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Alaska Fireplace Retrofit Project

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Update: August 20, 2013:

CCHRC Fireplace Retrofit Design Contest
Fireplace Contest FAQ

Go to July 9/09 update on performance testing results

To: "Alex Chernov" <alex_stovemaster(at)>
. . . "'Norbert Senf'" <mheat(at)>

Subject: Fireplace Design Contest
Date: Wed, 13 Aug 2008
Organization: CCHRC

Thank you both for participating in the Fireplace Retrofit Design Contest sponsored by CCHRC.
Each of your entries had extreme merit and I have no doubt that either would work perfectly well for this application. 
The designs were similar in size and output and even had a strikingly similar materials list.
Based on this fact, the homeowners were asked to review the designs and select the one they preferred.  
They selected Norbert's design.
So congratulations Norbert and thank you Alex.
In my mind, both designs are winners but the homeowner had to choose only one.  Alex, with your permission,
I'd like to retain your design and try to find a future retrofit  installation for it with another homeowner.  
It would give us another opportunity to install and do testing.
Best Regards,

David Misiuk, P.E.
Cold Climate Housing Research Center
PO Box 82489
1000 Fairbanks Street
Fairbanks, Alaska 99708
(907) 457-3454
(907) 457-3456 (fax)


CCHRC Fireplace Retrofit Design Contest
Retrofit - Plan

CCHRC Fireplace Retrofit Design Contest

CCHRC Fireplace Retrofit Design Contest
Front Section through firebox (inner bell) and outer bell.

Right section.

CCHRC Fireplace Retrofit Design Contest
Isometric Rendering.

design by Alex Chernov
Section drawing of Alex Chernov's double-bell design

design by Alex Chernov
Sample facing design, by Alex Chernov


From: "Dave Misiuk" <dave(at)>
To: "'Norbert Senf'" <mheat(at)>
Subject: retrofit
Date: Mon, 27 Oct 2008
Organization: CCHRC

Hi Norbert,
Hope all is going well.  Going on week 4 of the fireplace project; haven't even been in the office.
I've attached a photo of our seismic tie concept at the bells.  Castable refractory for compression, all-thread with a bond-breaker for tension. 
Also adds some heat transfer mass.
Weve got a City building inspector who is a structural engineer checking the work so the piece of paper in the plans portfolio that
says no seismic required for heaters is pretty much out the window.

CCHRC Fireplace Retrofit Design Contest

From: "Dave Misiuk" <dave(at)>
To: "'Norbert Senf'" <mheat(at)>
Subject: RE: retrofit
Date: Tue, 28 Oct 2008
Organization: CCHRC

Hi Norbert,

The threaded rod on the seismic ties gets bolted to an external steel
framework of angle and flat bar which is also anchored back to the main
fireplace structure on the sides of the bells. This framework stabilizes the
core and also gives a place to attach brick ties that will go into the rock
facing. I'll send a couple pics when I get the framework installed and while
Dan installs anchors in the face.  Seismic is an interesting topic in itself
in this instance given the shallow depth of the bells.

We are placing capping slabs today, completing steel framework and starting
to run facing today.

Pic attached.


CCHRC Fireplace Retrofit Design Contest

November 15/08:
Comments by Igor Kuznetsov

November 17/08:
From: "Dave Misiuk" <dave(at)>

Hello Igor,
Thank you for the comments.

Your ideas on the structural integrity are interesting because the overall
structural design for this heater does, in fact, include an exterior steel
frame, using steel angles and flat bar, that is anchored back to the main
structure.  The steel frame is between the core and facing and is applied
horizontally with no constraint in the vertical direction.

Please see attached photo.

