M116A3 Build

[featherliteCT1]

Beautiful ... fits like a glove!

[lfhoward]

Thanks Featherlite!

[S. Heisley]

Looks really good!

[lfhoward]

Thank you Sharon! It’s taken a while to get to this point, but all the careful planning and tank refurbishing was worth it.

More to come next week as I install the Propex heater, weather permitting. Today was 50°, an anomaly that I was happy to take advantage of. Next week there should be a few days where it could reach 44°.

[lfhoward]

Today I ran the electrical lines for the Propex in preparation for installing the unit.

The thermostat is installed. The controls you see, from the top down are: Propex thermostat, Inverter on/off, solar charge controller/battery readout, and dome & porch light switches.


Below in the heater cubby, the thermostat and 12V power pigtails are ready to be connected to the heater. The cardboard template for the heater is inside on the floor.


I had to remove the plastic pigtail to run the wiring through tight spaces. I took this photo so I could put the five wires back into their correct locations.


And finally, I got the cubby door to fit and fasten in place. The left vent is for cold air intake (will be under the bed), and the right vent is for heat.


The hard part comes on Wednesday: drilling holes in my perfectly good floor to install the Propex!

[lfhoward]

I was back at it today working on installing the Propex heater. It was very cloudy so I hooked up my auxiliary solar to try to get a little more power to recharge my drill batteries.


Last time I had installed the electrical but nothing else yet. I began today by putting the cardboard template in the cubby to help me know where to drill.


I started with small pilot holes to make sure everything was lined up. I’m glad I did, as one hole was 1/8” off and I had to redrill it.


Next I drilled out the holes for real. This is after cleaning up all the metal shards and the cutting oil. Then I zapped the bare metal edges with Rustoleum.


The next step was to install the wooden frame that the heater will screw down to.


The Propex can be fastened directly to the floor but I wanted room for insulation. The larger hole in the insulation corresponds to the exhaust pipe, which can get hot. I don’t want it touching anything that can burn.


Here is the Propex in place on the frame.


Attaching the electrical. It is very important to make sure the thermostat pigtail is connected before the power is connected. If not, a main fuse on the circuit board will blow and need to be replaced. After connecting the power I verified the unit can run its fan.


The gas connection. I used PTFE goop on the threads that is rated for propane and will completely seal the connections.


Underneath. Closest to the camera is the gas line, then the combustion inlet and the combustion outlet. The pipes still stick out 5/8” below the floor, so there is plenty of room to attach the intake tube and exhaust pipe.


While the seal around the gas line is with a rubber grommet, the seals around the intake and exhaust will be with this high heat silicone. I will do this step next time, as I ran out of daylight today.


The next steps are:
- Tidy up the wiring.
- Attach the hot air hose to the Propex in the cubby and run it to the vent on the cubby door.
- Seal the intake and exhaust pipes against the trailer to make them airtight.
- Attach the intake hose and run it to a protected location under the trailer.
- Attach the exhaust pipe and muffler and run it to the drivers side edge of the trailer.
- Run the gas line from the propane tank to the heater connection.
- Check for gas leaks with the sniffer.
- Fire it up!

[lfhoward]

I had a few hours today to devote to the trailer, so here is what I was able to get done.

First, I used the high temperature silicone to seal around the combustion pipes. While that dried, I went on to working on the gas line.


I flared the end of the copper gas line. I had the flaring set left over from the last time I made brake lines for my Jeep.


Pretty good. This was my second attempt.


Under the heater at the rear of the trailer, the gas line got attached...


...and run forward along the frame rail...


...until it needed to make a zig zag to reach the regulator on the tank...


...where I cut the line and made a second flare. I covered the copper line with conduit I had left over from fixing engine wiring on my Jeep. It is a nice and snug fit. The line is held to the frame rail using stainless cable clamps with rubber insulators.


The last thing I had time for today was to temporarily hook up the intake and exhaust. I will fix those to the frame rails in my next post.

[lfhoward]

Alright, let’s finish this out (almost).

First I fastened the exhaust to a crossmember using an L-bracket to the muffler. The pipe has a downward slope to the hole at the bottom of the muffler in case of condensation.


Then I extended the exhaust out to the drivers side of the trailer (away from the back door and the passengers side kitchen area) using P-clamps.


Here is the exhaust outlet. With the Propex fan on I can feel a breeze coming out of this.


Next I fastened the combustion air intake under the trailer. It’s a good 5 feet from the exhaust. It’s also out of the weather (hopefully) and won’t be subjected to much road spray.


That military steel is very tough. RIP to various drill bits and stainless screws. I probably broke one screw for every screw I was able to use on this project to run the gas line and the piping.


The reason I say “almost” is that I haven’t tested the system yet as the propane tank is empty. I successfully bench tested it from my 20 lb grill cylinder prior to installation, so I don’t expect any issues. I can hook up my gas pressure meter and dial in the regulator if needed.

[featherliteCT1]

Another clean install. ... congrats!

