Heat-kit HK-22fo Manuale utente
HeatKit core assembly manual
AUTHOR NAME
Heat-Kit System
Modular Contraflow Masonry Heater Core
Assembly Manual
HK-22fo
22” Firebox with Front or Rear Bake Oven
Updated on November 21, 2017
HeatKit core assembly manual
November 21, 2017
01
200
Standard Firebricks 4.5”x9”x2.5”
(2.5” dimension may vary.
Important: The 4.5” and 9” dimensions are important)
10
Firebrick “Splits” 4.5”x9”x1.25”
2 bags
“Mortar Mix” (ie., premixed with sand, as opposed to
“Masonry Cement”, which requires mason’s sand)
Material List (in addition to core components)
Assembling the Bottom End
The bottom end of a contraflow heater is the most complicated part of the whole job.
The two downdraft channels connect here, underneath the firebox. As well, the
chimney connection and the cleanout openings for the particular installation need to be
determined and located here.
We’ve removed as much of this complication as possible with the Heat-Kit system. The
insulated base slab allows you to do a dry layout first and make sure that everything is
located properly in relation to the chimney and the slab. As well, our thinwall refractory
castings simplify the job of making the necessary cutouts with a portable masonry saw
or a skilsaw.
If you take a little
extra time at this
stage, particularly
with the layout,
you'll avoid
problems later on.
Concrete tie wire
HeatKit core assembly manual
November 21, 2017
02
Position insulating base slab dry to determine layout for heater and chimney.
Mark final position at corners with a pencil.
Set insulating base slab in a 1/2" mortar bed, and level.
Determine location of chimney connection and location of 2 cleanouts, one for
each bottom channel. In the illustration above, a 7" x 11" cutout is shown in
the right channel, towards the back of the long side. Shown next to it is a
cutout for a 5.5" x 5.5" cleanout that will be in the facing.
The left side also requires a cleanout at the base (not shown).
Mark clean out cuts on the base channels. Mark chimney connection on base
channel.
Cut appropriate holes for chimney connection and for clean outs.
Set base channels dry. Use the plywood spacer to stabilize the channels as
shown. Bottom seam will be sealed later by mortar slush between channels
and facing.
HeatKit core assembly manual
November 21, 2017
03
Brick Cuts:
For firebricks
standard sizes are:
full ---- 9"
3/4 ---- 6-3/4"
half ---- 4-1/2"
1/4 ---- 2-1/4"
Build connecting
channel, using
refractory mortar.
If there is a rear
chimney, leave opening
and span with flat bar
supplied. Notch bricks
to accept flat bars, thus
allowing you to
maintain thin joints.
1'-11 1/8"
1/2
1/4
1/2
1/4
1/2
Firebrick shiners at the rear are flush with outside of slab.
(Note: “shiner” = brick set on edge)
Outside-to-outside on the firebricks (front-to-back) is 1-11 1/8" as shown.
Once first course is set,
install velcro strap
(supplied with core kit)
to stabilize bottom.
HeatKit core assembly manual
November 21, 2017
04
2 1/4"
1 1/2"
3"
1 1/2"
2 3/4"
1"
1/4"
Second course.
Refer to isometric views on next page.
Cut 1/4" deep notches
for flat bars as shown.
HeatKit core assembly manual
November 21, 2017
05
Set flat bars as shown.
You can use a
refractory mortar bed if
they need levelling.
HeatKit core assembly manual
November 21, 2017
06
Set sub-floor slabs in
refractory mortar. Use
a thick bed to allow
some room for
levelling.
Refer to install video
https://vimeo.com/211
742460 at 2:15.
Raise the strap to the
level shown above.
This will stabilize the
channels enough that
you can remove the
plywood spacer.
This will give you
better access for
working
Set the slabs flush with the front firebricks.
Use the channel edges as a guide.
Note (below) that at the rear there will be a jump and the slabs are
not flush with the firebricks below.
HeatKit core assembly manual
November 21, 2017
07
Do a dry layout of the firebricks for the firebox floor.
You are using standard shapes - 1/2's and soaps.
(Soap = firebrick ripped lengthways into two 9" x 2-1/4" pieces).
Cut the notches to fit the two grates.
2 3/4"
1'-0"
Set the floor bricks.
Line up the rear
corners with the slabs
below, using the
channels as a corner
guide for the rear
corners.
See next page for
notes on setting
firebricks with
refractory mortar.
1"
HeatKit core assembly manual
November 21, 2017
08
Setting Firebricks
Firebricks are laid up with clay air setting refractory mortar (“Sairset”, or
fire cement) with thin joints. Only enough clay needs to be used to
completely fill the joint. No joint thickness needs to be built up - you are
only filling in gaps and irregularities between the bricks. Although masons
are used to trowelling firebricks, the best joints are obtained by dipping the
bricks into mortar that has been thinned to the right consistency. It looks
messy, but the cleanup is easy later with a sponge.
The Sairset that comes with the heater core kit is at trowelling consistency.
For dipping, you will need to thin it with water. A drill powered drywall mud
mixer works well for this. You can tell if the Sairset has the right
consistency by floating a firebrick in it. It will sink about half way. We like
to dip the bricks and also keep a margin trowel (small rectangular trowel)
handy for the odd bit of trowelling.
Assembling the Firebox
The firebox is laid up from standard firebricks. Standard firebricks are 4 ½”
wide by 9” long by 2 ¼” thick. The thickness will vary between 2 ¼” and 2
½” depending on the supplier. Since the Heat-Kit is designed around the
standard firebrick module, it is important to check the width and length of
your bricks beforehand, to avoid having to make modifications to the
assembly procedure.
The firebox consists of two shells of firebricks set on edge. This allows the
inner shell to be a field replaceable firebox liner. The firebrick installation
sequence has been numbered. By following this order, you maximize the
ability to “bury” odd lengths where they don’t show and reduce the
amount of precise cutting that you have to do. Note that full contact
between inner and outer shell is not required at the inside corners. Where
convenient, a little play right at the corner provides some expansion room
for the liner.
HeatKit core assembly manual
November 21, 2017
09
4-1/4"
2"
Lay out the firebox as
indicated, using air
setting refractory
mortar.
Non-standard cuts are
indicated by
dimensions
(2" and 4-1/4" here)
instead of the standard
firebrick shapes
ie., 1/4, 1/2, 3/4, full
Firebrick corners sit dry
against the fiberglass
rope gaskets.
Channel edges act as
corner guides.
Outer width of firebox
is 31 ½”.
4-1/4" if your firebricks are 2-1/4" thick
or 4" if your firebricks are 2-1/2" thick
Exact bond is
dependent on firebrick
thickness, generally
between 2-1/4” and 2-
1/2”.
Front bricks on the
second course are
halves. Put the cut side
out (towards the front).
The grates are shown
for reference only.
Better to install them
at the end.
