshwater tank. I'm ordering yet another one to see if ten tries is the charm.

[Brian B-P]

If anyone has the tank heaters and no foam, it would be interesting to hear where those wires for 120 V AC go... but at this point is doesn't matter to the current situation.

[alanmalk]

Originally Posted by rubicon327

The pad you show has a built-in thermostat. Think of it as simply a temperature activated switch. It is not going to make and allow current flow to warm the pad until it is registering 45F or less. Did you consider this in your troubleshooting?

First my apologies for not thinking about the pad's built-in thermostat - we don't have these pads on our Escape. Since you live in the cold country it should be easy to check - as you have been doing according to your photos. The pad darn well better turn on at, or reasonably close to 45F. If it turns on at 30F it is broken by definition.
--
Alan

[steve dunham]

Why not coil & tape off the 120 VAC leads coming from the heat pad , put them in a plastic bag and place them toward the outer surface of the spray foam
That way if the 12VDC portion of the pad fails again you may be able to change over to 120VAC without tearing out all the foam and replacing the pad
Many pieces of electrical equipment are dual rated for different voltages , as long as the wires are marked - no problem - no worry.

[rubicon327]

This thread is a bit of a head scratcher. Even though there are dual voltage heating pads available (2 sets of wires) the OP is saying that the thicker wires are on the trailer side - not coming from the heating pad. I do find this confusing because (despite Dustin's explanation) Escape is not known to run extra wires that are not being used. Since we know the heating pad system Escape installs is 12VDC and wires under the trailer have been tested and confirmed with live 12V DC power the owner should just hook their new heater up the way it was wired from Escape. Admittedly it sounds like determining that has been the difficulty given the mess under there with the foam, burnt heating pad, "extra" wires, etc. I'm hopeful that with a new working heating pad hooked up to the 12V DC there will be success.

Another part of the difficulty is knowing whether the pad on the gray tank is even working properly. If they are wired in parallel (which they should be) and the connection nodes are further upstream then the gray tank heater should still be working even with the fresh tank pad disconnected. With the exposed 12V wires safed off near the fresh tank it might be worth using your multimeter to check to see if there is any current draw on the circuit during a cold night. You typically have to put the meter inline in the circuit to read amps so taking the connections off the interior switch and connecting to the meter leads should do it.

[steve dunham]

Going off memory and because we have never used the heating pads , I thought their was 2 toggle switches under the drivers side dinette seat , one for the fresh water tank and one for the gray water tank
If I was wiring the pads , I would feed each heater switch with a separate 12 VDC circuit and run separate load wires to each pad .
That way if a pad shorts it would only take out one fuse and the other pad could still operate plus it would be easier to troubleshoot
I have no idea what Escape did and I won’t venture a guess
I’ve read this thread twice and I am still not sure if the problem is electrical or in the wording of the questions and the responses
IE : Seeing OL on the meter doesn’t tell me if the meter was checked or it has bad test leads or a blown meter fuse

[TTMartin]

Originally Posted by medora

But I also distinctly remember being told that the heating pad only worked on shore power (thus we only counted on using it when we were plugged in).

This was because it would quickly run down your 12 volt battery with out the converter providing 12 volt power to the trailer. Not because the heating pads were 120 volt.

[rubicon327]

Originally Posted by steve dunham

Going off memory and because we have never used the heating pads , I thought their was 2 toggle switches under the drivers side dinette seat , one for the fresh water tank and one for the gray water tank
If I was wiring the pads , I would feed each heater switch with a separate 12 VDC circuit and run separate load wires to each pad .That way if a pad shorts it would only take out one fuse and the other pad could still operate plus it would be easier to troubleshoot

Understood Steve but was going off the fact that the OP shows one switch in post #1 with label "pads". I also recall all the other tank pad switch installations installed by Escape that I have seen on the forum are comprised of only one switch.

[brroberts]

It may be some had one switch and some two. When I inquired for our upcoming build I was assured two switches.

[rubicon327]

Originally Posted by Brian B-P

If anyone has the tank heaters and no foam, it would be interesting to hear where those wires for 120 V AC go... but at this point is doesn't matter to the current situation.

Brian: I know the foam is available with or without tank heaters but I don’t think heaters are available without the foam.

[Brian B-P]

Originally Posted by rubicon327

Brian: I know the foam is available with or without tank heaters but I don’t think heaters are available without the foam.

Good point!

Maybe someone has seen the heater installation before the foam was applied, or ETI could provide a photo... a description would work, but clear information doesn't seem to be readily available.