I'm having an idea for off-grid heat... doodle check?

Rednecktek

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So I was thinking to myself, after reading all these threads about people trying to have heat on a solar system and how that just never ends well, that there's got to be a better way of making a portable, emergency use, off-grid source of heating the house... and I was bored. :)

So my shopping list I think is:

5Kw Diesel Heater - 12v, comes with a 10l/2.5Gal tank, draws 11a for the 15min of warm-up time then drops to 1a to run, about 30Ah total per day.
Weather proof hard case - 22" x 14" x 8" inside space
Ampretime 50Ah LiFePo4 battery - should be more than enough power for a couple of days without sun
100w Folding Solar Panel - 100w, comes with a PWM charge controller
4" -> 3" Ducting Reducer - because the heaters use 3" and dryer duct comes in 4"
25ft 4" heavy duty dryer hose - but really, you can get this stuff anywhere and who's gonna hoard dryer hose?
Some wire to extend the thermostat/control board
DC Rocker switch and 15a inline fuse

My setup plan I think is:

Pack out unit to site
Take solar panels out of cradle and unfold/set up
Open lid of hard case, extract ducting and remote control
Rotate heater exhaust pipe up to get the fumes away
Run ducting and remote to window/cat door/whatever. Seal gap as best you can (Duct tape or board or YMMV)
Plug solar panel into connection inside heater case
Fill diesel tank
Turn on main switch
Go inside and turn on heater
Enjoy the warmth!

I know from experience that those diesel heaters will run for a little over 10 hours on that size tank at full bore, longer once you're up to temp and it throttles down.

So, thoughts? What am I doing wrong? Am I just being dumb?
 

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Weldman

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Speaking from personal experience the ducting better not be touching anything that can burn or melt, it gets hot! Got a 5kw and it kept my truck camper warm when it went down to 40 below zero with 60 below zero wind chill.
 

Short_Shot

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Also speaking from experience, don't count on 1 amp for the heater.

I don't know why everyone insists on telling one another this but they can use over 4a on high.

With the cheap oem controller it'll switch between low and high as the thermostat demands increased heat. For some small spaces this will almost instantly exceed your set point and be annoying but larger areas this smooths out well.

At any rate the average consumption will always be more than 1a as long as your space isn't continuing to heat up even on low. In which case you should use a 2kw, but that's hard to know up front and with a "house" as stated you shouldn't have that issue.

It also doesn't take 15m for them to start up either.

Oh and you should not run the exhaust "up" unless the muffler (with drain hole) is at the lowest point. Fuel and moisture can condense in there. Moisture is annoying, fuel can lead to sudden 'backfire'.

If you're drawing heated air from inside the house then there is little reason to expect the exhaust will somehow get into that circuit as it should be isolated entirely from outside air.
 

Rednecktek

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Well, the 1a figure is what my amp clamp said it was drawing after the glow plug shut off, and that was running full bore trying to get the place above -10F so that was the number I was using. Also, I find it's usually between 10 and 15 minutes to start blowing the HOT air out of the tube on the 2 I have at my camp, so I erred on the side of caution for timing. Even with the 11a startup power for the glow plug (again, according to amp clamp) I still think 50Ah should be plenty but I won't know for sure until I build it and fire it up.

Yeah, I'm still working out the details of getting the exhaust pipe away from the intake hole without bending the pipe too many times. The muffler is kinda a pain to factor in. Not that the "Drain Hole" actually does anything according to the backfires and puddles I got from the latest one. I'm thinking that since the unit will be outside, I don't think I even need it. The pipe can rotate on the exhaust port without stressing the flimsy exhaust pipe so I'm hoping I just need to bend it to shape the first time and twist it up and down upon deployment.

The primary test usage for this will be keeping my pump house warm (8ft x 16ft, insulated but drafty) when I'm passing back and forth past that freezing temps line. If it works well, then it might be the beta for a home version to keep the cats warm in a power outage since my wife is terrified of the fireplace. That "8" of clearance" sure looks a lot like 2" on my tape measure... Somebody obviously "Knew A Guy".

