Saturday, October 12, 2019

Truma Install in RoadTrek Simplicity

Truma Combi Eco Plus Install 

markoch at

I purchased this unit from  I also ordered the kit with the ducting elbows etc. The install instructions are very detailed and easy to follow.  The biggest issue is that there are no Roadtrek Simplicity/Zion instructions.  So you have to decide where to put the furnace and ducting. So I guess the point of this blog is to document my choices.

I recommend having a professional do the gas line installation and put in the 20 amp 120 volt circuit (only if you get the Truma model with the electric element).  Have this done after you remove the existing equipment, the old plumbing, and the wood partitions.  There is no need to remove any cabinets--just the face plate for the furnace/water heater compartment.

I refer to the C pillar in my install.  Thats the metal van pillar that has wiring and piping in it and to which the water pump is mounted.
  • First I removed the Suburban water heater and furnace. Note SHUT OFF THE GAS first.  This was straightforward.  Not many screws used to hold these in place!

  • Then I took out the wood partitions and platforms in the space.  I left the horizontal partition immediately below the drawer. I thought the plumbing was pretty sad and of course in the way so I cut them back to the wall.  The four pipe runs below are:
  1. Supply from fresh water tank
  2. Supply back to the pump
  3. Cold to the water heater
  4. Hot from the water heater

  •  In the picture below there are a few wood bits remaining next to the black ABS pipes shown--they came out later when I changed my mind about how to run the water pipes.  I moved the water pump a few times--totally not necessary, but I wanted to attach it to something other than the C pillar to make it quieter.  It did not remain where it was in the picture below.

  • Removed gas lines back to the tee underneath the van.  I replaced the tee with a new elbow.  The main line is 1/2 inch and the gas hose is 3/8 so it was a reducing elbow.  This is an odd size, there are other ways to plumb it, but would take two parts.  Don't turn the gas back on until the final hook up is done!

  • I made two panels out of 1/4 inch HDPE to fill the exterior holes left by the demolition.  In the larger one I installed an outside shower.  Not because this was necessary, but because it makes the exterior look more deliberate and because I did not have an outside shower.  
  • Then I installed the exterior air intake and exhaust cowl per the instructions.  I don't think that this is going to melt the HDPE, but if it does I will deal with that.  The Truma vent is larger than the Suburban holes so had to trace a circle and cut the top one larger and offset towards the front to avoid the C pillar.
  • Next I plumbed in the new shower below.  Had to add two tees in pipes above.
  • Then I set the furnace in the space and cut the intake/exhaust duct to length and measured where the plumbing needed to go.  This is the point to have the gas line installed and the 120v outlet if one is needed.
  • Installed exhaust/intake below.  The water supply line from the tank can be seen above the duct. I wanted to raise it above where it was in the C pillar so I just cut it back to the space behind the ABS pipes.
  • I added a vertical panel just to the left of where the furnace sits and ran the plumbing to where it needed to go.  Note the required drain (brass) which just fit into the old hole in the floor.  You can also see the pressure regulator (white) top center which protects the combi from any input pressure over 40 psi.  Also the three bypass valves needed to winterize.  I tested for water leaks at this point with the bypass valves closed.  I found that air was being sucked into the pump through a Shark Bite elbow so I replaced it with a regular pex elbow.

  • The below shot taken through the drawer opening shows where my water pump ended up right in between the C pillar and the old water heater opening.  It is mounted to a wood panel screwed to the van exterior.  Very quiet. There is no need to move the pump--just something that I did.
  • You will also note in the last shots that I added insulation panels to the outside wall.  I decided to seal up the entire rear of the furnace room/drawer space so that the cold air returning to the Truma would not come into contact with the van exterior or any of the spaces behind the refrigerator or shower.  This is not required, but I wanted to do it.  It was a bit tedious to do, but not difficult.  I used 3/4 inch foil faced polyiso. The sides are sealed to the cabinets--not the exterior.  Yes some plumbing and wiring is now buried. So be sure to test for leaks before you install the Truma unit itself.

  • Not shown, but I mounted the temperature sensor above the door as recommended.  Wires were pulled through the overhead by removing two lights fixtures.  I mounted the Control panel in the rear wall that encloses the refrigerator.  You have to remove the fridge to do this.  I insulated behind the fridge while I was at it.  Power for the control panel comes from the wires for the CO/Propane detector.

