M116A3 Build

[bdosborn]

I put some hardware cloth over the end of my heater exhaust; mud dabbers love to build nests in propane exhaust pipe.

Bruce

[lfhoward]

Time for a little electrical detour.

With the heater and propane tank installed, I realized that the electrical systems in my trailer we no longer floating. In other words, the heater/tank combo joined the negative ground of the DC system to the chassis where before there was no connection. I figured I needed to do something about that, so I started this thread:

http://www.tnttt.com/viewtopic.php?f=30&t=73359&p=1272006#p1271903

The conclusion there was I needed to ground the electrical system to the chassis using a more robust wire than the 16 gauge that fed the heater. I decided to ground the inverter to the chassis also, just to be on the safe side. That should have probably been done before.

Here is how things have looked for 5 years:


First I decided to install a main cutoff switch, because I thought it would be quicker and safer than always disconnecting the battery terminals when I needed to work on something.


Next I installed a ground screw through the metal floor. (After drilling holes for the heater, drilling this hole through the floor didn’t freak me out at all, lol.) The yellow 10 gauge ground is for the 12VDC system and the blue zero gauge ground is for the 1000 watt inverter.


Here is the system put back together. I taped around the positive leads to prevent accidental short circuits.


So in conclusion, the chassis is now negative grounded, just like on an automobile. Interestingly enough, the aluminum skin has electrical continuity with the chassis and the negative battery terminal also, just like the body of a car.

[lfhoward]

The burning question of the day: Will my EVA foam gym mat floor insulation catch fire being 1/2” from the Propex exhaust pipe?

Here is the experiment I devised to test this. I leaned a piece of angle iron against the side of my propane grill to simulate the trailer floor, then placed a remnant piece of foam on it, 7/16” from the side of the grill. 7/16 is just under 1/2”, to give myself a little more margin of error. Then I turned the grill on and slowly increased the grill’s interior temperature to simulate a hot heater exhaust pipe. The outdoor temperature was 45°F during the test. The test lasted 20 minutes and the grill temperature maxed out at 540°F. It was above 500° for half of the testing time.











There was a sight shrinkage of the EVA foam right at the edge, but no melting. It was soft to the touch and cool when I picked it up at the end of the test. The angle iron “floor” was pretty hot, too hot to touch for more than a second.





Since the EVA foam didn’t melt or catch fire with the adjacent grill at 540°F, I think I am fine with my heater installation as-is. The heater exhaust should be somewhere in the range of 300-360°F according to what I have read. Even if it is 400° I should be fine. I never smelled any plastic fumes at all either.

[lfhoward]

One more piece of good news to report. I took the trailer to a local propane place and had them examine my work and check for leaks. Everything is good and they complimented me on the tank & trailer. That’s a good feeling.

I got the tank filled. It took 2.7 gallons, which is what I would expect for a 3 gallon tank. Total cost: $6.75 for 11+ pounds of propane! (11 of the disposable 1 lb cylinders would be at least $44 if not $55.)

[bdosborn]

Nice work on the foam flooring test. I installed the same stuff in all the cargo areas of my trailer so it's nice to know it won't melt or burst into flames if its up against something warm.

Bruce

[lfhoward]

Today I had a few minutes to test out the Propex. It did run for 10 minutes, long enough for me to record some temperatures.

The cabin air outlet:


The exhaust pipe: (nothing near as hot as my grill test the other day)


Water is a combustion product from propane. Glad this is dripping outside instead of creating condensation inside, as a catalytic heater would do.


I had some problems getting the Propex to fire up and run consistently. The flame lights and tries to stay lit, but randomly fizzles out. This is not an issue with the flame sensor like I had before. I worked on troubleshooting a bit today but ran out of time. I was able to rule out gas pressure as an issue, as 37mbar (15 WC) is right where it was at, and that’s perfect for the UK spec unit I have.


