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Discussion Starter · #1 ·
Hello all, I have an older 1.5 story house. The basement has a geothermal heat pump (~1200cfm) which has a supply and return register for each area in the house.

We are installing a wood furnace with a 460cfm blower and 4 ducts
http://www.jaroby.com/index.php?page=fiche&no=27&cat=5

I am wondering the best way to distribute the heat. Should I tie the furnace ducts into the existing heat pumps supply duct using backdraft dampers? Alternatively I could install new floor registers (perhaps directly beside the existing?) in the important areas of the house.

At the moment I'm not so worried about return air, as the basement is quite old and definitely not air tight. I'm curious to see what happens if both systems happen to run at the same time though...

Any thoughts would be appreciated. Thanks!
 

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Are you planning on having the wood stove in the basement located next to the furnace?

There is a couple of ways to distribute the heat throught the house without cutting in new registers, that is, if you are locating the WS near the existing heating system.

1 - Build an enclosure around your existing heating system and the new wood stove, when your wood stove is fired up, the enclosure would warm-up. Connect a thermostatically operated damper to the return air of the existing heating system, set the Tstat to open the damper when the enclosure gets to a predetermined temp.

2- Connect the WS to the RA of the existing system via a manual damper, when the stove is fired up open the damper and allow the heat from the WS into the RA of the existing system.

I prefer the first method.

Mark
 

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Discussion Starter · #3 ·
Hi Mark, sorry I did forget to mention they will be side by side (The basement is not very large so I wouldn't need to build an enclosure)

The wood stove comes with a thermodisc which will operate the stove fan between 120-160 degF. I could wire the damper to this, and place the damper before the geothermal's fan. Then it could act as a return when the geothermal fan isn't running, or an intake when it is running.
 

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You could always interlock the (2) so that one couldn't run when the other is.
 

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Hello!

Any progress on this install? Looking for a progress report :thumbup:

I am looking to do something similar. However, the only location I have is about 15 feet away from existing heat pump furnace. I will need to install a slide-in damper into the existing supply plenum, I am thinking.

Jackofall1,

Can you tie into the supply plenum a few feet after the new slide-in damper? Is there such a thing as a passive "smoke type" slide-in damper? I say "smoke" as I wouldn't want any air going backward to existing furnace. Would a controlled louvered damper on the side of return plenum when opened allow WS to draw air from upstairs or does it need to be hard connected?

Shazapple,

Instructions for the Jaroby don't show thermostat connections, are they standard for use with any thermostat. Also is this unit available in US.
 

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OK, moving to another plan. I was wondering can this be done?

Sketch isn’t to scale but just for reference. The one problem we have to overcome is the lack of a proper return plenum/vent on the second HVAC unit. This will potentially solve both

See picture

HVAC unit is in the closet in the picture on the right. You can see return vents in floor and wall in the lower right corner of the picture. What I want to do is create a column from the floor (closet ceiling) to the second story ceiling and enclose a return plenum AND the wood stove chimney. Can I place the return plenum duct above the wood stove location? Goal will be to build this entire structure out of non-combustible materials. If we proceed with this I will probably include two PVC pipes the terminate in attic and capped off for the "new variable speed" type furnaces just in case. Since the furnace pipe is PVC does this have to be "walled" off inside the column? I'd assume PVC can melt this close to a chimney? Is there a non-combustible replacement?
 

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Discussion Starter · #7 ·
We did install the wood stove I mentioned in my first post. The ducts are completely separate from our forced air system and are placed in the main area and stairway. The thermostat for our forced air system is set to circulate (the fan will turn on for 2 minutes every 15, or something like that), so it is roundabout but does a goob job of dispersing the heat throughout the house.
 
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