Chimney Choices

Chimney are a biggest decision. Size and placement in an existing home sometimes leaves the homeowner with little choice.

The design folks do not take into account alternative heating needs. A huge assumption is that the “Furnace” will do all of the work if it has to and no thought is applied to this process.

Unfortunately the opposite is true. The alternative heating sources will save the house from freezing during an extended power outage and can actually be more efficient in heating costs than the primary furnace.

Quality alternative heating sources can usually operate without the need for electrical power. Obviously the blowers do not work in these appliances but enough heat can be generated throughout the home.

Many fallacies about chimney height, sizing, performance run rampant in the knowledge possessed by the common man. Sometimes it is not possible to introduce a newer concept to old fables.

In Alaska we live in a place that has a ZONE 5 rating. That means that our air is super heavy and that in most cases we are the exception to most venting rules as provided by NFPA-211. (National Fire Protection Association Code Book # 211).

Air has density and a weight value.
A column of air 15 feet high in a 6 inch tube (we will call this tube A) has a certain weight.
A column of air 15 feet high in a 8 inch tube (we will call this tube B) has a certain weight.
The air weight in tube A weights less than the air in tube B.
As it gets colder the air in both tubes will have greater weight.

End result is that a heating appliance needs to produce more heat in order to push the weight air out of the tubes (chimneys) and must sustain that push to maintain a draft. It is VERY CRITICAL to balance a chimney to an appliance for it to work properly.

What creates draft in a chimney is a warm flue. To get the flue warm heat has to be constantly applied to that flue to maintain draft. The very best drafts have been discovered to be of lightweight inner liner backed up by high temperature insulation and protected with a resilient outer core to protect it from the weather.

Consequently masonry chimneys come in as dead last in this ZONE 5. The best chimneys are pre-manufactured and tested to standards.

We discuss chimney installations with all of our customers and many times because of liability and insurance issues as we do the installations. Insurance companies are not the friendliest folks and many times will not cover claims should the homeowner do a self installation.

This issue should be visited with their insurance carrier for confirmation before they begin any chimney installation for any heating appliance.

Dan