Best Regards,
seismic detail

From: "Dave Misiuk" <dave(at)>
To: "'Norbert Senf'" <mheat(at)>
Subject: Fireplace Retrofit
Date: Wed, 10 Dec 2008

Hi Norbert,
Good news today.  I went to the clients house this morning to install the door, chimney cap and light the 
first small curing fire.  I burned about 6 lbs of dry birch and everything worked perfectly.  The wood lit
easily and quickly, burned very well, and with little smoke.  Flue gas is exiting from both bells under the
firebox to chimney as witnessed through the cleanouts at the heater base.  Couldn't ask for more so far. 
The client has break-in instructions.  We will probably go back and fire it with the first full load next week.
We will then begin testing when the heater is up to temp.
P.S.  Good job!

Initial curing fire, 6 lbs of dry white birch

Date: Thu, 18 Dec 2008
From: Dave Misiuk <misiuk(at)>
To: Norbert Senf <mheat(at)>
Subject: Pics

Hi Norbert,
Here's some pics of the last couple week's activities. (snip)

Finished two days of testing at the retrofit house today.  Initial results look very promising although I haven't had time to crunch the numbers yet.

Birch with bark about 1.6 times the catch of similar run w/no bark. 
Just comparing w/the dutch heater runs of < 1 gm/kg, the filter catch was ~40% more with 2.5 times the wood and same sampling rate.  Stack temperature briefly over 300 F for one run, higher for the run when we opened the doors to see what would happen.  Combustion air...perhaps lacking as seems to be par for the course here.

Instantaneous efficiency readings during burn generally 83 to 85% except at tail-out.

Hard to say with varying facing rock properties, but large bell side seemed to run just slightly hotter judging by surface temps; again, hard to say definitively.

This is a responsive heater; the facing is about 4" thick.  Just the curing fires with a cumulative 65 lbs of wood got the face up to a good temp.  But also, they left the damper open last night and the heater was still very warm at noon just before our testing.

The homeowners are VERY pleased.

More soon.

Dan Givens - Alaska Retrofit Project
Dan Givens sets the stone facing.

Dan Givens - Alaska Retrofit Project
Testing setup.

Alaska Retrofit Project
Testo gas analyzer is on top of the step ladder, with sample line going up over the stone
to the test port in the chimney. Large vacuum line to the Condar dilution tunnel on the right. The red flue liner is visible directly behind
the Condar.

Alaska Retrofit Project

Alaska Retrofit Project

Alaska Retrofit Project

Alaska Retrofit Project

Date: Mon, 9 Mar 2009
Subject: Retrofit
From: Dave Misiuk <dave(at)>
To: Norbert Senf <mheat(at)>

Hi Norbert,

We filmed the final segment of our Fireplace Retrofit video last week.  The homeowners said that the heater exceeds all of their expectations on many levels: functionality, convenience, aesthetics not to mention ~20-25% savings in their oil heating bill.  They are extremely pleased and are actively spreading the word.  I hope to have the video for Wildacres; it will be about 45 minutes long.

I would like to put 3D graphics or an animation of the model in the video to explain the flow path, etc.  Would you be willing to share the original .dwg file to accomplish this?


CAD rendering
(Autocad model by Norbert Senf
Autocad rendering by Dave Misiuk)

Date: Thu, 9 Jul 2009
Subject: fireplace retrofit results
From: Dave Misiuk <dave(at)>
To: Norbert Senf <mheat(at)>

Hi Norbert,
Still have to double check the math, but the first run of the fireplace retrofit came in at 1.69 g/kg with white birch with no bark, top-down ignition:

Particulates= 1.69 g/kg
Combustion Eff= 94.9
Heat Transfer Eff= 76.7
Overall Eff= 72.8 (HHV)

The second run was white birch with the bark, top-down start but it fell from the top and ignited the whole fuel load (oops):

Particulates= 2.46 g/kg
Combustion Eff= 92.3
Heat Transfer Eff= 76.2
Overall Eff= 70.3 (HHV)

Still not bad for a first-pass design, with field modifications based on judgement, I think.

It qualifies for the IRS 75% efficiency by their LHV definition:




This page was updated on June 4, 2014
This page was created on October 28, 2008