I have a section (new) of 6" s.s. chimney and I am curious as to whether or not it can be used as a riser. I have read both "yes" and "no" to this question. However, this pipe is only rated at 650ºC, or about 1,200ºF. I understand that the burn temps inside the riser can get up to 1,800ºF, so my thinking is that this is NOT suitable.

What is the definitive word?

Thank you.

Keith s elliot : This one is simple actually, this pipe will only last longer than other types of Iron/steel. the problem is a condition called High Temperature Hydrogen
Attack, and hydrogen embattlement, there are good articles on these effects in Wikipedia!

You can try looking in the oldest hardware store in your part of the country for a thin gaged very lite weight grade of Blued or Japanned stove piping suitable for
ductwork, as these pips (if found) come in large sizes you can find a 6'' piece to be the inside wall of your Heat Riser, and a 10'' piece to make up the outside
wall of the Heat Riser, then filled with Cob and perlite. There have ben a few reports of The expansion of the inside metal pipe applying enough pressure to cause
cracks in your penlight /cob Heat Riser and some people are making up the Heat Riser with son tubes the kind you fill with concrete-

( never use concrete any where near the rocket mass heaters RMHs burner base, it can not take the heat ether! )

These tubes are available at Lowes, Menards, Home Depot, the big box home improvement stores ! Hope this helps and is timely !







used as a form into which you pour a mixture of Cob and perlite,

Thank you Allen. It seems that I shall need to find a source of clay with which to make cob. I don't believe there is any on this island, so I shall expand my search. I think I already have a couple of different sizes of Sonotube here.

keith s elliott : I wood be very surprised if you did not have mud flats and sand bars that were not clay or clay sand, the older maritime charts used to mark
what kind of bottom was close to shipping lanes, but very few captains 'throw out the lead, any more !

Excavation contractors have always been my goto people with maps carried in their heads of Exact locations depths found at and thickness of the Clay bands !

Also good are the local highway crews, who know where landslides from old/new road cuts cause roads and ditches to be blocked and increase flooding after
heavy rains ! Big AL

allen lumley wrote:keith s elliott : I wood be very surprised if you did not have mud flats and sand bars that were not clay or clay sand, the older maritime charts used to mark
what kind of bottom was close to shipping lanes, but very few captains 'throw out the lead, any more !

Excavation contractors have always been my goto people with maps carried in their heads of Exact locations depths found at and thickness of the Clay bands !

Also good are the local highway crews, who know where landslides from old/new road cuts cause roads and ditches to be blocked and increase flooding after
heavy rains ! Big AL

Hello Allen, I see your line of thinking. This island is very small, 1.4 miles long and .4 mile wide, and much of that area is taken up by bays which surround the island. There are no roads here, hence no road or highway crews, nor any heavy equipment of any kind. My immediate neighbor has his main house over on Gabriola Island some 10 miles away. He is a contractor. He does know of one good clay deposit over there which is on private property. He did some work for the property owner in question and asked if he could have a little clay to line a pond with. the answer was a flat NO, neither free or for any amount of cash.

There are no mudflats or sand bars here that I am aware of, and I've been here for over 17 years. We have shell beaches (very small) or rock beaches.

However there is a fellow here (Terry) who is a potter. He lives in Victoria, and the next time I see him I shall ask if he can direct me to a source of clay. If anyone knows, I think Terry would. He teaches the "how-to's" of pottery.

It would seem to me that one wouldn't need a lot of clay to make a riser. Obviously I must research the making of cob and find out what the various ratios/formulas are.

Again, many thanks for your reply.

I did a bit of hunting this evening, and I ran across a lady potter up on Mudge island, just a short boat ride from here. Apparently she has found a source of clay right on Mudge island.

Now I also ran across an old article on coal mining, which was very big in this area for many years. It seems that there was a large amount of clay overburden on a coal mine over at Ladysmith on Vancouver Island. Clay seems to have been commonly associated with the local mines, as there were further reports of yet more clay up at the coal mines at Cumberland, which is just a few miles north of Nanaimo.

To make this even more interesting, I am told that many years ago, long before this island (Ruxton) was developed into lots, that machinery was brought over here and used to dig out an area in the middle of this island in the hunt for coal. The subsequent information that I found out has been vague to say the least. But there is evidence of a coal seam (apparently) in the middle of the island here. The area became known as "The Pond" and covers about ten acres. So I might take a couple of glass jars up to the pond and see if I can find anything that looks remotely clay like.

Probably much easier just to buy some...