Backdraft dampers

[P0ZBURN]

Where can you buy these backdraft dampers that would go inside your hot air supply ducts for an add on furnace installation? Is it something that has to be specially made? I'm looking for 8" x 16" or 8" x 18" and 12.5" x 21.5".
I have a PF100 with the 3- speed 1000cfm blower and I'm trying to install it in parallel with my heat pump system. I was also wondering if and 8" x18" duct is big enough hot air supply for the PF100 since that is the biggest duct size on my existing heat pump hot air supply.
Thanks ahead
Patrick

 

[hossthehermit]

I use a homemade setup, I have a piece of stainless that slides into a slot in the duct up from the oil furnace, for when I'm running the Revolution, which is most of the time. There is another slot I cut into the ductwork from the Rev. that I can slide another piece of stainless into if I want to run the oil. Whichever slot doesn't have the damper installed, has a piece of hi-temp foil tape over it. Works for me.

 

[P0ZBURN]

I found this, I'm just waiting on the guy to give me a quote. If its outrageous I'll probably be making my own slide gates too.

http://pottorff.com/cat/bd-20.pdf

 

[exoilburner]

I did the same as hoss. I put duct filter slides in the hot air ducts for both furnaces. Then made blanking plates to slide in them and covers for the hole in the duct. Don't know what the Revolution's duct set up is but the PF 100 owners manual states: Isolation dampers should be installed in the ductwork in the warm air supply duct for the existing furnace and in the warm air supply duct of the PF100 after “downstream” of the high limit/fan control. These dampers can be manually operated or fully automatic. In either case, **the unit that is not being used must be prevented from being operated. (This also can be done manually or automatically.)

If you fire up a furnace with the blanking plate in it's hot air duct the Fan/hi-limit switch will stop the furnace when the duct reaches the hi-limit temperature. I've done it a couple of times; worked good and no harm done.

**I used a 3 way light switch as an electrical transfer switch wired so only one of the two furnaces could get electrical power.

Oil Furnace Manual Isolation Damper

 

[P0ZBURN]

Thanks for the replies. What do you all think about the duct sizing. I know the book says 160in for the hot air duct but what if my existing main duct ain't that big anyhow?
What size did you use running off your pf100 exoilburner?

p.s. the guy quoted me 100 bucks for two dampers.

 

[exoilburner]

POZBURN, my duct size off the PF100 is 7"x24" (168 sq in.) so I just made it in spec.
Sounds like a good price on your quote for new dampers if they are automatic. Is that installed? Are they automatic or manual?
If your ducts are too small you may not want to put any obstructions (like dampers) in them which would reduce the air flow more.
Is it possible to replace your old ducts?

Here is a video of my PF100 set-up:

 

[P0ZBURN]

Thanks for the video. It was $100 for the automatic dampers themselves. I plan installing all of it myself. Would be too much trouble to replace my existing duct work. I think the 8x18 duct will handle 1000cfm but might be noisy.

 

[P0ZBURN]

I'm trying to install my PF100 hot air supply. Exoilburner ,how did or where did you get that plenum that comes off the top or your PF100 like I saw in your video. Looks like it comes off at an angle to make it bigger. I need to do the same thing to make it fit my existing duct work.

 

[exoilburner]

I'm trying to install my PF100 hot air supply. Exoilburner ,how did or where did you get that plenum that comes off the top or your PF100 like I saw in your video. Looks like it comes off at an angle to make it bigger. I need to do the same thing to make it fit my existing duct work.

POZBURN, You are correct about the angle. I had my ducts modified by a furnace install business. He designed that piece to get the max square inches at the output of the PF100. The space was limited by the open position of the pellet hopper door and the furnace vent pipe. As you can see in the video he designed it so it would conform to the open position of the pellet hopper door to get maximum air flow. As you probably know that piece has a lot of heat going into it so the more internal area in it the better. That piece works well and also contains my removable damper plate. You can see the damper plate leaning against the vertical vent run in the video.

If you drew it up in a drawing your local sheet metal shop could build you one. If you need any info, or dimensions from mine let me know. The furnace estimator just sketched it out on his clipboard and his sheet metal shop built it. It fit perfectly.

 

[P0ZBURN]

What are your dimensions Exoilburner?
Thanks

 

[exoilburner]

What are your dimensions Exoilburner?
Thanks

If you PM your email address to me I will email you the drawing file and you can print it out. You can modifiy the dimentions to fit your install.
Or you can right click on the drawing below and click PRINT PICTURE in LANDSCAPE.