Quadrafire 7100 - additional zones worth it?

[glenintenn]

We're closing in on purchasing a 7100. One of the intriguing features is the additional ports for additional zones/rooms to be added. Due to our 2 story vaulted ceiling where the 7100 is planned to be located, I have a strong suspicion that our other 1st floor rooms will need some additional ducting from the ports on the 7100 and, while we have the walls open (we're working on existing construction, not new) I want to do all the work we're going to have to do.

1. Does anyone have any experience with the output from those ports? The vendor-supplied kit has a 160cfm fan on it... that doesn't seem terribly robust but... maybe it just doesn't take that much?

2. Our installer has never had a request to send the ports to the same floor the unit it sitting on by going under the floor... has anyone tried this or tried/been denied due the max 3 elbow guidance from the vendor? (in other words I'm wondering if there's any limitation on going under the floor on the same level as the stove and having the heat enter the room via an existing floor vent? )

3. if #2 is not a problem, does tying in one of these ducts to an existing hvac floor vent violate the "don't tie the 7100 into a central hvac system"? What I mean is that I understand that guidance to mean "don't try and divert the entire output of the 7100 into your hvac system and substitute for an alternate heating source in that system". Is tying it to the end of an hvac duct a bad idea?

 

[begreen]

I don't own and haven't installed this fireplace, so this is more general hvac advice. The airflow will be reduced by the number of elbows and the length of the run. The fireplace ducts out of the top, so dropping down to below the floor would add 2 - 90º turns, then another 2 - 90º turns to exit a floor register. You can do this but you will be at the maximum amount of turns and will add a lot of resistance. If there are two takeoffs from the unit and the other run is straighter, say with only one elbow, air will take the path of least resistance and will favor the straighter route, thus starving the more circuitous route. Is a wall vent not possible or is the remote room not adjacent?

It looks like another option would be to place the return (aux convection air) in the remote location and let that recirculate the heat. This can be very effective because cooler air is denser. Also the heat will be more evenly diffused between the stove and the return. If you can post a sketch of the floorplan indicating location of the fireplace there may be other options to consider.

 

[glenintenn]

• It's probably 50% an OCD thing of not wanting "yet another" thing on the wall.
• It's 40% that the crawlspace offers a straight shot to the floor heating vents. For the route through the walls, there are intervening rooms between the two target rooms (zones) and the firebox. I have some idea that there are going to be lots of adventures routing that 6" pipe and then getting electrical to the fan location on the most convenient walls (I'd much rather switch the fan in the room where the duct is going to terminate than tie it back to a rheostat back where the fireplace is )
• It's 10% having lived in a house with wood heat growing up and being over 6 feet tall where your feet are freezing and your head is sweltering in the inversion layer... bringing in the heat on the floor is not solving that problem entirely but it's starting in the right place.

Not sure about my weighting of those... looking for input.

The other question is whether it's worth it at all. Multiple dealers in area: stumped (no one wants to commit to what a 160cfm fan can really do as far as heating square footage ... thus my question: is it worth it at all?). I then called Quadrafire directly and they had no answer for "what approximate square footage per zone is supported" (the tech seemed to be reading the same docs posted on the website that I can read ) . QF is supposed to call me back. A sales person at one of our local stores described the zone idea as more of a marketing gimmick on an older idea of a "heat dump" for the stove when the stove is stoked more than intended and the room where it's located gets too hot (I guess older stoves had options to simply port excess heat to the outside? He seemed to think someone had an "aha" moment and rather than selling it as a moderating device for high temps in the main heating space, why not market it as "additional zones!" -- "but wait Bob, there's more!.......... " . )

Thoughts?