Van heating thread

86scotty

Cynic
Added quite a bit of info to the intro. Leaning toward Everest Star at the moment. Need to calculate consumption.

I have no idea how to calculate consumption but can offer this. In my last van, which had the EverestStar, I had no fixed propane tank. I set a 20# outside on a quick release hose. One night, just to try it, I put an adapter and a 1 lb. cylinder on the hose. It ran all night. It was empty (or felt empty) the next morning but it still ran all night. This was not extreme winter camping. It was probably around mid 30's to 40 or so that night, and I did have the huge CCV pop top up so the furnace ran a lot more than when down. I see you have a pop top. When it's just one or two of us I leave my pop top down on cold nights. That way you're only heating about half the space.
 

Jb1rd

Explorer
So I was curious last night and did a little field test; went out and fired up the furnace in the beast and waited to see how long it would take to heat up the van. It was 20 F no wind to speak of. From dead cold it took approx 30 min for the inside to get to 60 then another half hour-ish to get to 68 it seemed to hold there. My unit is a hydro flame 12k BTU input 9k output. In my opinion this is not a good choice, first off the majority of hot air is being exhausted to the outside (first pic) secondly the heater is in the very back of the van by the toilet, you have to add some type of diversion to get it into the main cabin more efficiently.I think the radiant style heater would suit my needs better and will now be investigating that route. I have been wanting to add a propane expansion system, to run an outside BBQ and or outside radiant heater under the awning, this could easily be used to feed all three, not at once of course.
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Sent by magic, I mean come on really, pictures through thin air, MAGIC!!!
 
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Mwilliamshs

Explorer
So I was curious last night and did a little field test; went out and fired up the furnace in the beast and waited to see how long it would take to heat up the van...

Jb1rd, thanks for that!

...My unit is a hydro flame 12k BTU input 9k output. In my opinion this is not a good choice...

Too bad you don't have the low amp model, I'd be pm'ing ya an offer.


...In my opinion this is not a good choice, first off the majority of hot air is being exhausted to the outside...

Should only be ~25% of the heat (furnace is 76% efficient at heating the inside) but since the exhaust (waste heat) is taking a shorter path and is being felt outside in the cold vs the heated interior I'm sure it feels like more.

...secondly the heater is in the very back of the van by the toilet, you have to add some type of diversion to get it into the main cabin more efficiently...



Does yours have any vents other than the front discharge? If not I don't get why they installed the higher wattage blower but I do think that adding another discharge point would greatly improve heat distribution from a poorly located furnace. If yours does have just the front you could either add vents or swap to the 1.8 motor for ~$100. Either should work since both the high and low amp models of 12k btu furnaces use the same orifices, etc. There are only two motors, the 1.8a is PN 36122 (~$60, fits only model #8012) and the 3.4a is 31036 (fits all others) but there are also two blower wheels, PN 33431 (~$30, fits only 1.8a motors) and PN 33286 for all others and different sail switches, PNs 36134 (1.8a) and 36133 (all others), both ~$10. The higher amp motor spins a blower wheel about twice as wide, hence its greater air output. The combustion fan blades are the same for all models.
757911.jpg

Samba 7916 (16,000 & 3.4) to 8012 (12,000 & 1.8)swap.
.1.8 blower\/

.3.4 blower\/

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If swapping motors/blower wheels or adding vents doesn't suit you, this might also help: http://www.amazon.com/Atwood-36959-Directional-Hydro-Furnace/dp/B00CLSVRPQ
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It's an Atwood factory accessory called a Directional Air Box and it installs inside the front grille. It's louvered at a 55° angle to divert airflow from straight-out off to one side. It's reversible. To blow either direction just remove and flip 180*, then reinstall. I've heard good things about them and they're under $20.
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The diverter is discussed here, a cool Everest Star install into a Westfalia pdf from The Samba.
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I think I'd install one of these if I were you. It's a Flying Insect Screen for that exhaust vent. They may not be a problem in your locale but dirt-daubers, bees, wasps, etc can stop a furnace in its tracks around here and $10 is well worth not having to disassemble the whole works to knock out a chunk of mud. There may be a model that fits better. That one overlaps about an inch-and-a-half.
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Re: the add-on propane stuff, I just found a neat (cheap) part the other day: http://www.expeditionportal.com/forum/threads/133982-Propane-Butane-adapters (last post)
 
