Hey Everyone,
I wanted to touch on a few things real quick with you before I go into the next video.
First is I get a lot of comments about the rocket mass heater and mainly about the materials
I'm using in it.
I actually choose to use some of the steel in here mainly to keep the costs down and
it allows me to do a lot of experiments with this.
I'm well aware that the steel is going to wear out relatively quickly but since it's
so cheap, it just makes it easy to use.
Next is the question about fresh air intake.
A lot of people say I should do a fresh air intake on this.
This is in a greenhouse, so there's plenty of air leaking in through various areas of
the building.
Also, I like to help to reduce the amount of humidity in the building but just pulling
the humid air out of the building and into the rocket mass heater.
So usually for the first hour or so I'll see a lot of condensate coming out of the exhaust
and it helps a lot of reduce the humidity in the building.
Lastly, I've have several people say that I should vent some of the CO2 exhaust directly
into the greenhouse to help out the plants.
This is just something that I'm not willing to do, it's a safety concern, and it's better
off just venting the exhaust directly to the outside.
Thanks a lot and I hope you enjoy the work that I've done on the rocket mass heater!
Near the end of the heating season last year, I decided to rebuild the burn tunnel and heat
riser.
The antique clay bricks had mostly fractured so I replaced it all with fire brick.
This time I wanted to slow down the burn a bit and decided to go from an 8" heat riser
to a 6".
Since I didn't want to weld up a new grate for the pellets, I left the fuel supply area
wider and then tapered the burn tunnel down to fit a 6" chimney.
This year I wanted a heat riser would last a bit longer.
I decided to use a section of 304 stainless steel pipe for the inner area and regular
10" galvanized stove pipe for the outer area with rock wool as the insulation.
Jumping through almost the entire heating season, I've burned with this setup for around
700 hours.
The pellet grate has had enough.
The steel frame wore away in the hottest burn area, but the stainless steel grate slats
survived...barely.
I was surprised that the tabs that I welded on to the ends with my regular MIG welder
survived, and only a couple had broken off.
I'm also a bit surprised the grate didn't fall apart sooner since the rear holder for
the slats was completely missing.
The failure of the grate came at a bad time since the temperature was around 3 degrees
so I had to scramble to make up a new one.
Luckily I still had some stainless left over for the slats, but had to make the frame out
of regular carbon steel.
This version has a couple of slight differences based on some observations over the winter.
The previous design worked well, but I noticed a few small issues with it.
The first change I made was to remove the back wall that supported the grate and added
a bar for it to rest on.
This allows for some more air flow behind the grate and also lets me see what's happing
in this area.
The grate got lowered down into the ash pit a bit more so that the heat doesn't have to
work downward as hard.
The front gap on the grate remained as it still aids with allowing some additional fresh
air into the burn tunnel.
It's handy to have since I can pull any remaining ash out of the burn tunnel and drop it through
this spot into the ash pit.
I also lengthened the grate by an extra inch to provide more burning surface area.
The slat spacing was widened to be just a hair narrower than the pellet diameter.
The previous grate was a bit too thin and occasionally the ash would build up if it
burned for several hours.
Instead of welding legs on to every other slat, I only put on two.
I bent the top screen down to keep the pellets from sliding off the end of the grate and
the legs are used to hold the screen in place.
With the previous version, the screen above the pellets worked well, but the pellets were
too thick, restricting some of the air flow through them.
I lowered this screen so there can be more air flow going through the pellets.
This allows them to burn faster, creating more movement of pellets over the grate which
helps to break up the ash and prevent clogging.
The system is easy to load with pellets and can start right up.
It certainly helps to give it a squirt of diesel to move things along.
After a few minutes it's up and running a full speed.
When I had switched from the 8" to 6" chimney I went from burning 12 pounds and hour to
8 pounds...thinking that it was the chimney size that reduced the burn rate.
However, with my latest modifications, I'm back up the 12 pounds an hour.
The stainless steel cover typically glows orange and I usually can see the top of the
barrel glowing -- that's with the fan blowing to help circulate the heat.
Here's a view from under the grate where you can see all the pellets are glowing and some
pieces are falling through.
With the increased burn rate and temperatures, I'm starting to find flakes of stainless steel
from the heat riser.
With my sophisticated imaging system, I probed inside the heater to see what was happening.
The fire brick on the roof of the burn tunnel is in perfect condition with a few flakes
of ash stuck to it.
But, once we can see inside the heat riser, it's very clear that the stainless piping
is buckling and won't last much longer.
That's all the footage I have for now.
Make sure you subscribe to see the next update about the rocket mass heater!
Thanks for watching!