Vented Cat Heater in a Van?

[ascii_man]

Has anyone here actually used http://ventedcatheater.com/? I think I would need the big one (5200 BTU/h) to give me the option of staying warm in extreme cold, but am concerned about its minimum cycle time overheating a van.

 

[Canine]

I have the same question myself. Since I didn't know the specific answer, my answer was to purchase the small one and if I end up needing more heat, then I will get another one. Even if I get a non-vented, supplemental, catalytic heater, the PlatCat will probably provide suitable venting. The small one does put out a decent amount of heat- it's not wimpy. The inside temp might get a bit nippy, but you aren't going to freeze to death.

Also, the larger one had a longer backorder when I ordered mine. Since the smaller one had only a 3 week waiting time, that was all the much better.

Maybe I should hook mine up somewhere as a test? An old junker van would give some real world numbers. The heater is small in size and easy to hook up; a temporary set up wouldn't be a huge demand of my time. The hard part would be finding a van and such. If I were to do some testing, now is the time while it is still winter.

 

[ascii_man]

Canine, we need to determine a couple of things:
1) The minimum amount of energy the heater will produce in a cycle. You can do this just runn the PlatCat in a garage or outside or in your room with a hose hanging outside. Set the thermostat so that it starts up, then immediately turn the thermostat down. This would tell us what the minimum cycle time is: the manufacturer told me it is 10 minutes, but the instructions only talk about a 40 second startup and 3-5 minute cool down. See if the gas sounds like it's flowing at full speed for 10 minutes.

2) How effective that is in heating a van. For this, you would only need a $12-$15 electric heater and an extension cord. Be sure to take detailed readings of the inside over time as well as the outside (or just go to the NOAA / NWS Web site for your nearest airport). You should probably start by seeing how much the minimum cycle (from above) raised the temperature. Then you could leave it on a fixed setting for a few hours and see what happens to the internal temperature. A Kill-A-Watt meter would be helpful to ensure you're getting the heat you think you need.

(You could also try running Vented Cat on a 1-pound cylinder or BBQ tank and running the hose out a window)


If you don't have a van, you can do what I did last night: rent a U-Haul for $19.99 (plus mileage and tax, of course).

 

[SoulRaven]

A factory camper van usually comes with at least 20k BTU heaters, and being a frequent cold weather camper, I wouldn't want any less than that.

Since it doesn't appear to be UL approved, I would be very careful about running one of these without additional ventilation as well.

 

[ascii_man]

That's a good point Off Grid. But looking at similarly-sized vans, Roadtrek installs 16k BTU/h in the 190 Popular, so I agree 3000 BTU/h seems tiny.

But I believe that the 16,000 BTU/h is input power, rather than output power, and catalytic heaters are substantially more efficient. And it's more efficient than an unvented catalytic heater (e.g. a Wave) due to not requiring open windows. But that's why I was definitely planning on the large unit (5200 BTU/h), and possibly more than one.

I asked about the UL listing, and he said that it was certified to a different standard back when they were being actively manufactured. I was planning to set up a CO and propane detector wired to an electric propane cutoff valve (as well as an alarm) as an additional layer of safety.

 

[ascii_man]

But on the other hand, several esteemed posters have reported excellent results with Wave 3 (3000 BTU/h) heaters.

On the third hand, http://www.builditsolar.com/References/Calculators/VanHeatLoss/VanHeatLoss.htm estimates that insulating a ProMaster reduces heat loss at a 38 degF delta from 11293 BTU/h to 2410 BTU/h. I'm not really sure if this reflects real-world measurements, nor how a typical high-top conversion van would compare to his ProMaster.

If his calculations are accurate, then 3000 BTU/h can maintain only a 47 deg F (26 degC) difference with insulation (the larger heater could maintain 82 degF or 46 degC). Without insulation, the small heater is only good for 10 degF (6 degC).

So at this point, without testing myself on a representative van, I basically have no clue. If anybody has a digital thermometer and a mid-top or high-top conversion van, I'd gladly walk you through the experiment.

 

[SoulRaven]

BTU stands for British Thermal Units, and refers to heat output, not input.

 

[ascii_man]

BTU stands for British Thermal Units, and refers to heat output, not input.

British Thermal Units (per hour), and often refers to input heat, as seen on page 4 of this Suburban service manual:
http://www.bdub.net/manuals/Suburban_Service_Manual.pdf

 

[Gideon33w]

As far as sizing I would look at all the people using the ceramic catalyst Buddy heaters. 

The standard size model is 4,000btu on low and 9,000 on high though the designs are unvented. 

For sizing concerns I can tell you that a heater of that size can drive you right out of a small space even with ambient temps at freezing and startup temps at or below 50. Within a well insulated van you would only want to run it in bursts.

Food for thought.

 

[ascii_man]

As far as sizing I would look at all the people using the ceramic catalyst Buddy heaters. 

The standard size model is 4,000btu on low and 9,000 on high though the designs are unvented. 

For sizing concerns I can tell you that a heater of that size can drive you right out of a small space even with ambient temps at freezing and startup temps at or below 50. Within a well insulated van you would only want to run it in bursts.

Food for thought.

Well that's exactly the point: the Vented Cat heaters have a singe power setting (3000 BTU/h or 5200BTU/h) and run on a thermostat, but have some sort of a minimum "burst", and I'm having trouble getting hard numbers from the manufacturer on what that minimum "burst" is. But at the other end of the spectrum, last night's low was 1 degF, and I would like to visit places which are even colder, so I don't know if the 5200 BTU/h version will be powerful enough. Obviously I can take some drop in colder weather, but I was pretty cold at 20 degF in a Gander Mountain "zero degree" bag. Plus I might have a small sink, so I'd like to keep everything at least above freezing (and as a practical matter, once I've acclimated to winter weather, temperatures around freezing don't feel all that cold to me).

