box with external vent for catalytic heater?

[dower.bill]

I have been hesitant to put a catalytic heater (wave 6, e.g.) in my Avion (25' 1985) due to concerns about breathing the oxidation products. Has anyone tried to put a 'duct free' radiant heater in a box with a glass front, or under a hood? Either approach would involve providing an external vent and likely an external air supply. I see you can get a 24" x 18" sheet of high temp tolerant glass; some bent aluminum sheet metal could be used. It would not have to be completely air tight, just able to capture and vent most of the combustion products. I welcome your thoughts, ideas, and experience. I also understand that this may trigger some strongly held beliefs, which may not all be in agreement, so I am grateful for the gentle and reasonable tone that is part of any discussion on this site.

[SuperTrouper]

http://www.walmart.com/ip/30194018?w...052057&veh=sem

[markdoane]

I would be less concerned about inhaling combustion products (like carbon monoxide) and more concerned about oxygen depletion.
I don't know if that would change your box design or not.

[BigAl]

Check out PlatCat heater online.
Al

[JCWDCW]

If you just want to take off the chill then I wouldn't be worrying about some CO2, water vapor and a bit of CO. I set the bedroom fan to run 'in' and open the living area vent about 1/2. That is more than enough to meet the standard for 22 sq in for passive vent area. I would never go to sleep with the catalytic running, but I routinely use it while sitting watching TV or making meals on a cool day. Personally I can't stand the noise of the furnace and it has such a large dead band in the thermostat that it is useless for anything but heating the trailer first thing in the morning
JCW

[hahnstead]

I have catalytic heaters in both of my trailers. Never worry about letting them run all night while I'm sleeping. I sometimes forget to crack a window. Just about any trailer is drafty enough that one doesn't necessarily need to open a vent, but opening the bathroom vent is a good idea, I suppose.

[HowieE]

In the history of Airstreaming there has to have been thousands of Cat heater used. Mine for close to 20 years.While I do not leave it on while sleeping I have never heard of a problem from those that do.

Enclosing and venting this type of heater has got to reduce is effectiveness by more than 50%. These heater have a convective and radiant component. The glass would slash the radiant and the vent would exhaust most of the convective heat.

[kdickinson]

If you use the trailer at lower altitudes you can check out the marine LP heaters that boat owners install for overnight trips - but apparently don't work well above about 1500-2000' above sea level. They don't require electricity to run and from what I understand they do a really good job as a back up heat source when you are not plugged in. Dickinson (no relation) makes some models that look nice and I heard about them on the forum from people that are installing them in new Airstreams. They do require external venting and of course a source of fuel. We learned the hard way that, if you camp in the cold, you really do need an alternate heat source when camping even if you think you have electric. Having shore power may not always be the case. Power goes out at trailer parks too. And other things can happen like the time our inverter went out on us on a cold night (low teens F) in New Mexico and the furnace fan ran the battery down within 30 minutes. We now carry a Camco catalytic heater as a back up. We have a quick connect off the furnace to supply LP and the extension LP hose is long enough to place the heater most anywhere in the trailer depending on where we are while using it.

[ijustlee]

How about buying one of the newer ones that come with a built in power exhaust and can be used with a thermostat? They use little current and they were supposed to re-start production on these units. I don't think you could go wrong with one of those Dickerson fireplaces either. I tried an unvented catalytic heater and loved the way it heated but I'm sure the amount of moisture it adds to the air would ruin an Airstream over time from the moisture condensing inside the walls. I never could decide where I was OK with putting a hole for a vent so I ended up just resigning myself to situations where I had the power to use electric heaters. I'm sure a good powerless venting system could be fabricated for a catalytic heater and would be worth the hassle if you wanted to do it, but I don't think a box enclosing the whole heater would work. You would be better off with a fireplace type. I thought of fabricating a hood with a 2" chimney that mounted on my catalytic heater and exited out the roof thinking that would make a self powered vent but it would probably need a drain setup for condensation at least until the chimney warmed up. Never did that because I like to keep the bedroom above 45 degrees while I sleep so I had put an electric outlet controlled by a thermastat in the bedroom before I even had the catalytic heater. Quiet heat is a good thing!

[dower.bill]

So I pulled the forced air furnace out of my 25' 1986 Avion with center bath, because I almost always boondock, and that furnace used too much battery.

I put a 'wave 3' high on the wall in the bathroom, near the ceiling vent. If I want a shower on a cold day, I open the vent, and turn on the Wave 3. The exhaust gasses go out along with a lot of moist air. The heater is enough to keep that little room nice and warm.

