[GaryBIS]

".Can't I fill the ribs with foam? I know the through-metal will conduct a lot of heat away but most covered ones seem to have only a thin veneer over it anyway. Whether they stay exposed is too fine a detail for now, i just think it would be a good look."

I think this is worth discussion. Especially for a multipurpose van. Exposed ribs certainly make future mods easier. And 1/8" paneling is only 1/8" of extra insulation; a small fraction of an R value. Stuff or foam ribs with any type of insulation and slip reflectix into the holes for a smooth finish. This is like the ROI discussion. How much extra heating would I need? Maybe not really measurable.

I did a heat loss on my PM:

Van heat loss :
Item area R value Tavg outside Tin Heat loss (BTU/hr)
walls 210 6 32 68 1260
Floor 78 9 32 68 312
ceiling72 6 32 68 432
windows single 30 1.5 32 68 720
windows double 18 3 32 68 216
infiltration 468 32 68 82 at 3.0 ach
Total Heat Loss 3022 BTU/hr

Edit: the heat loss table formating does not come through very well: the colums are Area, R value, Outside temp, Inside temp, and heat loss in BTU/hr


So, a 12K BTU/hr furnace would be running (3022/12000= 25% of the time)
Propane burn per day would be (3000 BTU/hr)(24 hrs)/(92000 BTU/gal) (0.8 efic) = 0.97 gal/day

So, the last column is the heat loss in BTU per hour with a 30F outside temperature.
This is with the insulation values I used, which were R6 foam in place foam for walls, ceiling and roof. AT the time I did this heat loss, I was thinking I'd get double glazed windows, but ended up with single glazed, so the actual heat loss is about 200 BTU/hr greater than what's shown.

So, on a cold night, its about 3200 BTU per hour -- without the insulation it could easily be more than double that. To me, its more how large a propane tank you would need to carry to have a few days operation in cold weather, than it is saving the cost of the propane (although that's nice too).
The insulation also allows us to use a fairly small (12K BTU/hr) furnace.

I spray foamed over the walls and ceiling, and as I go, I've been filling in the hollow ribs with Great Stuff foam. For me, its as much about stopping condensation as it is about insulating -- I think the spray foam does a good job of keeping moist air from reaching the cold metal, but I could be wrong about this?

Gary

 

[D K]

Is this a diesel or the Penta?

I have a 1500, 136, high roof. Bought it new March 1, 2014. I have just over 21,000 miles on the odometer. 95% highway use from Chicago south thru Tennessee mountains and Georgia area. If I make the trip with about 500lbs loaded in the van I can expect to get around 21mpg. I have gotten as high as 25mpg if I slow down and maintain 65mph without a head wind (535 miles , 21.3 gallons) on a couple occasions. The van will rarely down shift unless it's a steep hill or heavy head wind, no issue at all. The taller gear ratio is awesome for great fuel mileage. I also tow a trailer some of the time. Total weight for the 6x12 trailer is 2,500 lbs. I typically get 18.8 mpg while towing at 65mph. It can drop by 1 to 1.5mpg with headwind and at times it increases slightly but mid 18's is the norm. Towing on up hills will down shift , very reasonable if bigger uphill, but even with a lower final ratio it would down shift. I think your fuel mileage with a lower final gear, 2500 or 3500, will drop your fuel mileage by 1 or 2 mpg.

 

[zwarte]

Diesels weren't out when he got it.

 

[Chance]

I did a heat loss on my PM:

Van heat loss :
Item area R value Tavg outside Tin Heat loss (BTU/hr)
walls 210 6 32 68 1260
Floor 78 9 32 68 312
ceiling72 6 32 68 432
windows single 30 1.5 32 68 720
windows double 18 3 32 68 216
infiltration 468 32 68 82 at 3.0 ach
Total Heat Loss 3022 BTU/hr

......cut......

Gary

Nice to see estimates Gary. I'm curious where or how you got data for factory windows. In my present window van the glass areas transfer so much heat that it would be pointless to insulate the rest of the van.

The 1.5 R-value for windshield and front door glass (assuming I'm reading estimate right) seems higher than what I would have expected. But then again I haven't seen much insulation data for auto glass.

Thanks for posting your estimate. It compares different areas effectively.

 

[MsNomer]

I have noticed that the heat gain through PM's windshield and front windows is significantly less than our other vehicles. Even the windshield is tinted--I didn't know that was even legal, but I'm sure not going to tattle on them.

 

[archangel]

My thoughts for insulation are as if there is no supply of additional heat.
So how well will it insulate 2 people through the night?

I've seen a van that had a ridiculously small wood burner stove mounted to the wall and no sooner had they got it going, they shut it down as the vehicle was heated more than enough and the insulation kept it that way for quite a while.

God forbid a blizzard hits, you run out of propane, or can't drive out for a couple days.

 

[Chance]

My thoughts for insulation are as if there is no supply of additional heat.
So how well will it insulate 2 people through the night?

.....cut.....

I've done this a few times with my Econoline window van when outside temperature was in the 30 degree range, and the inside temp dropped to within 2 degrees of outside.

 

[Brian P]

I routinely sleep inside my ProMaster (although we are finished for the season as of this past weekend). Uninsulated except for carpet on the floor.

