Quadrafire 7100 ducting

[tuolumne]

I am installing this fireplace. We are building in Vermont, and can anticipate very cold weather. My thought was to duct the combustion air from the basement and the positive pressure air from the outside. It appears that the positive pressure air duct can be bi-passed manually?? Should I also bring combustion air from the outside if feasible? Can the large potential delta T's cause any burning difficulties? I need to go about 10' to get outdoors, so one 6" pipe is OK, but snaking both through the joists is a bit trickier! I am not using quadrafires air cooled chimney if that affects anything.

 

[jtp10181]

The 6" outside air which I think is the lower of the two holes on the side MUST be run outside. There is a gasketed damper that seals with a magnet to keep cold drafts out. Personally I recommend NOT hooking up the "AUX" (posi pressure) air in cold climates. From what we have heard you will get incredible amounts of cold draft in the bottom of the fireplace. The AUX air slider adjustment in the front of the unit does not have seal, its just metal on metal. The other metal cavities that the AUX air dumps into are not air tight. The AUX air hooked up to outside air would be like cutting a 6" hole in the house and ducting it outside.

Now... if you plan to be burning 24/7 when its cold out that might another story. But for occasional burners the AUX air is a bad idea.

If you need anymore info let me know, also if you do hook up the AUX air you will have to let us all know how it works out. We never hook it up around here because of the cold draft issues.

 

[Hogwildz]

I can't answer all questions, just do not know enough about that fireplace. But a newer home is presumably going to be tighter, so the outside air intake would probably be best.

 

[tuolumne]

This home is high density spray insulation, so very tight. We will be heating with a central wood boiler, so we will not be depending on the quad to heat the house. However, we have heated with a wood stove for six years and have come to love a fire in the living area, so we will be frequent burners I am sure. Also, if the power is out I would more likely be running the quad off a battery backup than the circulators etc. for the boiler. I hope this added information can help with the responses.

 

[jtp10181]

Same thing I said still stands

 

[tuolumne]

Thanks. I see that I want the combustion air drawn from the outside in a tight house. I will need to rely on natural convection and radiation to move heat through the house rather than positive pressure. Sounds fine with me.

 

[jtp10181]

Just to clarify. I was looking at a manual today and noticed the outside air is actually the top one, and the lower hole is the AUX air connection.

 

[tuolumne]

Regarding the outside air, is 6" really necessary for this stove or can I transition to 4"? 6-1/2" holes are mighty big in floor joists. I only need to punch through 1, so it can be reinforced if the 6" duct is necessary. Has anyone else used 4"? How does the stove behave?

 

[jtp10181]

It would not directly effect the unit. The 6" outside air dumps outside air under the unit. The unit draws combustion air basically from the room. When the outside air is open it will use a mix of outside and room air for anything else it needs. Reducing to 4" would allow less flow and if the fireplace is burned for long periods of time you could develope a negative pressure in the house. We have never questioned Quad on reducing it to 4", we always run the 6". I know if you ask Quad they will tell you it must be 6", if it was an option to reduce it they would state that in the manual.

 

[tuolumne]

Thanks. Where is that gasketed seal with magnet that you referenced? As near as I can tell, the air comes straight through the duct into the void below the unit. What keeps that air from the house?

 

[jtp10181]

Make sure you are looking at the correct intake hole, which I corrected myself as being the top one. The bottom one which is the AUX air does just dump into the void below. The last one I looked at one unboxed I could see the gasket and magnet from the side pitched at an angle. I remember playing with it because I was curious to see what they did to resolve the cold air issues. There should be a rod with a knob sticking out from the front fascia. If you rotate it, it should flip the damper open/closed.