Increasing or decreasing the propane pressure didn’t help. I also tried shortening the exhaust pipe run by disconnecting the muffler. This had no effect. I suspect air in the propane tank is the issue, since the tank wasn’t really purged. (The technician didn’t think it was necessary since I had put about a 1/4 lb of gas in it and bled it for 2 minutes previously.)

Speaking of the tank, I got the Mopeka Bluetooth sending unit to work! The tank is full at 80%.


And last, I installed the magnets to hold this insulated fantastic vent cover by Quest Overland in place. That should keep us warmer during cold weather.

[lfhoward]

In terms of troubleshooting the propane, I’m thinking about hooking up the Coleman stove and seeing if the flames are yellow and blue, instead of just blue. This would confirm whether air is in the line and is creating an inefficient burn.

For those of you who have been in a similar situation with a non-purged tank, how long until things worked themselves out? By the next refill?

I don’t think there is anything amiss with the heater itself. I got it running reliably on my back deck using my grill cylinder, prior to installing in the trailer.

[bdosborn]

On another subject, I was amazed at the stratification that occurred in our teardrop the first time I used a heater in it. Crazy hot ears and my feet were freezing. I added a computer fan to circulate the air and it made a huge difference. Just another mod to think about.

Bruce

[lfhoward]

On another subject, I was amazed at the stratification that occurred in our teardrop the first time I used a heater in it. Crazy hot ears and my feet were freezing. I added a computer fan to circulate the air and it made a huge difference. Just another mod to think about.

Bruce

This is a true statement!! Stratification was the worst when I used a plug in space heater or the Little Buddy propane heater, as the hot air would go straight up. My solution was to use a battery powered fan hanging on a hook above the heater, to blow the hot air forward in the cabin. That helped a lot. I’m hoping with the Propex that the heater’s own fan is powerful enough to mix the hot air throughout the trailer. The heating duct can be angled like in a car dashboard to direct the airflow.

[lfhoward]

I found a solution to the Propex burner not staying lit issue. The combustion air inlet pipe was too short. I stretched it out to be closer to 0.75 m than the 0.5 m length that it was at, and that totally did the trick.

I also ruled out purge issues with the propane. The stove made a nice greenish blue flame with no yellow flecks in it, so I did indeed properly purge the tank myself. Efficient burn. That’s good to know.

The heater is working flawlessly now. It raises the temperature inside the trailer about a degree a minute. In 20minutes it went from 45°F to 65°F inside the trailer. Heat doesn’t seem to be terribly stratified. The corner opposite the heater outlet is the warmest, but my feet aren’t cold sitting here doing the testing. The fan provides good circulation.

The outside temperature and starting temperature of the trailer was 40°F. The lowest thermostat setting is equal to 55°F. At 1/4 turn, the heater kicks off at 65°F.

So excited! Can’t wait to boondock now that I have off grid heat!!!!!

[KCStudly]

Congratulations, great job on the restoration in installation!

[lfhoward]

Congratulations, great job on the restoration in installation!

Thanks KC! You have been here since the beginning, and I really appreciate your following my build these last 6 years.

[lfhoward]

I’m excited to report I have plans for the M116A3’s first real boondocking trip next month.

We will be camping in the Delaware State Forest (which is in PA by the way, near the Delaware Water Gap). There are a few dozen campsites off of dirt roads in the state forest, which have picnic tables and fire rings but no other accommodations. The best thing of all is that camping there is free! All you need is a free permit from the state forest office. More info can be found here: https://www.dcnr.pa.gov/StateForests/FindAForest/Delaware/Pages/Camping.aspx

Evidently many of the state forests in PA allow free permit camping. All you have to do is find your site on their maps and contact the state forest office. Now that we have the Propex heater installed, boondocking may become our preferred mode of camping, depending on how easy the logistics of water, trash, and poop are. The area certainly will not be crowded. And did I mention it’s free?!

[pchast]

I'm glad everything is coming together for you.

[rjgimp]

I found a solution ...

So excited! Can’t wait to boondock now that I have off grid heat!!!!!