# What size mesh is the screen in a catalytic propane portable heater?



## drizler (Dec 22, 2018)

Ive got one of those grand old Coleman single hood heaters .    The kind that clamps on top of a barbecue bottle and has 3 settings on a dial 10-40k BTU’s.     It’s been warming my shop spot heating where needed for 20 years now.    The screened burn chamber started cracking and rusting out long ago but finally gave up the ghost.     It still works without it but definitely does burn nicer and light easier with it in place.    
      I hate the new styles and replacement screens are long ago NLA.     Since it’s simplistic I’m just going to make another.     I assume it’s stainless steel but not sure what mesh to buy as I’ll have to order it rather than buy locally .     I doubt the exact size matters much as it runs ok completely naked.     100 and 200 mesh is both cheap and available.    What’s better or is something else better yet??


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## wooduser (Dec 23, 2018)

wooduser said:


> I have NO idea!



Unfortunately,  this post illustrates the hazards of using unvented equipment.

I dont know the model number of this heater,  but I wouldn;t be at all surprised if the manufacturer recommended it's use only outdoors.

Indoors,  any defect in the burner can cause large amounts of carbon monoxide gas to fill the space in which it's used,  causing a real hazard to occupants.

For similar reasons,  using the equipment while the burner screen is worn out is also a hazard,  and the idea of doctoring it up with a home brew screen a bad idea.

With unvented equipment,  my recommendation is that anyone using the equipment should READ,  UNDERSTAND and FOLLOW   ALL the warnings give by the manufacturer.  Unfortunately,  in my years as a gas appliance repairman,  I have never yet met a single user of unvented equipment who met that standard of operation.  .  For this reason,  and because the margin of safety with this equipment is so narrow,  I recommend against operating any such equipment indoors.

The hazard of carbon monoxide poisoning is real,  and can occur at any time.  In my opinion,  the risks aren't worth it.

Here's a link to a Coleman warning notice describing the hazards of using the kind of heater you have indoors:

http://campsafe.org/2014/02/07/hello-world-2/

In my view,  the smart move is to junk your 20 year old unvented heater and to buy some kind of vented heating equipment.  Pretty much any kind or variety will be far safer than what you have.


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## drizler (Dec 29, 2018)

Well, I will just Be disregarding all that Uber Safety fluff and corporate legalese CYA.    I use this in a drafty garage as spot heating and believe me CO poisoning just isn’t in the mix.      That’s what I love about this rig.    It’s smaller and tosses a lot more heat if I want it.    There’s no safety concerns whatsoever if used with a trace of common sense.     


Sent from my iPad using Tapatalk


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## KeithO (Jan 4, 2019)

If the mesh that you get ends up being too open, tou can always add additional layers of mesh to reduce the sensitivity to drafts.  Alternately, get some different densities and sart with the tightest and see how it works.


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## wooduser (Jan 8, 2019)

drizler said:


> . I use this in a drafty garage as spot heating and believe me CO poisoning just isn’t in the mix.



<<The pilot comes on fine, clicks away for 30 seconds or so and then finally gives in.


Actually,  I don't believe you,  because you lack the experience to understand the hazard to which you are exposing other people.

I have seen people sick with carbon monoxide poisoning from a small dirty range burner pilot burner.

Believe me when I tell you that a 30,000 BTU gas burner that's not burning properly can put you and anyone else in your garage out of business.


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## KeithO (Jan 10, 2019)

Some years ago I built myself a ground blind "hunting shack" in which I could wait out coyotes that were raiding the sheep herd on the farm of a friend.  Usually arrive at least an hour before dawn and if there is to be any activity it is usually just as the sky lightens but before the sun is actually out.  Twilight, is probably the correct description...    The blind was 4x8ft floor plan and the peak of the roof 8ft high so that it was efficient at using plywood sheets.   The 4 foot dimension was really too narrow in hindsight, I wont do that again...

