Finally - Tank Monitors That Work!
Dave and Helen Damouth www.damouth.com
21 January, 2000 (Addendum added 28 January 2006)
Like most RVers, we've found that our tank gauges are very unreliable, particularly for grey and black water tanks. Vigorous chemical or abrasive cleaning can get them working again, briefly, but it doesn't last.
A few months ago, I bought the AcuGage Monitor System at Camping World. It has a monitor panel and tank sensors for up to four tanks. The sensors attach to the outside of each tank, electronically sensing the liquid level through the side wall of the tank. For this reason, the system can not be used with metal tanks.
I bought the version with an LED display - five little lights labeled Empty, 1/4, 1/2, 3/4, Full. This costs $129.60 with President's Club discount. A version with digital display is also available for $179.10, although only through the catalog (so I haven't had a chance to examine one). The kit contains everything needed, except for the hookup wire - in my case, about 230 feet of #18 hookup wire, purchased from Radio Shack for about $18. I also had to supply the 4 small screws needed to attach the new monitor panel in place of the old one.
Over the past few days, I installed this system on my three tanks. The installation was straightforward, although it took me many hours, spread over three days. Camping World will do the installation for $73 - a bargain, if you can trust them to do it right. After installation, a simple calibration procedure requires filling each tank, then turning a screw on the monitor panel for each tank until the gauge barely reads full for that tank.
The system works very well. The sensors and their attachment method seem robust, so I see no reason why the system shouldn't continue working for a long time.
Following is some additional detail about the installation process, for those who might consider doing it themselves.
On my trailer, the biggest problem was gaining access to the tanks. My trailer has an enclosed underbody, and removing the panels which cover the bottom and hide the tanks involved removing hundreds of sheet metal screws, some of them rusty.
Once the tanks were accessible, the sensor installation involves (for each tank):
1: Identify a spot on a vertical side of the tank, near the center of the tank. Clean the surface in this area with alcohol.
2: Coat this area with a contact cement (supplied in the kit).
3: Cut pieces of aluminum foil tape to fit the side of the tank, extending from 1/2" below the top to 1/2" above the bottom. Stick these on the tank. Attach self-adhesive electrodes from the sensor modules to the aluminum foil.
Two wires from each sensor module, plus a shared ground wire (seven wires in total) must be run from the tanks up to where the monitor panel will be mounted. How difficult this is will vary widely, depending on the layout and type of construction of your rig. In my case, I was able to run the wires through the floor at the point where the hose from the fresh water tank goes up through the floor to the water pump, under my living room sofa. (It might be possible to use some or all of the wires from the old sensors - worth checking before you buy new wire).
From here, I ran the wires along an existing bundle of wires which run along the wall behind the sofa, then through the back of a cabinet under the refrigerator, then up through the area behind the refrigerator (accessible through the outside access panel), then through the wall into the microwave compartment, then down to the front of the hood/fan assembly above the stove, where the original monitor panel was mounted. This was easier than it sounds, but was time-consuming.
The new monitor panel mounted in the same space where the old panel was, secured by four small screws. The installation looks reasonably neat.
The system should be tested before the tanks are covered up again, since the sensors might have to be trimmed to get an accurate reading.
Re-installing the bottom panels was a bit difficult because quite a few of the sheet metal screws had stripped threads out of their original holes over the years, or when I removed them. I had to drill quite a few new screw holes as well as buying and installing oversize screws in other holes. Some of the (plastic) panels had cracked areas around the screw holes along the panel edges, requiring reinforcement (with body washers) or relocation of the screws to new holes. (This trailer is 12 years old).
Notes added 13 Feb. 2003:
I sold the trailer in 2002, about 2 1/2 years after installing the AcuGage sensors. At that point, they were still working perfectly. The only problem is that the printed text on the stick-on labels on the buttons (used to identify the several tanks) was wearing off and hard to see. No big deal - it would be easy to stick my own labels on - or perhaps the factory would send new ones for free.
The AcuGage is manufactured by Snake River Electronics. http://www.snake-river.org/Products.asp?ID=3.
The vendor's web site has interesting information. Their newest version, the Ultra-8, displays tank level in 10% increments for up to 8 tanks, and has alarms, so you can have it warn you if your fresh water tank is low or if your grey water tank is nearly full.
To locate vendors or other reviews of the product, do a Google search on "Snake River Electronics" or on "AcuGage". One source that seems to have the complete product line and good prices is http://www.boatfix.com/elec/acugage.asp.
The basic product works only on non-metallic tanks, and you need access to the sides of the tanks to install the sensors. The above source (boatfix.com) also has rod sensors that can be installed from the top in metallic tanks or in tanks which do not have access to the sides.
Addendum: updated 28 January 2005:
There are several relatively new products which compete with
the AcuGage. Each has slightly different features, and a couple
of these offer a pressure sensor rather than electrical
sensing, offering very different installation options. The
other products I'm aware of are:
Catcon Micro Pulse
www.catconproducts.com
Vena Tank Monitor
www.vena.com
Garnet SeeLevel II
www.rvgauge.com/rv.htm
SensaTank RV100
www.matsci.com
New Providence Marine
www.ferriellosales.com/
I'm in the process of selecting one of these products for installation in my motorhome. After I complete the selection and installation, I'll write another article.