Catalytic Heaters - Page 3 - Fiberglass RV


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Old 11-27-2007, 11:18 PM   #29
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PeterH, do you know that the altitude limitation is because of the ODS or is it because of the fact that gas burner orifices often need to be changed to correspond with changes in oxygen function at higher altitudes?
Hmmm. Here's what I know:

I don't understand ODS (oxygen depletion sensor) systems well, but I've read in other news groups that ODS systems are altitude sensitive and tend to read lower values as altitude increases, so they shut down the heater early or don't allow it to run at all. The troubleshooting FAQ on the official Mr. Heater (non-catalytic) website mentions problems with running their heater at altitude and attributes the problem to the ODS system. I haven't found this caution for systems without ODS sensors, so this part of the explanation sounds very likely.

The other half of the question, whether the gas orifice size needs to be adjusted to match changes in oxygen function at altitude . . . I would venture a guess that this isn't a safety issue for catalytic heaters. Platinum catalyst systems, as I mentioned earlier, will happily suck up every atom of oxygen they can get to as long as it is at operating temperature and the gas (propane) flow rate does not saturate the platinum catalyst and exceed the its ability to foster the propane through the reaction. Since atmospheric oxygen concentration at the various altitudes we can live at is pretty much constant at 21%, and because the regulators on our gas systems keep the pressure difference between the air outside and the low-pressure gas feed lines constant, I doubt the gas flow rate could saturate a catalytic heater unless it had problems running at lower altitudes as well. It would put out slightly less heat at altitude because the volume of propane gas put into the system gets throttled back at altitude.

--Peter
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Old 11-29-2007, 01:08 PM   #30
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I think the oxygen depletion "system" is a lot more primitive than some of us may be expecting. During a previous discussion I did some research and found that the ODS was just a temperature sensitive shutdown: as oxygen content decreases the combustion runs cooler, and so at some threshold temperature it gets shut off; this was documented for an appliance with a flame, but the same effect would work with a catalytic device. At higher elevations the same effect occurs (as a lower elevations with a low oxygen content), so the ODS shuts of a perfectly safe and otherwise functional burner.
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Old 11-29-2007, 08:34 PM   #31
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OK, this is making sense -- The ODS system fails safe when there is insufficient oxygen for combustion, be it from altitude effect or from lack of ventilation. One poster on another group put his ODS heater in a closet with a sensor from his oxygen meter (he's the kind of guy who has stuf like oxygen meters) and reported that the ODS shut down the heater well before there was insufficient O2 to be a health problem. I believe he ran the same tests on some cat heaters with equally safe result.

There may be more than one kind of ODS system:

http://www.amio2.com/sensors.html

FYI, here's what the manf of my Empire heater has to say in a FAQ:

QUOTE
Do vent-free heaters take all of the oxygen out of the room?
All products which burn gas and draw combustion air from the living space or "take oxygen" from that space, (Gas ranges are vent-free units). The owners manuals on our products and your local code official will inform about the need for make-up combustion air. A typical well-insulated home still has sufficient air movement to completely exchange indoor air for fresh outdoor air several times per hour. If this air exchange did not take place, normal human breathing would eventually take all the oxygen from that space. This normal air exchange provides more than enough make-up air for the vent-free heater. Vent-free heaters have an ODS or Oxygen Depletion Sensor which automatically shuts off the gas supply in the rare event that the oxygen level in the room falls to 18%. This is well above unsafe levels as established by ANSI (American National Standards Institute).

How much moisture is produced by the vent-free heater?
Vent-free units when used as supplemental heating devices generally do not add any more water to a living space than the bathroom shower does in a normal day. Specifically, for every 1,000 Btus, the vent-free unit will create 1 ounce of moisture per hour.
END QUOTE
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Old 12-01-2007, 06:25 PM   #32
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How much moisture is produced by the vent-free heater?
Vent-free units when used as supplemental heating devices generally do not add any more water to a living space than the bathroom shower does in a normal day. Specifically, for every 1,000 Btus, the vent-free unit will create 1 ounce of moisture per hour.
END QUOTE
Just did the water vapor calculation for burning one pound of propane, which is what a 3000btu catalytic heater burns in 8 hours. Burning one pound of propane creates 3/4 of a liter of water vapor; thats 1.05 oz of water per 1000 BTUs of heat per hour.

