|
Post by shilo on Jan 11, 2015 12:27:43 GMT -8
Hi I have the fire in the left and a long single-bell bench in the right. if the chimney in the right end of the bench, I can't make a bypass for cold-starting. (I can by-pass it by a T in the chimney high in the bell, but it considerably less effective compared to direct bypass) if the chimney at the left side of the bell, I have to deal with two issues: 1- to prevent immediately bypassing between the inlet and the exit. 2- to prevent the gas from heating the bench only partly - having the left side warmer then the right side. I understand how to deal with the first issue but what about the other? TYVM!
|
|
|
Post by matthewwalker on Jan 11, 2015 14:38:39 GMT -8
I have a couple suggestions.. First one: When Pat was doing his bell/bench project we speculated on a flue pipe within a half barrel or a bell, to take the gasses to the far end first. You could come out low from the riser chamber, through a length of flue either adjacent to or inside the half barrel, then let the half barrels be the return to the flue. Pat did something similar here: donkey32.proboards.com/thread/1065/non-metal-barrel-downdraft-chambersThe other solution is to make a bigger plenum at the firebox side of the half barrel bench, like two thirds of a barrel vertically or something. Something that increases the volume right there, so you can plumb in an inlet and outlet with enough separation. So, in practice it turns the half barrel bench from a bell with one height in profile, to a bell that has a larger volume at the input end. Like this, B is barrel, H is bell/bench, I is flue. BBBB I BBBB I BBBBHHH BBBBHHHHHHHHHHHHHH BBBBHHHHHHHHHHHHHH
|
|
|
Post by matthewwalker on Jan 11, 2015 14:39:07 GMT -8
Oh, ha ha. Or like in my avatar. That's what the little side boxes are there for in that modular design.
|
|
|
Post by shilo on Jan 11, 2015 14:54:17 GMT -8
First one: When Pat was doing his bell/bench project we speculated on a flue pipe within a half barrel or a bell, to take the gasses to the far end first. You could come out low from the riser chamber, through a length of flue either adjacent to or inside the half barrel, then let the half barrels be the return to the flue. 1. that way, I pay twice... 2. after doing that, what will be the way to calculate the ISA?
"The other solution is to make a bigger plenum at the firebox side of the half barrel bench, like two thirds of a barrel vertically or something. Something that increases the volume right there, so you can plumb in an inlet and outlet with enough separation. So, in practice it turns the half barrel bench from a bell with one height in profile, to a bell that has a larger volume at the input end." if I make a good separation, I solved my original first issue.
what about the other issue?
|
|
|
Post by matthewwalker on Jan 11, 2015 15:19:40 GMT -8
A dead end bench should have fairly even heating, although I imagine the left side will be warmer than the right. My bench has a lot of temperature difference across it's length, I have never thought of it as a bad thing.
I don't know about the ISA calculation.
|
|
|
Post by shilo on Jan 11, 2015 20:56:01 GMT -8
"A dead end bench should have fairly even heating" after 7 meters and 2 corners?
|
|
gjh42
Junior Member
Posts: 61
|
Post by gjh42 on Jan 13, 2015 11:59:47 GMT -8
How about placing the half-barrels nearer the inlet & outlet lower and raising each succeeding one an inch or something, so the nearer ones have more mass to absorb and diffuse the heat, and the heat can accumulate more at the far end? This would require enough height to play with, probably including sinking some of it below floor height, so not applicable in many cases.
|
|
|
Post by shilo on Jan 13, 2015 13:21:44 GMT -8
|
|
|
Post by patamos on Jan 13, 2015 23:17:44 GMT -8
Hi Shilo,
Saw Matt's mention of my earlier RMH build so thought i'd pipe in. If you can find some furnace ducting to carry flue gasses further into the bells, the material cost is little. Around here in west coast Canada (spoiled as we are...) a 5 ft length of duct is about $5. Maybe you could find some used ducting from someone ripping out a forced air heating system. Hope i am not being naive about the availability of salvage where you live. I am often disgusted by the amount of readily reusable material people throw away in this part of the world - as wasteful as it gets!
If ducting is not available, then maybe some old flue liners. If not that then maybe old bricks stacked into a divider wall. It doesn't have to be air tight. Just enough to get most of the gasses heading in the desired direction...
Also, as Matt suggests, the variable heat with different rates of flywheel can be an advantage. In the above-mentioned build the flue encased in thick cob at the far end of the run takes vary long to heat up and never really gets hot. But if the heater has not been run for two days, it is still warm enough to offer comfort from the cold. Other areas of the bench vary in heat up time and temperature. So people can choose just where they want to be for how long...
Another thought. If you can get a hold of some 1/4" ceramic gasket, or perhaps tightly woven fiberglass wool, that could offer a thin but effective layer of insulation at the high point of the half barrel bells. This might be a way of lowering the overall height without removing too much of the cob layer.
|
|
|
Post by satamax on Jan 24, 2015 19:04:11 GMT -8
|
|