Heated Tanks

Snowyowl · 10-11-2010, 07:01 AM

This my first trailer with heated tanks. Presently there is water in the black tank and water in the fresh water holding tank but nothing in the gray tanks. My question is whether it is safe to turn on the tank heaters with the gray tanks empty? I couldn't find anything in the owner's manual. I can easily add water a couple of gallons to the two gray tanks but hadn't done so to reduce weight when we start traveling again. A second question is regarding leaving the tank heaters on while we are rolling down the road. Is it ok to do so and are the heaters effective during towing?
Temperatures are dropping every night now and it won't be long before it starts to freeze. We won't be heading south until 2 Nov. and while I don't expect extreme cold by then, overnight freezes are almost inevitable.
Thanks!

jimh · 10-11-2010, 08:21 AM

hopefully, u will get another answer that is more informed than mine. i've read on the forems says that u shouldn't turn them on unless there is liquid in them. i don't believe they actually work until the tank gets around 40 deg.

on the weight of the water while traveling. have u tried pulling with ur fresh water full and empty and compairing performance of ur viehicle (acceleration, braking, and fuel economy)? on mine, i can't tell any difference. useto always run dry until i spent the night in a full hook up campground that lost the water 1 hr after we got there. like to have some water to flush with while on the road (traveling between campgrounds).
it makes sense that the weight would reduce performance but it is such a small percent added. u can carry less. i usually run abt half.

**Herk7769** · 10-11-2010, 10:07 AM

Jim,

That is my understanding as well. The heater pads are supposed to have a thermistor that modulates the current to maintain a constant temperature. This arrangement is similar to the "belly band" I use on my wine fermentation bucket to maintain the temperature of the fermentation when it gets colder than 70 degrees in the basement. It just plugs in and modulates itself.

All things being equal, I don't think you can burn the pads out, or melt the plastic, running them with an empty tank.

I would not take the chance myself though.

Snowyowl · 10-11-2010, 11:04 AM

Thanks, guys! I'll pout some water in them this PM. There's a frost warning for tonight.

jimh · 10-11-2010, 07:49 PM

Quote:

Originally Posted by herk7769

Jim,

That is my understanding as well. The heater pads are supposed to have a thermistor that modulates the current to maintain a constant temperature. This arrangement is similar to the "belly band" I use on my wine fermentation bucket to maintain the temperature of the fermentation when it gets colder than 70 degrees in the basement. It just plugs in and modulates itself.

All things being equal, I don't think you can burn the pads out, or melt the plastic, running them with an empty tank.

I would not take the chance myself though.

Somehow, i would have thought it would have been a little more elaborate than a simple thermistor....interesting. maybe now i can find out if mine are really working or not. the light doesn't come on on the switches.
i would love to see actual schematics of the control boards for the frig and whatever else is in there. i haven't tried but doubt if the manufactures want u to see them.

**Herk7769** · 10-11-2010, 08:07 PM

Jim,
The light should come on with the switch. If you are not getting a light you need to check the circuit breakers. The pads are AC and only work on shore power.

I will try to find the site that sells aftermarket circuit boards for the fridge. I seem to recall there was more info there.

Ah, there is more info here:
http://www.dinosaurelectronics.com/

jimh · 10-11-2010, 09:17 PM

yep that was the site.

i haven't found a blown fuze or a breaker off. i'm hoping that it is something as simple as the bulbs burnt out on the switches. (my switch handles light up). probably would put a lot more emphsis on it if it got cold here. there is a general wiring diagram on the cardnal web site.

those frig boards, i keep treatning to go out and make some parts placements on the board and take a few voltage readings. then if it goes out, i should find what is different. i've been threatning to do this for the last 8 yrs. still wouldn't mind studing a schematic and seeing what they are doing.