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Mwilliamshs

Explorer
I have no idea how to calculate consumption...
Well here ya go:
The Everest Star model # 8012-II uses 12,000 BTU of propane to output 9,120 BTU of heat into the cabin (76% efficient). I determined if I insulate my van from the front seats back to an average R value of 7.58 (costs ~$425) its heat loss in 30*F weather will be 1,349.95 BTU/hr when heated to 65* with the Penthouse closed and a curtain drawn behind the front seats. This number is likely higher (worse) than reality, as I figured the van's size by it's overall exterior dimensions, see first post rectangle pic. The 8012-II @ 9,120 BTU output can maintain 65* @ about 14.6% duty cycle. That means about 9 minutes of an hour (8.88) it's running to hold 65 *in 30 *degree weather. 8.88 minutes x 1.8amps = 15.84 amp minutes, or 0.264AH, which is under 6.5AH per day (6.33) if it stays 30* and you just “set it and forget it.” Under those same conditions the furnace will burn 12,000 x .148 = 1,776 BTU of propane per hour, or ~2% of a gallon per hour (1.94%) and ~½ a gallon (46.5%) per day, again if you set thermostat at 65* and leave it there on a day when the outside temperature stays at 30* for 24 hours (or averages 30 overall). With a built-in tank that’s common on van’s this size like the B190s, etc of ~10 gallons and ~8.25 of it usable, that’s over 430 hours of heat, almost 18 days (17.95), during which time it'll use ~113 AH of battery power.
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...I did have the huge CCV pop top up so the furnace ran a lot more than when down. I see you have a pop top. When it's just one or two of us I leave my pop top down on cold nights. That way you're only heating about half the space.
Good thinking!

Popping the top drops the average R value of the space to 6.28 and the area becomes 349.235 sq ft. This makes the heat loss 1,946.37 BTU/hr and requires the #8012-II run at a 21% duty cycle consuming 2,561 BTUs per hour, 2.7% of a gallon, and 66% of a gallon per day to maintain a 65* interior with a 30* exterior, 24/7. With a typical built-in 10 gallon van tank of propane (~8 gal propane) it’ll run over 12 days that way, on 84 AH of power.
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In more real-world conditions, like camping in winter where nightly lows are 30-ish and the furnace is run maybe half the day (but having to heat the van up from 30* before bed then keep it 65* through the night), you're looking at about 33% of a gallon burned for heat per day with the top up (30,240 BTUs) and 23% with it down (21,024 BTUs), which extends run time to over 25 and 35 days, respectively.
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In my build thread I calculated my daily cooking needs on an extended Central America trip and came to ~8,400 BTUs of propane per day for meals. That’s a couple boiled eggs, some bacon and coffee for breakfast, plus lunch and dinner so not exactly roughing it for the sake of saving fuel and I have considerable “cushions” built in to that figure. If I heated the van as described in the “real world” conditions above and cooked as expected, keeping the top down while heating, that’s 32% of a gallon of propane per day (29,424 BTUs), and the 10 gallon tank (filled to ~8 gallons for safety) should last 25.69 cold days (or over 90 days of cooking with no heat).
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Incidentally, last month in Mexico propane was .56 per gallon. That means my 21 (COLD) day supply for cooking and heating would run me ~$4.62, or about $6.60 per month of 30* days, and yes it's USD, not pesos. I can handle that. At their 2014 peak, last February, propane prices in Mexico hit $1.44 USD per gallon, so still under $17 per month of 30 degree weather.
 
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Mwilliamshs

Explorer
...In my last van, which had the EverestStar...One night, just to try it, I put an adapter and a 1 lb. cylinder on the hose...It was empty (or felt empty) the next morning but it still ran all night...was probably around mid 30's to 40 or so that night...the huge CCV pop top up so the furnace ran a lot more than when down...
No idea what model you had and hourly consumption varies from 18,000 to 12,000 BTU on these furnaces with no exterior clues as to which any particular unit is (have to pull the front grille and check the label as in Jb1rd's post). The 1 lb tank you mention holds 21,600 BTUs when new and factory-filled. That gives a continual run time of 72-108 minutes depending on which model of Everest Star furnace you had, or 5.7-8.5 hours @ 21% duty cycle (pop-top up) as described above, which sounds about right for "ran all night".
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I've been a big fan of that van for a long time by the way. First-class homebuild!
 
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86scotty

Cynic
Thanks. I passed all the manuals and paperwork on to the new owner and don't remember which size furnace I bought, but I can tell you it was the smallest or next size up at most. I was on a tight budget and was happy just to get a furnace. I figured any fired furnace would do the job in a space that small, and it did fine. i can find out by contacting Panther RV if you really want to know. I don't mind. Let me know.
 

