Saturday, December 8, 2012

Fireplaces


FIREPLACES


The typical open fireplace is notoriously inefficient.  In a typical masonry fireplace, most of the heat goes up the chimney instead of warming the house.  In addition, the air that it consumes in the combustion process gets sucked in from the outside which usually cools the house rather than heats it.  Still they have an undeniable charm. What could be cozier than being bundled up on a sofa in front of a crackling fire, drinking hot chocolate on a cold winter evening? 
When Ben Franklin invented the cast iron freestanding stove, efficiency dramatically improved.  The stove and the chimney were both in the room and radiated heat into the room rather than sending most of the heat up the chimney.
A further improvement was the the prefabricated fireplace with a blower system that circulated air around the steel firebox and back into the room, allowing the firebox to be in the wall but function similar to a woodstove.

Just before we were to order the fireplaces I got the bid for the installation of the fireplaces and. realized something was wrong.  The bidder proposed using triple wall stove pipe for a Napoleon Direct vent gas fireplace insert, which I knew wasn't right.  So I decided to rewrite the bid myself.  In the process I downloaded all the installation manuals for the gas fireplace insert, which was supposed to be in the loft, the Heatilator wood burning fireplace insert on the main floor, and the freestanding wood stove for the basement which I had bought from Lowe's.  It was then that realized that there was not enough clearance around the Heatilator for the triple wall stovepipe coming up from the basement.  A 6 inch triple wall pipe is actually 10 inches in diameter and requires a 2 inch clearance around it for a total of 14 inches for a 6 inch pipe.  I pondered our predicament for a long time and came to the conclusion that we had to put the Napoleon in the basement.  That way the Direct vent tubing would clear the side of the Heatilator and could continue up the chimney. Then if we put an angled offset in the Heatilator stovepipe and took it to the other side of the chimney, the pipe from the woodstove could go up the center.  We had to take into consideration complicated building codes  surrounding fireplace installations.  Finally I drew up plans and diagrams for installation of all three fireplaces and. a list of materials.  It seemed to satisfy the contractor and building inspectors.  I was a little concerned about one requirement the the top of the chimney be at least two feet higher than any nearby point within 10 feet.  I think that because we have a slate roof we didn't have to raise the chimney another three feet.  We did have to have custom chimney cap made to allow for required vertical and horizontal separation of the various terminations of each stovepipe.





The showpiece is the Heatilator.  We asked the contractor to build a stone surround for the front of the fireplace, and he also found a beautiful massive piece of slate for a mantel which he installed using concealed metal brackets and supports to give it a very realistic appearance.  The overall appearance is a fireplace constructed of natural stone, but is in reality a steel firebox lined with firebrick and having a sophisticated blower system and outside air intake for maximum efficiency.  The hearth likewise has a natural stone veneer. 


 


The Napoleon gas fireplace has a gas log, but similar to the Heatilator, has blower system that circulates air around the combustion chamber and brings in outside air for combustion for good efficiency.





The freestanding wood stove is resting on a section of ceramic tile over cement board to satisfy code requirements.  The woodstove is a basic design, but does have a airtight door and a damper.






We elected not to install central heating in the cabin for a variety of reasons.  First, I wanted us to be less dependent on the electrical grid,  which is sometimes unreliable and in my opinion, quite vulnerable  in our neck of the woods. We remember what happened with the Wallow Fire of 2011, which took out the main power transmission line and shut off power to the entire areas for 2 weeks.  Second, is to maintain the rustic charm of having a cabin in the woods and to get away from "civilization" in a small way.  Thirdly, there is the satisfaction of being self-sufficient and we do have plenty of free firewood,  with the trees that we cut down for the construction. 

There was a possible problem which we anticipated,  of convection.  Heat rises, and with the open stairwell that goes from the basement to the loft,  we anticipate that cold air will sink to the basement, and hot air will rise  and collect in the loft, making the loft unbearably warm.  We installed a fan in the basement, which will draw cold air from the basement, and force it up the elevator shaft through vents in the floor of each level, up into the loft.  This will cause air to circulate vertically through the cabin   Additionally, we have ceiling fans on the main floor and loft to circulate the air.

Just for insurance, we also have radiant heating elements under the tile in the kitchen and main and upstairs baths.  Originally, the architect drew the plans with radiant heat in all the floors,  but the contractor was uncomfortable with that, so we compromised and just put it under the tiles.  We think the radiant heat elements will help keep the house warm,  in addition to making the tile more comfortable underfoot.

And that, folks, is our HVAC system (heating, ventilation, and air conditioning) system, in a nutshell. 

Here's good book about fireplaces, with lots of pictures of different fireplace styles:  Fire Places: A Practical Design Guide to Fireplaces and Stoves Indoors and OutJane Gitlin, The Taunton Press, 2006

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