More efficient propane furnace

[howardwheeler]

I have a fair-sized fifth wheel and am often surprised at both the propane usage and 12v power the furnace consumes. It is 18 years old but works good and is clean (no dirt dauber nests and so on). Has anyone come out with a more efficient furnace that big over the years? I can live with this one but it sure would be nice to have a more efficient unit.

[Bobbo]

Study by the Consumer Products Safety Commission

Relevant section of posted study:

CPSC study wrote:
CO Emissions
When the catalytic heater was operated at the test conditions specified in the standard for infrared
radiant camp heaters (ANSI Z21.63), the steady state CO concentration ranged from 67 ppm to 109 ppm.
Steady state was achieved in approximately 2 to 6 hours, depending on the air exchange rate. Since the
CO concentration in the chamber exceeded 100 ppm during several of the tests, the catalytic heater would
not comply with the CO requirement ANSI Z21.63 (2000). Assuming a limited exposure time of up to
6.5 hours at these CO concentrations, the catalytic heater does not appear to pose a serious CO hazard to
healthy adults when the CO concentration is considered by itself. When the CO emissions from the
catalytic camp heater are compared to those of a typical radiant camp heater, the catalytic heater
generated much less CO (Tucholski, 2002).
Unlike the standard for infrared radiant camp heaters that limits the CO concentration to 100 ppm
throughout the entire test, the current draft of the voluntary standard for portable catalytic camp heaters
(ANSI Z21.62-draft) only limits the CO concentration at two specific O2 concentrations. At an O2
concentration of 19.4 percent, the CO concentration cannot exceed 35 ppm, and at an O2 concentration of
15.1 percent, the CO cannot exceed 250 ppm. When the catalytic heater was tested in a closed room
(ACH ~ 0), the CO concentration in the chamber ranged from 24 ppm to 27 ppm at an O2 concentration of
19.4 percent. During the same tests, the CO concentrations ranged from 101 ppm to 110 ppm at an O2
concentration of 15.1 percent.
Although the catalytic heater would meet the CO emission requirement being proposed in the
new standard for catalytic camp heaters, CPSC staff does not agree with allowing the CO concentration to
reach 250 ppm in a closed room. Sustained exposure to a CO concentration of 250 ppm for 6 to 7 hours
could pose a serious CO hazard to healthy adults. Depending on an exposed individual’s activity level,
this could result in carboxyhemoglobin levels ranging from 24 to 29 percent, where severe headache,
nausea, vomiting and mental confusion could be expected.1
Instead, CPSC staff recommends that the CO
concentration be limited to 100 ppm, the same limit as that specified in the standard for infrared radiant
camp heaters. Camping heaters that meet the CO emissions requirement in ANSI Z21.63 (2000) should
not pose a CO poisoning threat to healthy consumers when the heaters are brought into enclosed spaces.

Synopsis: Risk is small, but not non-existant. We all have different risk tolerances.

[valhalla360]

prichardson wrote:
As mentioned earlier in this tread; a big part of the equation is the lack of insulation in the average RV. The average home has at R values of at least 6 in walls and 13 in the ceiling and HVAC ducts are insulated. Most RVs have little if any insulation in walls and ceiling and none on the undersized duct work.

This along with the majority of RVs not being used in really cold weather. By the time the lows get around 40F, most people are putting them to bed for the winter, so there isn't much to gain for the vast majority of people, so it's a hard sell to install a more expensive unit.

A more efficient air/con would be a much easier sell.

[Skibane]

pianotuna wrote:

Skibane wrote:


Really?

A carbon monoxide death is so common that it no longer gets reported?

In what country? Bangladesh? Mongolia?

In Canada and Saskatchewan.

I realize that Canada has cultivated a particular penchant for suppressing freedom of speech and media lately...

...but Google covers an area considerably bigger than America's Hat.

Where (anywhere in the world!) are there ANY news accounts of an RVer being killed by CO from a catalytic heater?

Anywhere?

At any date since the beginning of time?

[dieseltruckdriv]

pianotuna wrote:
dieseltruckdriver,

What make and model do you have?

The study I saw is quite ancient now.

What make and model of what are you asking? The CO detector or catalytic heater? I will make sure and include you when I do the test I spoke of.

[pianotuna]

dieseltruckdriver,

What make and model do you have?

The study I saw is quite ancient now.

[pianotuna]

Skibane wrote:


Really?

A carbon monoxide death is so common that it no longer gets reported?

In what country? Bangladesh? Mongolia?

In Canada and Saskatchewan.

I'll not be answering you again.

-30-

[dieseltruckdriv]

pianotuna wrote:

Skibane wrote:

You'd think that if there was a significant danger associated with catalytic heaters, there would be at least one published news story about some hapless RVer being killed by one.

It happens frequently enough that it is no longer newsworthy.

A blue flame heater may self extinguish before oxygen levels become too low to support life. A catalytic heater will quite merrily continue to work at extremely low O2 levels. Of course, as O2 goes down, CO increases.