Snowyowl · 10-12-2010, 04:58 AM

If the pads only work on shore power then obviously there could be a problem with towing in cold weather. I'm really surprised that they don't work on DC as well.

jimh · 10-12-2010, 06:36 AM

i was looking at some wiring diagrams for a 30ts but haven't looked to see what year yet. in that diagram, they work on 12 v. draw abt 5 or 6 amps each.
i've never tried mine when i wasn't plugged in to shore power.
my trailer was purchaced new in 2002. they worked when i got it and a couple yrs later, they didn't indicate that they were on. dealer repaired didn't know what they found. now they aren't indicating again. they haven't been a priority because they aren't needed here.
now that i'm retired, i'm tending to want to look a little deeper into it now.
i downloaded several wiring diagrams and will post the link if i can find it.

try this and see if it works.
http://www.cardinalrvclub.org/redbird/viewforum.php?f=42&start=0

**Herk7769** · 10-12-2010, 07:11 AM

Quote:

Originally Posted by Snowyowl

If the pads only work on shore power then obviously there could be a problem with towing in cold weather. I'm really surprised that they don't work on DC as well.

Just think of the wattage involved. It would destroy your batteries amp hour capacity.

As for towing, I doubt if the tanks were warm to start out, that they would freeze in route.

I worried about the plumbing since we drive to FLA from PA in January.
Last year it was VERY cold and we did not get above freezing until GA.
I thought about leaving the heater running with the cabinets open, but decided against it for safety reasons.

As it turned out we had planned our trip with 4 hour legs between campgrounds and the camper stayed well above freezing the entire trip with no additional heat. I did leave the cabinets to the plumbing open so the warmer air in the camper would circulate into the pipes.

I also used a 12DC clip on fan to force the warm air into the cabinets while we traveled.

Hipshot · 10-13-2010, 01:46 PM

I just checked my Roockwood 2604SS and the tank heaters seem to be DC. With shore power disconected the tank heater switch lites up when turned on.

**Herk7769** · 10-13-2010, 01:53 PM

Hmmm...

Gratz, I think. Do you have a TM-2025?
I would love to know the DC amps they pull.

Apparently they make both kinds. Here is what the manufacturer has to say about the products.

Q) When should the UltraHeat® Tank Heaters be turned "ON"?
When should it be turned "OFF"?

A) The 13.5 VDC power switch for the 13.5 VDC UltraHeat® Tank Heaters should be turned "ON" or the power cord for the 120 VAC UltraHeat® Tank Heaters should be plugged in when the outside temperature approaches freezing 32°F (0°C.) The 13.5 VDC power switch should be turned "OFF" and the power cords unplugged when the outside temperature stays above freezing. All UltraHeat® Tank Heaters are thermostatically controlled, they turn "ON" automatically when the holding tank temperature is 44° F (7° C) and turns "OFF" automatically when the liquid in the holding tank reaches 64°F (18°C.) The UltraHeat® Tank Heater should be turned "OFF" or unplugged when dumping the holding tank.

Another update: They also make a dual powered pad. (120VAC and 13.4VDC) not sure how you select which one to use. Also the 12VDC units pull 10 amps when running (PER PAD) and I have 2 in my unit. The units with a galley tank have 4 pads (one on the galley elbow).

With nothing else on but the tank heaters, my 75 AMP HOUR (as delivered) DC-24 battery would last about 3 hours. Add the furnace and it would not make two hours.

Not an issue while towing for you though since the pads would draw power from the TV. I will need to check this further. Been over a year since I looked at my tank heater paperwork.

Hipshot · 10-13-2010, 05:52 PM

I don't know the current draw and have no way to measure it. The company insisted I leave their test equipment with them when I retired.

We don't dry camp and at home the TT stays plugged in all the time.

**Herk7769** · 10-13-2010, 05:57 PM

The Ultra Heat site says 10 Amps DC per pad.

jimh · 10-13-2010, 09:40 PM

ur not going to last very long on the battery. if ur going down the road with them on, i don't believe the circuit from the truck will keep up. i'm not completely sure but i think the circuit from the truck is 20 amp.

**Herk7769** · 10-14-2010, 07:57 AM

Quote:

Originally Posted by jimh

ur not going to last very long on the battery. if ur going down the road with them on, i don't believe the circuit from the truck will keep up. i'm not completely sure but i think the circuit from the truck is 20 amp.

I need to check, but I think my GMC Sierra's circuit is 30 amps. It would really be an issue if you were charging the camper battery and more than one pad fired up at the same time.

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