8" blind single blind bench RMH with s portal

[josephcrawley]

I started this guy a week ago. I'm hoping to get it finished by next Thursdays since a bunch of people will be coming over and my house is a shit wreck.


Here's a picture of the firebox which is more massive than I though it would be



I rounded out the riser for the first four courses after the advice of folks on this forum.




I made the riser about 5 x B instead of the spreadsheet recommendation of 10 x B trusting in the new revelations from Shilo.

[morticcio]

Sounds like an interesting build, but only one of the photos is showing - can you edit and link to photos instead?

[josephcrawley]

Thanks for letting me know it was working on my computer so I would have never known. It is fixed now?

[josephcrawley]

Here's some more photos of the project



Here's the bench being closed up the center bricks are there to allow the top bricks to make the span. Hopefully they won't impede gas flow to much.



and another of it closed up.







and finally a very poor picture of the low entrance to the chimney.

goo.gl/photos/JZzAAdFR2UDYEQP1A

This is a link to the all the photos

[DCish]

Cool! Do comment on temp distribution when you fire it. I have a blind bench about 8' long, slightly narrower and with no center bricks. Temperature differential from end to end is relatively low, in the under 10 degree range. Hopefully yours is similarly good.

[josephcrawley]

Here are the rest of the photos.



Here's a view of the oven the bottom left is the internal chimney. The floor of the oven is a kiln shelf.



You can see the top of the heat riser on the left I put the oven back about a brick's height above that.





I'm happy with the stove in most respects. The oven gets up to 475 after two loads of wood. The thing smoked into the house like crazy the first time I lit(for about 2 hours) it but it was also soaking wet. I have had problems lighting it from a cold start and wish that I had included a bypass. For now I can open the clean out and stuff burning paper below the internal chimney opening before lighting the fire. The next step will be to cover it in 70's colored bathroom tile to class it up a little. Thanks guys for all the advice over the years.

Joseph

[josephcrawley]

Oh yeah and the temp differential on the bench from end to end is at least in the 10 degree range probably more.

[time]

how hot does the bench get??

[josephcrawley]

A comfortable warm. It hasn't been that cold yet so I haven't it up crazy style yet.

[josephcrawley]

With the freakishly warm winter were having I have had several cold starts with my stove. After smoking my house out for an hour every time I decided to add a bypass. It's a small sliding door about 3 and 1/2 by 8 at the top of the internal chimney. It works great thus far. Sorry no picture I was in a hurry to get it back together before the upcoming cold spell.

[pinhead]

I love the look - this is the direction I'll be going with my next build. I've also decided that the Batch Box w/bell configuration absolutely needs a bypass if a highly efficient/effective heat exchanger is in use (overly large bench/bell, etc); it's simply much easier for the heat to rise in the firebox and out the door than it is for the heat to go down into the port. As you've noticed, once the system is up and running with a warm mass and chimney, lighting the stove is easy as pie.

Did you make your own door(s)? Is the outside skin double-walled? Do you have any trouble with the roof of the bells shifting/cracking?

[josephcrawley]

I made one of the doors a buddy made the other. It is all single skin. I have had no problems with cracking thus far

[DCish]

I'm currently trolling for door design ideas. If you are up for posting more detailed door pics, I would be appreciative.

[lawry]

Lovely looking build Joseph. I take it the visitors were quite warm on the bench. ?
Are you still planning to finish the heater with tiles? How will you attach them to the heater?
Also can someone explain the blind bench. I think the flue gasses heat up the gasses in the bench even though the flue gasses will quickly turn right into the chimney... Am i right?
If i m right then what have you guys found to be the optimal size for a blind bench?

[peterberg]

Feb 14, 2016 0:22:40 GMT -8 lawry said:

Also can someone explain the blind bench. I think the flue gasses heat up the gasses in the bench even though the flue gasses will quickly turn right into the chimney... Am i right?
If i m right then what have you guys found to be the optimal size for a blind bench?

No, you aren't right, I'm afraid. The blind bench is completely open to the main bell and in that sense it's just a part of it. Hot gases want to fill the top of every space first, thereby replacing cooler gases. In effect, where the bench opens to the main space of the bell this is suddenly quite a bit larger so the gases will stream slower. Warm air is streaming into the top of the bench and cooler gases stream out at the bottom. The exhaust opening to the chimney is at the lowest point of the whole bell/bench combination so that's where this cooler gases will exit. The crux is, the exit opening is lower than the top half of the bench.

The same with a house which is heated with hot air is always hotter at the top and coolest at the lowest floor, isn't it? The longest blind bench I've seen so far is 2.5 meters (8.2 ft) long inside. Getting warm without a sign of hesitation. I haven't heard about a blind bench built as a curve but I think it's possible.