Question Installing B-Vent for Zone Heating-

[wnc_burner]

Long Time Lurker, First Time Poster


I bought a house that had a QuadraFire 7100FP. Awesome Fireplace btw.

The folks that built the house chose not to hook up the zone heat kits, probably because of costs as I'm finding, but I'm hoping to eventually recover costs if this works out. I'm thinking about running one to each of my daughters rooms. The fireplace has two ports on the back that according to the manual I can run two runs of B-vent to each room room and hook up the 'Heat Zone Kit-Wood' and blow warm air into the room.

Issue: I have access to the rear of my fireplace and I was making some preparations to run the B-Vent. Space is limited and it's pretty tight. Both vent pipes will run down together into my crawl space and then over-n-up through the floor of each room. Opening up my portal to the crawl space I ran into a floor joist. My current situation I can easily run one vent pipe and keep a safe distance from combustibles, but the floor joist if preventing me from running the other. I'm trying to avoid having to cut that floor joist and move it out of the way. It's doable I think, but as I said, it's tight and it'd be tough to get in there and do it.

My question is this: Can I join the two ports on my fireplace with a Wye or Tee and just run one vent pipe down through my troubled area. Then once in the crawl space, split it into two and then continue each run to the bedrooms separately. The vent kit has a fan/register in each room blowing air into the room. My concern is, would joining the ports on my fireplace into one make it get to hot? and also would merging the vents into 'one' then splitting it back into 'two', would I lose efficiency somehow.

A lot to take in, hopefully it makes sense and someone has some input. I can upload some construction pics later, here's a pic of my fireplace at least.

 

[begreen]

Yes, just taking off one zone is permitted. You can tee or wye the pipe so that it feeds two rooms. Half the amount of heat will be delivered to each room, but that is still a lot more than nothing and could very well be sufficient. Insulating the b-vent pipe in the crawlspace with a fiberglass wrap will reduce heat loss. Keep the total run length under 40ft.

 

[wnc_burner]

Yes, just taking off one zone is permitted. You can tee or wye the pipe so that it feeds two rooms. Half the amount of heat will be delivered to each room, but that is still a lot more than nothing and could very well be sufficient. Insulating the b-vent pipe in the crawlspace with a fiberglass wrap will reduce heat loss. Keep the total run length under 40ft.

i understand what you're saying. i guess my question is could I join the two heat zone ports coming out of my fireplace to gain more heat efficiency, run that through my troubled area, and then split and run it to each room. instead of just running one vent and splitting that, would I gain more heat efficiency by combining the two first? or would that make the pipe too hot at first? sorry for not having pics yet, busy weekend, splitting wood

also, since I've got some lookers, are the heat zone kits really worth it? the kit itself is like $270 a piece. but we run space heaters in the girls rooms all winter. our house was built well in 1999. even the crawl space is sealed pretty well.

 

[begreen]

You'll have to ask Quadrafire about combining the duct but my guess is the answer will be no. Also, you can only push so much volume of air through a 6" pipe. I would think you could make up their heat kit using available items like Tjerlunds booster fans.
http://shop.tjernlund.com/products/register-booster-series

Getting heat to the back bedrooms is a common challenge. Besides ducting off the fireplace, there are a couple options. Both involve pushing the colder air toward the heated air. Sounds counterintuitive but it works. Cooler air is denser than warm air and easier to move. Working with cool air also means ordinary fans will work without concerns of overheating.

For more even heat in the house option one would be to put a table or box fan at the far end of the hallway, placed on the floor, pointing toward the stove room. Run it on low speed. It will blow the cooler air down low, toward the woodstove. The denser cool air will be replaced with lighter warm air from the stove room. Running this way you should notice at least a 5F increase in the hallway temp after about 30 minutes running.

The other option is a bit more complicated and involves running an insulated duct under the floor with the intakes in the far bedroom floor, tied to a duct that blows out into the stove room. A quiet inline remote bath fan works well for this. The cool air will be replaced with warm air from the stove room. This will require that the bedroom doors be normally open or at least have a 1" gap under the door or a grille in the door to allow circulation.

 

[wnc_burner]

You'll have to ask Quadrafire about combining the duct but my guess is the answer will be no. Also, you can only push so much volume of air through a 6" pipe. I would think you could make up their heat kit using available items like Tjerlunds booster fans.

http://shop.tjernlund.com/products/register-booster-series
Getting heat to the back bedrooms is a common challenge. Besides ducting off the fireplace, there are a couple options. Both involve pushing the colder air toward the heated air. Sounds counterintuitive but it works. Cooler air is denser than warm air and easier to move. Working with cool air also means ordinary fans will work without concerns of overheating.

For more even heat in the house option one would be to put a table or box fan at the far end of the hallway, placed on the floor, pointing toward the stove room. Run it on low speed. It will blow the cooler air down low, toward the woodstove. The denser cool air will be replaced with lighter warm air from the stove room. Running this way you should notice at least a 5F increase in the hallway temp after about 30 minutes running.

The other option is a bit more complicated and involves running an insulated duct under the floor with the intakes in the far bedroom floor, tied to a duct that blows out into the stove room. A quiet inline remote bath fan works well for this. The cool air will be replaced with warm air from the stove room. This will require that the bedroom doors be normally open or at least have a 1" gap under the door or a grille in the door to allow circulation.

WOW! those Tjerlunds booster fans look nice and could save some serious coin using those as to buying the quadrafire kit at $269 a pop. Will they handle the heat? and is 75 cfm enough for a bedroom? Thanks for all the advice, it's greatly appreciated.

Also, by the design of my house I have a cold basement/room directly below my fireplace room. I'm looking into the Tjerlunds level-to-level transfer fans to pump that cold air up into the room with the fireplace like you suggested. Of course all this could have been avoided by having the burner in the basement, but I didn't design the house.

 

[begreen]

75cfm should be fine for a bedroom.

If you decide to go with plan B and suck the cooler bedroom air out and blow it into the stove room then I would use a remote mount bathroom fan. Panasonic makes some nice quiet units. For 2-3 bedrooms I would use an FV-20NLF1. Use 6" R8 flex duct to connect.

 

[wnc_burner]

75cfm should be fine for a bedroom.

nice, i had read in other places where guys were ducting hot air off their fireplaces using an inline fan that was over 200 cfm. i was concerned about the register boosters mainly because of it being a 'booster' . but with my application it'll be a stand alone fan, but i guess 75 cfm is 75cfm.

i couldn't find any info on the cfm rating of the official quadrafire heat zone kit fan, but i bet it's about the same.

 

[begreen]

If the room is 1100 cu ft then a 75cfm fan is going to provide an air change every ~15 minutes.