Diesel Air Heater Theory/Installation/Operation

WilliamA · December 2019

I've been busy. One of the things I've been doing is chasing the tech/principles of diesel parking heaters for about 6 months now. I've not been excited about propane options so after looking about for an alternative, I decided to go with the more Euro style options.
I am installing a 2000 Watt (equivalent) diesel heater. A few photos should pique the imagination:

Here's the heater unit. It's a 2,000 watt equivalent air to air heater. It burns diesel but can also burn kerosene and other oil-based fuels. It's my understanding that it works best/longest when running straight diesel. It's 13" long, 4.3" wide/tall and weighs around 6 lbs. This one runs on 12v power but they can be had for either 12v or 24v. The history is that they have been used primarily as a heat source for large trucks both as primary heaters and now more as a heater for the sleeper.

Here is the box I built to put it in. There is a whole entry forthcoming about where I put it and why but that can wait until later in the dialog. This box is made from 16 gauge aluminum sheet that I bent up in my small 18" metal brake. It's popriveted together with 3/16" aluminum rivets. The box size is 6 1/2"wideX 8" tall X 16" long.

This is the enclosure complete with the box installed. The enclosure in this photo is upside down. What you see is closest to the road. The "lid" shown here mounts the heater, then is placed up inside the box and fastened in with 16 #10x24x3/4" pan head screws. The two "doors" on either end allow for getting my hands up inside once the heater is mounted up in so I can connect the cold air/hot air ductwork to the heater.

Here's the complete assembly with heater installed. Note that this is also the bottom. The pipes protruding from the enclosure are the combustion air in/exhaust out. The small pipe next to the cold air in is the diesel fuel line.

There is a lot to this. I am about half-way through the process so there is much yet to do, but other than sourcing a few more components and a lot of time lying on my back doing the work (I'm looking forward to that part), it is far on the way to a good alternative/suppliment to anything I've come up with so far in the way of heating my trailer.

Let's do this.....
WilliamA

WilliamA · December 2019

Now that we're doing it, let's see how things are going. I had a red-letter day today and got a ton of stuff done. I spent some quality time a couple of days back snaking the trailer into the polebarn and am glad today that I did. I spent about 3 hours cutting out the hole under the trailer to stuff the heater enclosure into its new home and I was glad for the dry ground to lay upon.
First things first, a few photos are in order:

Here's the heater mounted to the base of the enclosure with the enclosure sitting the way it will go in. You can see the openings at either end to allow me to get my hands up inside in order to attach the ductwork.

Here is the enclosure stuffed up into the trailer bottom. I've got some C-clamps here holding it in while I drill a few holes for fasteners.

Here's a photo looking back into what would be the microwave cabinet. As any who have followed my threads know, I removed my Microwave and built a cavernous drawer for the space. You can see the top of the enclosure at the back of the opening. As the open space in the trailer for the A/C duct was about 4 1/2" wide and the enclosure is 6 1/2" wide, I had to surgically remove 2" of stuff from the the floor as well as the portion of the rear cabinet wall you see here.

The gas line for the stove came up in that space and this just wouldn't do. I needed the 2" so I moved it over so it comes up behind the refrigerator, then across the top of the microwave cabinet where it hooks back up to the stove. This is the "before" photo:

Here's the "after" photo. Fits fine and clears the back of the refrigerator slide fine as well. I should have done this when I built the drawer....

Here's the entire unit in and mounted, sans any weatherproofing tape or caulk. I need to remove the whole affair and bench-mount it for a day's worth of testing. I'll run it and gather data on internal enclosure temp, run time, shut down temp (residual) and a load of other things before I do the final installation. I also ordered a few other bits that will be a week or so out. If you look sharp you can see the combustion air inlet (black pipe) goes over to a small silencer/inlet screen. I ordered a bit more inlet hose so I can actually drill the frame and put the inlet on the outside of the frame rail. The exhaust pipe goes more or less straight back and terminates in a small muffler right at the back of the frame. I'll need to make some stand-offs for the bottom of the trailer to protect the underbelly from heat, make a couple of tasty brackets for the exhaust to sit in and many other details. I'll post up my progress but for now, it's in and fitted. If I get around to it tomorrow, I'll pull it back out and start setting up a bench mount so I can do a test run. I want to put 5 hours on it before I'll feel comfortable stuffing it in the trailer, but the hard work is past. Now, it's just putz, putz, putz.....

WilliamA

WilliamA · December 2019

A couple more photos....

A closer view of the installation. I removed, cut and repurposed the natty looking louvers. They work...Meh....

Here's the entire exhaust with the diminutive muffler. I have ordered another section of exhaust pipe and may move the exhaust over toward the corner of the frame. We'll see how it runs first.