  • I ran the two right side ducts right out the front (above).  I bought a 6 inch duct insulation and cut it down to fit the 2.5 inch Truma ducts.

  • By mounting the furnace all the way to the right side of the compartment, I ended up with the storage/plumbing access space above which is accessed through the old water heater door. You can see the pump supply side strainer up top.  Not visible behind it is the winterization valve/inlet.  The clear tube is from the Truma and goes out through the existing hole in the floor.  The propane supply is also visible right behind the strainer. In the lower left is the 20 amp outlet for the Truma (optional).  I added the hole in the wall for a the cold air return.  I am pulling all the air through the inverter space.  Might be better to add a grille in front.
  • I ran the lower left side duct through the inverter compartment and the upper one up and out through the wall on the left side of the drawer.
  • Here is what the water and gas connections look like.

  • I used some of the wood removed to fill in the hole in the front panel.  The right side ducts are shown here.  The ducting is fastened to a scrap of wood behind the panel--the louvered vents then are in the front panel.
  • Hookup the 12 volt power.  I used the water heater wires--just put on the new terminals provided.
  • Done!

Friday, April 27, 2018

RV antifreeze in drinking water tanks -- Never again!

The dealer was kind enough to winterize the rig when we picked it up for free.  They must have put 10 gallons of that foul tasting stuff in the tank.  Getting rid of all the taste has been a real pain.

From my sailboat I know better than winterize this way.  The RV needs a valve and a siphon hose just before the pump.  Drain water heater and tanks.  Turn valve, put siphon host into antifreeze bottle and send to fixtures.  Done.

I'll add the siphon hose in the lines that have the filter in the water heater compartment.

Toilet lid won't stay up--Fixed.

Boy this seems pretty dumb.  You lift the lid and it falls back down before you can sit.  If I had not seen others complain about this I would believe it was just an error in our Van.

After thinking long and hard about magnets, latches, or some other solution, I finally just grabbed the toilet and twisted it about 10 degrees counter clockwise.  No tools required!

Now the lid stays up.

Backup Camera

I got a backup camera from amazon.  Pulling the wires through the van was a pain.  But it is nice to have now.  I powered it from the van cigarette lighter so it is always on--a virtual rear view mirror.

I learned how to remove the radio and dash.  Two u shaped pieces of coat hanger suffice to pop the radio out.  Then just remove screws to pull the pocket above radio and or clipboard above.  The cupholder panel is held in with screws and four very strong clips.  So once the screws are out pull hard!

Below is a view of the cupholder panel removed to install the backup camera controller.  Lots of room back there to put stuff.

Bike rack

A bike rack was a must for us.  I wanted a tray type that did not require a trailer hitch to be installed.  In my opinion a trailer hitch works badly for bicycles since the single point of attachment bounces around and blocks the back doors.  Also you end up with a lot of weight, which the RT really does not need.

So we spent the $$ to get the Fiamma rack.

It was easy to install and is working very well.  Doors open easily.

One not unexpected problem is bikes collect dust and crud on dusty roads or when it is raining.  I would like to cover them, but that is a different project.

I did move the rack to the lower position (there are two) to make loading and unloading easier, to keep them away from the backup camera, and to eliminate the hitting of my head.

Trunk - outside storage

Since we do not have a spare tire, I made a trunk to keep outside stuff like the shore power cord, hoses, lawn chairs.

I used a 1/4" HDPE panel.  It can be bent if you heat it up with a heat gun.

It works pretty well although some dust gets inside--I will have to seal it better at some point.

Thursday, April 26, 2018

Furnace failures

We have had the furnace lock out a couple of times while running it overnight in colder temps. I am pretty sure it locks up when the voltage is low. Every time the refrigerator cycles on there is a voltage sag at the meter. Not sure if the solution is better wiring, a second battery (only one 100 amp currently), or a less sensitive pcb on the furnace.

If it is so cold that we need the furnace on at night I'll turn off the fridge for now. Normally we don't need the furnace after we get in bed.

I did install a new thermostat for $14, which we like a lot. Analog is so much nicer than the digital one. We can reach it while in bed and just slide the lever Yay!