Storage heater bricks for RMH

Ive been visiting these forums for some years now in order to do the background reading and study in the hope of building my own RMH. I live in the UK, in Ianto country actually, Wales. One of ther main things holding me back is the materials I should use. After doing much research I believe the general consensus of opinion is that metal isnt that brilliant for the construction of the burn tunnel and heat riser, and most people tend to favour bricks. I have quite a few bricks that I could use, more than enough I believe, of the bricks that are placed inside electric storage heaters. They are heavy, seem very dense, and the ones that I have come in 3 different shapes and sizes, Im guessing thats down to the variation of type of storage heater they were placed in. My question is, are these suitable/useful in the build, and if so, where might I benefit most regarding the placement e.g. burn tunnel, heat riser or drum support? Im hoping that they have excellent insulating qualities and may save me the job of insulating the area that I could possibly use them I can provide photos of the bricks but would have to be tomorrow Many thanks
Incidentally, if I have put this question in the wrong area of the forums, please let me know and move to the correct area if so.

Those are accumulating bricks, designed to take up vast amounts of heat, called magnetite bricks if I recall correctly. Just because they are dense, they will take up heat and won't insulate. Please don't use those for any core part of the heater where heat is produced. It will take nearly forever to heat up sufficiently and achieve clean combustion. The lighter the bricks, the earlier the core will be at the right temperature.
Those heavy bricks are unbeatable at heat storage, so you'd do much better to incorporate those in the mass.
By any chance, is the colour of these bricks a dark purple?

Carol Morgan wrote: I believe the general consensus of opinion is that metal isnt that brilliant for the construction of the burn tunnel and heat riser, and most people tend to favour bricks.

You did not mention the clay / perelite composite core . . . made from one large piece of duct work, and one smaller piece of duct work . .  then fill the space with clay/perelite .. . when you fire the stove, it turns into a fired porcelin.

You can always use the bricks for your mass / heat storage . . .

Many thanks for both replies Peter I'm going to try to post the pics of the three types of brick. The flatter ones are a kind of purple colour and are about 1.5ins thick I suppose I should have realised they would be more useful in the bench area as the job they do in the storage heaters is pretty much the same, absorbing the heat to give off the warmth at a later point  In terms of using metal in the riser, does the metal stay intact or is it sacrificial? If sacrificial, do the exhaust contain gases given off by whatever metal I might use?  

Type 2 brick

Type 3 brick

Carol Morgan wrote: In terms of using metal in the riser, does the metal stay intact or is it sacrificial? If sacrificial, do the exhaust contain gases given off by whatever metal I might use?  

As you can see in the pictures I first posted, I used galvanized piping to build the core or riser of my rocket, and yes, once your stove mass dries out, and everything gets running nice and hot, the inner core just flakes away . . . leaving your baked core intact ..  . I am sure there is some off gassing when the inner core is cooked, but the outer surface of my core is covered with a fine white ash . . . so I don't think the outside of the unit gets hot enough to off gas. . .

NOTE :  If I am incorrect on this one, I am sure someone will correct me . . .

Here are a more pics for ya .. .  what I found inside the J tube after a nice HOT burn  . . . .. the inside of the riser (you can see where I packed the clay too hard and made a "bump" on the inside surface  .  . . ..  .  and outside of the riser . . .