WilliamA · December 2019

If you have followed my threads in the past, you know that I have an 800 watt, 110v electric furnace. I'm happy to say that it's fine and comfortable up behind the TV and will stay there. After almost 2 years of use, it is still my "main" source of ooooh, aaaah comfort. I have had a bit of trouble with it the past month but traced the problem to the line voltage thermostat. It seems the cheesy plastic cover on the thermostat has gotten a little warped and now occasionally hits the bi-metal spring that adjusts the temp, giving an occasional false setting. I fitzed with it a bit but have decided to just replace it. At $20 bucks for a replacement, it's not worth the trouble of filing down the cover and trying to make it more accurate. Besides, as a line-voltage stat, there have been many thousands of switching cycles, so it's time to put in a fresh one. It's a 10 minute job.

On to the diesel heater:
The WHY...
One of the most (environmentally) miserable experiences of my life was a month-long field exercise in the Army in Germany. It hovered around 45-50 degrees and rained every day. Everything I had was wet. I've never been so cold before or since. I vowed then to never allow myself to go through that again. While falling short of a "Significant Emotional Event" in the tradition of Massey & Maslow, it is still something I remember with dread. Add a couple score of years along with the requisite arthritis, aches, pains and maladies of a life lived fully and it is more important now than ever for me to look to my own comfort. My brother and I spent a week in Joshua Tree NP last Jan and it was cold at night. Once I'd burrowed down into my sleeping bag, I was fine and warm, but again, no way to dry things out "off the 110v grid".

The WHERE...
There are a number of places within a T@G to stuff a heater. Especially one as small is the diesel model I'm working with. I originally thought I might put it in the front storage box and run the hot air/cold air return through the front of the trailer ala Little Guy. In the end, I decided against that location as being too busy (I put a bunch of junk in there and like the space) and too close to the battery. There was also tongue weight to consider. I thought about putting it under the basement space on the passenger side. I thought I could build a box and hang it below the floor, running the ductwork around and up into the dead space between the bedroom and kitchen. That proved to be problematic as well mostly for reasons of too much ductwork and too many turns needed to get the heat from there up into the bedroom. Also, it would partially hang down below frame level. Not ideal. I thought about building a box and literally just sticking it to the bottom of the trailer somewhere close to the frame. Same basic problems, plus the level of the fuel tank would then be much higher than the heater. That may or may not be a problem, but I suspect that if the unit is much below the fuel tank level, the pressure of the fuel could weep past the valves in the fuel pump, flooding the combustion chamber over time. I don't know this to be a valid issue, but it bears some research. That is one of the things I plan to test during my bench test sessions. These heaters have no carburetor and depend upon precise metering of the fuel through the pump to burn cleanly. If there is more fuel than needed, it could cause potential problems with running rich and sooting up of the combustion chamber or fouling the glowplug.
In the end of the debate, I elected the location I did for the following reasons:
1. There was already a large-ish hole under there.
This is where the (cheesy, problematic A/C) vent gets its backside air for cooling/dehumidification. If I stuffed it up under there, the ductwork is short and needs only make one sweeping turn into the cabin.
2. It mounts higher there, being a few inches above the frame. If I put the fuel tank on the side of my front storage box, the line of flow will be much more horizontal and less vertical. That makes the check valve in the pump much happier and, while still allowing gravity feed from tank to pump, provides much less vertical fuel pressure on the inlet side of the pump.
3. It's close to the rear of the trailer and makes for a nice, short run out underneath for the exhaust. My trailer is very high and I have few concerns about ground clearance so I can afford to run the exhaust straight out the back. That's as far away from any fresh air inlets (cowbells, windows, roof vent) as possible.
The only potential downside to this location is residual heat buildup inside the enclosure once the heater has shut down. As you can see by the photos, I am providing a lot of venting in the box. I also plan to add a vent stack from the top hole in the enclosure up to and then into the kitchen area through the back wall. That vertical stack will act as a chimney, pulling warm air up out of the enclosure and coaxing cold air from under the trailer into the enclosure at the bottom louvers. I've no doubt that this will be more than enough thermal flow to keep the bits cool after shutdown. I have adhered to the minimum stand-off requirements as per manufacturers directions, plus the addition of the thick aluminum box will provide a pretty beefy fire-break in the event that becomes an issue. While it may be wandering over into the "Good grief....Let's not get carried away" side of installation, I am also adding a 1/4" steel brake line into the top of the enclosure that I will hook to a small, dedicated CO2 fire extinguisher. In the event of overheat, I can pull the fire extinguisher handle and dump the whole bottle into the enclosure, nipping any potential catastrophe in the bud. It's cheap, easy to do and is one of those: "If only I had...." additions that I am almost certainly never going to use, but will feel better knowing it's there.

