Water tank issues

[Per Walthinsen]

It is time I dealt with the fresh-water issues in my trailer. The water pump is banging away (Aquatec variable-speed unit, no less) and it quits pumping when there is more than 3 gallons left in the tank. Two issues here, but I want to deal with the tank first:

When I inspected the tank I found that the earlier problem had reappeared. The tank (underneath, long transverse design) is held up by two stout chains: on the drain end it is tight, but the other sags despite a turnbuckle arrangement I put in. That chain is not at the end but at least 1/3 of the way in from the end, so it takes most of the weight. I need to cobble together an entirely new method of attaching the tank, since something is evidently gradually giving way. I think I can do this.

Now for the related questions: 1) The vent pipe, a transparent flexible plastic tube, bows down as it leaves the top of the tank before it heads for the water connection housing up on the side of the trailer. Therefore it in effect produces a P-trap effect, always keeping a small amount of water in the dip. Near the end of the process of fillng the tank, this tube therefore spits out water and usually gets me wet if I'm not paying attention. I don't think it really affects the water pump action, but I suppose the water trapped could freeze and split the tubing. Is there a legitimate reason for this tubing to act as a P-trap (keeping insects and dirt out maybe) or can I just support this tubing so it does not act as a P-trap?

Question 2. The intake fitting from the tank is maybe an inch above the bottom, so it contributes to the pump quitting early. The drain for the tank is at the very bottom of the tank and empties it out well. What would happen if I connected the intake to the drain fitting to make it do double duty? Are we talking about dirt, and whatever junk gets into the tank being sucked into the pump? I drain and sanitize the tank many times a year, we have what should be pretty clean water, and there is a filter before it enters the pump. This filter looks clean all the time, so the amount of contaminants does not seem to amount to much. Maybe having the intake above the floor of the tank is what keeps it clean? (I'd like to be able to let the pump suck out more of what I put into the tank).

I am considering shimming the tank and tilting it ever so slightly toward the drain end. It may be a better solution.

I

[Gina D.]

Mine does both of those things.

As far as the somewhat unempty wet tank, I just fill again and don't worry about it. The rest gets drained at home.

I actually like the "spitting" feature. When in a site where the spigot is far away, I use this "feature" to let me know when to shut the water off.

Keep in mind, I use forest service sites, and over half do not have threaded faucets, so I have to use a water thief and stand and hold the valve open. I can see and HEAR the "spit" of the water and know it's time to let go before I have a flood under the trailer from overfill.

[Donna D.]

Would it be possible to put a filter between the tank and the pump....something inline like those clear gas filters for tugs??? You could even put it just inches from the pump if it's visually accessible...rather than under the trailer. And yes, I'd worry about gunk invading the pump without it if you pump water from the very bottom of the tank.

For several years now, manufacturers have been making plastic gas tank for classic rides. Perhaps instead of chains holding up your tank, you should look at straps...like these...padded with rubber inner tube?
Tank Straps

[Gina D.]

it is below freezing here right now. I will go look and see if it is frozen or not.

I suspect that the water would just expand into the other areas?

Let me see if I can see

[Gina D.]

well, I put a glass of water in, and out it came from the tank drian.. must not be frozen!

[Per Walthinsen]

We have had a break in the weather long enough for me to get started on this issue.

It would be interesting to know how they attached the tank in yours, Gina, because on mine the two chains holding the freshwater tank up are not spaced equally along the length. One is right at the water connection end and the other is roughly two-thirds of the way toward the curbside. That last one is the one holding most of the weight and seemed to gradually lose grip, in some small way, over time. The extreme curb end was unsupported and sagged some. I'm not sure I can understand the thinking behind this or the manufacturing process reasons for it. No logical reason?

These chain attachments don't seem very remove-and-replace friendly, so I finally decided to cobble together an attachment system which did not depend on going through the floor (inaccessible, for the most part) but attaches to the angle-iron members of the frame. I think I found a solution, which I applied to the unsupported end. It is much sturdier but a cinch to undo. The existing chains have been cut and fitted with turnbuckles and redundant screw links in case the turnbuckles should fail. (If the new system tests out well I will probably drop the tank and replace all the chains with it.)

