MHA News - HMED Heater Mason Education and Training, September 2013, Perth Ontario

Return to Masonry Heater Assoc. Home Page

  Gallery   The Mall   Member Directory   MHA News       Library   Links    

MHA HMED Class
Sep 12-15, 2013  -- Perth, Ontario

Photo story by Norbert Senf
MHA HMED 2013
Standing, left to right: Stan Grabowski, a mason from Mississauga ON, instructor Norbert Senf,
instructor
John McDougall, who hosted the workshop, Nathan Lamberts, a mason from Guelph ON.
Front row: Alexandre Paquin, an apprentice mason from Gatineau QC, John Scott, an instructor
in the Algonquin College
Heritage Masonry program, Adam Janowski, a mason from Mississauga ON,
and Scott Horrocks from Rupert QC, who is planning to build a house with a masonry heater in Nova Scotia.
Not shown: Mathew McCartney, a mason from Kingston, ON.


MHA HMED 2013
HMED is MHA's Heater Mason Education Development program.

We guide the class through the build of the 22" Contraflow heater from the MHA Heater Plans Portfolio

MHA HMED 2013
John had precast a firebox floor (shown) and insulating base slab. These are the first two castings
used, and allowed us to start the build right away. As an exercise, we formed and cast all the castings
for this heater during the workshop.


MHA HMED 2013
Firebox floor with the air plug removed


MHA HMED 2013
Setting the insulating base slab into a bed of mortar.


MHA HMED 2013
Alex brought a
two paddle mixer, which we checked out. Here we are mixing a very dry batch of
castable, which would be impossible with a drill mixer. Because the two paddles rotate in opposite
directions, the bucket does not spin.


MHA HMED 2013
John Scott re-assembles the firebox floor mold to do another casting.


MHA HMED 2013
Regular castable refractory concrete has to be mixed very dry. There was no mix ratio printed
on the bag, so getting the water right was an important part of this demonstration.


MHA HMED 2013

MHA HMED 2013
Vibrating the concrete with a stinger.
Click for video

MHA HMED 2013
The top is floated with a magnesium or preferably wood float. A steel trowel is not used, to
leave the surface open for drying.

MHA HMED 2013
Building the mold for the 3 oven pieces. Note that these slabs are steel reinforced.

MHA HMED 2013
Building the mold for the 3 ceiling slabs. Plastic eavestrough has been modified to make
improvised separators that will create lapjoints between the slabs.

MHA HMED 2013
The screws and seams are taped to prevent water getting into the MDF formica board and
swelling it.

MHA HMED 2013

MHA HMED 2013

MHA HMED 2013
Meanwhile, at the heater build, laying out the first course.

MHA HMED 2013

MHA HMED 2013
A view of John's beautiful new shop. Check out his masonry boiler fired hydronic slab.

MHA HMED 2013

MHA HMED 2013

MHA HMED 2013
Setting the firebox subfloor.

MHA HMED 2013
Firebrick firebox floor.

MHA HMED 2013
Outer wall of the two shell firebox, which has a replaceable inner liner.

MHA HMED 2013

MHA HMED 2013

MHA HMED 2013

MHA HMED 2013
Washing up the inner shell, which will be visible.

MHA HMED 2013
Demolding the bake oven slabs. Note there is some honeycombing - the mix could have been
slightly wetter. A vibrating table would handle a stiff mix like this, but would need beefier molds.

MHA HMED 2013

MHA HMED 2013

MHA HMED 2013

MHA HMED 2013
Detail of the lap joint in the ceiling slabs.

MHA HMED 2013

MHA HMED 2013
Intstalling the bake oven floor.

MHA HMED 2013
Installing the bake oven back.

MHA HMED 2013
Gasketing the rear of the bake oven rear slab.

MHA HMED 2013

MHA HMED 2013
The bake oven ceiling casting should have been cast upside down to get a better surface finish
on the visible side. Here John is resurfacing the slab with his favorite tool, a flush mount diamond
blade.

MHA HMED 2013

MHA HMED 2013

MHA HMED 2013

MHA HMED 2013
Installing the bake oven ceiling. This is a white oven, which means that the flames go around the
oven instead of through it. It is the 4th generation of the original Heat-Kit design,  with excellent
performance.

MHA HMED 2013

MHA HMED 2013

MHA HMED 2013
John Scott eyeballs a compound cut on the
Karl Dahm saw. This saw is very quiet and smooth.

MHA HMED 2013

MHA HMED 2013
Special German refractory blade. The blade is extremely well balanced and is the quietest
blade, by a long shot, that I have ever heard.

MHA HMED 2013
This 9" slice of firebrick is about 1/4" thick. On most saws, the vibration of the blade would have
broken it.

MHA HMED 2013

MHA HMED 2013



Check it out.

In the video, when the cut starts, there is not much extra noise above just the sound of the motor.
The sound was recorded by the camera standing right next to the saw. Compare with the
Target saw and regular blade starting up about 25 ft. away from the camera.