--Peter

NOTE: I corrected the above post after realizing that I used the wrong conversion factor for converting metric liquid volumes to fluid ounces. I used 40 oz of liquid per liter, which is wrong. There are about 34 fluid oz per liter. (40 is the rough conversion factor for inches to meters: 40 inches is slightly more than a meter.)
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Old 12-04-2007, 05:21 AM   #33
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After reading all the suggestions and spending a few hours on the computer yesterday, during our Nor'Easter, I think I am going to purchase:
http://ventedcatheater.com/index.html
I like the fact that it has a thermostat and is vented outside and it will fit in where the existing furnace is.
I have a warped mind that keeps on telling me that I will spend the $449.50 + shipping just to have it work like my old furnace did.
I know this is ridiculous but after spending almost $300 for what turned out to be having the shop take the furnace out and vacuum up dirt, because it never ran again, I'm a bit shy about taking out my wallet.
I know, I know, It'll be a new furnace......I.m neurotic....my wife says.
Anyway to all you smart people out there, I was reading on their ad and got to the part where it talked about Radiant heat.
A little over my head but the fact that it said there is no open flame really confused me.
Gerry the canoebuilder
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Old 12-04-2007, 09:04 AM   #34
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Gerry....... I like that cat heater you sent the link for because it will vent outside...... but what confuses me is the statement on that site which say "no windows need to be opened" because the gases are vented out.............. this unit needs to get oxygen from somewhere to burn and the chances of depleting the oxygen supply inside i think would be high without an open window......there was a post awhile back on this unit and it really looks like a good option (especially with the .5 amp draw on the vent fan).
There was also a post very recently (I think it was Gina or Donna) that they put an intake vent right in front of the heater on their Burro which was really a great idea that i would use
When they say no open flame that means that there is no flame burning that you can see......... it's like an orange glow across a screen (radiant) that glows to radiate heat........
I will save this link for future reference as this "MAY" be better than the olympia radiant heater (which does not vent outside)....i'm by far no expert with this and hopefully someone will chime in with more experience on this subject
Joe
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Old 12-05-2007, 03:31 AM   #35
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thanks JOE, It seems good to have made a dicision about what heater to go with after months of looking and wondering if this or that is what we need or should I keep throwing money into the 27 year old Duo-Therm.

Sent an E-Mail to the company asking these same questions and got a nice response, in layman term, about how this radiant heat works:

..."No flame, the heat is radiant and warms you like the sun does. Thats why there is no motor to blow air
around the room. The heat is created because of the catalytic mat you see on the front of the heater. Gas
goes into the back of the mat and there of course is oxygen on the front of the mat from the air.
The catalytic mat is a high temperature ceramic insulation which has a catalytic solution finely deposited
all over the fibers on the catalytic mat.
The catalyst SPEEDS up the meeting of the gas and the oxygen a million times faster than it would normally
occur ---this releases heat without flame. This cracks the gas molecules and results in radiant heat, it
is actually a chemical reaction"

Also my question about the air in trailer was answered in his response to E-Mail:

..."There is no flash, no flame. The motor in the heater is there strictly to remove the water vapor and CO2
which are created when combustion occurs. It also serves to bring in fresh air through infiltration--via cracks around windows & doors-- because it is moving the exhaust air out. If air is going out of the RV, then it must surely be coming in"

I know I do have cracks here and there but I am sure it would not be enough so I do plan to install a fresh air inlet in the same fashion as Gina had in her trailer.
Lead time is about 12 weeks and since Lady-Bug is in hibernation now I do not think I will order just yet.
Gotta find out about warrentees also.
Gerry the Canoebuilder
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Old 12-06-2007, 02:26 AM   #36
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I know I do have cracks here and there but I am sure it would not be enough so I do plan to install a fresh air inlet in the same fashion as Gina had in her trailer.
Lead time is about 12 weeks and since Lady-Bug is in hibernation now I do not think I will order just yet.
Gotta find out about warrentees also.
Gerry the Canoebuilder
The Plat Cat brand heaters have a built in fan with their own air intake and exhaust ports to the outside of the trailer. It's their big selling point, but there are advantages and disadvantages to the system.

