Eric Kendall

Joe Danielek wrote:Nice craftsmanship, piece of art! Love the fact that it’s built from new materials.

Peter is right, too efficient... exhaust stream not warm enough or more correctly the assembly bottom isn’t getting up to exhaust temp as being exposed to ambient temperatures at the floor setting up a sustained flue gas condensation situation. Peter is right again that the “condensation fluid” is acidic: I assume you used ferrous material for your build that acid likes to eat. Get some litmus paper and check the condensate P.H. to see how aggressive it might be.

Thanks Joe, that's probably a good way to tell if the water is from the castings, or from the combustion. I'm assuming that water from the casting would still be neutral on the litmus paper. I'll get some and give that a try.

Joe Danielek wrote:

You mentioned a by-pass, is it located in the top horizontal flue Tee or the adjoining flange connection, hard to tell as expanding the picture shows some camera shake and can’t make out the fasteners. I assume it’s there and is a flue damper as there is no blast gate? Having to not use the by-pass with a cold startup kind of tells me your by-pass is by-passing in the closed position. Checking your bottom flue connection temp against your final discharge temp at the roof during a sustained firing with indicated if this is happening.  

Yes the by pass is directly at the end of the horizontal run. It has a butterfly control valve that can be opened or closed proportionally from the quadrant plate assembly mounted on the left side of the firebox. As mentioned, I can run from a cold start with this completely closed off and the lower exhaust fully open. The thermometer mounted near the bottom outlet shows around 140C to 150C after a couple of burns. The probe for this is close to the outlet.
I'll be sure to  check the exit temperature when the weather conditions allow. I've yet to do this. Thanks again.

Thanks for all that feedback Peter, most helpful.
I'll be sure to check that flue gas exit temperature, probably at the weekend.
Hopefully the horizontal flue run won't present any problems. I've included an access door just in case in does need a clean out.
I've got around a metre of clearance between the top of the riser and the lid of the bell.
I'll report back after a few more burns as to the status of the water.
Thanks again for your expertise and comments.

Andy Bhill wrote:Jordan you are probably correct as I’ve never been around one. I have been around a double barrel type heater.  I’m curious as how a thicker bell would do. Maybe a 1/8 or 3/8 Think bell/ barrel and how long it would take to heat up and store it longer. Most that I find on barrels are for small houses. I do have a couple old propane tanks laying around. I found Peter Berg YouTube page and like his double shoe box that he did with the barrels.

My barrel is 12mm thick Andy and it has somewhat of a lag time before it radiates, but once up to temperature, it holds it for hours.

Peter van den Berg wrote:Eric, it might be that the temperature of the exhaust gases is not high enough. As Michael explained, the process of wood combustion generates quite a lot of water. In case the exhaust gas temperature is too low, condensation will occur inside the heater or chimney. There are two ways to counter this effect: implementing a drain or raising the end temperature. Keep in mind these condensation fluid is slightly acidic, not every material is able to cope with that for years on end.

In short: maybe you built the extracting side of this heater too effective?

As an aside: is there any particular reason why you made the port less wide and full firebox height? In the past I found out this isn't the best configuration, efficiency- and pollution-wise.

Hello Peter, thanks for the advice. I'm hopeful that it's only water from the refractory castings. As I mentioned to Scots, it seems to be abating somewhat, so I'll just keep my fingers crossed.
The only reason that I changed the port configuration was for the ease of manufacture. I kept a similar CSA, but if you advise that using the original dimensions would be preferred, I can easily widen the port and reduce the height with appropriate inserts. I don't have a Testo, but it seems to burn extremely clean. No soot build up in the firebox and the glass stays clear and the bricks stay white. The output from the flue seems to show signs of water vapor, but no other coloring.
I'm also pretty happy with the fact that I don't need to use the top by-pass valve for cold starts. This is really the only reason that I included it. I'm quite surprised that it draws down 4 metres and makes the exit through the lower valve from a cold start. The actual flue outlet is around 7.5 metres above the heater outlet. It has a small horizontal run of a couple of metres.
Thanks again Peter. Let me know what you think.

Scots John wrote:That really does look cool,I would love to see a walk around video?
Kiln dried wood only has a low moisture content for as long as it is not exposed to moisture, perhaps try a different batch of wood, hardwood maybe?
I would assume the water is condensation caused by moisture inside the stove, so the moisture has to come from somewhere.
I know that fire bricks can hold a lot of water but after 5 burns it should at least be diminishing.

Thanks Scots, I did 3 burns yesterday and the water pretty much stopped halfway through the last burn,  so hopefully if was the refractory castings. I'll find out over the coming days.

I'm thinking if this is going to be an ongoing problem and not the refractory drying out, I can pump some type of high temperature liquid sealant into the base plate so that I get a seal between the base plate and the pipe bell. I can then attach a fitting with a flexible hose and just run it straight out through the floor. This would be a fairly easy solution if it persists.
The only question is what type of sealant would be best? Maybe  a high temperature silicone based sealant. The viscosity would have to allow it self level but be thick enough so as not to run out like the water currently does. Silicone would have the flexibility to cope with the thermal movement.
I don't think a self leveling grout type compound would provide the flexibility need, nor would it seal the edges too well.
Any ideas?

Thanks Guys, maybe I'll just stick a mercury thermometer in the flue at the outlet from the roof. I'll do that tomorrow if the weather's OK and I'll report back.

Hello Thomas, thanks for the reply. The wood that I'm currently using is off cuts of kiln dried pine framing timber, so I'd imagine that the moisture content would be on the low level.
You are correct in that there is no cob in the build. It's all steel and refractory construction. I'm just guessing that the exhaust gas temperature is around 60C. I have no way of measuring it as yet. I'll have to buy one of those infrared thermometers. The bottom of the bell sits at around 140C (as in the image). So from there it's about a 9 metre flue run to the exit point through the roof.
I'm still hoping it may be from the refractory castings that make up the riser segments. But it just seems a lot.

Thanks Michael, so I imagine this H2O that is generated would normally exit the system via the flue. I wonder why then that I'm having this problem? Any suggestions on how to overcome this?

Hi guys, I've just finished my 10 inch batch box rocket heater and it's working fine and burning clean, but it seems to be generating a lot of water that ends up dripping from the base. At first I thought this may be water being purged from the refractory castings, but now I'm not so sure. I've done about 10 burn loads over the last 3 or 4 days and it doesn't seem to be easing off. If I had to guess, I'd say I'm collecting about half a litre per burn cycle.
Any advice on this would be most appreciated. Thanks.