Why Diesel?:
That's easy. Propane sucks as a heating fuel. It's wet, wasteful and heavy. Liquid fuels are by comparison, much drier, have more potential energy and are easier to store/refill/haul. Gasoline? Not on a bet. Diesel is safer, has low volatility and is extremely stable when stored for long periods of time. If burned properly (hot and lean), it combusts completely, emits no smoke and very little smell. It's also readily available most anywhere. For off-grid use, the furnace uses a tiny bit of fuel and electrical energy. Start-up requires about 9-10 amps @ 12V to heat the glow plug, but once running, the glow plug shuts off and the heater uses between .7-1.5 amps per hour to run depending upon the heat setting. It also uses the glow plug for a few minutes during shutdown to clear the combustion chamber of any unburned fuel, but the start-up/shut-down cycle is not more than 3 or so minutes. If my research is to be believed, I should be able to run it for a week or two on less than 10 liters of fuel. Yes.....I'll be doing copious amounts of noxious gas testing. I've ordered a high-order gas monitor and will be doing lots of tests to determine safe levels of gasses. In any case, it certainly will be no more dangerous than a propane furnace and much less noxious than a buddy-heater style unit. I'm crazy, but I am not stupid. Those are two different things.......

WilliamA

WilliamA · December 2019

Today was test day. I spent an hour setting up a test rig, removing the heater from the trailer, making a dash to town for fuel and a couple of small things and then hooked it all up.

Here's the crude setup. Meh...It works fine. I wanted most to emulate (within reason) the exact fuel line distance and elevation from the tank to the pump and from there to the heater. I got within a couple of inches on all of it but most important, emulated the low spots in the fuel line to make sure there would be no problems with air-trapping. I did have a bit of trouble trying to bleed the fuel line as per instruction, but quickly realized the fuel tank cap was airlocked. I took the cap off and it immediately started transferring fuel. I dug about in the cap and discovered the tiny vent valve was simply stuck shut. I flicked it with my finger and it opened up.

Here's the tank and pump. I elected to put the fuel bung in the bottom of the tank rather than the side. The tank gravity feeds to the fuel pump so that's emulated here. Seems to work fine. For mounting the pump, the instructions are quite specific about the angle the pump must be mounted at. Here I've got it at the requisite 15-30 degree upward slant.

You can see the fuel bung at the bottom of the tank. It comes out and goes into a fuel shutoff, then to the filter and up to the pump. I taped the fuel line (1.2 meters from pump to heater) to the table to more or less emulate running it solidly affixed to the inside of the frame rail running along to the heater. There's a drop in the back and a small hump up in the front where it exits the fuel pump. Seems to pass cavitation bubbles just fine and there's no buildup of bubbles anywhere in the line. The small electronic gadget sitting in front of the fuel line is my digital temperature probe head. I used it to test all of the areas I was concerned about. You can just see the probe going into the top of the enclosure.

The color tells the tale. Once I had the fuel line bled, it fired right up and ran perfectly. I was surprised at how quickly it started. More specs to follow. You can see the fuel line going into the bottom of the heater next to the combustion air inlet.

During one of the cooldown cycles, I spent some time taking a 3" duct collar I picked up and reducing it to 2 9/16" for the thermal enclosure baffle. It'll run up and turn 90 degrees to exit into the kitchen space above the counter. It's just to help vent the enclosure from heat-sink during the cooldown cycle once the fan motor goes off. As it turns out, my thermometer readings show that it probably won't be needed, but better to have it and not need it....

I ran the heater 4 different times, allowing a cooldown cycle in between each. For each cycle, I ran it on high, set it to low, then back on high for 5 minutes (recommended before shutdown to prevent soot buildup) and collected data on all of the significant heat points. I was surprised to find the exhaust pipe was much cooler than I expected. Right at the bend where it comes out of the heater, it's HOT! This is to be expected. It cools off rapidly as it goes out to the muffler. The exhaust right behind the muffler is cool enough that it would not be too uncomfortable if it blow right on your leg from a couple of inches away. I wouldn't want to stand there, but passing in front of it is not at all unpleasant or dangerous. Don't stick your tongue on the muffler though....
Here's a few factoids I've gathered for initial ponderment:
Does it smoke/stink? No and no. Actually, it smokes a tiny bit on first startup for about a minute or so. It smells a tiny bit as well, but doesn't smell like diesel exhaust. It smells more like hot metal. A weird smell. Very faint.
Startup time from cold: 3 minutes....give or take. Fastest was 2 min 50 seconds. Slowest was just over 3 minutes.
Shutdown time: About 3 minutes or a bit less.
Noise level: It's never so loud you couldn't stand right next to the exhaust and speak in a normal tone to someone. It's noisiest when first starting and when shutting down. During those 2 times, the fan goes to maximum in order to burn remaining fuel and clean out the combustion chamber. Once it's running, I could turn it down to about 1/3 and it hardly makes any noise at all. I'd say the noise level is similar to being in the trailer and having the ceiling fan on low. It remains to be seen how much noise will transfer from the enclosure and fuel pump once mounted but so far as the fan, it's WAAAAAAYYYYYY quieter than the A/C, though that's not a high bar to clear. I have read some complaints about the ticking of the fuel pump transferring from the chassis into the compartment but that should be a simple affair to keep from drumming. It comes with a very nice rubberized mount and I plan to rubber-mount the rubber mount.
I could not check the amperage draw simply because I didn't take the time to hook it up through an amperage meter. I will probably do that tomorrow to satisfy my curiosity, but I am more than certain it pulls pretty much the advertised 8-9 amps for 3 minutes on startup and shutdown (glowplug) and otherwise uses around an amp per hour when running. I'll check that to be sure before installation.
Warmth?
It's, as I fully expected, waaaaayyy to warm for such a small space. Even with it turned down to 1/3 output, it is plenty warm. My past experiments have showed that about 800 watt equivalent heat is all that's needed in a T@G and this thing is closer to 3 times that. There is more to learn for sure, but once I get it installed and have my LCD controller hooked up I will be able to get much more information about details and use.

