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Observations 28 Year Later

July 11, 2009

First contraflow heater, 1981
This is the first modern contraflow heater built in Canada.
It is a mile down the road, at my neighbour's house.  I built it in 1981.

It was immediately after a workshop in Lincolnville Maine, where Albie Barden
had invited Heikki Hyytiainen over from Finland to build the first contraflow heater
in North America.

At that workshop, the modern North American double skin heater
concept was worked out, in a collaborative effort. Traditional heaters in Finland
up to that time had all been single skin, finished with their traditional 5.5" x 11" face brick
and sand/clay mortar.

The Lincolnville heater used clay common brick and clay mortar for the downdraft
heat exchangers, as does the heater above.

Photo shows heater when new.

contraflow heater
Recent photo from June, 2009.
Ksenia Chumakova, an architect interested in heaters, was visiting.

Note that this portion of the chimney has an unlined 4"x16" flue.
Soft reclaimed bricks with traditional thin lime mortar joints. There is
about 1/8" soot deposit in the chimney, after 28 years.

contraflow heater repair
The warped metal plate under the lintel is part of a secondary air system duplicating the Lincolnville heater. It was designed
to take combustion air and route it to a series of slots at the throat.

Subsequent testing showed that there is no negative pressure at the throat, and therefore this concept does not work.

Note the small air inlets in the doors. This is the total air supply for the heater, and is the traditional system from Finland.

contraflow heater repair
The firebox was built from 3"x6"x9" Empire SM firebricks that came from a local iron mine that had closed.
A considerable amount of hairlining is evident, but no spalling. The firebox is still perfectly serviceable.
The heater has been in operation full time every winter since 1981.
I'd estimate that it has burned roughly 150,000 lbs of wood.

22" firebox.

The good condition of the firebox is in large part due to the air system. It does not have a large underfire air grate, which was
added to the Finnish design in 1985, and used for several years in North America. Recent air research at Lopez.

contraflow heater repair
Even the original cast iron ash dump is intact.

contraflow heater repair
I cut out the warped plate with an oxy-propane torch.

contraflow heater repair
A lintel brick fell out. It was replaced with rigidized ceramic fiberboard, to keep heat off the facing. The surrounding brickwork is sound.

contraflow heater repair
Refitting the doors.
The original Honda motorcycle spoke mounting system was replaced with 4 Tapcons.
Note the exhaust fan in the nearby window to keep fine dust from migrating throughout the house.
The shopvac has a HEPA filter, and is handy to keep dust escaping from the firebox, etc.

This page was updated on July 17, 2009
This page was created on July 12, 2009