Couple of tundra questions

[clayh88]

Just installed my new tundra. Flotek has been answering a lot of my questions so far but I have a few for other people that have this furnace or other furnaces attached with a backup heat. I plan to use my Tundra as my main heat source but still want to be able to use my electric when im away for a weekend and then in the summer time the same ductwork is used for my A/C. I am going to install a backdraft damper into my main plenum to keep tundra from blowing back into return ducts . My concern is with installing spring return damper into the supply ducts from the tundra. During a power outage, blower stops and dampers close. All the heat it trapped in the 8 inch duct with no where to go. That I don't like. Im considering just installing manual dampers that I will close when im gone for weekends and in the summer time. Any thoughts on this?

Next Question.
In order to get the tundra ducted into my main ducts I had to reduce to 6 inch for about 3 feet right before it dumps in to the main duct. So from the tundra I go up with 8 inch for 4 feet then turn 90 degrees along my ceiling about 5 feet in 8 inch then have to reduce to 6 inch for 3 feet then turn down into my main duct. Will this cause any problems. ?

Next question.
How much duct area do I need for return air. Im thinking of using the space between my floor joist as the path back for the return air. Joist is 2X12 with 16 inch center spacing. I thinking about just coming from the main return duct lining the bottom of the joist section then down to the furnace with ductwork. total length is about 15 feet across the ceiling and down to the blower. Will this work?

Last Question.
I have a outside air kit that was hooked to my legend stove. Furnace sits in an open basement right now but should I leave this and just put the vent close to the furnace somewhere to help with the draft of the furnace.?

Any input of concerns with what I have going on would be great.

 

[laynes69]

Anytime you place a 90° elbow in a duct, you reduce the flow. On top of that, reducing from an 8" to 6" reduces the area to almost half. Your furnace will overheat with that kind of reduction in your supply lines. As far as dampers are concerned, the 8" manual dampers are fine, and shouldn't cost as much as the spring loaded dampers.

As far as return air is concerned, you want at least the size of the supply ducts, and going a little larger won't hurt. As far as panning the joists for return air, it will be connected to a solid fuel unit. I would check with the manufacturer. I've heard it's okay but also it's not. I choose not to pan mine.

Unless your house is very tight, you may not need the outside air kit. That's an area of debate. If it's not causing any issues, or you don't mind, keep it there.

 

[ziggo_2]

to answer question 1. im assuming your planing on using round ducts. well if all you can get in there is a 6in round...how bout making it a rectangular duct? and using a plenum to attach to the tundra. Thats what i would do. on my furnace i think the 8in ducts are already restrictve enough.

 

[flotek]

Use a rectangular duct and an adapter so your getting the clearance * and the required volume .. I'd not use a outside air kit most houses have plenty of leaks even new ones . I would not neck the diameter down I'd use that rectangle square duct idea first .

 

[clayh88]

Would it work to go up off the tundra with two 8 inch pipes right into the bottom of 8x10 rectangular ducts across the ceiling to my main duct. The 8x10 will be running inside my floor joist and be above my main duct. I would just attach the 8x10 directly to the main duct. I would eliminate all the elbows.

Does anyone run a plenum on top of their tundra. Thought the manual says not to do it. If you are doing it do you still block off to holes of leave them all open?

 

[clayh88]

Also as far as the clearances go what can I do if I am going to be close in a spot. it will be on the bottom side of the duct that running across my ceiling. Any recommendation besides asbestos blanket : )

 

[Lovin Locust]

Would it work to go up off the tundra with two 8 inch pipes right into the bottom of 8x10 rectangular ducts across the ceiling to my main duct. The 8x10 will be running inside my floor joist and be above my main duct. I would just attach the 8x10 directly to the main duct. I would eliminate all the elbows.

Does anyone run a plenum on top of their tundra. Thought the manual says not to do it. If you are doing it do you still block off to holes of leave them all open?

Clayh88 can you use all 4 of the 8" outlets, into a plenum off of the Tundra, or can you only use the 2 outlets??

 

[clayh88]

I ended up just using two of the eight inch outlets.. the front and rear. The front one puts out a lot of heat compared to the back one.