Temperature readings:
Internal enclosure maximum temperature was 82f. That highest reading was during cooldown after the fan shut off as I expected. There is some residual heat left in the heat sink and it has to go somewhere. That's much cooler than I expected though and that's a very good thing. Once I have it stuffed into the rather confined space and surrounded by insulation, I expect the temperature to go up slightly, but not much. I doubt it will get to 100 degrees inside there. The specs are up to 200 degrees max so I'm well inside the safe zone. I doubt you could run it out in the open and get much less than 75-80 degrees heat sink. It just has to go somewhere.
During operation, I could not get any reading within the enclosure much above ambient. Perhaps 10 degrees or so. No problem while running. Outlet temperature (this one is an eye opener) 4 inches into the outlet end of the heat duct was over 200 degrees. Woah.... The ductwork is thermal and there was no time during operation when I couldn't grab the duct and hold it, but it was not particularly comfortable either. It's hot. Oddly, the temperature of the output does not go down when the unit is turned down. What is does is balance the fuel burn to the fan speed so while the fuel use goes down, the fan speed follows, keeping the temperature of warm air about the same at all speeds. Temp is the same. Just the flow rate in cfm's goes down. Interesting.

I ran for a total of 2.5 hours today and am happy to say that the heater is working (so far) according to Hoyle. The enclosure seems to be fine and doing exactly what I designed it to do. I could put it in now but think I'll spend another day letting it run for a couple more hours, then pull the cover off the heater unit and have a close inspection of wire runs, grommets etc before stuffing it into the trailer. As I said, I still need to wait for the UPS guys to get me the rest of my ductwork and widgets before I can finish. I'll cut the holes inside the trailer and tidy all of the other rough bits up in the meantime.

So far, so good....This is proving to be a game-changer for my boondocking lifestyle...

WilliamA

WilliamA · December 2019

I was able to get the fuel system all mounted up to the trailer and have that all put to bed. I installed the fuel tank on the front box and will be picking up a couple of things to make it more permanent. I also got the fuel pump installed and ran the fuel line from tank to pump and pump to the heater location.

The fuel tank mounts with 3 bolts. I need to pick up a few rubber washers and a rubber stick-on pad to apply to the back of the tank. I also will be putting on a couple of aluminum straps around the tank just to make it a bit more secure on there. I'll pick that all up soon.

The fuel pump mounts on the frame rail about 3 feet from the heater. I ran the hose along the inside of the frame rail and got it all tidied up with zip ties and frame fasteners. Now all that's left for the fuel system is to bleed the line from the tank to the pump. I'll wait to do that until I install the heater to avoid making a mess.

I also got the cold air inlet duct installed in the trailer and am waiting for my duct order to come on Friday. Today I am going to be working at the wiring harness modification and installation. That will take a bit of messing around.

WilliamA

HellFish · December 2019

I'm thinking I might not try to replicate this mod. I'll stick with the "shelf under the sink" and "cool decals" projects.

DaveB · December 2019

Nice, I have been looking at these types of heaters for the same reasons you stated. Probably a couple years away for me though. Are you planning to change the fuel container? Isn't there a DOT requirement for deisel containers to be yellow in color? Or does that only apply to portable containers, and this one is 'fixed'. Pricey, but a Rotopax set up might be pretty slick for this, in the warmer months you could remove the diesel tank and carry extra water or gas for a genertor.

WilliamA · December 2019

The fuel tank issue is definitely on the table. This one came in the kit and isn't bad. I don't really know what the federal code is on fuel containers but I think that color only applies to portable containers as you said. I already have a Rotopax mount and will probably go that route, but as my hero Teddy Roosevelt once said:

"Do what you can,

With what you have,

Where you are"

That saying has spurred me to action on many a sketchy project along with my own mantra:

"Relentless Forward Motion"

WilliamA

Sharon_is_SAM · January 2020

@WilliamA, are there any concerns of road debris taking out the fuel tank and creating a fire hazard? It is rather exposed on the driver’s side of the box.

WilliamA · January 2020

Hi Sharon,

Indeed. I have ordered a small tank that will go inside my storage box and vent outside.

https://www.usplastic.com/catalog/item.aspx?itemid=84275

Not to worry. I am neurotic and cautious...

