Hi Everyone,
I have a quick update on the rocket mass heater since the stainless steel heat riser finally
rotted out.
Once again, taking a look at the barrel, there is still some flaking on the top and also
along the sides.
My guess is that this is from the extremely high humidity in the greenhouse along with
cycling the heater on just once a day and then letting it completely cool which is condensing
a little moisture on it.
Looking down inside the barrel, there was a little ash at the bottom which was expected
considering it has run the entire season without being cleaned.
What I found to be a bit surprising were the pieces of stainless steel that were also in
the ash which had blown up and out of the heat riser.
Looking down into the heat riser, or what someone likes to call a "well", the insulation
has settled a little bit, but the stainless steel pipe has collapsed down nearly a foot.
The outer shell of the heat riser, which is 10" galvanized stove pipe, is in excellent
condition.
These sections can be used for other experiment.
The rock wool insulation was in fairly good condition along the top, but had hardened
up a little so I disposed of it.
It was interesting to see what happened to the rock wool.
The first inch that was on the inner part against the heat had discolored and hardened,
while the outer inch was still soft and looked new.
There was a very distinctive line between the differences.
I got about 1000 hours of burn out of this heat riser so it did surprisingly well considering
the abuse I put it through.
Once I pulled the stainless steel pipe out, it became very apparent that there was nothing
left to it, and once again, the rock wool which was exposed directly to the fire had
melted.
Laying out the remains of the stainless steel pipe showing the original 5' of length, this
is what was left of it.
Now that the old heat riser has been removed and the base has been cleaned up, it's time
for a new heat riser.
I'm finally going to buckle and install a heat riser made from fire brick.
I decided to dado some of the fire bricks so that they couldn't collapse into the center.
The original heat riser was 6" which is a profile of 28.3" square inches.
To minimize the waste of brick, I dado cut two bricks and then set two complete bricks
on their ends.
With this setup, the profile area is slightly less by 2 square inches.
Even though it's slightly smaller, I decided to take the risk since the heat riser is taller
than most heaters and it should have a stronger draft.
A cheap wet saw goes right through the fire brick and it's brittle enough to tap off any
extra material that didn't come off from the saw.
For the last step, I built a steel cage around the outside to hold everything in place.
Since the steel frame isn't directly in the blast zone, it should hold up for quite a
while.
That's about it for this heating season.
I have a few more ideas in mind for next year so hopefully I can get them built before we
start heating again.
Thanks for watching!