I need help ... My rmh is giving me 3lts of water a day in the exhaust pipe

Hi
Can any one tell me why I'm getting so much condensation running down the inside of my exhaust pipe

I've used 6 inch flue all round and I'm getting a clean burn however I'm getting 3 lts of water a day everyday . I lit it for first time three days ago ....

Is it because my exhaust does not run parallel to the ground ... I have it going uphill

My wood is super dry as you can see I have it on top of stove to ensure its not water from the wood

Hi Lynne; If this is a new build, then your condensation is coming from the moisture in the cob and with your pipe not flat its all coming down to one collection point. Keep burning !!! you're drying your cob out and it will take awhile. In my greenhouse it took 3 weeks of hot burning before I stopped getting moisture. By the way... If your rocket stove starts to rocket,... then the top of that barrel is going to be hot enough to light that wood you have drying /heating on it !

Thank you for your answer
Yes I expect moisture from the cob drying out
However it is literally running down the INSIDE of the flue pipe

Should I have the flue pipe horizontal with the ground

When I feel inside the barrel the cob is dry and baked hard .......

Could it be condensation due to your humidity VS. room air / outside air temp ?

Thank you for your answer
Yes I expect moisture from the cob drying out
However it is literally running down the INSIDE of the flue pipe

Should I have the flue pipe horizontal with the ground

When I feel inside the barrel the cob is dry and baked hard .......


The water is actually forming a deep v hot puddle well more like lake two ot three inches deep inside the bottom of barrel
I'm mopping it out through the ash clean out just after the barrel
I thought it might be condensation due to different ain't temps. So today I covered the rest of the exhaust pipe in a 2 inch layer of cob to see if it made a difference
Alas no
I know when it's full again as the fire begins to slow ....Every half hour I have to mop out the lake

Isn't this much water too much
On the outside of the building there is lads of steam leaving the pipe even when the lake inside is dry .......
Ahhhh

Does anyone know if I should run the exhaust flue horizontal to the ground?
As you can see from the pic I have not totally cobed all the pipe in yet so it's not too late to re build the exit flue .....

I will post more pics tomorrow

While I am not vastly experienced in all things rocket stove, I did recently complete HVAC school and I think I know what your problem is. Super efficiant furnaces (90% efficiency) have condensation hoses to drain water that condenses on the heat exchanger. You are sucking moisture in with the air that fuels the fire. There is no way to get around that, it would seem to me that your thermal mass is collecting enough of the heat that some of the water vapor is condensing back to water as it loses heat, since you have a slightly slanted pipe, it then runs down hill. I am actually surprised more people dont have a problem with this since the design seems to efficient. Logic would suggest that they are getting as much condensation as a very efficient natural gas furnace. It may take some Rocket stove surgery but you could try getting some sort of drainage hose attached to pipe that leads discretley outside. If your flue pipe is going up then try a drain hose at the bottom of it, Or try running the exhaust pipe horizontal like you suggested before, the only problem with that is you may need a fan to assist the draft of the flue gasses. If your thermal mass is absorbing enough heat to condense that much water, the exhaust gasses may be too cool. If Venting the flue gasses is the easiest way to drain the water, i would start with that. Otherwise try the drain hose. You would be surprised how much water can condense out of heated air if you cool it enough.

Lynne; Having your mass pipe horizontal is the common way of building a rmh ... this may be why. I haven't heard of anybody getting as much water as you, but i suspect that it collects and evaporates in a horizontal pipe.consider making your pipe flat and other than the steam outside I suspect that your problem will go away. As far as your cob feeling hard and dry... I can assure you that in a fresh build in the winter that it is not . My rmh was built slowly in the summer and it took 3 weeks of steady hot burning to really heat up and dry out all of the mass THREE WEEKS ! So whatever you do.... Keep Burning !

Lynne,
Even when your fuel is bone dry, burning it will produce water. Complete combustion of wood will produce heat, CO2 and water. In fact, every kilogram of bone dry wood will produce about 0.5 liter of liquid water. Since your bench duct is not completely covered yet, this pipe will shed heat very quickly and the water vapor will condense. The rest of the stove could not be dried out yet in three days so this will cool the exhaust gases even more.

Please follow everyboy's advice and keep burning. Those clouds of water vapor is part of the game, it will always be this way when the air outside is around freezing point.

This may seem stupid, but try throwing a bunch of old blankets over the exposed heat ducts and see if that helps. If it does, there's your answer, cob in that duct, but that corrugated aluminum you seem to be using is going to easily collapse.

Lynne B. : Keep burning, there will come a point where you will use less wood fuel, this will seemingly happen overnight and then you will be left with a 'new normal'
that will be a LOT Drier ! For the good of the craft! Big AL

Also don't forget that when exhaust carbon monoxide is re-burnt to make CO2, the reaction also creates H2O. I'd have to think for several hours (and go back to my science days, I use to be able to figure this out in 5 minutes.. sigh) to figure out how much CO -> CO2 + H2O would equal 3L per day, but just wanted to remind you that these reactors naturally create H2O in the burning process.