MHA HMED 2013

MHA HMED 2013

MHA HMED 2013

MHA HMED 2013
Height adjustment course above the bake oven to bring both sides level.

MHA HMED 2013


MHA HMED 2013

MHA HMED 2013
Ceiling transition. Rather than mortaring in the individual bricks in place on the core, we tried
mortaring them together on the bench, and installing them in bulk. 

MHA HMED 2013

MHA HMED 2013

MHA HMED 2013

MHA HMED 2013
Result: much faster.


Check it out


MHA HMED 2013

MHA HMED 2013
Cutting ceramic blanket into strips for use as expansion joints on the two downdrafting
side channels.

MHA HMED 2013

MHA HMED 2013

MHA HMED 2013

MHA HMED 2013
Stan starts the side channels.

MHA HMED 2013
Side channel half completed.

MHA HMED 2013
Each day there is a classroom component to HMED.
For this course, we also added the combustion seminar that I have done a couple of times at Wildacres.
Visible on the table is a Testo 330-2 gas analyzer (black case).
In front of it is a Condar portable dilution tunnel, used to sample PM-2.5 particulates (smoke).

MHA HMED 2013
Adding a cleanout for above the bake oven.

MHA HMED 2013

MHA HMED 2013

MHA HMED 2013

MHA HMED 2013
Ready to install the ceiling slabs.

MHA HMED 2013

MHA HMED 2013

MHA HMED 2013

MHA HMED 2013
Adding a cardboard slip joint to the core. Expansion in the major left to right direction is
handled by the 4 ceramic wool expansion joints, so expansion there is not an issue. However, the
core does need to be able to slide up and down inside the facing while maintaining good contact
with the facing for heat transfer.

MHA HMED 2013

MHA HMED 2013
Bonding out the facing bricks, and discussing the various issues that may come up.

MHA HMED 2013

MHA HMED 2013

MHA HMED 2013
Cutting a connection opening and a cleanout into an 8x12 clay flue liner.

MHA HMED 2013
Cutting an 8x12 flue liner to length on a 14" wet saw. The Target has more clearance and a
greater depth of cut than the Karl Dahm saw does.

MHA HMED 2013
Laser plumb bob.

MHA HMED 2013
Setting jack lines with the laser.

MHA HMED 2013

MHA HMED 2013

MHA HMED 2013
Jack lines are fastened to the temporary plywood, after marking the laser locations. Note the
long screws against the ceiling slabs, to prevent the plywood from moving.

MHA HMED 2013


MHA HMED 2013
Laying out a heated bench. Here, John demonstrates a great technique for laying out a
non-45 degree bevelled corner.


MHA HMED 2013

MHA HMED 2013

MHA HMED 2013
Finished result. Three pieces are cut from one flue liner.

MHA HMED 2013
The chimney connection is dismantled and modified to accomodate a heated bench layout.

MHA HMED 2013

MHA HMED 2013
John demonstrates a technique for adding a ledge to the facing, to hide the joint at the back of
the bench top.

MHA HMED 2013

MHA HMED 2013

MHA HMED 2013
Half of a wraparound bench. There are two loops, and the bench is left empty underneath the
firebox door, to allow access to the ashbox where the heater is slab-on-grade such as this.

MHA HMED 2013

MHA HMED 2013

MHA HMED 2013
A very important discussion about firewood. John is demonstrating the use of a moisture meter.

MHA HMED 2013
We took a walk to John's house to have a look at his heater, and do a burn. John's driveway
crosses the Tay river.  There is great bass fishing from John's bridge.
This is the troll that lives
underneath the bridge.


MHA HMED 2013


MHA HMED 2013
John used a cardboard slip joint on the left side of the heater, and an aluminum foil slip joint
on the right side. Since the chimney exits rear center at the floor, the two sides are perfectly
balanced. He has not taken surface temperature readings of the outside to see if there is a
difference, but plans to do it this winter.

MHA HMED 2013

MHA HMED 2013

MHA HMED 2013
We had a look inside the oven cleanout.

MHA HMED 2013
Photos of John's heater project. It involved removing an existing Rumford fireplace, as well
as several interesting structural and envelope thermal issues.

MHA HMED 2013
The heater was cold, and it is on an outside chimney. We had a torch ready in case it needed
a boost for startup. However, careful stacking of a top-down burn with 14% dry wood and small
kindling did the job.

MHA HMED 2013

MHA HMED 2013

MHA HMED 2013
A small amount of black smoke (soot) is visible from the heater flue at the start. If the firebox were
 warm, ie., a fire 24 hours previously, there would be no smoke, based on MHA's extensive
testing.

MHA HMED 2013

This page was last updated on August 21, 2014
This page was created on  September 17, 2013

Back to:
Return to Masonry Heater Assoc. Home Page