Initially it had 3 sliding windows, single pane. The walls were built using 2x4 studs laid on their side so the "core" of the walls was 1.5" thick.  It had 1/2" plywood outside, rigid foam insulation 1.5" thick and 1/4" plywood on the inside.  The roof was also insulated with 1.5" of rigid foam.    Initially I had a "Mr Buddy" catalytic heater running off a 20lb cylinder, later I went up to a 30lb cylinder for longer times between filling.   The door was hand made without insulation, 2 layers of 1/2" plywood.

Suffice to say that the water vapor produced by the ventless heater had the windows covered with a layer of frost on the inside, long before the space was comfortable, and then I had to wait until the frost thawed, before I could use a towel to wipe the condensation off the window to peer outside.   This obviously was completely useless at its intended purpose.   Also, after a bit of snow and the first thaw, all the window channels were full of ice which meant that the windows could not slide to open.   Also pretty useless when you needed to poke the rifle barrel outside to shoot the insurgent coyotes as they launched an attack.

So then came version 2 of the shack, out came the sliding windows, to be replaced by double pane tilting windows (casement windows I believe).  They were a bit of a hassle because the tilt mechanism wouldnt hold them in position so I had to add some paracord ties to hook onto the latch arms to hold them in position if I needed the window open.   The Mr Buddy heater was replaced with a Marine Dickinson propane heater which was vented (or so I thought)....






The way the product picture is taken as well as the fact that this is intended as a heater on a boat, would make you think that it has a sealed combustion system.  As it turns out, it is basically built like a single burner heater like used for camping, with a cone positioned above the burner to capture the combustion products and a woefully inadequate 1" flue pipe...   Anyway, I digress...

The combination of double pane glass and somewhat vented heater did mean that the windows were no longer frosted up and only minimal condensation ocurred on the inside of the glass.   So the changes did resolve the issues I set out to cure.    This was in a space that had a volume of less than 256 cu ft and it was sealed up pretty tight excluding the B vent style flashing poking through the roof into which I ran the 1" flue pipe.

Now this is a rambling kind of post which doesnt seem to be making any point, so here it is:   Neither the Buddy heater, nor the inadequately vented Dickinson heater produced any sort of safety problem, headaches or otherwise.   I will say that the vented heater was a much more functional solution.

Now if I need to work on my truck in the barn, I am usually working with a diesel powered torpedo heater about 6 feet away and I would just be one of millions of northeners who have to do this in order to get work done when it is sub freezing outside.  I dont think anyone has invented a portable, relocatable vented heater yet. so we just do what we need to do and as Mike Rowe says, perhaps its safety second and not safety first....


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## wooduser (Jan 10, 2019)

KeithO said:


> The way the product picture is taken as well as the fact that this is intended as a heater on a boat, would make you think that it has a sealed combustion system. As it turns out, it is basically built like a single burner heater like used for camping, with a cone positioned above the burner to capture the combustion products and a woefully inadequate 1" flue pipe...




A gravity vented gas appliance like a furnace or water heater commonly has a "draft diverter'  above the appliance which is a break in the venting system.    If the chimney gets plugged up,  the combustion gasses from the appliance will spill into the room where the appliance is located.

That may sound bad,  and  an appliance that isn't venting needs to have the vent repaired so that it does vent.

But consider what happens if the draft diverter isn't there and the appliance doesn't vent:  now you don;t have fresh air for the gas to burn,  so you start producing massive amounts of carbon monoxide which look for a way to escape into the room air.  That will kill people a lot more reliably that blocked vent and a draft diverter.  

Your buddy heater with the 1" vent doesn't look like it has a draft diverter,  and it looks like the 1" vent may be too small to let enough fresh air in to burn the gas reliably.  So it looks like you are at risk for making a lot of CO with it.  

Then again,  perhaps I'm wrong.


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## KeithO (Jan 10, 2019)

The pic is not the buddy heater, it is the "vented marine heater"...  Look at the price tag !

This is a buddy heater 





Here you see what the marine heater looks like when lit


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