60,000 BTU heater in M1079

[XCRV]

Someone saw our ad on another forum and asked:
“Hi - what would you say the your truck's minimum temperature capability is for semi normal habitation? Not the truck chassis but the living quarters.”

My answer was:
“As long as you’ve got plenty of diesel, the 60,000 BTU military heater should handle just about anything. (No need to run truck’s engine but this heater is diesel powered with an electric fan.) We picked this truck up outside of a base in Fairbanks, Alaska. This LMTV had been special ordered for severe cold since it was presumably meant to be used in or near the Arctic Circle. Fresh water tanks, pump and filter are under the bottom bunk. Weak point would be the grey water system. Those tanks are outside, under the habitat and use a bilge pump. We’ve just run water through it periodically to prevent the pump from freezing. Another work around would be a simple drain hose to bucket. Hubby remembers camping with temps in the teens. I’ll ask around and see if I can get a number from veterans who have been stationed in cold places.”

Anyone have experience with the M1079 box and 60,000 BTU heater in really cold weather?

 

[Ronmar]

Thats a lot of heat! An 8x8x12 structure has 512 sq/ft of surface area. If it had 2“ of insulation it might make R10? At 70F inside and say -20 outside, crunching some numbers with say 24SQ/ft of R2 windows and one air change per hour, that is around 7000 BTU/hr required to maintain 70F inside? so your heater would run 6 minutes or so out of any hour?

 

[XCRV]

Yes, it’s a LOT of heat! I never timed it but the heater doesn’t need to run very long. Thanks for doing the math.





I should have marked them but pretty sure the thinner one is from the wall and the thicker one is from the floor.

 

[Third From Texas]

Mine has that Hunter heater and I've slept in the hab before.

In sub-zero it works quite well. It's still a bit of overkill if you plug an insulate the other two front/upper sections. But I was in there this past week several times while we enjoyed our first winter in S. Texas (thanks for the solar and wind farms when we needed more fossil plants). As you would expect the heater does not cycle nearly as often while in colder temps.

In near or above freezing, the thing never rests. The fan comes on, the fan goes off, the primer and igniter are heard, the fan comes on, the fan comes on It gets hot fast, the thermostat kicks the fuel off, the blower comes back on, the fan runs for two minutes to cool the heating element, the blower goes off. This all takes about 8 minutes (for a one minute burn), so now it has cooled off and the whole process starts over.

The diesel heater smell is present of course. No carbon monoxide issues ever (I have two new detectors that are frequently tested by me), but mine tends to make the hab a bit foggy after a couple hours. Not enough to trip either detector, but you can see it in the right light. It will go into fault and shut down at random times (which may be related to the fog, but I'm thinking that it's possibly attributed to losing fuel pressure ). But I'm looking for more technical info on the Hunter..

 

[Ronmar]

Yes, it’s a LOT of heat! I never timed it but the heater doesn’t need to run very long. Thanks for doing the math.

View attachment 826351

View attachment 826352

I should have marked them but pretty sure the thinner one is from the wall and the thicker one is from the floor.

Wow, an honest 3-1/4” in the floor, I wonder whats in the ceiling? that extra insul in the floor only saves you about 300 BTU/hr at the above temps...

 

[Ronmar]

Mine has that Hunter heater and I've slept in the hab before.

In sub-zero it works quite well. It's still a bit of overkill if you plug an insulate the other two front/upper sections. But I was in there this past week several times while we enjoyed our first winter in S. Texas (thanks for the solar and wind farms when we needed more fossil plants). As you would expect the heater does not cycle nearly as often while in colder temps.

In near or above freezing, the thing never rests. The fan comes on, the fan goes off, the primer and igniter are heard, the fan comes on, the fan comes on It gets hot fast, the thermostat kicks the fuel off, the blower comes back on, the fan runs for two minutes to cool the heating element, the blower goes off. This all takes about 8 minutes (for a one minute burn), so now it has cooled off and the whole process starts over.

The diesel heater smell is present of course. No carbon monoxide issues ever (I have two new detectors that are frequently tested by me), but mine tends to make the hab a bit foggy after a couple hours. Not enough to trip either detector, but you can see it in the right light. It will go into fault and shut down at random times (which may be related to the fog, but I'm thinking that it's possibly attributed to losing fuel pressure ). But I'm looking for more technical info on the Hunter..

That doesn’t sound right. I would hope there is no way for combustion gas to enter the airstream. But a fuel leak before the combustion chamber might allow fuel to come in contact with the burn chamber or heat exchanger and get heated enough to generate smoke/vapors which are being drawn into the supply airstream and into the hab...

