Dimensions for a 28" drum

Hello, I want to build a rocket mass heater at my workplace. I have a steel 28" diameter (1/2 inch thick) steel pipe and I want to use it as a drum.

I have been searching for what should be the dimensions of the system, but couldn't find a ratio.

I attached an section image of the important dimensions.

I'm waiting for your advices..

Thanks..

This is the steel pipe I want to use as a drum attached below

Burak Unver wrote:Hello, I want to build a rocket mass heater at my workplace. I have a steel 28" diameter (1/2 inch thick) steel pipe and I want to use it as a drum.

I have been searching for what should be the dimensions of the system, but couldn't find a ratio.

I attached an section image of the important dimensions.

I'm waiting for your advices..

Thanks..

The height of the heat riser must be three times (at least)  the height of the feed tube where you load the wood.
The height of the heat riser must be two times (at least)  the length of the burn tunnel .
So if the height of the heat riser is 48 inches ,the height of the feed tube can not be more than 16inches and the length of the burn tunnel
cannot be more than 24 inches.

The gap from the top of the heat riser to the barrel rim is 5 cm/2 inches.  
The length of the feed tube opening and the heat riser opening should be the same as the height of the burn tunnel(the two courses of brick that you stack for the burn tunnel's height).
It would be good to purchase the Rocket Mass Heater Builder's Guide.
Regarding the gap of the manifold i would like to hear it from someone else in the forum.Are you going to use a 6 inch or an 8 inch system?

Panagiotis Panagiotou wrote:

Regarding the gap of the manifold i would like to hear it from someone else in the forum.Are you going to use a 6 inch or an 8 inch system?

Actually It depends on the items I scavenge I'll buy fire bricks for feed tube and burn tunnel.

I'm planning to use a steel pipe for the heat riser but didn't get it yet.

I have another question on my mind. What should be the thickness of the insulation layer? I'm asking this because If I make a thin insulation like 1.5 inches and we assume that the heat riser is 8" (8+1.5+1.5=11 inches for the riser and insulation)
The insie of my drum is 27 inches. (27-11)/2=8 inches of gap around the heat riser (B dimension in the first picture I post) 8 inches seems to much to me.. Should I make it even with the insulation layer? Does too thick insulation layer makes a negative effect on the system?

And can I use a mixture of broken glass , sand and pumice for the insulation?

Thanks..

Burak Unver wrote:I'm planning to use a steel pipe for the heat riser but didn't get it yet.

You might want to spend some time reading through this thread before you do get it - using metal in the burn tunnel and heat riser

Burra Maluca wrote:

You might want to spend some time reading through this thread before you do get it - using metal in the burn tunnel and heat riser

Hi, I read the whole article and totally convinced. But the thing is this, The place I want to build a RMH is a temporary workplace for me. It's a construction site and will last 2-3 years. After that we pack our stuff and settle another place

In the future when I move in to my own house, I'll definetaly build it with bricks..

I'm new to RMH and want to build one before the winter ends, because winters doesn't last long here in Istanbul. So I'm a litte eager to build one soon.

Thanks..

For insulation, Pumice would be the best choice of the three materials you mention.

John Harrison wrote:For insulation, Pumice would be the best choice of the three materials you mention.

Do I need to crush them? Because the grains are like 1/2 or 1 inch size. I was thinking to fill gaps with sand.

Don't fill the gaps with sand, it's the trapped air that provides most of the insulation.

You wan't a low mass substance with plenty of air pockets - pumice is ideal.

Thank You John, I've noted that..

Burak Unver wrote:

Panagiotis Panagiotou wrote:

Regarding the gap of the manifold i would like to hear it from someone else in the forum.Are you going to use a 6 inch or an 8 inch system?

I have another question on my mind. What should be the thickness of the insulation layer? I'm asking this because If I make a thin insulation like 1.5 inches and we assume that the heat riser is 8" (8+1.5+1.5=11 inches for the riser and insulation)
The insie of my drum is 27 inches. (27-11)/2=8 inches of gap around the heat riser (B dimension in the first picture I post) 8 inches seems to much to me.. Should I make it even with the insulation layer? Does too thick insulation layer makes a negative effect on the system?

Thanks..

Some lay two inches of clay-stabilized perlite around the heat riser that then they support around the riser with metal mesh or sheet metal etc.
Usually problems in the draft are being caused by a small  cross sectional area in the manifold.

My drum is very thick 16mm (3/5 inches) Would it be a problem for emitting heat? Should I choose a thin barrel?

It will take longer to heat up, but once up to temperature it will put out a lot of heat and stay warm for some time. A thinner barrel will heat up quickly but also cools down faster once the fire is out.

I would vote for a thin barrel. You want that fast heat when you light a fire,  the mass is a better place to hold your heat.  Just my opinion, but that extra heat at the barrel could be uncomfortably hot on a not very cold Istanbul night.