alternative to blower?

[SilverLeaf]

In my house we have a fireplace insert that burns wood quite efficiently. The key to its efficiency is a pipe that sucks fresh air from underneath the fireplace and brings it up and over the fire, dumping it onto the fire from above. There's a damper that allows us to control how much air flows in. There's no blower of any kind involved.

So my question is: is this a kind of design element that would be of value inside a firebox? Has anyone tried something like this? Could something like this replace the need for a blower, or would a blower still do a better job of increasing the efficiency of the burn?

We're in the process of building an arch, and my dad suggested this, while we still have time to incorporate it into our design. And I thought, "hey, why not?" But then again what do we know - neither of us have ever used a "real" arch before. :confused: So I thought I'd throw the question out to all you experienced fellows....

[C.Wilcox]

Dan,

Lots of discussion on this topic at the following thread: http://mapletrader.com/community/showthread.php?t=5534&highlight=over+fire+air

The experts say that you'll need air blown in both over the fire and under to get max efficiency. I think the ratio was something like 75% over and 25% under.

A number of guys on the forum have since tried adding over the fire air and it sounds like there were some mixed results. I am only a hobbiest at this, but my personal opinion after reading their posts is that if you're going to go that route you need to invest a lot of effort in it to get good returns. You can't build it to the halfway point and expect it to work as well as you hoped. I know Gary R. has modified his arch to have over-fire air. Might want to check out his experiences here: http://mapletrader.com/community/showthread.php?t=3621

Corey

[SilverLeaf]

Thanks, Corey for the links! I had done a few searches, but obviously didn't get to the right threads, as there was way too much info to sift through...:)

This should get me right where I need to be with figuring this out.

[brookledge]

Dan
The concept with a fire place using out side air is to reduce the amount of air that is pulled in from cracks and windows etc. Basicly without a seperate air feed wth a fire place it makes it very drafty that is why a fire place is so inefficient. But with out side air brought in, in the fireplace then you can put a closed front.
However an evaporator needs alot of air and to get the most out of the wood blowers are used and it has been determined that air over the top of the fire increases efficiency. Without adding oxygen on the top many unburnt gases(black smoke) goes up the stack.
Keith