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2017 MHA Annual Meeting

Test Heater by AFPMA

36" Castable Refractory Oven Experiment
Kachel Workshop
Large Double Bell
Squirrel Tail Oven
Pat Manley Oven
Test Heater by AFPMA
Firetube Multifunctional Masonry Heater
Batch Rocket Cookstove and Heater
HMED 22" Contraflow
Small Finnish Contraflow for Beginner Masons
Quick Grill by Chris Prior
Tulikivi TU-2200 Top Vent
Tiileri Brick Heater Kit
Archguard demo

Download assembly drawings
Download Sketchup model

Base and firebox floor.


The gap between the firebox and the outer skin is a passageway for combustion air,
which enters the firebox through horizontal slots at each course.

Horizontal air slots are visible. The are created by sitting the firebricks on spacer shims.

Firebox lintel brick.

Strips of white ceramic fiber create expansion joints between the firebox and the heat exchanger.

The gases will exit the firebox at the top and then downdraft through the first heat exchange channel.

A stainless tube is embedded that will act as a pressure measuring location for the top of the firebox.

Firebox ceiling is a piece of vermiculite board

Exit from the downdrafting heat exchange channel is visible at the bottom. The vertical brick is a temporary support.

View of the air slots.

After the gases leave the downdrafting heat exchange channel, they enter the left side of the horizontal bench.

They return at the end, and will exit the right side at the top of the bench.

The gases enter a vertical section of brick chimney. The transition section, shown above, will support 8" stainless pipe.

Firebrick chimney section.

Capping slabs over firebox.

Ready for stainless pipe.

Capping the bench with soapstone slabs.

Soapstone slabs are installed as bench tops.

Installing the firebox door.
Damien Lehmann designed the heater. He is a founding member of AFPMA, the Masonry Heater
Association of France. He has developed an open source version of a handbuilt heater calculation model, based on EN-13384.
AFPMA is collaborating with MHA to build a testing lab in France and in Canada to do verification testing to proof the calculator model.

Curing fire with small wood.

Carsten Homsted sets up the Condar portable dilution tunnel particulate sampler.

Curing fire continues with a load of regular firewood. The goal is to have the heater completely dried out for testing the next day.

Next day mid-day.
First test load was lit at  1:07 PM. Note that the camera shows one hour earlier. This photo is at 1:40, ie 33 minutes into the test.
The heater has clay plaster, and you can see it starting to dry out around the door.

Very intense fire with the Eco-labelled air system. 
Austrian air specification.
The heater was burning way too fast, and the Condar filter plugged up at 38 minutes, highly unusual.
PM was 5.08 g/kg, or very high (for a masonry heater).
Spoiler alert: we increased the size of the wood slightly for the next test, and the PM cam down to 0.7 g/kg.

Burning clean.

Note the progression in the drying of the plaster from 54 minutes earlier

Carsten Homsted pulls the final set of Condar filters for weighing.

Laboratory balance for weighing the 4" glass Condar filters. Set on a solid non-vibrating surface.
Balance resolves to 0.0001 gram

Test #2, the following day. 
Ben Myren weighing kindling for fuel load.
Ben runs an EPA accredited testing lab in Colville, WA and has more than 30 years experience in the field

For the first test, the firebox was still fairly hot from curing late the day before, which also contributed to the over-amping. It was a valuable demo. Comparing predicted values from the calculator, indicated that the heater needed more heat exchange. Ie.., stack temperature was too high..
This resulted in the burn rate going high enough that there was not sufficient air anymore, resulting in high emissions.

Alexandre Paquin helps Ben Myren with the wood.

The weight is written on each piece, and the geometry of the fuel pile is documented.

The computer on the right runs the Testo 330-2 gas analyzer.
The other computer is from the MHA lab in Shawville Quebec

A scaled down 5 channel version of the pressure sensing setups that we have at the MHA and AFPMA labs.
The Sensirion SDP-610 digital sensors are very accurate and repeatable with a resolution of 0.1 pa.
They are part of our collaborative project to verify a software model for one-off handbuilt heaters.

MHA lab computer. The white dongle at the back is an IOWarrior
It provides the digital interface between the sensors and the computer's USB port.
Note there are only 4 wires, yet up to 128 separate channels of pressure readings can be connected via the
I2C digital communications protocol. The data logging is done via DAQFactory Pro.

Stacking the load for the second test run. Larger fuel pieces were used, compared to run #1.
Fuel load was 21.9 kg at 16% moisture.

Weight and piece number (position in the firebox stack) is marked on each piece and recorded.

First row.

Second row.

Third row.

Kindling sits in a gap between the two larger pieces.

At 10 minutes, only white steam is visible from the stack.

Ben Myren made a drawing explaining how fire box volume is calculated for EPA certification testing, to determine the fuel load.

Fuel load was 21.9 kg plus 0.8 kg kindling for a total of 22.7 kg.
According the new ASTM cordwood method that will be used for EPA testing for woodstoves, the load for a firebox this size should be 25.0 - 30.4 kg.

Labjack T7 Pro
It can handle up to 40 channels of thermocouples or other sensors, and is interfaced with DAQFactory Pro at the MHA and AFPMA labs.

At 13 minutes, the stack temperature is high enough that there is no steam condensing.

PM for this run was 0.7 g/kg, which is cleaner than the average of 6 common pellet stoves that we have measured with the Condar.

View of portable testing setup showning pressure and temperature connections.

Firewood pieces with individual weights marked (in lbs).

Stacking fuel load for third test run, Friday afternoon (pizza party day).

Test nearing the end, as the pizza party is gearing up in the background.

One of many reloads.
We had the chance to do a bit of destructive testing ;-) to see how the single thickness firebox would stand up.

Lab Notes:

See also:

2016 Photo Report

2015 Photo Report

2014 Photo Report

2013 Photo Report

2012 Photo Report

2011 Photo Report

2010 Photo Report

2009 Photo Report

2008 Photo Report

2007 Photo Report
2006 Photo Report
2004 Photo Report
2003 Photo Report
2002 Photo Report
2001 Photo Report
2000 Photo Report
1999 Photo Report
1998 Photo Report
1997 Photo Report

This page was last updated on February 2, 2018
This page was created on April 18, 2017

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