False Readings on Black/Grey Water Tank

[stevegoldfield]

I bought a new 2018 Carado Banff in July, and so far, I've taken it on one long trip. The gauge on my Black/Grey water tank got up to 2/3. I dumped it, but it stayed at 2/3. Yesterday, I filled it with water and dumped again. It still reads 2/3 even though I know it's empty. I tried a couple of Valterra devices. The first was a wand to spray the tank from above, but it won't go down the toilet or the drain. The second attaches to the black tank drain with a hose attachment to spray upward. So far, neither of those has worked. This appears to be a very common issue for RV owners. I see various products which say they can help, such as Happy Campers Extreme Holding Tank Cleaner. Some people add ice or water and drive around and then dump. I'm assuming that something is blocking the sensor and making it think it is 2/3 full when it isn't. Can anyone suggest a reliable solution or should I just live with a tank with false sensors?

[rvsprinterguy]

Since your unit is new, why not pursue a warranty fix?

[markopolo]

Hymer / Roadtrek might be using the most basic probe type tank level monitor system.

They can get fouled up from gunk but I wouldn't expect it after just one trip and after a complete flush out with fresh water.

Originally Posted by stevegoldfield

............. Yesterday, I filled it with water and dumped again.

Did you see if it read full after filling it? If it didn't change then maybe the probes or wiring or both were not correctly installed.

[JohnnyFry]

I hate to break the news but this is an almost universal complaint among RVers. Manufacturers should have taken the hint years ago and moved on to a more reliable system. The best I have heard about is the “SeeLevel” system which does not touch the interior of the tank.

[mumkin]

I wish I had a dollar for every new RV purchaser who posted this question. The only time I have had a black tank that correctly read empty was the day I took them off the sales lot and it had never been used. One it was full... it always read 2/3 to full. This has been true of all three of my RVs... over 14 years.

With my first rig I tried all the advice... ice cubes... various different chemicals and cleaning options. And never putting toilet paper of any sort into it. Didn't matter... was still invariably wrong. Actually my first one did read empty once, but I knew that it was full. After a few months, I now only read the black tank gauge if I need a laugh.

But, with regular use, you begin to know when it is full.

[markopolo]

You do hear about problems with that basic probe type system but you don't hear about all of the relatively problem free good systems out there.

Winnebago uses True Level and that is a step up from the probe type systems. https://winnebagoind.com/key-feature...ures/truelevel

I'd think that Tank-Edge by Tech-Edge https://tankedge.com/index.html would have accurate systems. In addition to new systems they support older monitoring systems manufactured by Snake River Electronics, Geckotec or Larson Electronics. They sometimes have an Acu-Gage label or coach manufacturer label.

I find that old no probe system to be accurate and you can easily calibrate it yourself. The end user calibration allows for customization. In my Class A, I set the 40 gallon grey waste tank to show Full at the 30 gallon point. That allows two more showers or so before it is a must dump situation. I have the propane level set more or exact. The black tank is set to the Full light coming on at 34 gallons - only 4 gallons less than actual full capacity.

[Bud]

I'm lucky with my 05/04 Roadtrek 190P back and gray displays. They are lousy, but when I did the math concerning all the tank sizes I did not need either the black or gray displays. When I stop, it is because I need fresh water and dump too without any risk of either tank being full.

Bud

[<<B-Guy>>]

Over many years of RV'ing in different RV's, I have just learned to live without them - mine have always been nothing but a frustration

- now water from tap? fresh water tank empty.
- grey water backing up in shower? dump grey tank.
- look down into the toilet tank, level high? dump black tank.


These are extremes of course and I rarely get to this stage - you soon learn typically how many days you can go before you will be getting close and arrange accordingly.

In the past my experience has been mostly with trailers, I am thinking that with the "B" van we have on order, things should be even easier. What I mean is that if we don't have hookups and our site, well, we will likely be going out in the van at least every coule of days if not every day, so just a quick stop at the dump station on the way in or out should be no big deal even if not entirely necessary.

Just my thoughts! ................. Brian.

PS - I thought some of the newer systems had probes that were actually outside the tank wall and still sensed the level inside. if that is so, I would expect those ones to be much better.

[markopolo]

With a combined black/gray tank you'd never want to experience waste water backing up into the shower pan when showering. That's a gross enough experience when it is only gray water!

[<<B-Guy>>]

Originally Posted by markopolo

With a combined black/gray tank you'd never want to experience waste water backing up into the shower pan when showering. That's a gross enough experience when it is only gray water!

Agreed! never had such an animal!

Brian

[booster]

The Tank-Edge setup looks to be relatively inexpensive for a 3 tank system. I did look at the install section and it requires double strips of wide aluminum tape with a gap between, so finding enough flat area on class b sized tanks might be an issue.



The Truelevel, with just stamp sized stick on sensors would probably be the easiest to find a place for on odd shaped tanks, but you lose some resolution with 1/3,2/3, full increments.


The Seelevel that we have would fall somewhere between the above two brands. The sensor needs full height flat on the tank, but the area is narrower than the the Tank-edge, so would be a bit easier to find a spot. It does have the 100% range for resolution.


Any of the mentioned outside sensor gauges are going to be much better than the inside the tank versions.