Cole

Expedition Leader
FWIW, I've got two Espar coolant heaters for sale from a Sprinter. The guys on the Sprinter forum have figured out how to make these work off just a switch. So might be a good option for someone's van heat. This is what I use to heat my Sprinter.

Normally about $1200 -ish new.

Copy of the ad.



I have two D5 Coolant heaters for sale for a T1N Sprinter.

The first one came out of my 2004 7 day timer van. It has the 2 plugs on it. I took this out for a "F42 water pump short" error code. The heater worked fairly well before this error but it probably has a bad control unit in it. So I would consider this a *parts* unit or one to play with. $200+shipping

The second one I bought just recently on eBay. It only has 1 plug on it. So it was intended for Sprinters without the 7 day timer. Which means it doesn't run off my 7 day timer. It works 99% of the time but has thrown an "overheat F68 flame sensor code" randomly a few times when run all day long. This could easily be set up to run off a switch if you follow the threads here. I just wanted stock 7 day timer functionality without cutting wires so I tracked down another 2 plug unit. I'll take $300+shipping for this one.

Both located in the Denver, Co area.
 
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Jb1rd

Explorer
Thanks for the beta Mw!!!! Will def be playing around with options and you now have me curious to see if there is another outlet???!!!!!
 

Jb1rd

Explorer
Not convinced with my last test I tried a little more accurate test tonight, *outside temp 35degrees F starting inside temp 45 degrees F, turned furnace on set to 75 degrees F and set timer for 1hr, checked temp 30 min later temp inside temp was 70 degrees, checked again at 1hr heat was at 72-3 furnace was not running so I am guessing it was cycling at this point. I turned the furnace completely off and checked temp again 30 min later and the temp was 58 degrees F. Take away, the furnace actually works fairly well, all be it a little noisy (maybe a clean and lube?)the weak point is obviously the insulation. Now the 64k dollar question, spend the time and effort to take the inside apart and insulate properly or just let the furnace run????? Common sense would say it's time effort well spent because it would also improve summer cooling, but laziness says, what the hell, run the furnace and a/c :sombrero:
***BTW upon further inspection there is another vent that outlets to the main cabin however, it is in the cabinet right by the barn doors.
*****First step will be to pull the furnace out check for wasp debris and proper alignment, and see if I can lube it to make it run quieter.
 

Mwilliamshs

Explorer
I'll do math on your results later. Thanks again
...
***BTW upon further inspection there is another vent that outlets to the main cabin however, it is in the cabinet right by the barn doors.
*****First step will be to pull the furnace out check for wasp debris and proper alignment, and see if I can lube it to make it run quieter.
Betcha that extra vent is plumbed with lousy flex duct. A couple hours with rigid dryer vent and tin snips will make a world of difference.
 

Jb1rd

Explorer
Yep, a brief inspection revealed that super thin plasticy looking ducting!!! One more thing to add to the list!!
I'll do math on your results later. Thanks again

Betcha that extra vent is plumbed with lousy flex duct. A couple hours with rigid dryer vent and tin snips will make a world of difference.
 

Mwilliamshs

Explorer
Yep, a brief inspection revealed that super thin plasticy looking ducting!!! One more thing to add to the list!!
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There are 4 types of vent ducting. Because it's a common size (4") and typically used on dryers, thus widely available at hardware stores, etc, that's how I tend to refer to it, as dryer duct. The good and bad I'll discuss here are strictly furnace related, so no lint, moisture, etc. The picture below shows the types. #1 is plastic wrapped around a coiled wire, like a slinky toy shoved into a bread sack. The convulutions create air turbulence which is bad for flow and the plastic itself causes friction which leads to static electricity. The plastic doesn't hold up well to the 200* output temps and dries out, cracks, and leaks or even delaminates into different layers which trap the air. #2 is a rigid steel pipe. It's stiff and smooth both inside and outside. It flows ideally. It lasts basically forever. It's is basically perfect but does typically have a seam that must be taped. #3 is similar to #1 except that it's metal foil instead of plastic, still a flimsy flexible shell wrapped a coiled wire. It shares all of #1's shortcomings except that it withstands high temperatures better so it lasts longer. #4 is semi-rigid. It's as close to #2 as you can get but still be some-what flexible. It's all metal construction (and not just foil) lasts and lasts.


