Post by flybyjohn on Oct 3, 2019 9:35:54 GMT -8
Hi, all. been a long time since I have been active on here.
I bought materials to refab my heat riser before last winter but never got to it so I am trying to remember what my plans were so I can get it together before this winter.
I originally built a heat riser, lower and upper out of a perlite/fireclay mix and it worked great for a couple years. I noticed last year that the lower part started to crack out and is missing chunks of material. I decided to just make a whole new riser from bottom up and wanted to combine several different materials. I have already cut all the brick but started to second guess myself if it was going to be adequate or not and wanted to run it by the professionals before finishing it up and putting it to use.
So just to give you a picture of what I have going on. The firebox and riser are built inside of a 2' x 2' x 3' steel stove. The steel stove's door was modified to be the door to the firebox. The firebox is built out of dense hard firebrick. The lower riser is cast in one piece and consists of the back of the firebox wall and lower heat riser. This is held against the firebox with some steel springs, and a sheet metal sling that goes around the back of the riser. It pulls it against the firebox wall bricks and uses a ceramic fiber blanket material for a gasket.
My new riser will be of the same configuration but using different materials. The new materials will be 1.25" thick 2600 soft insulating fire brick cut in pieces to form a hexagon. The insides of the hex pieces were sanded to a curve to make a 6" bore, leaving a minimum of 1" thick at the thinnest area. The port will be formed out of 2" thick 2600 insulating fire brick. These will be cemented together with the hexagon riser with furnace cement and then a form will be made around them to then be filled and compacted with a perlite / waterglass mixture. The perlite and waterglass mixture is to both insulate and hold together the insulating firebrick components. The upper riser will consist of a 5 minute ceramic blanket riser.
The concerns that I have are if the perlite / waterglass will stand up to the heat that the riser might get too. Keep in mind that there will be a minimum of 1" of the 2600 deg insulating firebrick separating it from the direct contact of the heat. I have tested a couple small 1/2" thick bricks of the perlite / waterglass inside the firebox up in the top back by the port last winter and the glass and or perlite started to melt somewhat. I coated some test bricks with a coating for forges and it did stop the melting at that temperature. Not sure just what the temperature was in the top back of the firebox was but definitely hot enough to need welding glove just to load the stove.
The other concern is that both the insulating firebrick and the perlite / waterglass mixture are porous in nature and seem to leak air. Will these materials need to be sealed to keep a draft in the stove. I had an idea to use some firberglass cloth and waterglass as the binder to go around the outside of the whole lower riser to seal it and help keep it together in case is cracks some.
So professionals. Does this sound feasible. Do you think it will work? Any thoughts?