WilliamA

Sharon_is_SAM · January 2020

Sometimes it’s best to be neurotic and cautious!

WilliamA · January 2020

Lots to tell today. As normal, I've been doing about 10 different jobs throughout the past couple of days. I got the lions' share of them finished and jumped back on the trailer for a bit of poking.
Having disassembled the test stand, I needed to measure/modify the wiring harness to fit the trailer. I carefully measured where everything would go and it turned out some of the harness tails were too long, others too short. I took the whole affair into the kitchen where it was warm and did the work there, hoping I would be close to accurate on my lengths. I was as it turns out. I installed the harness and went on to a few other areas. The harness raises its ugly head a bit later in this episode...

Next order of business was to prepare the hot air ductwork inside of the trailer. I had a dream location for it but sadly, ended up with my second pick. I had intended to put the hot air duct on the cabinet face next to the 110v outlet on the drivers' side of the trailer. Once I got the trailer gutted and started to look closely, I wasn't comfortable with how close the ductwork would have had to be to the converter. My second choice was in the center directly below the A/C cabinet (now storage cabinet). In order to fit it there, I needed to bring it out 10 inches or so off the wall so that I could be sure it wouldn't be blocked accidentally with blankets or whatever. To make that location work, I needed to make a metal duct/diffuser so it wouldn't be blowing all the heat on one small spot. Here's the wooden diffuser/cover I picked up from Menards for the job. In this form, it's 13" X 3 1/2". Too tall for the job. I knew I'd be cutting it down as much as the meat allowed. My target was 12 1/2" X 2".

An hour of fooling about with some 20 gauge aluminum sheet and this is what came of it:

Here's the duct installed, hooked up to the hot air outlet duct from the back and screwed temporarily in place. I will need to pull it down and put some thin insulation between the cabinet and the aluminum, but it's pretty much done.

Here's the diffuser with an inch cut off and held in place. Once I build a box to go around the duct, I'll trim the bottom edge as tight as possible to it. A bit of woodwork to do.

I also have been receiving a few packages of minor widgets. As they trickle in, I've been installing the contents. Here, I've finished the exhaust. I needed another section of exhaust pipe so once that came in, I trimmed it to fit and made the hanger brackets to keep things nice and orderly.

Now to the "Dashboard". In all lives, some rain etc, etc. I installed my wiring harness, got it all tied in and hooked it up. After a few minutes, I started getting an error code on the display. The code was "E-001" which means Low Battery Voltage. I didn't panic. I went on and did a few other things while I thought it through. My first thought was to open the harness and check the connectors I had installed. I did that and could find no problems. I went in the house, made some coffee and did a bit of online research. I typed in my problem and the very first response in the search was that exact error code problem. A bit of reading and it was clear that when I disconnected it from the test stand, it had lost the presets in the controller and when I hooked it back up, it came back up in 24V mode. Finding the problem was the easy part. Fixing it sent me back into the net to try and work out the magic combination of keystrokes on the controller to change the setting back to 12v, then save it. As it turned out, you need a 4 number code to access the long term memory. I found one on the net, entered it and was able to immediately access the sub-memory. I changed it back to 12v and then had to spend some time trying to work out how to actually save the change. I finally fell into the key stroke combination and now it's on and holding with no codes. Now that I know how, it's easy and takes only a minute to do.

Here's my controller quietly waiting for a start command. You will notice that I have 2 voltage meters side by side. Well, yes. The one on the left next to the heater control is for the heater only and is wired with a shunt for monitoring amperage, which I've not checked during the test run. These heaters pretty much demand a completely separate circuit from the battery for both hot and ground wires. The reason for that is because if you errantly shut them off during operation without going through the cool-down cycle, you'll cook the pcm board within the heater. You can't simply "shut them off by cutting a wire or turning off a switch. They need the shut-down cycle to prevent damage to the internal circuitry. I ran that separate circuit direct from the battery and have it wired so that if some small grabby-patties get in the trailer and start poking switches, lights and the like, they can't errantly shut down the heater without going through the standard cycle. With it wired directly to the battery, the only way to shut it down is through the controller. The way I have it wired, you could even turn off the battery switch and it would continue to run. In the event of a problem with no-start, etc, I can go up to the battery and pull the fuse for that circuit. It IS interesting to see the 2 voltmeters reading the same battery and coming up with different readings. I'll have to ponder that one...
I already had two holes in the dash there. One had a USB charger in it and was conveniently the same size. I ordered the voltmeter on the right with the digital readout and sweep meter combo for monitoring the remaining systems. In the summer when the heater won't be needed, I'll pull the fuse. While I was ordering a new voltage meter, I got the one with the sweep-lights for a simple reason: I'm blind as a bat without my glasses and the lights are readable, even by me, without them on.

I also got the fixed fire extinguisher system mostly installed and need only a bit more time to make a bracket for that. I'll post that when it's done.