From my point of view their big advantages are that they don't dump water vapor (a byproduct of burning propane) into the air inside my trailer and they have a thermostat control. (Given the low oxygen consumption of a catalytic heater I'm not really worried about oxygen depletion, but yes, the Plat Cat heaters vent fresh air in and carbon dioxide and water vapor out. )

The disadvantage of the Plat Cat is it requires battery power. Not a lot, but some, so if the battery goes dead . . . it's going to get cold. (I assume some of the heat it puts out is vented out with the combustion by-products, too, but I expect the loss there would be similar or even less than having vents or windows open.)

So the trade off is thermostat-control and drain on the battery vs no battery power required for an Olympic Wave heater. As long as you're OK with the battery thing the Plat Cat looks like a good choice.

--Peter
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Old 12-06-2007, 05:44 AM   #37
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So the trade off is thermostat-control and drain on the battery vs no battery power required for an Olympic Wave heater. As long as you're OK with the battery thing the Plat Cat looks like a good choice.

--Peter

Peter, I assume you have looked at the add for the PlatCat....
In your opinion, what would use more power, this new heater or my old Duo-Therm?
When the Duo-Therm did work we could go a week on Battery power because we only used the heat in the night with thermostate set at 68.
Also we do not do any hard core winter camping and only expect to be out there in temps that may go into the low 40's
I do not know what kind of draw the Duo-Therm has but I am sure it has to less then the PlatCat.
Sure the initial draw is high but we will not have the pilot to worry about.
Gerry the Canoebuilder
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Old 12-06-2007, 10:09 AM   #38
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that is good news knowing that the plat cat vents air in and exhaust out too........... with a .5 amp draw (the same as my single fluorescent tube light)that is very good compared to my 3.0 amp draw on my old (1994) furnace.
wonder if it would still work with no battery? probably not because of the thermostat and the ignition to start it up?
Gerry........ when you do get that heater hooked up in the spring please let us all know how you like it....looks like a real good choice..
Joe
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Old 12-06-2007, 07:19 PM   #39
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Gerry -- No idea about the Duo-Therm. Can't find stats online and don't have a unit I can meter.

Joe -- If I understand the Plat Cat correctly it requires power for ignition (no pilot) and the fan.
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Old 12-06-2007, 07:26 PM   #40
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If I understand the Plat Cat correctly it requires power for ignition (no pilot) and the fan
Yes, it does. It's one of the reasons I took mine out. It did not seem quite as power friendly as the specs printed here. Tho I never actually measured the draw with mine, I could only get a night out of it before my battery was not up to the job. Even with a fresh charge, I would get a "Brown out" when it was running.

I also had to light it manually (With a lighter) when the power was low. The fan would still run, but there wasn't enough poop to spark. And that made the thermostat useless. I had to get up to light it in the middle of the nite at times.

Wish I could figure out how to do that with my furnace.
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Old 12-08-2007, 06:01 AM   #41
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Yes, it does. It's one of the reasons I took mine out. It did not seem quite as power friendly as the specs printed here. Tho I never actually measured the draw with mine, I could only get a night out of it before my battery was not up to the job. Even with a fresh charge, I would get a "Brown out" when it was running.

I also had to light it manually (With a lighter) when the power was low. The fan would still run, but there wasn't enough poop to spark. And that made the thermostat useless. I had to get up to light it in the middle of the nite at times.

Wish I could figure out how to do that with my furnace.

Interesting...Not knowing how much you use the battery while on trips I can not worry too much yet. Although you got me thinking bad thoughts now.
Do you have just one battery? I do.....Does your fridge run on propane? Mine does. do you sit in the trailer alot, and use interior lights? We use our lights very little?
I appriciate your input but unless we do buy one and try it there will be no way of knowing I guess if it will will work under the conditions we camp in.
I know after this last fall when temps got down to the 30's and we only had the pilot light in the furnace to keep warm by (and by the way it keeps the 13ft Lady-Bug tolorable) if we do go off and it gets real cold we will survive.
Wanna sell your old one to me...?
Gerry the canoebuilder
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Old 12-08-2007, 07:03 PM   #42
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I have a group 24 battery. I also have all LED or cold cathode lighting, and for boondocking, I had (In the 13) hand water pumps and back ups for all standard items requiring 12v. I always run my fridge on propane unless I have 120v power available. Same with my incandescant lights. My usage for lights is conservative, I only have on what I need, when I need it just like at home.

I intend to switch to hand pumps in my 17, just haven't gotten around to it.

Sorry! I gave th heater away a LONG time ago.

I noted wally world has group 27 marine and RV batteries on sale for 56 bucks. I will be picking one up soon!
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