Compared to sleeping in a tent (which was my previous arrangement) ... the van does a much better job of keeping wind and rain out, so at that point, you can use a good sleeping bag and it will do the job!

 

[keeponvaning]

I slept in my uninsulated Sprinter one night (at a WallyWorld) when I woke up it was snowing out and the temp was about 8° Inside and out. I was nice and warm in my bed with a good blanket over me and just started the van up and fast idled it fir about 10 minutes then went about my business. I'd rather too much cold than heat personally.

I did insulate the Promaster but it is a big metal box with a lot of glass and I'm not really that concerned about how well the insulation works, if at all. Insulation is a consideration for me but its at the bottom if the list I guess, as far as I'm conserned. I'd rather spend the money on solar in the future.

 

[RDinNHandAZ]

Great information on the insulation. Our practice is to sleep w/o the heat on.... and we have camped in our truck pop-up at 19 degrees F. We have a sleeping bag fit for the job. BUT... I like to have the heat switch or thermostat near enough to switch on when I am still in bed so the area is warm when I get out of the sleeping bag to make the coffee. I too am much more interested in preventing condensation than absolute heat loss. At 20 degrees or so ventilation is necessary or your breathing condenses on the inside of the cabinets and everything else! For us, a 20 lb propane cylinder running a Dometec 3.3 cu ft refer, heat in the evening and early morning, stove top, and hot water for a 1 or 2 gal shower every three or four days is over two weeks when cold out. Its can be less if warm as the refer uses more than what we use for heat. We carry only 21 gal of fresh water so that can be a limit that makes us go into town.

 

[GaryBIS]

Nice to see estimates Gary. I'm curious where or how you got data for factory windows. In my present window van the glass areas transfer so much heat that it would be pointless to insulate the rest of the van.

The 1.5 R-value for windshield and front door glass (assuming I'm reading estimate right) seems higher than what I would have expected. But then again I haven't seen much insulation data for auto glass.

Thanks for posting your estimate. It compares different areas effectively.

Hi,
You know, I can't remember why I used the R1.5 for the single pane glass. I normally use R1 for single glaze, R2 for double glaze, and R3 for double glaze with low e coating. I might have been accounting for the extra R value for a curtain, but not sure.

Glass itself has almost no R value, its the air films on the inside and outside of the glass that provide the R value. Its fairly standard to use about R0.65 for the inside still air layer, and R0.17 for the outside layer which goes with some small wind velocity -- they add up to (very roughly) R1.

A bare metal van wall would have about the same R1 as a window does since it has the same air films inside and outside, and the metal wall (like the glass) has near zero R value itself.

It seems to me its worth insulating the walls, ceiling and floors, as they normally add up to quite a bit more area than the windows, so, it seems it will cut total heat loss significantly? If you you use curtains on the windows at night, they provide some additional insulation on the windows, and they could be made pretty effective insulators if they fit well and could be made for one of the more insulating fabrics?

We are still in mid convervsion, so have no actual experience.

Gary

 

[Roblee]

Great info Gary. The 12K furnace u use gives me practical advice for my 2015 plan. I have an 18K in my 14' RV that is more than I need. Using velcro attached foam pads to cover windows and skylight when dew point reaches inside temp. Keep vent cracked and heat before bed and again in AM. Ill not use pressure lines so no fear of frozen pipes.My everyday driver conversion will sill be simple an cheap except furnace, fridge, and AC. You guys have encouraged me to make what I want rather than get what I Need. I plan this to be a palace compared to my homebuilt 1666 VW van conversion. My guess is that paneling over or avoiding the ribs won't matter much as long as the air flow is controlled. Thanks all.

 

[MsNomer]

Ah, another VW convert. I think of my PM as a Vanagon that runs--I hope.

 

[motosmile]

Hello everybody!
I gone through all thread, but (probably, because English is not my first language), still did not get answer - Is 1500 more efficient in gas consumption compare to 2500?
Thank you in advance.
I'll probably will buy my tomorrow (but there is excellent deal on 2500...).
I am, actually, "in love" with 1500.

 

[archangel]

Probably not as I believe they all use the same engines and transmissions and only have different final drive ratios.
We have the 3500 high top and just ah hour ago was getting 18 mpg @ 80 mph!

 

[motosmile]

Thank you for respond.
18 for 3500 (!) - makes me feel pretty confident toward 1500. Means, it will be really economical...
My deal was canceled (dialer did some mistake), and because it is winter time I decided to wait till spring (insulation better to do when it warm outside)...
Thanks again.

 

[Brian P]

From what we could figure out earlier, even the final drive ratio is the same. (Gasoline engine)

My 1500 shows approx 1850 rpm at 100 km/h (about 60 mph) and all indications have been that they all do.

 

[archangel]

I was probably catching a bit of a tail wind but when taking off I SERIOUSLY put my foot into and, keep an "enthusiastic pace" on the freeway, all the time.

 

[keeponvaning]

I think the real difference between a 1500 and 2500 is simply $1000! Plus, if you want a 159 WB, tall you are forced to get the 2500. Marketing is a wonderful thing (for the seller at least)!

 

[RDinNHandAZ]

If you opt for a 3500 you get a $200 sway bar and a $3500 price increase IIRC! Ignorance is bliss they say but it is expensive too.