There are many through the wall heaters that do not need electricity. They cost a little more, but are MUCH safer.

You may do as you wish Skibanel, and I'll continue to NOT use an unvented combustion heater while sleeping.

Hmmm, you gave me something to check. I am going to test at what O2 level my catalytic heater stops working. The literature says it will not go below a safe O2 level, but I can check mine. This is something I always point out, it is mine, not all of them.

I will build a small enclosure in my unattached garage and see at what O2 level it self extinguishes. Actually I think it will do it outside, in case of fire danger. Oh, by the way, I was also a deputy chief on our fire department before I was forced to retire for medical reasons. The test I have in mind just screams fire danger, but that is the best way to test for CO. 😉

[Skibane]

msmith1.wa wrote:
There is this thing called Google use for yourself and don't expect other's to do it for you.

I have used it - and can't find any examples of RVers being killed by CO from catalytic heaters.

If anyone else has found anything, please post it.

Camco bought US Catalytic (the original manufacturer of Olympian catalytic heaters) almost 20 years ago. Before that, US Catalytic had been manufacturing essentially identical products since at least the early 1990's.

If this was an unsafe design, it would seem that at some point over a 30+ year time span, a lawsuit would have ended its production.

pianotuna wrote:
It happens frequently enough that it is no longer newsworthy.

Really?

A carbon monoxide death is so common that it no longer gets reported?

In what country? Bangladesh? Mongolia?

[pianotuna]

Skibane wrote:

You'd think that if there was a significant danger associated with catalytic heaters, there would be at least one published news story about some hapless RVer being killed by one.

It happens frequently enough that it is no longer newsworthy.

A blue flame heater may self extinguish before oxygen levels become too low to support life. A catalytic heater will quite merrily continue to work at extremely low O2 levels. Of course, as O2 goes down, CO increases.

There are many through the wall heaters that do not need electricity. They cost a little more, but are MUCH safer.

You may do as you wish Skibanel, and I'll continue to NOT use an unvented combustion heater while sleeping.

[howardwheeler]

I agree about the slim insulation. A few years back I did secure below the entire underbelly one inch solid sheet urethane foam sealed in place by polyurethane spray foam. So the floor ducting is now much better than factory, but I fully realize it’s not up to residential specs. There’s not a lot more that I can do. I have installed full acrylic storm windows throughout that help some with temps but mostly to help with sweating in the cold. It just seems that the current furnaces ought to have progressed in efficiency but I don’t think they have. These old Alpenlites are generally considered to be well made, but again, I do realize they aren’t super insulated. It does have, relatively speaking, okay roof foam insulation.

[jkwilson]

howardwheeler wrote:
I know my camper isn’t insulated like a house, but the furnaces in RVs seem unusually inefficient, even crude. It does seem like someone would improve on what is essentially thirty year old technology. My unit is in fact 18 years old. And it was no state of the art furnace when new. Someone mentioned a two stage unit. That sounds very interesting. A better heat exchanger seems possible. I know two stage units in houses do have greater efficiency. Anyway, every time I get home from boondocking I complain to myself and just thought I’d share my complaint. Does anyone know someone who makes a two stage furnace?

I think you dismiss too readily how badly insulated most are. The space between the floor and the belly is often heated space, effectively serving as duct work, Over the years, major leaks can develop causing your furnace to pull in outside air and expel heated air back outside. A couple of hours with silicon sealer and underbelly tape can make a big difference in the performance of your furnace. Probably more than you’ll ever find by upgrading to a more efficient burner.

[dieseltruckdriv]

Piano, I tried to buy one of those when I first remember you mentioning that story of your daughter, but that company is NOT serious about selling anything. I tried for nearly a year with multiple emails and phone calls going to voice mail with no reply. This was over four years ago and I am still waiting for a reply. I am not going to fight with someone to get them to take my money.

I did the research and the catalytic heaters are safe. I have also tested mine, as well as my CO detector to ensure it's proper operation. I know almost no one can do this, but I actually do the CO testing and calibrating of CO monitors at work. I have also tested the output exhaust of my Honda EU2000i generators, and I am comfortable running them all night. Since I have added solar I don't need to anymore, but it is not something I worry about. I did check the accuracy of my Kidde CO sensor with a readout and I found mine to be accurate. When I get another one, I will have to test it to trust it, but right now I can test them with a good degree of accuracy.

All of that being said, I trust mine because I can test and verify them. But I also do run at least two CO detectors in an RV.
Piano, I pay great attention to your knowledge of batteries, and I understand why you judge unvented heaters, but CO is a product of incomplete combustion and catalytic heaters are very efficient.

[handsome51]

I use the furnace to warm my 5th wheel up. Then I use electric heaters to maintain the temperature in the 5th wheel. That way you don't use all the propane up. Been doing that for 15 years now.

[3_tons]

No doubt CO is a real hazard, but it kinda makes me wonder whether some folks forget to open up a vent when running the oven or stove??…Recognizing and mitigating the hazard is what counts most…

3 tons