Jan 162016

Continued from Part 2

Next step was making clearance and moving electrical/gas out of the way.  The water heater was connected to an iron iron pipe (running the length of the TT) with 3/8″ soft copper tubing and flare fittings..and done with a big loop that extended into the center of the frame.  I cut this out and left things hanging for now, I’ll run a new copper line after installing the tank. (edit: ended up not having to run new copper)

Today I had time to see about mounting the tank.  The rear frame rail that the tank ‘ear’ fits into was very tight, I create a wood block to use as a gauge and used pliers to bend the bottom of the C-channel until the block fit snugly.

wood spacer

I test fit the tank, used a couple of trailer stab jacks to hold up the forward mount bar (no pics, was busy).  Using a rubber mallet I gently gave the forward outboard tank edges a whack or two to make sure the tank was seated.  Snugged up the forward mount bar and verified clearances.  Then into the trailer I used a paint pen to mark the existing toilet flange and vent holes.    I also marked the holes in the mount bar so I could pre-drill the frame.

Prior to removing I marked the tank and frame as a reference so I could the tank in the same position as before.  I carefully removed the tank and brought into the garage.  Hole markings were positioned nicely and clear, went ahead and cut holes for the fittings.  Back outside, drilled frame holes for mount bar.

Brought the tank back out, fitted, bolted up mount bar and verified hole alignment on the inside..BINGO.  The only possible problem was the opening in the floor for the vent pipe (behind the access panel for the rear of water heater) is a bit sloppy.  I’ll have to open that up to make sure I have good clearance to install the fitting.

In this picture you can see the copper line for the water heater, and the tank in place and fully installed.  The mount bar is red’ish (looks like rustoleum).. You can also see the gray water tank to the right.


I did a test fitment of the dump valve. Everything looked good, measured, cut.  Checked again and everything looks like it’s lining up very nicely. As a bonus the black tank dump is straight, that’s going to make for easy/good dumping!  It all looked good so I slathered on some ABS glue and installed.  I’ll need to purchase some 1.5″ pipe to extend the gray dump but that’s not a big deal.  I’m very pleased with how well this is going.


You can see behind the tank the black plastic wire loom bit I have to deal with.

Tomorrow I’m going to fill the tank with water and make sure it’s mounted well and nothing sags or leaks.


  • Filled the tank with water, everything is water tight and the tank itself didn’t seem to sag at all (entire back end of TT sank a bit, not surprising).
  • Gas fitting to water heater: I ended up swapping the T fitting so it was T’ing off to the outboard side which brought the pipe a couple of inches closer to the rear. This allowed me to cut off the munged end of the 3/8″ soft copper tubing, flare it and attach.  Pressure tested, no leaks..ran the water heater a bit and it’s all working.

I think this my be the last update.  All that remains are what I could consider easy/common tasks.  I’m going to pick up some 1.5″ schedule 40 ABS pipe and 2 couplings to re-connect the gray water drain to the output.  Going to use some self-adhesive cable tie mounts to tie up the wiring run that goes from side-side of the trailer.

Only major work remaining is to attach the ‘grommets’ to the tank, reinstall vent and toilet.  I’ll probably take some pictures of that and describe the process, however for anyone handy those parts should be easy.

Update: Everything else went pretty well.  I wish I had more space around the vent fitting, it was a bit of a challenge getting it seated properly. Other than that buttoning up the project went smoothly.  I filled the tank to full capacity using buckets, counted 24 gallons until it was full… a nice upgrade.

Thanks for reading, if I add a Part 4 I’ll link here.


Jan 112016

Continued from Part I

New tank arrived today, appears to be in good shape.  I was pleased to find that the outlet already had an adapter attached so that I can connect directly to 3″ ABS pipe.  Note the slight difference in size, tank on the left is also approximately 2″ deeper.  The added depth isn’t a problem as prior to this upgrade I flipped the axles to underslung which increased ground clearance by about 4.5″, lots of articles on that so not posting one here.


You can see from the huge length of plumbing for the dump that there’s a bit of extra space under the trailer.  My plan at this point is to center the tank (old tank was offset to door side) and use the straight section of pipe from the old tank.  This should result in a straight shot for dumping.  The existing valve assembly has the gray tank coming in at a 90 degree angle already so I should be able to just extend the gray dump to the new valve location and be done.

I crawled under the trailer with the tank to verify fitment, plenty of space.  There are a few things I’m going to have to re-position, some wiring that’s attached inside the frame rail will be moved to outside (hidden behind the bumper) and I may have to redo the gas line for the water heater.

It’s still fairly cold out here, I’ll work on preparing the underside of the trailer at a leisurely pace.  Once I can position the tank temporarily I’ll be able to start figuring out all the details, final position, plumbing, etc.

Proceed to part 3.

Jan 112016

I’m upgrading our travel trailer black holding tank and realized that there’s not much information about this on the net (for some reason, probably everyone wants to sell new RV’s). So a useful non-controversial post! This is the first part of a x part series, following along the process.

First some important details you will need before embarking on this ‘adventure’ yourself. You will need to find the GAWR (Gross Axle Weight Rating) of your trailer, the GVWR (Gross Vehicle Weight Rating), tire rating (make sure total of all tires is equal or greater than GAWR). Then get your trailer weighed, ready for camping (gear packed, food, etc.), full propane, I would recommend empty holding tanks as we can calculate their weight(s).

Measure your holding tanks! This can be a tiresome process, however I feel it’s very important as you may find (as I did) that my TT black holding tank was listed as 12 gallons in the trailer specifications however the tank + 2′ of 3″ piping + the neck of the toilet only manage 6 gallon total! Manufacturers get away with this by simply stating ‘specifications subject to change’. In my case I found out that both the tank AND trailer manufacturers over stated the capacity.
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