Batchrocket.eu, information site

[ericaus]

Hello Peter, I think you meant to say "avoid external air supply". It may confuse some people.
Eric

[peterberg]

Changed it, thanks.

[Jura]

Apr 21, 2017 13:40:37 GMT -8 ericaus said:

Hello Peter, I think you meant to say "avoid external air supply". It may confuse some people.
Eric

The fun fact about it is I got it properly :-)
I don't even remember what was written previously there.

Thanks for the info and the link.
I loved it. as it touch subjects I'm often trying to promote personally
(even the issue of fuels EROI is addressed).

I'm  building the stove @ my friends place (he is the investor) in the place which hosted an open firebox and the outside air supply already exist right in the place where the firebox is to be placed.

I'm not so convinced by the argument you used (it will suck in air from outside, thereby refreshing the room air which is a good thing in itself. )  as IMHO ventilation installation is  the one meant to do the task of maintaining air quality.  

(I'm personally an outer being and fresh air lover & I hate stuffy and moist air in flats)
I'm trying to explain that  rising  temp by 1 deg of an air with a significant CO₂ & H₂O content uses much more fuel than rising the temp by the same amount of fresh air. 
Often I  can see a strong tune of disbelief in the interlocutors' eyes. sad. 

Back to the issue of external air supply:You wrote
One of my acquaintances likes to put it like this: why would you feed fresh air to the heater and breath the farths and stale air yourself?


Those words are kinda rhetorics. And they are logically false.
The fact I'd feed a stove with a fresh external air does not implicate I was going to breath with  a stale air myself.
(As I'm still having the properly working vent system and the  stove is not meant to be a part of it).

The  args that convinces me as an engineer are  the one about insignificance of the amount of energy saved by using the external air in comparison to the internal one and reversed draft while starting the fire.

 If I were to  build a stove for myself and there wouldn't be an existing external air supply I wouldn't definitely bother to construct one. (EROI & systemic complexity issue) 

[stoker]

In the section about the floor-channel and pre-port tube (as an alternative to a P-channel above the fire) it says

In contrast with the normal implementation this version should be lit on top of the fuel pile at the back, known as "upside down firing". This method will deliver the best results.

batchrocket.eu/en/designs#floorchannel

I couldn't find anything on the site that says the best place to start the fire in the "normal implementation" though (where I suppose "normal" means with secondary air running over the top of the firebox to the top of the firebox-riser throat.)

[watto]

Thanks for this thread. Very easy to follow. My contribution is can the floor channel (to replace the P channel) be simply a channel, no metal, with a fire brick cut out to provide a protected exit for the air. That way maintenance should very infrequent replacement of the air exit fire brick "upright". Any thoughts on that suggestion? I want to remove metal from the inside system completely hence the question

[peterberg]

What you propose has been done before, the air could be delivered at the right spot this way. But there's one snag here: combustion results aren't that good due to the cooler air. The point of the steel duct is considerably heating up of the incoming air, up to 450º C not accidentally very close to self-combustion temperature of wood gas. By heating up the air the duct itself is cooled so it will survive a lot longer than initially expected.

As a side note: my red bell heater has been run for two winters and is due to the third season, the 2 mm thick floor channel is still there without holes. It might be that my next floor channel item will be made out of stainless steel 304 or even better 310. And when I am at it, I might do a spare one as well. Thicker steel won't help since the temperature difference between inside and outside of the channel would be greater so the outside would corrode more rapidly.

[Orange]

for the riser, it's probably easier just to buy fireclay pipes (at least here in Europe)instead of cutting the bricks. Or make one out of vermiculite board.

[peterberg]

The fireclay pipes will crack due to uneven heating, the vermiculite board won't survive very long in the hottest part opposite the port.

[briank]

Sept 29, 2017 22:27:44 GMT -8 watto said:

Thanks for this thread. Very easy to follow. My contribution is can the floor channel (to replace the P channel) be simply a channel, no metal, with a fire brick cut out to provide a protected exit for the air. That way maintenance should very infrequent replacement of the air exit fire brick "upright". Any thoughts on that suggestion? I want to remove metal from the inside system completely hence the question

I built a secondary air channel into layers of ceramic fiber board underlying the firebrick splits forming the floor of my firebox, but it still terminates in metal tubing.

[Orange]

Oct 1, 2017 11:51:15 GMT -8 peterberg said:

The fireclay pipes will crack due to uneven heating, the vermiculite board won't survive very long in the hottest part opposite the port.

thanks man, I've never heard this info before!

[Orange]

Oct 1, 2017 21:36:43 GMT -8 briank said:

Sept 29, 2017 22:27:44 GMT -8 watto said:

Thanks for this thread. Very easy to follow. My contribution is can the floor channel (to replace the P channel) be simply a channel, no metal, with a fire brick cut out to provide a protected exit for the air. That way maintenance should very infrequent replacement of the air exit fire brick "upright". Any thoughts on that suggestion? I want to remove metal from the inside system completely hence the question

I built a secondary air channel into layers of ceramic fiber board underlying the firebrick splits forming the floor of my firebox, but it still terminates in metal tubing.

Isn't the classic P-channel better than the "sidewinder type" because it is positioned higher and draws hotter air and it is easier to make?

[briank]

Oct 4, 2017 12:32:05 GMT -8 Orange said:

Isn't the classic P-channel better than the "sidewinder type" because it is positioned higher and draws hotter air and it is easier to make?

This one lies directly underneath the firebricks for the whole length of the firebox then terminates in a faily simple metal tube assembly. I think I recall that Peter had said the metal survives because of air passing through and that most of the heating only occurs in the vertical section of tubing exposed inside the firebox.

[serg247]

www.forumhouse.ru/posts/32432274/