[avanti]

Originally Posted by markopolo

With a combined black/gray tank you'd never want to experience waste water backing up into the shower pan when showering. That's a gross enough experience when it is only gray water!

Certainly true. But, a properly-designed single-tank system will have a one-way check valve in the shower drain, or at the very least a tub-style step-to-open stopper to keep the shower sealed between uses.

[GeorgeRa]

Between internal electromechanical float, capacitive, ultrasound or external capacitive I think that the most reliable, very insensitive to potential build-up would be an internal pressure-based level sensor like for example this one - Waste water level gauge|Narrow|Boat|Marine|RVs|Tank|Plastic|black|gr ey. I am certain that there are more companies manufacturing pressure sensors with or without a meter. The sensors could be mounted anywhere as long the sensor itself is on the bottom of the tank.

With reasonable costs for immersible pressure sensors I am surprised that this technology didn’t penetrated make yet the RV world. https://www.alibaba.com/trade/search...sGalleryList=G

[ponti33602]

We read here somewhere and did this...............after adding the chem pak and measuring the what we put in at that point, we then count the number of 3-second flushes. We have ~20 flushes till full. Gives us a good idea especially where we only have a 10 gallon black tank. She just marks each flush on a post-it note.

[Roadtrek Adventuous RS1]

Originally Posted by stevegoldfield

I bought a new 2018 Carado Banff in July, and so far, I've taken it on one long trip. The gauge on my Black/Grey water tank got up to 2/3. I dumped it, but it stayed at 2/3. Yesterday, I filled it with water and dumped again. It still reads 2/3 even though I know it's empty. I tried a couple of Valterra devices. The first was a wand to spray the tank from above, but it won't go down the toilet or the drain. The second attaches to the black tank drain with a hose attachment to spray upward. So far, neither of those has worked. This appears to be a very common issue for RV owners. I see various products which say they can help, such as Happy Campers Extreme Holding Tank Cleaner. Some people add ice or water and drive around and then dump. I'm assuming that something is blocking the sensor and making it think it is 2/3 full when it isn't. Can anyone suggest a reliable solution or should I just live with a tank with false sensors?

YES.... I called Roadtrek and inquired about this...... they fully admitted to me that the gauge they use is an "estimate".... might as well not have any guage at all.....

We've had the same issues... really annoying......

I'm thinking about SEE LEVEL guages...they work and are quite different in how they function....

[mumkin]

Why would they deny what has been the standard inaccuracy for the last..20? 30? more years?

[Roadtrek Adventuous RS1]

Originally Posted by ponti33602

We read here somewhere and did this...............after adding the chem pak and measuring the what we put in at that point, we then count the number of 3-second flushes. We have ~20 flushes till full. Gives us a good idea especially where we only have a 10 gallon black tank. She just marks each flush on a post-it note.

Probably wise .... where do you keep this journal...in the bathroom?

We just experienced what appears to be a failure of the macerator..... after a long conversation with Roadtrek.... seems like we have a dumping problem.?

Probably have to get the unit replaced?

The guy on the phone said he was pretty cautious about putting anything in the tanks.. unless they dissolve by themselves........ recommended ice.....

[BBQ]

.

There are 2 types of sensors.

The old type uses a float-switch inside the tank.

The new type uses a transducer on the outside of the tank.

[Roadtrek Adventuous RS1]

Originally Posted by BBQ

.

There are 2 types of sensors.

The old type uses a float-switch inside the tank.

The new type uses a transducer on the outside of the tank.

Exactly..... the ones outside the tank are much more precise.

That's what the SEE LEVEL guages are...... just expensive and labor intensive to install. I looked into it.

$1,000

[booster]

Originally Posted by Roadtrek Adventuous RS1

Exactly..... the ones outside the tank are much more precise.

That's what the SEE LEVEL guages are...... just expensive and labor intensive to install. I looked into it.

$1,000

There are some misconceptions on the accuracy or how "precise" the Seelevel gauges are, I think. The gauges only measure the level of the liquid in the tank, and they have a tolerance on that reading like any instrument would, but that is not the big error you will get in your daily life.


Since they only measure the level in the tank, they are only accurate for a constant crossection tank, eg one that is linear in depth vs volume as it fills. If the tank is odd shaped like nearly every class b tank is, you are only as accurate as the amount of change in crossection of the tank. This can be a very large error.


If the sensor isn't in the middle of the tank when level, it will not read correctly if the tank slopes, and if the van is not sitting level, the reading will vary depending on if the sensor is on the high or low end of the tank.


All of these errors make the reading another "approximation" of how much is in the tanks, but a much better approximation than a 2/3 light that stays on all the time


I tend to like accuracy, so I just made a crossreference chart that I have on the wall by the panel. All I did was completely empty the tanks and then fill them one gallon at a time, taking a reading from the Seelevel at each gallon in each tank. When done, all we do is look at the reading on the gauge in %, find the closest % reading on the chart and it shows us how much is in the tank in gallons left to go or gallons in the tank. Being within a gallon or two is about as close as you will come, unless you make the chart by the quart or some other smaller increment.


So, the Seelevel gauges aren't all that accurate or precise, but they are very repeatable from what we have seen, as long as you have the van at the same level between comparisons, which can be an issue sometimes. Our chart is based on level per out setup level.