I have one more package coming on Monday and that's the last bit of duct hose for the cold-air inlet. I have the inlet screen mounted and that's all ready so when it shows up, I only need poke it through and put the clamps on both ends. Once that's on, I can test it. In the meantime, I'll spend some time with my woodworkers hat on making the diffuser and housing so it looks nice. Then there's a few debris piles about that need some sorting and a lot of cleaning and vacuuming to do.

Bird by Bird....

WilliamA

WilliamA · January 2020

Rereading my post for inaccuracies/lies/etc, I realized I've not included any links. Here are a couple for anyone interested in a bit of research. The first link is to a series of youtube videos (15 videos!) and to my mind, is far and away the best, most comprehensive information I've found. The videos are well done and have pretty much all the pertinent data. Kudos to John for a great job!

https://youtu.be/tvwmU_CcmGI

Here are some great videos that come in a very close second. They by David Mcklorkie (sp?) and in addition to being informative, are also fun and occasionally hilarious. David is also a tinkerer after my own heart and does a lot of "what would happen if I do this?" Kind of stuff:

https://youtu.be/9YthaCqkMOs

WilliamA

WilliamA · January 2020

I received my package today so I installed the cold air return onto the heater. It's nearly ready to try out. I have about an hour of work to do in the morning (mostly going through and checking everything) and, assuming I have the energy to do so, will pull it out and run a test.

In the meantime, I finished my woodworking project on the diffuser cover this morning. It's fine and fits well. We'll see how it works tomorrow...

WilliamA

WilliamA · January 2020

Well, it's working. I am pleased and happy to have the rather stressful in-trailer test behind me. I'm far too neurotic to actually enjoy it.
Here's the fixed fire extinguisher installed "mostly where it's going to live. I need to move it back against the shelf wall and move the top clamp over a bit, then make a "loud" label so no one mistakes it for a portable. I wanted to have it hooked up just to give me a bit of peace of mind during the initial tests. Come to think of it, it's there to give me peace of mind all the time.

Here's the end shot so you can see the hard line that hooks to the nozzle and goes down behind the wall. There's room to move the extinguisher back about 2 1/2" to the wall. When I installed the extinguisher, I was generous with the room as I wasn't sure how long the line would end up once I got the hard line attached to the end of the extinguisher. I'll move it back.

Here's the roughed-in topside enclosure vent that exits into the cabinet space. As it turns out, during tests today the temp in the enclosure never got close to what I would say might be hot. The hottest I could get the enclosure during operation was about 72 degrees against an outside temp of 22. I'm still very glad I put this in there and perhaps, the low temps within the enclosure are the result of careful planning for thermal effects. I still need to attach the upper vent end that screws to the cabinet, but it hasn't arrived yet. A happy detail that takes just a couple of minutes to install.

Here's the upper enclosure vent along with the hard line for the fire extinguisher nozzle. I built the fire extinguisher system so there's no back pressure on the line at either end. It is tapped to the extinguisher and just basically empties into the enclosure through the brass fitting that I tapped into the aluminum. I'll JB weld the aluminum fitting in place now that I know it's where I want it. Then I'll make a hatch for the open hole after cleaning it up and squaring things away in there. I want to be able to access the space, but also want it covered from road dust and so forth.

Here's a photo of the shut-down routine in progress. It would take a long time to explain this crazy controller, but the important stuff can be seen. The small fan icon actually spins to let you know it's on. Right in the top of the heater icon, you can see a small red illuminated icon. That's the glow-plug icon. To the right of the glow-plug icon is the small green icon that says the temperature monitors are working and in the green. If it over-temps, this one turns red. Hope that won't happen. You'll see on the voltmeter that the amperage is 8+ amps. This is during the shut-down phase where it comes back on for about 45 seconds to clear any leftover unburned fuel in the ignition chamber. The shutdown takes about 6-7 minutes from start to finish, but the glow-plug only runs for less than a minute.

Here's a photo during the run-phase. You can see the small fuel pump icon to the left of the heater icon. Also, you can see the heat bars within the heater icon. You can see that during operation, amperage use is nominal. The lowest I saw was around .10 amps and the highest (with the heater on high) was about .4 amps.

This is my temperature probe inserted into the hot air outlet duct. The left temp is the temperature probe. The hottest I could get was 217 degrees. Most of the time, it runs about 208-210. While this sounds really hot, it's actually the same as during my bench tests and also the same as reported on internet tests by others.

So far, I'm pleased. I ran it for 2 complete run cycles today and it ran for an hour each time. I tested temps throughout the system both running, during shutdown and after shutdown and everything is well within the parameters spec'd in the instructions.

It's incredibly quiet. As I reported before, it's noisy on start-up and shut-down for a few minutes because the fan goes into high mode, but during normal operation it's whisper quiet. It's certainly no louder than my electric furnace heater and I can barely hear that.