Now with regard to insulation, I was hoping to keep my build minimal and reversible, but my experiment with an uninsulated U-Haul was that it was pretty noisy, so I would want to insulate for sound more than for heat. But I'm not sure how practical that is.

So that's why I'm hoping someone can run one of these and quantify the minimum "burst" as well as the actual heat loss from a van. Really, the former is more important: as long as the minimum burst isn't too much, more power is better. Also, assuming 75% efficiency on a 16,000 BTU/h input, 10 minutes of 5200 BTU/h output is equivalent to a little over 4 minutes of a more powerful furnace; I'm pretty sure the forced air furnaces also have a minimum cycle time.

PS; this would make a great YouTube video: put a thermostat inside and run the heater for its minimum cycle (startup, minimum run, cool-down) and the YouTube counter would show the exact times. I'm sure I've invested 100x the time in research that it would take to do an actual video.

 

[SoulRaven]

British Thermal Units (per hour), and often refers to input heat, as seen on page 4 of this Suburban service manual:
http://www.bdub.net/manuals/Suburban_Service_Manual.pdf

Sorry to disagree, but you're not putting heat into a furnace or heater.  You are putting energy into it, in the form of either fuel or electricity, it is the output that is heat, which is then measured in BTU's.

 

[ascii_man]

BTUs can be used to express energy also. The first sentence of the Wikipedia entry: "The British thermal unit (BTU or Btu) is a traditional unit of work equal to about 1055 joules."

And if you look at page 4 of the spec sheet, they clearly say Input.

In any any case, I agree with you that 5200 BTU/h is not all that much, and have some concerns about whether it would be sufficient.

 

[Gideon33w]

If running too short of a cycle is an issue than use the unit that will result in the longest cycles (ie the smaller unit). 

Besides the unit itself you should keep in mind that the more heat/cool cycles you perform the more condensation will form. 

We have successfully heated with the Buddy heater I mentioned as well as simply laying a cast iron griddle over the stove top burners and setting them as needed (5,000btu max each). That's with pretty sparse insulation but the body heat of 2 people.

At the end of the day I think you are substantially overestimating your heating needs. The smaller size is only relevent for dismissal if the net output of it running CONSTANTLY is still too small to heat the given space. Which is bullhonkey when it comes to heating anything considered a van.

 

[akrvbob]

I can tell you without any question I've heated an uninsulated cargo van at 14 degrees with a Little Buddy Heater. At those temperatures I think the Mr Buddy would be better.

I also think you are greatly overestimating your heating needs.
Bob

 

[ascii_man]

I can tell you without any question I've heated an uninsulated cargo van at 14 degrees with a Little Buddy Heater. At those temperatures I think the Mr Buddy would be better.

I also think you are greatly overestimating your heating needs.
Bob

Little Buddy is 3800 BTU/h in 14 degF. You recommend the 4000/9000 BTU/h Portable Buddy, and I'm talking about colder temperatures (0 degF) with only 5200 BTU/h, hence my concerns.

 

[Gideon33w]

He was talking about a raw cargo van. No insulation or panelling means direct induction cooling of the interior as the ambient air temps cool the outer skin. Simultaneously wicking away the sub 4,000btus he was generating.

Why don't you just take ten minutes and read through the section here on cooling/heating? You will find plenty of examples of setups and obviously the people posting about them didn't freeze to death.

Many people have a very simply insulated van and run the standard Mr Buddy heater. 4,000 btu low and 9,000 btu high. Pretty much everyone agrees that it is much more than enough heat. Furthermore, these are unvented units which means that they are being ran while wasting tons of heat through ventilation. They also lack fans to circulate the hot air. Still plenty of heat and typically only ran for a few minutes at a time. 

Keep in mind, heating is not on/off like a lightbulb. 3,000btu constant output for an hour is the same as 9,000btu output for 20 minutes and then off for the next 40 minutes.

 

[ascii_man]

Gideon33w, I definitely am listening. The problem is that the largest Vented Cat, 5200 BTU, is only about half the Portable Buddy on high, and it's one-speed.

But I got some clarification today on the minimum cycle: it really is NOT 10 minutes of heating. So I'm not concerned about overshoot, and will choose the larger heater and hope it is sufficient.

 

[akrvbob]

Little Buddy is 3800 BTU/h in 14 degF.  You recommend the 4000/9000 BTU/h Portable Buddy, and I'm talking about colder temperatures (0 degF) with only 5200 BTU/h, hence my concerns.

Have you insulated your van? If you insulate your van it will be fine. The little one worked for me at 14 degrees but with zero insulation.


If I insulated the van it would be fine.

The reason I recommended the regular Buddy is it has the 9000 setting, that should solve your problems and save you a bunch of money.
Bob

 

[Gideon33w]

Should be roughly 300 cubic feet of air space in something the size of a Chevy Express. The human body produces about 340btu. That leaves 5,000btu to raise the temp one degree F per minute. In other words, if your van interior matched the ambient temp of 0F then it would take 1 hour to raise the temp all the way to 60F with the heater on the whole time. Once 60F is achieved it will only take a small fraction of that runtime to maintain that temperature.

 

[SoulRaven]

Generally speaking, I am a real world test kind of a guy. I would take a double burner camp stove, most of them are about 10k BTU per burner that I've had. Crack each front window 2 inches, fire up both burners full blast, and see how long it takes to heat things up to where you want them.

By doing this you will have a base figure to start with, that with simple math you can CORRECTLY figure out your needs.