@MattiFin: Where's the fun in that? :) Plus this is cheaper and doesn't have the source of ignition inside the building so I'd feel more comfortable walking away from it for hours on end.
 

Short_Shot

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There's no way you're pulling 1a on high with a 5kw heater. Either your reading was in error or your unit wasn't on high at all, which could be due to them defaulting to "hz mode" which usually starts out at low by default.

The one in my camper defaulted to 2hz pump speed which is almost minimum output (which was 1.6hz).

If you set it to thermostat mode or crank the pump hz up to max you'll see.

The fan is much higher wattage than that. I've seen mine pull as much as 5.5 amps running on high after turning up the fan speed to ridiculous rpm.

I've installed several of them and they all pull much more than 1a at full speed, and I've read hundreds of posts and reviews all citing the low speed 1a number as gospel. Probably all for the same reason of people mistaking the default as high?

Mine actually pulls rather less than 1a on low because I've tuned it way down to about 900w output.

Regarding the drain hole, it does its job perfectly if it's placed at the lowest point. That is to prevent anything from accumulating. It will not stop anything from coming out the end of course because the air is blowing by, so naturally both will occur.

50AH of lithium will get you through a night no problem. 50ah of lead likely will not.

Depending on the area heated, temp setpoint, and your specific heater your average could vary from absolute minimum 1a/h to as much as 5a/h, with reality most likely in the middle.
 

Rednecktek

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Well, IF it happens that I can get up there I'll do some more poking at the 2 I have installed and see if I can't get more accurate data.

As for the drain hole, the 2 I installed on my 2nd heater would refuse to drain. A drill bit fixed that but it was still mighty annoying when the heater would just crash.

Yeah, 50Ah of lead wouldn't stand a chance. :) I'm just hoping there's enough ambient heat in the box to keep the battery warm, but there should be.

The only idea I ever get for High vs Low is the ticking of the pump, the airflow, and the bar graph on the controller.

So worst case scenario I might have to find a way to stuff a 2nd battery in there? Other than that it looks good?
 

Short_Shot

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Yeah I just don't want you to come up short.

I can get a quick video of mine running on high and showing you the power consumption on my victron shunt if you'd like.

Regarding the drain, they love to clog up with crap lol
 

Rednecktek

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Mind you this project came about because it was afternoon coffee time, I had NOTHING I could get started on, it was too early to hide from the Chief, and I was BBBOOORREEDDD!!!

And missing my camp... but it's the reason I sail so.... PROJECTS!! :)
 

Short_Shot

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Also 0.51L per hour fuel usage on max out of the box. Much less on low of course. Much more if you change settings.

My camper one capped out at some 0.48l/hr by default.

So the 10l tank, which is usually a bit under 10l Would go over 17 hours full send.

A few nights I ran mine on max heating a large uninsulated area and I definitely made it more than 12 hours.
 

circus

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There's one in my van and it's great but I don't see any advantage fitting one to heat the house. It's just a smaller, less efficient, version of the house furnace that burns really expensive fuel. Maybe just figure out a way to power the house furnace if the power went out. Or better yet build some solar hot air collectors. Won't replace the furnace but will replace half the fuel and super safe.
 
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Short_Shot

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There's one in my van and it's great but I don't see any advantage fitting one to heat the house. It's just a smaller, less efficient, version of the house furnace that burns really expensive fuel. Maybe just figure out a way to power the house furnace if the power went out. Or better yet build some solar hot air collectors. Won't replace the furnace but will replace half the fuel and super safe.
I actually agree with this to an extent.

If you only need to heat one room it can be much lower investment vs the power needed to run the furnace fan.

In the unlikely event natural gas service goes down or if you're in the boonies on propane then it's a viable alternative.

They are ~18k btus, if you're into that sort of unit, and the forced air makes them a bit more effective than a typical catalytic propane heater, and safer.
 

circus

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I know they're taboo but, for a emergency, my 30 year old kerosene heater is good enough. The smaller radiant one's with the removable fuel tanks are better. Fuel level, the wick is in, doesn't change while being consumed so the heater never smells. As long as the heater's out of the living space while being lit and extinguished, it won't smell. Caveat: It is an open flame, they do consume oxygen and produce gallons of moisture so using it in a small space is not a good idea. The only electricity needed are the two ten year old D cells used to light it.
 
