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Post by patamos on Jan 20, 2014 8:55:41 GMT -8
Hi folks,
I'm getting down to building a 6" J-feed and am planning a 5"x10" window placed flush to the exterior surface of the burnchamber wall. edges protected and cushioned with ceramic felt. And i am thinking about placing a second pane with a 1/8" layer of felt separating the two. BUt i am wondering if air pressure issues between the two could cause trouble.
If so, perhaps the outer pane could be set 2"+ away (closer to the exterior of the stove body) with an intentional pin hole to neutralize expansion contraction pressures...
Has anyone had experience with this and has advice to offer?
Any thoughts will be much appreciated
well being
pat
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Post by matthewwalker on Jan 20, 2014 9:01:51 GMT -8
I'd be nervous about that Pat. The only reason even ceramic glass can survive there is because it can throw the heat out to the room and shed it. If it were insulated I fear it would exceed it's working temp. I think the Robax is rated at 1500 F. I'd leave it single glazed myself, although, it would be an interesting experiment. I'd probably want to do it outdoors the first few burns though.
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Post by Vortex on Jan 20, 2014 10:09:38 GMT -8
I've seen someones post of this forum where they'd built a double glazed stove glass window, unfortunately I dont remember who it was. In my experience if you can keep some distance between the glass and the fire so there no contact with the wood then its usually OK even at really high temps. Also dont ever tough hot glass with anything cold, it will crack.
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radek
Junior Member
Posts: 94
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Post by radek on Jan 20, 2014 11:08:37 GMT -8
interesting this question is coming up here.Few days ago i have finnished a 20cm J style RMH where the owner realy wanted to see the fire.So i have made a metal frame with fire glass insert in it.Its single glass aprox 4cm a way from the fire.Right now i cant say how it will perform in longer run,but im more confident with one glass not two.I have seen on the net somewhere double insulative fire glass and i think that would be the best choice. It seems i cant add pics so here is a link www.facebook.com/#!/media/set/?set=oa.700801029940000&type=1 |
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radek
Junior Member
Posts: 94
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Post by radek on Jan 20, 2014 11:12:55 GMT -8
the link doesnt work sorry and when i want to add pics in here i get this Error: This forum has exceeded its attachment space limit. Your file cannot be uploaded.
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Post by pinhead on Jan 20, 2014 11:19:29 GMT -8
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radek
Junior Member
Posts: 94
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Post by radek on Jan 20, 2014 11:25:25 GMT -8
Thx Pinhead yes those are the stoves
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Post by patamos on Jan 20, 2014 20:53:46 GMT -8
Cool Y'all
Thanks for the replies.
Radek that is a beautiful heater.
Sounds like one window pane is the safer bet. I found a product in town called 'cermi-glass'. Not sure of its temp rating but will confirm. 'I'll likely set it 3" or more back from the inside surface of the feed/burn tunnel. At first i thought flush with the outside of the fire bricks (with gasket) but maybe further away embedded in a perlite-clay-sodium silicate blend.
I'm casting a beam to span the window opening. Might carve a little arch into it for effect.
well being
pat
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Post by Vortex on Jan 21, 2014 10:30:57 GMT -8
Nice stove! I'd really like to see a video of what the fire looks like through the window while its running.
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Post by matthewwalker on Jan 21, 2014 10:46:22 GMT -8
Here's a couple of mine:
Believe it or not, that second one is at normal speed. I know, it looks sped up. Here's a different look:
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Post by colinsaengdara on Jan 21, 2014 11:42:48 GMT -8
Matt, I know you've figured out the placement of the glass in terms of keeping it clean. Could you talk a little about that?
Thanks,
Colin
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Post by matthewwalker on Jan 21, 2014 14:15:43 GMT -8
Sure Colin. I've found the best placement for keeping the glass clean in a rocket heater is to put the glass as close to the flame as possible. For sure you can do the opposite, and with a hot air wash you might keep it clean that way as well, but I've had really good luck using a burn chamber design that forces the flame right against the window. It will soot up a bit at the beginning of the burn, which you can see in that last video since that's right after start up, then as things heat up the flames will burn the glass clean and it will stay that way. When I placed the window too far from the flame it would soot up and stay that way. All my window designs now incorporate a part of the core that is designed to force the flames to wash the glass.
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Post by patamos on Jan 21, 2014 19:27:54 GMT -8
Hi Matt,
So if i place a 6"x9" piece of glass flush to the outside face of a 2" side wall. Would that likely do the trick in keeping things self-soot-cleaning?
By hot air wash do you mean the burn chamber gasses eddying/circulating through that space?
well being
pat
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Post by matthewwalker on Jan 21, 2014 19:40:43 GMT -8
Oh yeah, for sure. I assume you are talking about placing it along the burn tunnel, like in Radek's heater. That'll burn clean.
Well, I think maybe I showed it in one of those older outdoor videos. I basically obstruct the tunnel such that the flame path is redirected towards the window. Since the window opening opens up the CSA right there, I come in the same amount from the opposite wall and pinch the flame towards the window.
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Post by patamos on Jan 21, 2014 20:52:54 GMT -8
Cool I think I'll give that a go  |
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