You might consider rigging up some sort of cover boots for the ends of your exhaust and intake tubes under the trailer to keep out debris and water and also to keep critters from nesting. Just a thought.

[OP827]

May that foam mat insulation around floor exhaust hole area still melt and cause a fire hazard or you fireproofed it with some heat barrier? Just trying to be on a safe side here..

QUOTE: "The Propex can be fastened directly to the floor but I wanted room for insulation. The larger hole in the insulation corresponds to the exhaust pipe, which can get hot. I don’t want it touching anything that can burn."

[lfhoward]

Another clean install. ... congrats!

You might consider rigging up some sort of cover boots for the ends of your exhaust and intake tubes under the trailer to keep out debris and water and also to keep critters from nesting. Just a thought.

Thanks! That’s a good idea. Maybe a removable rubber cap like you would find on the bottom of a cane for the exhaust pipe in between trips.

May that foam mat insulation around floor exhaust hole area still melt and cause a fire hazard or you fireproofed it with some heat barrier? Just trying to be on a safe side here..

Dang. I hope I left enough space between the gym mat insulation and that exhaust pipe. It seemed from the van builds I found online with insulated or wooden floors that the space around the pipe would be enough. It would be a PITA to have to remove the heater to get to that insulation and cut more away. I have some pieces of floor insulation left over from the project that I can experiment on to see if they melt or burn. Thanks for the concern. Fingers crossed. I do have a fire extinguisher in the trailer but hope to never need it.

[lfhoward]

Because I’m now nervous about my gym mat floor insulation, I went back to the website I got the gym mats from and found out what they are made of. They are made of high density closed cell EVA foam.

Then I looked up a safety data sheet on EVA foam, which I found here:
https://www.foamorder.com/about-us/material_safety.php?page=closedcell
It says to “Avoid fire and temperature over 625°F, 329°C”. It also lists “None” for a melting point.
A different safety sheet lists 266-392°F as the melting point and > 572°F as the flashpoint.
https://www.briggatemedical.com/pdfs/msds_eva.pdf
Probably the statistics vary depending on the specific formulation of the foam.

On Propex’s website they sell a fiberglass exhaust sleeve that is rated to 500°F, so I expect the exhaust temperature must be somewhat lower than 500°F.
https://www.propexleisure.co.uk/shop/exhaust-heat-sleeving-lagging/

I can’t find any hard data for what the exhaust temperature for my heater actually is. One forum post by WestyVentures on TheSamba.com estimates “Exhaust can reach 300 degrees. 190-200 heat output is normal” for the HS2000 model (mine is an HS1600).
https://www.thesamba.com/vw//forum/archive/index.php/o-t--t-601703--start-60--index.html

More generally, I found the exhaust temperature for a “Liquefied-petroleum gas-fired heating appliance with draft hood” is 360°F according to:
https://www.engineeringtoolbox.com/amp/fuels-exhaust-temperatures-d_168.html

Since there is a 1/2” air space between the pipe and the gym mat, it won’t have to deal with direct contact and will be somewhat less hot than the exhaust pipe itself. Thinking it will be ok. I’m still going to test whether the foam mat will melt or deform or catch fire using the remnants I have left over. I’ll report back on this.

[KCStudly]

I would advise against putting a "travel" cap on the exhaust. This would rely on "the human element" to remember to remove it before use. Not the safest practice.

Maybe some 1/4 x 1/4 mesh mason's wire mat formed into a screen cup held on by a worm drive clamp; would at least keep the bigger pests out; and would not have to be removed because it would (most likely) not create any back pressure.

I'm also assuming that there is some other provision that keeps lint and dust from passing thru the system (if not the burner), such that the screen would not become a debris or soot trap; and thus create a potential hazard not considered (or intentionally omitted) by the OEM designers/product testers.

Just saying, consider all of the ramifications before "over re-engineering".

[rjgimp]

Because I’m now nervous about my gym mat floor insulation...

Considering all the data you have pulled together, I'd say you are well within the safe zone.

I’m still going to test whether the foam mat will melt or deform or catch fire using the remnants I have left over. I’ll report back on this.

Never a bad plan.

[rjgimp]

I would advise against putting a "travel" cap on the exhaust. This would rely on "the human element" to remember to remove it before use. Not the safest practice.

Perhaps one of these would be wise?


Seriously... I like the idea of a cover, but maybe KC is on the right track with a mesh screen.

Many moons ago when I was young and single I spent a great many days astride a motorcycle. Up here in the frozen tundra we generally need to pickle the things for the winter and a couple years I didn't quite get the task done properly, part of which involves covering the exhaust and airbox intake to prevent critter intrusion. One spring following just such a chain of events I opened the airbox to install a new filter for the season and O, what wonders did I behold within but a large cache of dog kibble! After cleaning that mess out and getting everything ready to fire it up.. all is ready... hit the starter, blip the throttle, and whooosh! out from the exhaust shoots... you guessed it...more dog kibble!


Filthy buggers...