I've heard that an exposed masonry chimney on an exterior wall is not efficient, as it radiates heat into the outdoors, and fireplaces in general are not efficient.

I'm considering a house plan that is rated as being green, (LEEDS, etc), that has a fireplace on an exterior wall. I would plan on having the "fireplace" built around a wood stove insert, rather than retrofitting one to it after building.

Another change to the plan is that I'd also consider moving the chimney to the center of the house. Are there any good reasons for an exterior chimney vs one in the center of the house, other than esthetics? I've heard water infiltration around chimneys can be a problem. Do exterior ones leak less?

I have suffered through one house with an exterior fireplace in Minneapolis and would not do it again in the north.  An exterior fireplace keeps a large quantity of cold air just waiting to fall through cracks and gaps in the damper.  After a fire in very cold weather, we had a residual smokey smell for days afterwards from this infiltration.  My houses with interior fireplaces never had this problem.  Pressurizing the house solved, or at least minimized, the problem. 

The exterior fireplace was also hard to light against the cold air falling down from the damper.  Unless you got a big fire going quickly, smoke in the house was the result.  Once it started drawing, it was fine and worked OK.

The fireplace on this house was on the exterior at the low side of the roof and had a very tall freestanding chimney to get above the roof peak, so it held a big column of cold air.  A 24' ladder let me get precariously to the chimney cap.

Having said that, an exterior fireplace near a gable peak (very short chimney) in Houston was not a problem, so I think it was a combination of the very cold weather and tall, freestanding chimney that caused this problem.  Moving from Houston to Minneapolis in the winter is more than a person should bear!

Fireplaces are a waste of money in my view.....but everyone wants one.  In our Minneapolis home, the chimney had a second flue that was roughed-in in the unfinished walkout basement.  We did a woodburning stove there when we finished the basement and loved it (it had the same problems as the fireplace).

I do not think a chimney on a gable end is any better or worse than an interior chimney from a flashing or potential leak standpoint.  It is all about good design and workmanship.

Bruce

In a interior fireplace, you get all the added benefit of all the thermal mass of the fireplace on the inside of the house. Also, your fireplace will be preheated for when you start a fire, preventing most of the initial backdraft due to a cold chimney.

A chimney that comes through the roof at the ridge will give you the least potential for leakage, because it is where the roof drains into the chimney that is prone to leakage.

But you also don't have to have a big masonry chimney. A free standing wood stove with a stove pipe chimney will be efficient, use class A through the ceiling and roof.

The wood stove would be more about decor, (and a backup heat source should the electric power go out long enough for the backup generator to run out of fuel), so I want a masonry fireplace look without the heat loss associated with fireplaces. I guess I could encase it in masonry up to the ceiling, then just run the stack through the roof as you would with a freestanding stove. I've seen a house with some stacks through the roof that the owners have recently built boxes around which I guess they'll "brick face" in the spring to improve them esthetically.

I'm not sure you could get a "Leeds" certification if you have a masonry fireplace in your design. Masonry fireplaces are considered as a heat loss factor, and have a negative effect on your heating system. There are several reasons for this.

Say you want to have a fire for the evening, just for the ambience ( that is about all you will get with an open hearth fireplace). After enjoying the fire for a couple hours, you have succesfully heated up the thermal mass (chimney) that will stay warm for hours to come. That warm chimney will suck the heat out of your home for hours. Fireplace dampers cannot seal off this heat loss.

Yes, some claim to get heat in the room that the fireplace is in, (radiant heat only), but the heat lost up the chimney (warm room air) outweighs the benefits. In other words, you will feel the heat on your body as you sit near the fireplace, but at the same time the chimney is pulling tons of warm air out of your house until the thermostat turns on the heating system, feeding the chimney a considerable amount of your heat.

If you are going to proceed with a fireplace, the absolute best location for the chimney is to keep it within the envelope of your home. As already observed, the thermal mass will be somewhat conditioned, aiding in a smoke free start-up.

The biggest reason to have an interior chimney is because of negative pressure in your home, which likely exists: Negative pressure is caused by lots of things such as bathroom fans, clothes dryers, range hoods, and furnaces. This negative pressure (vacuum) will pull air from wherever it can. A cold exterior chimney has a marginal draft already. Negative pressure could cause the flue to reverse, spilling smoke into your home.

Additionally, the 'stack effect'  will cause smoke spillage in many homes. This happens because sometimes a house makes a better chimney than the chimney itself. In a heated home, as the heat rises to the upper levels, you are creating negative pressure in the lower level, which will pull smoke out of the fireplace.

The 'stack effect' will worsen with any type of air leak(s) in the upper levels, including some types of recessed lighting, open windows, etc..

There are some new style fireplace dampers which are installed on the top of the chimney. These are of a much better design, as they are gasketed, and are less prone to the problem of cold air infiltration when the fireplace is not in use. Also, since they are not open to the sky when not in use, the collumn of air inside the chimney will be conditioned, somewhat warmer, providing instant draft as soon as the damper is put into the open position. Even with this type of damper, everything mentioned above is still of concern, since the damper has to be in the fully open position when burning, and left fully open until the fire is fully extinguished... hours later... heat loss...smoke spillage...etc.

Mark

Well, I don't like fireplaces, but this plan has one and they claim it can be LEEDs certified. It perplexed me, too, as I know fireplaces are inefficient. http://www.FreeGreen.com/Free-House-Plan-Selection/6/Rustic-Retreat.aspx My preference would be to build a masonry enclosure around a wood stove insert.

wtb;

there are several fireplaces that are very efficient and some with EPA approved


http://www.icc-rsf.com/en/fireplaces/foyer_opel.asp#


http://www.americanenergysystems.com/magnum_zc.cfm


http://www.renaissancefireplaces.com/index.html


I have a fireplace in my home now, but the next home will have an efficient fireplace that we can actually rely on to heat the home

Also check out the Fireplace Xtrordinair wood burning fireplaces. They are the only ones (that I am aware of) that actually provide positive pressure to heat your home with. The remote fan comes on after the unit is hot, supplying your home with pre-heated outside air. Excellent idea for anyone concerned with indoor air quality. Plus, the drafting issues mentioned earlier are minimized or eliminated.

www.fireplaceX.com

They look like a traditional fireplace, but act more like a built-in wood stove. The "36 Elite" model has the highest effeciency rating ever achieved by a  wood burning fireplace.

I would reccomend insulating the chase all the way to the top if you are building in a cold climate.

Another option may be a free standing wood stove. Your plans look as though they could be modified very simply to accomodate one. Instestead of a fireplace, build an alcove (bump-out) for your stove to sit into. Just be sure to leave a finished inside width of about five feet! An alcove installation has special requirements. If you have your stove picked out ahead of time, check the alcove requirements as far as the minimum inside width. Otherwise, you will be forced to accept another model that you may not have chosen.

Mark

When you visit Cape Cod, there is no doubt that you are witnessing a unique style of architecture rooted in colonial times when simplicity and functionality where at their best. There are many characteristics of the Cape Cod architecture style that permeate still in todays modern versions.