|
|
Post by pasto76 on Jan 18, 2012 12:03:19 GMT -8
is the floor acting as a heat sink, and/or are there air gaps in the bottom half of your mass fill?
|
|
|
|
Post by grizbach on Jan 18, 2012 12:18:21 GMT -8
Pasto, The floor is held up off the floor by two plywood legs. So there is a 6 inch air gap below the bench. No gaps in the mass of the bench.
|
|
|
|
Post by pasto76 on Jan 18, 2012 13:46:07 GMT -8
interesting. Im insulating the bottom of mine so Im not trying to heat the garage floor until after the mass is heated.
|
|
|
|
Post by grizbach on Jan 18, 2012 15:52:31 GMT -8
It still is a good idea to insulate the floor. I wouldn't want to loose any heat.
|
|
|
|
Post by pasto76 on Feb 3, 2012 13:32:43 GMT -8
so.....maybe the material I have selected is a better insulator than conductor. What materials have you all used for the mass with great success(!). Ive been running the stove for 9 hours now and the temp of the gravel right above the duct in the mass is only 110 degrees, while the gas temp inside the duct is about 335
|
|
|
|
Post by canyon on Feb 3, 2012 14:23:58 GMT -8
I have experienced this also and my theory on it is that there is actually some stratification in the stream with hotter gasses riding higher. Once the heat is exchanged into the mass then it flows equally in all directions but in the flowing stream there is a bell like effect. Also, ash/particulate tends to build up deeper on the bottome thus insulating more.  |
|
|
|
Post by canyon on Feb 3, 2012 14:27:53 GMT -8
Heat travels in ALL directions equally.HEAT DOES NOT RISE!!! Heated fluids will move by convection in a gravity well.. This is a property of fluids, not heat itself.(can you tell this is a peeve of mine?) Hey Donkey, My bench Is about 6 inches off the floor. I'll have to say after a few hours of firing the bottom is slightly warm and the sides and top can be almost hot. This is with the flue equal distance from the surfaces.  ?? I should've noted that my previous post was in reply to this post! |
|
|
|
Post by canyon on Feb 3, 2012 14:34:16 GMT -8
so.....maybe the material I have selected is a better insulator than conductor. What materials have you all used for the mass with great success(!). Ive been running the stove for 9 hours now and the temp of the gravel right above the duct in the mass is only 110 degrees, while the gas temp inside the duct is about 335 Again, these materials need to be monolithic (without voids) in order to conduct well. I have found claycrete to be the best material for my needs as it is local,cheap and effective and you can break it apart when needed. That is, you take your material and add clay slip (and possibly more sand) and tamp into forms. Forms can also be cob walls. Sounds to me like you might not have enough sand in your mix. Donkey likes to do cob walls and fill with plain sand. At any rate it takes a while to get these things up to temp. |
|
|
|
Post by pasto76 on Feb 3, 2012 15:13:33 GMT -8
edit: dug out the road base today and relaid it mixed with clay slip. There is immediate improvement!
|
|
|
|
Post by grizbach on Feb 3, 2012 22:25:08 GMT -8
I have experienced this also and my theory on it is that there is actually some stratification in the stream with hotter gasses riding higher. Once the heat is exchanged into the mass then it flows equally in all directions but in the flowing stream there is a bell like effect. Also, ash/particulate tends to build up deeper on the bottome thus insulating more. Makes sense Canyon, I have actually put dams in my pipe to create more turbulence and get more heat extraction. |
|
|
|
Post by Donkey on Feb 5, 2012 20:11:03 GMT -8
edit: dug out the road base today and relaid it mixed with clay slip. There is immediate improvement! I've been re-thinking the straight sand, pour it in and cap it theory.. Sand, even with high grain diversity, has holes in it. Gaps between the grains that act like insulation. Lately I've been thinking that it seems better to mix it in with slip or something. More direct contact between all the bits for better heat conductivity and flow. 'Course, the sand's been working, so... |
|
|
|
Post by canyon on Feb 6, 2012 14:13:24 GMT -8
edit: dug out the road base today and relaid it mixed with clay slip. There is immediate improvement! I've been re-thinking the straight sand, pour it in and cap it theory.. Sand, even with high grain diversity, has holes in it. Gaps between the grains that act like insulation. Lately I've been thinking that it seems better to mix it in with slip or something. More direct contact between all the bits for better heat conductivity and flow. 'Course, the sand's been working, so... Donkey, that's what I've found in my experiments. I've seen that adding slip and tamping makes it more monolithic and function better for conducting heat, but, as you say the straight sand works. Just a matter of what your needs are. Here in Alaska we have much more demanding heating needs than southern latitudes so we are trying to optimize. |
|
|
|
Post by leewaytoo on Feb 7, 2012 5:13:07 GMT -8
canyon, if you were to leave your home for X amount of days...
how long would it take to bring the temp up to your
"comfortable" level, upon returning?
or do you leave your "grid" generated heat on, set to a lower
temp to avoid freezing pipes and such?
if so, then how long to bring the temp up from that temp?
also, have you found anywhere on the net plans for
creating one's own "thermal electric generator".
I have visited many sites and you tube vids. still have yet
to view any that show the actual manufacturing of a teg.
just links to where you can buy one, then use that in whatever
setup you wish.
i like the "beer can" passive solar heating ideas, although not
one that would be attached on the outside of the house w/pass though holes into the house.
just messing around with a two liter plastic pop container and two pop cans i came up with what is in the attachment.
you could hang as a "mobile", or connect a series vertically,for inside the house.
the temp gain was modest in that the sun was passing through
dbl pane windows and dbl visqueened frames i place in windows during the winter.
|
|
|
|
Post by canyon on Feb 7, 2012 9:01:55 GMT -8
canyon, if you were to leave your home for X amount of days... how long would it take to bring the temp up to your "comfortable" level, upon returning? or do you leave your "grid" generated heat on, set to a lower temp to avoid freezing pipes and such? if so, then how long to bring the temp up from that temp? leewaytoo, I can leave my place for three days in single digit F temps and return to an unfrozen house without any backup. When in the 20's I can go 4 or more days. This is assuming it isn't blowing hard as I have lots of drafts from experimental natural building not completed. A tight house would be something else. To do that I have to stoke up the bench prior (over the preceding 36 hours) for an extra 8 hours of burning than I would do to coast through normally. Also, I blanket up the bench extra to release the heat slower and get it up to a higher temp. When I return it takes a bit (a day) to get the mass of the bench and house back up to warm cruising but the barrel of the rocket adds quick warmth to the air. If I have to leave longer than 3 days in below zero F I set my place up to be able to freeze (I have a full celllar that doesn't freeze so I can put anything that is freeze sensitive down there) so I don't use any back up but of course one could. I have not any knowledge or experience with TEG's. Please share if you come up with anything. My solar experience is primarily with hot water. Solar hot air can be done very cheaply like my friend did for his warehouse with simple trombe wall like (without the big mass though) window areas but that is another subject for another thread/forum location? |
|
??