Thomas Winters

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since Aug 11, 2013
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Recent posts by Thomas Winters

I have read through that thread.

Most of those ideas are a bit more than I can tackle at this time given the time constraints.

As mentioned, I'm thinking of pea gravel surrounded by concrete blocks.

Anyone used this method? Or some similar material?

I'm familiar with phase change material used in solar hot water heating applications.

Anyone used this material for a heat sink battery for a rsmh?

7 years ago
Besides cob (and water) what is the best material / method for a heat mass battery?

I've a rsmh to heat my shop with.

Thinking of a concrete block "form" to hold pea gravel mass in place around the first 10' or so of 8" horizontal exhaust pipe exit flue.
I'll insulate behind and under the mass battery bed to keep the heat from dissipating into the wall and floor.

Pea gravel is not the most efficient heat sink I realize, but easy to remove when the time comes.

Any comments?

7 years ago
That photo is a picture of my project.

Good idea Peter. Yes, I did do a minimum of testing with the air flow. I'll play with the air intake once I get the stove installed with the longer length of exhaust pipe I have planned.

The stove actually achieved 452* as a high temp, not 425*.
That temp was measured on the metal on the back side of the stove at the top of the outershell, not in the heat riser itself.
My guess is the heat riser temp itself was a bit higher.

Also, it was a 90* + temp day, so the draft was not quite as good as it should be under normal cooler/colder weather use.
And the exhaust pipe was only 9" long.

Thanks for your input. T

7 years ago
"Thomas, an all metal construction is doomed!"

Absolutely agree.

That is precisely why I did not build an all metal rocket stove mass heater.

Thanks for your input.
7 years ago
Yep, seen those videos Big Al.

Thanks for your input.

7 years ago
Thanks for your replies.

Feed tube is about 18" tall bottom to top. Any harm in being taller than 15" ?

I've seen feed tubes angled like in the photo.

Why does the feed tube "have to be vertical" please?

Thanks, TW

7 years ago
Hello everyone. Thankful for this forum. Would appreciate your input.

After what I thought was sufficient research, (yes I have "The Book" lol) and close attention to the proper dimensions,

I started in on my first rsmh -

1 1/4" x 9 x 4 1/2" firebrick lined, three 8" masonry chimney flues - 36" tall.

Burn chamber is (approx.) 7 3/4" tall x 5" wide x 13" deep.
Total burn area is 21" long including the 8" flue width.

Feed tube is a 6x6 rectangle metal tube cut at a 45 d angle.
(This angle was chosen to allow for a self-feeding pellet option at future date).

A 1" high metal grate sits on the brick and fuel then sits on this grate while burning.

Door when open fully allows air into burn chamber opening which is (as above) 7.5"h x 5"w.

Two air intake baffles allow adjusted air in under the 1" metal grate when door is closed.

Burn chamber is insulated 1 1/2 w/Perlite both sides, but not the top or bottom.

Top of stove was not fully sealed. (No gasket material installed yet on the top inspection plate).
Consequently, stove was losing heat out of the top before it could be directed down to the exhaust pipe.
Can be easily rectified with gasket material installed.

Exhaust diameter is 8".

Chimney is insulated with 1 1/2" Perlite all four sides.

Fired the prototype up yesterday.

Stove drew well, little smoke back-up. After 4-6 mins, no smoke out of exhaust flue.

Heat at the top of the chimney was + - 425 d. F.


Stove doesn't achieve that "rockety" sound when burning.

Could not detect the vortex type fire expected in the flue.

Should not the stove generate higher temps?

My thoughts are:

1. Because of the angle of the feed tube, (45%) the wood is burning too close to the chimney, with not enough (length) time for a good burn?
In other words, burn chamber needs to be longer?

2. Burn chamber is too tall?

3. Burn chamber is too wide?

4. Needs insulation bottom and top of burn chamber?

5. Feed tube is too large due to the angle? A 5"x5" tube at 22.5 d would be better?

Those are my thoughts.

Your thoughts welcomed and appreciated.

7 years ago