 

[Third From Texas]

That doesn’t sound right. I would hope there is no way for combustion gas to enter the airstream. But a fuel leak before the combustion chamber might allow fuel to come in contact with the burn chamber or heat exchanger and get heated enough to generate smoke/vapors which are being drawn into the supply airstream and into the hab...

Rgr all.

Fortunately I prefer my little electric over the Hunter. My diesel gen is loud enough w/o an enclosure still, but add in a blower that will drown it out (unless you do quite a bit of plugging and insulating because the blower is LOUD).

 

[TechnoWeenie]

An average 2,000 sq ft house needs about 80K BTU of heat... That comes out to about 40 BTU / Sq. ft

Of course higher/lower depending on where the house is, but that's the average.

You have 60K BTU for 90 sq ft.

That's 666.66 BTU / sq ft.

You have more than 10x the heating capability per sq ft. than the average house.

 

[ZiggyO]

That's 666.66 BTU / sq ft.

I guess one can literally make it hot as he11 in there............. (I'm sorry, I just had to)

 

[coachgeo]

does anyone know the insides of these things well? as in..... if you could likely heat a smallish whole house with it.... could it actually handle that much time spent fired up? Where as in the 1079 it will run for like 6 minutes as mentioned earlier.... aka... its normal use is a very short duty cycle... where something larger like a bigger tiny home would have a longer duty cycle.

just asking for a friend..

 

[Third From Texas]

does anyone know the insides of these things well? as in..... if you could likely heat a smallish whole house with it.... could it actually handle that much time spent fired up? Where as in the 1079 it will run for like 6 minutes as mentioned earlier.... aka... its normal use is a very short duty cycle... where something larger like a bigger tiny home would have a longer duty cycle.

just asking for a friend..

I think it would heat my garage in the winter. So tiny house, sure...

The only reason it has such short cycles is that it's a blast furnace that reaches temp far faster than it can cool. But it's just doing what the thermostat tells it.

 

[Ronmar]

Yea, the manufacture may have a specified duty cycle, but duty cycles are usually imposed because of an inability to dissipate heat. I would guess if this unit can maintain a steady temp when operating, it probably has no duty cycle...

 

[XCRV]

Short chimney may explain some fumes getting into habitat. (That’s the moon, not a puff of smoke.)

 

[Mullaney]

View attachment 826459
Short chimney may explain some fumes getting into habitat. (That’s the moon, not a puff of smoke.)

Wonder of a piece of pipe came with it originally?

Maybe something that you could drop down on top of the existing chimney that extends 2 feet or so?

 

[XCRV]

Thermostat (gray box with coil) mounted to wood. We used Velcro for about 1/8 inch separation from surface vs original location directly against metal.

 

[XCRV]

Wonder of a piece of pipe came with it originally?

Maybe something that you could drop down on top of the existing chimney that extends 2 feet or so?

That‘s the original chimney/exhaust pipe. The extent of an odor nuisance would depend on wind speed and direction. I agree that a longer pipe would likely help. RVers sometimes attach a tall exhaust to their generators, especially at a rally where they are jammed close together.

 

[XCRV]

Added ducting (silver) improves circulation considerably. Cool air intake (vertical) draws from below bunk. Hot air blows (along ceiling) toward rear of habitat. Electric mattress warmer doesn‘t use much battery power but adds a lot of comfort.

(Gray foam is removed during use of heater. White plastic is a tablet holder for reading in bed.)

 

[Ronmar]

View attachment 826466
Thermostat (gray box with coil) mounted to wood. We used Velcro for about 1/8 inch separation from surface vs original location directly against metal.

I have used those for years, never had one fail, and always pretty consistent Performance. I have a few in the drawer removed from project upgrades and intercepted before they reached the dumpster, saved for future use

 

[Third From Texas]

View attachment 826467
Added ducting (silver) improves circulation considerably. Cool air intake (vertical) draws from below bunk. Hot air blows (along ceiling) toward rear of habitat. Electric mattress warmer doesn‘t use much battery power but adds a lot of comfort.

(Gray foam is removed during use of heater. White plastic is a tablet holder for reading in bed.)

Nice adaptation.

It still sounds like a jet engine? Mine is so loud I can't hear the TV when it's running. If I can get mine sorted out, I may keep it (but it's going to take a ton of soundproofing).

 

[XCRV]

Yes, the diesel fired heater is loud. Fortunately, we don’t have to run it long. Haven‘t tried any noise reduction for the heater.