I ran it on low most of the time and even at that low setting, it's waaaaayyy too much heater for such a small space. The lowest I could get the interior temperature to stabilize at was 71 degrees with all windows, vents and doors shut. I suspect it will need to be run with a window or two open, or perhaps keep the roof vent open a bit. That will all take some trial and error. I don't plan to run it at night anyway and mostly want it for the cool/cold evenings of reading, then shut it off for bedtime, then start it again for a warm morning.

I'm very happy and glad for the days' tests to be behind me. Lots more, including a trip to the local fire department so they can check my noxious gas levels with good equipment (as well as do a test of my own Carbon Monoxide detector) and many small details to finish so far as sealing through-hull fittings, caulking a few things and more experiments.

Lots more to investigate but so far, it seems to be working as designed.

WilliamA

WilliamA · January 2020

https://teardrop-trailers.vanillacommunity.com/discussion/comment/6813#Comment_6813

Always Sharon, always...

WilliamA

WilliamA · January 2020

I've learned over the years of building things that when a specification during testing is outside of parameters, so long as it's not dangerous or detrimental, just continue with more testing. That's true here as well. When running the heater yesterday, the 6 heat bars on the controller were all lit, regardless of where I set the temperature. That could mean many things from a bad controller to some other problem. One of the things that might cause that is wind. Yesterday during testing it was very windy with the wind coming in toward the combustion air exhaust. Before I change anything, I'll run the heater again by turning the trailer with the exhaust away from the wind. It's possible the additional back pressure on the exhaust is causing heat to "pile up" and increase combustion chamber temperature. Start analyzing with the easiest first, then get more data before making changes. Everything affects everything.....

WilliamA

BBsGarage · January 2020

Looking more and more like the command module.

WilliamA · January 2020

I ran the heater for another 3 hours this afternoon. I had cleaning up to do so I busied myself with other things in the meantime, collecting data every 30 minutes or so.

While I was cleaning, the UPS dude came hot-footing it up the driveway. Here's my new fuel tank. It's 2.5 gallons and will fit nicely inside the front box. I assumed it would come with a fuel cap but such is not the case. I called the company this afternoon and they got one on the way for me for $1.98 plus USPS shipping. Nice folks. Took good care of me.

I bent up this sort of cheesy exhaust cover to keep vermin out of there. It'll do until I either find another, nicer one or just get tired of looking at this one.

After I did the shutdown, I pulled the LCD heater controller and put in the one that came with the heater and I ultimately want to use. I've collected enough data with the other, clunky one so I swapped it back out for this one. This is the one that I used to do the bench tests with. It's much simpler, uses less power and isn't nearly as bright. While it doesn't have the same bulk information, it will still read and report trouble codes and a few other nice-to-have data streams. You just have to interpret the flashing lights instead of reading the LCD screen. In the event of controller failure (unlikely) while the heater is on, one can unplug and swap controllers without interrupting the heat cycle. A nice feature considering.... John Mckay recommends that anyone who has one of these heaters get a spare controller. The LCD one was inexpensive at $12.79. I got it off of Amazon. I'll keep it in the spares box.

While the diesel heater was purring away, I swapped out the troublesome thermostat for my electric furnace. 5 minutes...no problems.

I took some video today mostly for the sound-bites and will edit and upload it. Don't expect it for a day or so. I suck at video editing.

WilliamA

WilliamA · January 2020

I spent the morning building a box to go in my front storage box to house my new fuel tank. It turned out pretty well:

I had the last bit of 16 gauge aluminum sheet that I picked up to make the enclosure so I used that. The box is riveted to the sides and bottom of the storage box. The lid is screwed to the top of the box. All sides of the fuel tank box are lined with 3/4" pine (1"x6") to shield the plastic container from contact with the aluminum box itself. I'll line the pine with some automotive carpet I have left from another job.

I received an email that my fuel tank lid shipped today from Ohio and should be along in a few days. Once it comes in, I'll remove the outside fuel tank, remove the fuel outlet from that and put it in the bottom of this tank. I will need to plumb a vent for this tank by drilling the cap, installing a vent bung and running a 1/8" hose up, through a fuel filter (to eliminate slosh-drooling), then out the side of the box and down under the trailer. The folks at U.S. Plastics asked me if I wanted a vented or unvented cap and I said no vent. I don't want any venting inside the front storage box. Besides, vented caps only allow venting in, not out. I want venting in both directions.

Here's a JPEG of one of my original composite drawings that I did for the enclosure assembly. It's a bit muddy but I have flattened all the layers into a single drawing.

While I was making up the fuel tank box, I ran the heater again for 2 hours using the new/old, simple controller. It seems to work just fine and I like the simplicity a lot better. I have one more package coming with ductwork that I will install whenever it gets here. It has a "T" connector with it and I plan to split the hot air out duct into 2 directions. I'm going to route a bit of heat back to the kitchen area with the second outlet and see if I can balance the heat a little better (as in: cool it down a bit) and also provide a heat source to keep kitchen bits from freezing. If I'm clever enough with the placement of the 2nd outlet, it will also go a long way toward keeping my water tank from freezing. I'm working on it. It would be nice to carry water in the tank and not have to worry about that freezing.