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Kornbread

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We used the round style kerosene heater for several years and while we could not smell it, visitors who were not using kerosene could smell the odor in the house. Like on the commercial, sometimes we become nose blind. But yeah, if possible, light and extinguish outside. A side benefit, it makes a fair stove as it does get hot enough to cook eggs, warm soup, etc..
 

Short_Shot

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Catalytic propane heaters are excellent for emergency use in my opinion. I would consider them second to diesel heaters though.


They do not have a carbon monoxide concern like "normal" heaters do. Carbon DIoxide and oxygen depletion are a concern in smaller spaces of course. They also put a lot of moisture into the air, but that's a good thing for some people in the winter.

I ran a 9000 BTU Mr. Buddy in my friends open concept house which was roughly 1000 square feet of space. It was just barely enough to keep the interior above 60 degrees for the night that his furnace was out. For a while I used it in my 10x10 tent, but will be switching to a diesel heater rigged up for portable use soon since I carry diesel for my camper heater anyways.

Carbon monoxide meter didn't register anything by morning. If you are looking for something in line with that, there is also a Mr. Buddy that does up to 18,000 BTUs. They have low oxygen and tipover protection which works very well.


They make adapters to larger propane tanks if you need it.
 

sjkted

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I have one of these installed. Yes, they do use about 1 amp. I repurposed an RV fuel tank and have about 60 gallons of diesel just sitting for whenever I need it. I would recommend getting a German brand like a Webasto or Eberspacher. The install takes a lot of work/time/planning and it would really suck to finish all of that to find out you can't use it because you bought something that was Chinese junk. I also have some concerns about the unit exploding or catching on fire due to not following safety guidelines. Mine is a Webasto that I bought from Russia on eBay. They don't carry a US warranty, but they are new and less expensive.

sjkted
 

Short_Shot

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I have one of these installed. Yes, they do use about 1 amp. I repurposed an RV fuel tank and have about 60 gallons of diesel just sitting for whenever I need it. I would recommend getting a German brand like a Webasto or Eberspacher. The install takes a lot of work/time/planning and it would really suck to finish all of that to find out you can't use it because you bought something that was Chinese junk. I also have some concerns about the unit exploding or catching on fire due to not following safety guidelines. Mine is a Webasto that I bought from Russia on eBay. They don't carry a US warranty, but they are new and less expensive.

sjkted
Eh.

For the price of a name brand one you can buy half a dozen Chinese ones and still come out ahead.

They're very simple designs that can easily be inspected for safety issues. There is like 3 moving parts in them. A fan/shaft and two bearings. They are mechanically identical to the expensive ones just lower quality control.

They won't explode or catch on fire either due to the inherent safety of diesel fuel. The only way you could catch one on fire is if you poured fuel onto one with a bad gasket and the same would occur with a "good" one.
 

offgriddave

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I bought the German version of the diesel heater and haven't hooked it up yet. The German one looks very well built and I think it was only $150. I have it here in a box I just need to punch a hole in the wall. It isn't very cold where I am at.

It claims 40w draw, 12v-24v. I was going to use it in my RV. I haven't hooked it up because it hasn't got below 50f yet and the lowest it gets is mid-40s in the winter. I use a propane Big Buddy right now, yes, inside. I have a CO meter it has never gone off. I have used this setup for over half a decade. When it is really cold and you stay inside, yes you need to get fresh air every once and a while. But I crack open a window to vent out the water vapors.


About your other items/ideas:

Somebody here told me about San Tan solar I would purchase panels from them instead of amazon. I am really happy with them.

Also BatteryHookup.com for batteries. Happy with them.

And USA MPP Solar for an invert but I don't think they make a small one you need. Ian responds to emails pretty quick with detailed information and he's on here (told me about this site)
 
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Short_Shot

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Lol no way did you get a "real" German one for $150.

The Chinese ones go for $120 to $150. The eberspracher and webasto units are 7 to 10x that cost.
That said if you have any questions about the install hit me up. I've done a few.
 
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