Therefore I have been able to insert shims to tilt the tank down about half-inch at the business end. The original irritation came when the tank monitor, which had been pretty well calibrated, kept showing a lot of water left but had the pump choking on air. We sometimes camp where there is not even water available, so this kind of surprise is unwelcome.

There is a filter at the intake to the pump, but it will come off temporarily as I test the pump and attempt to get it to simmer down a bit. Could be a bigger, less restrictive filter will be needed. On the other hand I am not pulling the water from the drain outlet yet, so no excess junk should be getting into it.

[Kurt & Ann K.]

Per,
When I first saw the chain tank supports on Gina's McMansion, I couldn't believe my eyes. All tanks I've encountered have used insulated strap supports. Chains were a new idea to me for this application and appeared to be a quite make-shift solution. Each chain link looked like a point to wear holes in the tank. Bolting through the floor also seemed a poor idea given the occasional floor rot problems that have been known to occur.
Using the frame rails to support angle-iron cross pieces with the tank on top would be much more supportive. If the tank is too tall to fit between the underside of the floor and the bottom of the frame rail, the cross piece could be hung below with all-thread pieces cut to the appropriate length. I'd use aircraft nuts with nylon inserts on the top and bottom of the all-thread as a safety measure. Straps over the tank top with the ends terminating at the cross pieces would keep the tank from sliding as long as the straps are snug. Heating and bending the strap ends at a right angle will provide a place to drill for a bolt to also go through the angle iron cross piece. An inexpensive insulation to protect the tank from abrasion is vinyl baseboard material used in commercial institutions like schools and hospitals. Many hardware stores carry it in strip or roll form. It can be cut to width and length with tin snips or a sharp razor cutter. In it's normal use it is glued in place, but if the bands compress it a little it should remain in place. It should also be used between the tank and cross pieces.
Tilting the tank could be achieved easily with a spacer under one end or side as necessary.
I'm encouraged to find someone else is doubting the wisdom of using chain in this manner to support a water or gray water tank.Please keep us posted on your ultimate solution.

Kurt & Ann K.

[Per Walthinsen]

Kurt:
Thanks for a thoughtful reply. I am sure there are myriads of ways and variations on how to do this, and the one you suggest seems like a good one. To be sure, the tank does not show any discernible damage from the chains, but eventually my intuition says there will be some.

Probably the main issue I have with the original arrangement is the actual way the chains are attached to the angle iron and floor. It may have been quick and easy, sturdy even, but it ignores completely the eventual need for removal and adjustment. (Hand me the hacksaw, honey)

I will attempt to take a couple of pictures of the arrangement I've experimented with so you can get an idea of what's involved.

[Per Walthinsen]

Kurt:

A couple of pictures. The piece attached to the angle iron on the frame is 1" square steel tubing, fastened with 5/16" grade 8 carriage bolts. The long bolt is 3/8" grade 8.

The long piece of square tubing underneath is 1" square aluminum and the support piece above is 2" wide. What you can't see here is that it is curved up on the far end to keep the tank from moving. None of it has been treated against corrosion yet. What this gives is support as opposed to the crushing action of the chain around the tank.

This is a trial run, and I'll keep tabs on how the aluminum tube is doing. It could be replaced with steel, and both pieces could be changed to solid bar stock, which I hardly think is necessary.

At the end of the long bolts I elected to put a flat washer and two nuts with a lockwasher between them. Easy to undo.

As for the tank sliding around, I have some tropical weather resistant wood cutoffs which could be screwed alongside into the floor with SS screws. Should keep it nicely in its place.

[Kurt & Ann K.]

Per,
Looks good, are you going to do the other end the same way? The aluminum tubing could be replaced with 1"X1" angle-iron if electrolysis proves to be a problem. Personally, I'd still provide insulation between the tank and the metal supports. Our concepts are alike as far as the tank sitting on supports rather than being suspended by chain.
Proves the old adage, "there's more than one way to skin a cat".

Kurt & Ann K.