WilliamA

WilliamA · January 2020

The numbers:

Electrical consumption:
It's difficult to get good, solid numbers but I have a good average of start/run/shut-down amperage.

Starting amps (per amp gauge) 8.2 amps for (about) 2 minutes.
Running amps (per amp gauge) .2-.3 amps continuous. It's an average because the fuel pump pulses are about .2 amps and the fan takes .1 amp, so let's call that .3 amps continuous.
Shut-down amps (per amp gauge) 7.9-8.1 amps for about 1 minute, then fan amperage for an additional 4 minutes average.
So electrically speaking, it's much more efficient to just let it run than start and stop it.

Fuel consumption:

My fuel tank is a tiny bit less than 10 liters, so let's call it 9.5 liters.
That's 9,500 milliliters of fuel carried.

Hz (pump cycles per second) X .02ml (fuel dose per pump cycle) X 60 (seconds per minute) X 60 (minutes per hour).
I've been running my heater on its lowest setting of 1.6 Hz so:
1.6 x .02 = .032 X 60 = 1.92 X 60 = 115.2
That's 115.2 milliliters per hour
115.2 X 10 hours = 1.15 liters of fuel in 10 hours.
That's 2.74 liters in 24 hours.
That's 3.64 days if it runs 24 hours per day.
If it were 100% efficient, that would be 82.4 hours of run time on a tank.

So at that fuel burn rate, If I run the heater an average of 5 hours per day, I can go 16.48 (5 hour) heating days on a single tank of fuel.
As I charge my trailer when needed with my Jeep or (occasionally) with my generator, voltage is not, for all practical purposes, an issue and depends solely upon how long my Jeep and generator will run on the fuel I carry.

I can handle that.....

WilliamA

WilliamA · January 2020

I received my ductwork kit today so I (stupidly) braved the -4 windy, nasty day and put it in. Working with ducts, parts and hose clamps in that cramped space is a bit of a ship in a bottle, but I was able to get it accomplished. I have a couple more hours of odds and ends to finish things up but it's working well and I'm happy. I ran the heater today for an hour or so after my ductwork addition and even at -4 it came on and quickly was purring like a kitten. One of the positive aspects of this heater compared to my electric furnace is that it heats up the cabin much more quickly. My electric furnace does a fantastic job of it, but from cold to 68 degrees takes some time. This thing will do it in a few minutes. That will be nice for my truck-stop lay-overs. It should. That's what it was designed for.
My fuel cap is en-route and should arrive Saturday so I'll not remove the "test tank" until then but in the meantime, I can finish the detail work and put all the post-carnage cleaning in order.

WilliamA

WilliamA · January 2020

I got my internal fuel tank finished and filled with fresh diesel. Seems to be working:

Here's the underneath shot of my fuel line and vapor/vent line. The blue line is the vapor line and It's not run to length yet. I'll get another 1/8" brass barb fitting and screw that into the floor of the storage box, then put the vent line over the top of that. Just to get things more tidy.

Here's the box with vent line run out and down. I tapped the plastic cap and then put a good dose of CA (thick) glue on, under and around the threads just to keep things snug there.

A close-up of the cap and rubber through-box grommet.

WilliamA

Rick67 · January 2020

Stunning work, very professional.

Mine has a steel stud as a diffuser that runs a few inches from each wall and is about a half inch off the rear wall. Allows it to feel like hydronic heat more then blown air.

WilliamA · January 2020

https://teardrop-trailers.vanillacommunity.com/discussion/comment/6869#Comment_6869

Thanks Rick. Got any photos?

Rick67 · January 2020

Didn't take pics of the set up as I didn't install. I just picked this Tag XL up and besides running the diesel heater for a day besides the house (to see if it would burn up). I have'nt had much time to tinker yet.
I took a pic of the stud for you. Looks a little ghetto but disperses the heat rather well.

WilliamA · January 2020

Rick,
That's brilliant! Very clever. I'd love to see the whole installation, or as much of it as can be seen without disassembly.

WilliamA

WilliamA · January 2020

Details, details...

Here's the new kitchen heat outlet plumbed and working. There's a reason it's where it is. I'll get to that during the testing photos...

Here's my grey-water tank in its travel position. The short section of hose goes inside the tank.

I found this little gem at a snowmobile shop closeout table.

It's perfect, save about a 1/2" too long. I'll shorten it up and swap it into the diesel tank. Nice

So far, so good....

WilliamA

WilliamA · January 2020

WilliamA · January 2020

I got my fuel gauge modified (had to shorten the float-way an inch and recalibrate it) and it's working well. I also got my fixed fire extinguisher brackets moved and tidy. Looks and works better. Now I need to make up a few labels and install them.

WilliamA

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