Air Heat Exchanger

If that is what you have come to understand about this system then a little more info on what your looking at is needed to get any idea of air quality. How about a link to the product?

I do not believe that the air is being drawn from the fire box. The heat exchanger is drawing air in from outside the fire box from the room and it is being heated and returned. So the only factor in air quality would be the quality of the air in the room.

Then maybe they are. I have question about the part of the exchanger that would be at the bottom. Heat rises so it would be better and more efficient if on the top.

Thank you for your answer!

As you correctly say, air in not drawn from the fire box. Air is circulated from and to the room .

Is it allowed to pass air through pipes in fire, and then deliver that hot air in the rooms?

re: "Is it allowed to pass air through pipes in fire, and then deliver that hot air in the rooms?"

I can't imagine why it wouldn't be--many similar heating devices (even hot air furnaces) do something similar--take air from the room (or house), pass it over or thru something hot, then recirculate it back into the room (or house).

Lynlynch's picture is helpful, but small--from my vague recollection of such devices, the actual air intake is off to one side, presumably far enough away from the fire to avoid sucking in combustion gases.

Put your cursor on the picture and left click. You will then see the air intake.

lynlynch's picture is very similar to the one I have seen. The difference is that at the outlet of the five pipes, there is an other header, that guides the hot air the the room. The air intake and the fan is located near the room.

I think it would not be safe to heat air directly from a pipe in fire. A small crack could allow combustion gases to enter in the hot air delivered to the rooms.

I think I heard that a safety rule in never to have only a single barrier between combustion gases and room air, or something like that. In that case a double wall pipe would be better for the safety (and worse for the efficiency of the exchanger).

Could you give me links to furnaces that are made by a single barrier between fire and air?

My Gibraltar wood / coal burning stove (fully approved when it was purchased some 30 years ago) has only a single layer of (fairly thick) steel between the firebox and the (room) air that is forced around it for heating.

The elements of my electric (resistance) furnace are directly in the air stream.

Other that that, you can google as well as I can ;-)

Just about every furnace only has a single wall. I am not aware of any with a double wall. Most codes now require a CO monitor and alarm to detect if combustion gases are present in the living area.

Be sure to check on local codes regarding these types of exchangers!

This model in particular is not legal in California do to the fact that the combustion air and the heated air are one and the same. There is no separation.

My father built a system similar to this years ago, for a workspace heater.

It did not work well until he converted it from wood to propane due to the smoke

and we still had to provide fresh outside air. Not so efficient.

The fire needs to be burning good and hot so to 'draft' up the chimney prior to starting the fan. Otherwise, and possibly always, the movement of the air leaving the tubes will tend to draw smoke and/or noxious gases into the room. It is a venturi effect.

This type would be legal and is much safer.

http://www.fireplacedoorsonline.com/acatalog/copy_of_Classic_Ultra_Great_Heat_Exchanger_4028.html

Is it worth it? If you haveradiant heat coming off the fire, just leave the doors open

yes it is worth it. You lose a ton of heat going straight up the chimney. A system like this will cook you out of a living space in no time if you keep the fire blazing. We had one similar that was home built many years ago. It would heat a fairly large family(party) room quite quickly. With a couple of ceiling fans pulling air, you could heat most of our house from that one room. As an added benefit, the pipes will continue to push heat into the room long after the fire is out.

An appliance based on this principle was turned into a commercial product in 1927. It is called a "Heatilator".

http://www.heatilator.com/

My grandfather built one into the fireplace of one of the houses he built. It was wonderful! It produced a nice, even heat and warmed the living room very quickly.

Since the air in the heat exchanger is being warmed and is expanding, there will be some resistance to the entry of combustion products even if there is a small hole.

Our new house has a propane fireplace with a sheet metal box surrounding the fake logs, and a blower at the bottom that forces air to go around the outside of the box and out vents at the top. It's an OEM unit and the house has been inspected, so I'm sure it meets any codes, at least in Oklahoma. And I've seen the tubed units, like yours, in lots of houses. God, I hope politicians don't read this forum and get ideas for new laws!

They work ok if the stick out far enough. My ex's father had one that he had made himself. Never had problems with it drawing the smoke into the room; drew from about a foot to the side and the tubes stuck out almost a foot, they turned up at the ends. Aesthetics ( thank you dictionary.com) be damned.

I would use stainless steel if possible.

a slight aside: You can run a simple ceiling vent from the far end of the house to the room with the fireplace. It sets up a circulation and moves the heat to the back of the house. An inline fan work even better.

Dave P