Windjammer - Tank Heater Switch Not Lit

[cobiker]

Not quite ready to winterize the trailer, and the temps are supposed to drop to 20 degrees tonight. So the furnace is on but when I turn the switch on for the tank heater, it doesn't light up like the water pump and water heater switches do. Checked breakers and fuses and all looks good.

How can I tell if the tank heaters are on? Since the underbelly is enclosed no easy access to underneath.

Thanks,
Scott

[dcheatwood]

I believe they only kick on when temp drops below 40°. Just leave switch on for safe measure.

[Herk7769]

Here is the web site FAQ.

UltraHeat, Inc. - FAQs

UltraHeat, Inc. - Before You Buy an RV

[cobiker]

Nothing in Owners Manual about Heated Holding Tanks, so called dealer about how they are supposed to operate. Said the light should go on when the switch is on, also there should be a 12V fuse labeled "HTH" (Holding Tank Heater). Well there's not fuse on the panel for the WFCO 8900 labeled like that. We have 12V fuses for things like

Porch
S/O
Living
Appli
A/C
Stereo
TV
Bath
Pwr Jack

I'm curious what we why there's a fuse for the A/C or TV. Both would use 110V. So makes me wonder if the switch even got wired up.

So I did find in the 2011 Windjammer Brochure under list of features something called "Electronically Controlled Heated Holding Tanks" as "Standard".

And found the following in the Forest River "Motorized" Owners Manual.

HOLDING TANK HEATING PADS
1.) When the outside temperature is near freezing, simply turn ON the holding tank heater’s 13.5 VDC power switch and/or plug in the 120
VAC power cord.
2.) There must be liquid in the holding tank, pipes, and elbows when UltraHeat™ heaters are ON.
3.) The tank heater immediately starts protecting your holding tank from freezing up.
4.) The thermostat on the heater will turn ON the tank heater as soon as the tank temperature drops in the tank 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.
5.) If using a generator or other power source, which exceeds the heaters voltage requirements, turn the heater OFF and/or unplug the power
cord to avoid eventual damage to the heater’s thermostat.
6.) Turn the power switch OFF (and/or unplug the power cord on the Dual Voltage Model when the outside temperature is above freezing.)
7.) Failure to follow these operating instructions could result in the voiding of your warranty. (The control is generally located in the command center.)
NOTE: Tank heaters are thermostatically controlled. This product has been tested and designed to be used as a heating device for RV fresh water supply and waste water holding tanks
made of standard grade plastics. UltraHeat, Inc. assumes no liability for any usage of product for purpose other than what is consistent with the original design and testing.

Guess I need to pull the control panel and the cover for the Power Distribution Center (WF-8900) and see what we've got.

Will post findings.

ps. Looks like we made it ok last night with temps down to in mid-20's. Furnace and HW Heater running.

[dcheatwood]

I had read online about the thermostat coming on at around 40. Maybe it said 44°. Don't remember. I did hear the cooling fan kick on near the inverter when the tank heaters were on. Glad it all worked out.

[Herk7769]

The switch will not illuminate (when on) until the liquid in the tank falls to approximately 44F degrees. The pad will "make a ground" turning on the pad heat and the light in the switch. It will "keep it's ground" until approximately 64F degrees, when the pad and light will go out.

NEVER:

Use tank heat when any tank is empty. There must be SOME liquid in the tanks to spread out the heat and avoid damaging the tank or the heater pad.

Use the tank heat when the outside air temp is above freezing (32F) AND forecast to remain there. It is possible for the pad to overheat and fail.