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rocket mass heaters

Uncle Mud Rocket Heater Repair--Troubleshooting Poor Draft

Chris McClellan

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Location: Burton, Ohio

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posted 2 years ago

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This pretty rocket mass heater had stopped drawing so I got to bust it open and find out why. Some of the earlier Rocket Heater builds didn't include a way to easily remove the barrel for cleaning, so eventually the heater would clog and the fire wouldn't stay lit. I got to see this heater last year when the new owners of the home called me out for an inspection. Now I get to tear it apart and see why it has stopped working. Stay tuned for part 2

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Chris McClellan

gardener

Posts: 689

Location: Burton, Ohio

358

posted 2 years ago

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This is where we go up on the roof and take a peek down the chimney. Stay tuned for more

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Chris McClellan

gardener

Posts: 689

Location: Burton, Ohio

358

posted 2 years ago

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My local fire inspector declared the Rocket Mass Heater as "the first non-suicidal woodstove." He was very excited at the idea of a woodstove that doesn't produce creosote. Compared to other woodstoves Rocket Mass Heaters burn very clean if everything is working right but the chimney still needs to be cleaned and inspected at least every year. At the top of my most likely reasons for a heater to be misbehaving, a blocked chimney is Numero Uno. Bird nests, dead racoons, even just ashes can reduce draw, which kills heater performance.
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Chris McClellan

gardener

Posts: 689

Location: Burton, Ohio

358

posted 2 years ago

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Can a chimney really get clogged by cobwebs?

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Chris McClellan

gardener

Posts: 689

Location: Burton, Ohio

358

posted 2 years ago

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Inspecting and Cleaning the Chimney
Now that we can see all the way down the chimney we can see that there is some spalling in the liner and it will eventually need to be lined or replaced BUT this chimney is not blocked and it is not the primary cause of our draft problem. We are going to have to go back inside and tear things apart to discover why this Rocket Heater isn't very rockety. Stay tuned for more!

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Chris McClellan

gardener

Posts: 689

Location: Burton, Ohio

358

posted 2 years ago

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Uncle Mud Rocket Heater Repair--Tearing Into the Pipes
So now we've cleaned and inspected the chimney outside. It was a little dirty but not obstructed, so there's something going on inside also that is slowing down the draft on this Rocket Heater. I'm working backward from the chimney so I can keep track of where I've checked and note any improvements in the draft. Almost immediately I find something major. Stay tuned to see what happens next.

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Chris McClellan

gardener

Posts: 689

Location: Burton, Ohio

358

posted 2 years ago

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Here's the part where I report to the owner on what I found inside the chimney. I'm one of those "If you don't know how it works you don't own it" people so I want him to be very clear what is working and what is not. With the pipe taken apart and cleaned you can feel the draft, but you can also feel the cold mass of the clay tile and concrete working against you and causing a counter-draft of cold air going down the chimney. There's a lot about this heater that would work so much better if this old block chimney were replaced by an insulated stainless steel chimney, but that is a lot of money.

#unclemud #rocketmassheater #rocketheater #chimneyrepair

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Phil Stevens

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Location: Ashhurst New Zealand (Cfb - oceanic temperate)

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posted 2 years ago

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Great work. Expert diagnosis, Doctor Uncle Mud. And your explanation of the problem is clear, precise, and well-pitched so that just about anyone would get it. This series is a lightbulb moment for why masonry chimneys make fires work harder, not smarter.

Chris McClellan

gardener

Posts: 689

Location: Burton, Ohio

358

posted 2 years ago

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Chimneys competing for draft: A tightly sealed house with multiple chimneys can create a situation where the woodstove and the gas or propane water heater and furnace and clothes dryer are all competing with each other for the little bit of air that gets in through the cracks around the windows and doors. This can cause those appliances to draft poorly or even leak CO and CO2 into the house. I strongly recommend that each device has its own properly sized outside air source so the air in the house is mostly for breathing by people. Also get yourself a CO detector.

In this case we determined that there was plenty of air getting into the house but the missing door on the cleanout at the bottom of this chimney was using up a good chunk of the tiny amount of draft this massive cold chimney produces. We're going to fix that by closing off the cleanout and continuing to remove obstructions in the chimney.

#unclemud #rocketmassheater #rocketheater #chimneyrepair #chimneycleaning

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Chris McClellan

gardener

Posts: 689

Location: Burton, Ohio

358

posted 2 years ago

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Which Way do we Go George?

Working backward from the chimney we find ourselves staring down into the mass bench. From this angle it looks like the exhaust pipe is falling apart at the bottom or somehow opens up in multiple directions. It turns out that is an optical illusion. The pipe needs to be cleaned of ash and a little creosote but the cleanout ports are small and far away. Fortunately the residue inside a rocket heater is usually dry and flaky instead of sticky so it doesn't need to be scraped away at with a stiff handled chimney brush that needs direct access. We can easily clean a rocket heater with a vacuum with a good filter. I strongly recommend investing in an actual ash vacuum. A good long tube helps get around the corners of your exhaust where piles of ash like to hide clogging up the works.
Stay tuned as we go after them.

#rocketmassheater #unclemud #rocketheater #chimneyrepair #chimneycleaning

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Chris McClellan

gardener

Posts: 689

Location: Burton, Ohio

358

posted 2 years ago

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Now We start trying to figure out what the builder did with the pipe inside the mass.

Working backward from the chimney we find ourselves staring down into the mass bench. From this angle it looks like the exhaust pipe is falling apart at the bottom or somehow opens up in multiple directions. It turns out that is an optical illusion. The pipe needs to be cleaned of ash and a little creosote but the cleanout ports are small and far away. Fortunately the residue inside a rocket heater is usually dry and flaky instead of sticky so it doesn't need to be scraped away at with a stiff handled chimney brush that needs direct access. We can easily clean a rocket heater with a vacuum with a good filter. I strongly recommend investing in an actual ash vacuum. A good long tube helps get around the corners of your exhaust where piles of ash like to hide clogging up the works.
Stay tuned as we go after them.

#rocketmassheater #unclemud #rocketheater #chimneyrepair #chimneycleaning

You can follow my latest adventures at
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Chris McClellan

gardener

Posts: 689

Location: Burton, Ohio

358

posted 2 years ago

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We Need More Chimney Inspection and Cleanout Ports Here--The pipes going through the mass bench of a Rocket Mass Heater do accumulate ash from the fire over time so they need to be inspected and cleaned out at least once a year. I have been hired to come clean out this lovely old school Rocket Heater and figure out why it isn't drawing very well. My conclusion is that there are corners we can't reach inside the mass that are clogging with ash and we need to create additional inspection/cleanout ports to make it easier for us to take care of those trouble spots.

#unclemud #rocketmassheater #chimneycleaning #chimneyrepair

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Chris McClellan

gardener

Posts: 689

Location: Burton, Ohio

358

posted 2 years ago

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Cutting Off the Barrel for Cleaning and Improved Draft
Here's where we find out what's going on inside the Rocket Heater itself. The current build has no way to inspect or clean under the barrel without breaking open the lime plaster and cob bench then rebuilding it each time we want to clean. We also suspected that there is some sort of pinch point inside there that we need to resolve. Sure enough the space between the top of the riser and the barrel was so small that the ash building up on the rim of the riser was clogging things up. Our solution is replacing the cut off end of the barrel with a full new removeable barrel to give us more clearance and easier access for future inspection and cleaning and repair.

#unclemud #rocketmassheater #rocketheater #chimneyrepair #chimneycleaning

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