Photo ##433

For the living area, I put a hole in the wall where "the space behind" is where the burner for the fridge is. That is of course vented and well shielded from wind. Then I mounted a copper pipe (1 1/4") to duct the exhaust gasses out to that space.

I mounted a Wave 6 (on a slight angle to face the center of the room) on that wall. I folded some aluminum roofing flashing into a hood that captures the exhaust gasses, and holds them while the cool just a bit, then allows them to exit the cabin into the duct, and go behind the fridge.


I hope this series of photos provides enough to see what I did. It keeps the trailer pretty warm on cold days, and I have the CO detector to be sure I know if something is not keeping me safe.

[rugjenkins]

The pics did not post here

[dower.bill]

views of adding DIY ducted Catalytic heater and vent

[dower.bill]

second set of photos of Cat heater with DIY duct

[dower.bill]

photo inside heater cabinet, showing manifold for propane

Photo of upper wall in Bathroom, with ceiling exhaust fan, and wave 3 cat heater

[xrvr]

That is cool!!!

[djslf]

Hi. I was thinking of doing the same thing with my Wave 6 as what you did. I camp in cold weather and start to have condensation problems when the temps get down into the 20's. I've been looking into the Plat Cat vented heater, but can't get a reply from the company. It looks like the same idea as what you came up with, but uses a small fan to draw the exhaust gases and moisture out. Rather than replace my Wave 6, if I can modify it like your's it would save several hundred dollars. So, I'm wondering if you could comment on how well it removes moisture. Have you camped in temps in the low 20's? Did you ever try the Wave 6 before your modification and have a before/after comparison?
Thanks!

[dower.bill]

Hi DJSLF,

My experience suggests that the overriding reason to extract the exhaust from the catalytic heater is to avoid the twin issues of Carbon Monoxide buildup, and oxygen depletion (the latter is typically only a concern at higher elevations).

I put the modifications in when I installed the heaters, so I cannot talk about whether they impacted the condensation.

My issues with condensation are more related to cooking, showers, and wet clothes drying. Each of these puts so much moisture in the air that I believe the additional contributions from the heaters would be inconsequential.

Anything that takes indoor air and puts it outdoors (and vice versa) is going to have about the same impact on indoor humidity, and the more air, the greater the impact.

The use of a 1 1/4" copper pipe (salvaged from a pool heater input/output pipe) arranged with a mostly horizontal run of 6" inside the cabin, combined with the aluminum header, means that I extract an additional portion of heat from the exhaust gasses. I even have salvaged computer power supply fan that blows air over the top of the copper pipe, to get as much heat out as I can. I don't use that fan on moderate days, but the really cold ones, I think it helps.

If you are going to be below 25F, you might want to think about what you will do to keep the pipes and reservoirs from freezing in the undercarriage. The squirrel cage heater (that I removed) also helped by pushing warm air through minimally insulated metal ducting at floor level, which was useful for the lower part of the unit. My rig does not address that issue. I have been in Yellowstone in the snow, but I did not stay below freezing for more than 36 hours, and then I got out to lower elevations and higher temperatures, so I did not worry too much about frozen pipes. If you will be colder than that, for longer than that, you may need to consider your pipes and valves, and what happens if they freeze.

And depending on your need for comfort and the size of your rig, you might want the next size up, as well. My 6 works pretty hard to keep my 25' avion warm enough for my wife.


Best wishes.

[nevermoor]

Greetings. Does anyone know if Platcat heaters are still in business? I have emailed them and not heard in over 1 week.

Beyond that, are there any vented to the outside, catalytic heaters that any of you prefer? Many thanks.

diane

[djslf]

Hi Diane
I tried to reach Plat Cat back in 2018 and never got a reply so I assumed they were out of business. I had a non-vented Olympic Wave 6 heater and didn't like it. I was never comfortable running it without cracking a window and vent to make up for the oxygen that is consumed. In spite of doing that, I would get moisture buildup. Walls inside closets would get frosty, underside of mattress got wet and moldy. It would get too hot sometimes (no thermostat). I thought the Platcat would be the perfect answer. I eventually gave up and bought a Propex heater. It is vented. Forced air. Works great. Much quieter than the stock furnace. Thermostatically controlled. The downside is that it uses battery for the fan. It's about half the current draw of the stock furnace though. I didn't find any other passive vented catalytic heaters. Maybe someone can suggest one. Good luck.

[nevermoor]

i thought i replyed to you. sorry. i will check out the propex. thanks for the suggestion.

i have called 5 times the plat cat number on his website, and left a message with my number to please call. no response.

did your fan ever run your batteries down?

thanks again.
diane