Add on furnace ducting question

[turnNburn]

Hello, I just got a shelter add on furnace for my basement. It has a 12 inch round duct for me to tie into my existing duct work. The manual says I cannot reduce this to lower than 12 inches or 113 cubic inches. So for me to tie this into my existing duct work I need to take the 12 inch round duct straight into above my heat pump furnace. The problem I am having is the trunk coming out of the furnace in the picture is 13.5 x 20 inches. I think I would need a damper to keep the air from moving downwards into the heat pump furnace. I cant find a damper that size to fit. What should I do? Thanks for any help as I am new to this.

 

[hondaracer2oo4]

A quick google search turned this up. (broken link removed to http://www.alpinehomeair.com/viewproduct.cfm?productID=453068222&linkfrom=froogle&gclid=CMb-7cCx8c4CFQFZhgodMbQN1A)

 

[velvetfoot]

That damper is round.

I'm totally knowledgeable, but would both fans have to be on? Would that take care of it?

 

[turnNburn]

It would take care of it, but the blower on the wood furnace is a 1800 cfm so I shouldnt have to do that. Also thats more electric I would be using

 

[STIHLY DAN]

Replace your HP air filter with a piece of metal or a a board.

 

[hondaracer2oo4]

I would assume that you want your heat pump to work as backup without having to change out some sort of blockage in the heat pump furnace. My link was for the round duct on the wood furnace which also needs a one way flapper. The one way flapper just needs to be somewhere on the heat pump side. It could go on he return side too. It looks like the return side has a nice long section on maybe 12x16 or something. I would go to your local hvac duct installer and ask them to make you one for whatever size that is. It will probably be $50 bucks or something but I don't see a whole lot of other options.

 

[turnNburn]

I plan on getting a one way for wood stove so the HP wont push air into the wood furnace. So your saying I could have a local HVAC shop make a one way damper to go in the cold air duct? Thanks for the help

 

[hondaracer2oo4]

Yes. They should be able to make whatever you need.

 

[jb6l6gc]

Replace your HP air filter with a piece of metal or a a board.

This is what i do. Not automated but simple and effective.

 

[hondaracer2oo4]

I know the filter block works but it renders the hp unusable unless you go down there and remove it. No ones wife likes to be told "if the wood furnace runs out of wood you need to go and remove blah blah blah".

 

[jb6l6gc]

I know the filter block works but it renders the hp unusable unless you go down there and remove it. No ones wife likes to be told "if the wood furnace runs out of wood you need to go and remove blah blah blah".

Say what u will but my wife knows the drill or the hydro bill suffers!