The advantage to the flexible duct (besides being cheap) is that you don't need fittings to use it. If you need a 90* bend you just bend the duct and keep moving. Anything other than a perfectly straight run of duct will impede flow so you want to minimize the number of bends and you want to maximize the radius of the bends as seen below. I'm not saying you have to buy that specific fitting (called a long turn ell), but it's a good idea to make any bends as gentle as possible. Building codes dictate maximum lengths of dryer vents. Most say 25', and you have to deduct lengths for fittings, 5' for typical (sectioned) elbows. If you had one of the sectioned elbows you could only use 20' of straight duct because that one fitting has as much restriction as 5' of regular duct (more recent testing suggests it's more like 15' of straight rigid duct = 1 sectioned elbow). That's what the numbers in the picture below are about.


When hooking up your duct it's a good idea to tape all joints between parts like furnace-to-duct, duct-to-elbow, etc but also the seams of any fittings as seen below. They're all just stamped sheet metal so they're likely to leak a bit of air when new and after being man-handled during installation then bouncing down the road for a few thousand miles, leaks are inevitable if not sealed up so better to use a good duct sealing tape from the beginning. We're not talking about the grey tape with strings in it, inspite of what they call that stuff, but rather what's often called "foil tape". There are different kinds of this too and rather than getting too deep into it, I'll just say I prefer 3M or Nashua "foil mastic" tapes and Nashua 360-17 especially. These tapes are metal foil like the others but add to it a rubber backing (butyl I think) and super-sticky adhesive that sticks and seals and stretches and flexes like mad. Good good stuff just to have around but especially for duct work!

One very cool little trick I suggest is using what's known as a periscope fitting. Here's a pic of one installed to show how they work in general.


and here's a drawing of how you can take them apart, shorten them, and/or re-assemble them to flip their output 180*.


Periscope fittings are great where space is a concern and go from 4" round to about 6x2" rectangular (50% wider than round but 50% thinner) then switch back to 4" round. They're available in lots of lengths, offsets, etc but none are very expensive and they're at every ACE, Lowe's, HD, etc. under $20 at Amazon. With your van in particular, Jb1rd, where the furnace is on the passenger side and the secondary outlet is forward of the furnace, I'd use the periscope fitting to connect directly to the furnace, run back to the outside wall, then run straight forward with rigid duct. This gives you the best flowing, most compact system there is. Depending on how far above the floor level your outlet is and whether it's in the end or the face of the cabinet, you may use another periscope or an elbow, etc. If you found a way to actually use the extra 2" of space inside the cabinet like with deeper drawers or something you could use rectangular duct (like the periscopes) for the whole run too. I highly recommend strapping or otherwise securing the duct very well so it doesn't move around. This will keep it leak-free and prevent damage to the vents, furnace itself, etc but also keep it nice and quiet if you strap it a little closed-cell foam so blower vibrations are isolated. It'll also keep it from making noise as you drive. Hope this information is helpful to you or someone else. I often find little things like the periscope dryer vent that I didn't know existed by reading forums and use them in some way they're not necessarily intended, like furnaces :)
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On a more "Van Furnace" specific note, you should make sure there's adequate intake air flow available to the blower on the discharge (vents) side of the furnace. The best furnace in the world will fail to perform if installed improperly and Atwood demands,
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"NOTE: If zero clearance* is maintained from furnace to cabinet structure, a 4˝ x 4˝ air intake cutout must be provided to blower wheel side of furnace at air intake opening"
*When furnaces are installed to minimum clearances, an additional 16 in2 of return air must be provided to blower side of furnace, or a 2˝ clearance the full length and height on blower side must be maintained.*
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So if your furnace when installed is closer than 2" to the cabinet on its left it should have a 4" square opening next to the blower on that side to keep it from starving for air
. Starving will reduce output, kill efficiency, and increase noise. Try cupping your hand over a shop-vac hose sometime and listen to the motor. That's what happens to any blower in cavitation. I've seen lots of these furnaces (wish I could go back in time and grab one) installed, mostly in old ice huts, and most of them are zero tolerance with a square hold jig-sawed in the adjacent cabinet. Back then they were Hydro-Flame furnaces (later bought out by Atwood I guess). Some were without cabinets, just set in open-air with the exhaust butted against the wall and that's it. If the jigsaw guy was sick the day your van was at Airstream, or if they just plain didn't perform that step, it could certainly explain your furnace's poor performance.
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http://www.livinlite.com/pdf/service/furn/Atwood7900EverestSeries2.pdf <-Everest Star Manual
 
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Jb1rd

Explorer
Mw, you rock. I am off tomorrow and Wed and will be pulling the furnace and making a home depot run:elkgrin:
 

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