Pics inside- is my set up a good candidate for an add on furnace?

[tlhfirelion]

im new to the world of indoor furnaces and am doing my due diligence to see if my system is a good candidate for an add on furnace. I have a partial basement and all my ductwork in either on the basement ceiling or under the floor of the upstairs in the crawlspace. (Please see pics). If I understand the piping correctly, the hot air from the furnace would come out of that and into the return air supply before the indoor air handler, correct? Now, the return air set up in my home is set up using a void in the walls as part of the enclosure. It's covered in metal on the face and aluminum tape has it sealed. One of my questions is is that type of set up, with the exposed wood inside part of the the return air is a problem for an add on furnace. My other question is what are your thoughts on my set up that you see in the pics. Basically the air handler pushes air up to the trunk and it runs 60' to the other side of the house with flex ductwork shooting off to supply the registers in the floor along the perimeter of the home.

The wall to the left of the water heater is where I plan to core drill a hole and go out and up above the eve with high temp pipe. For reference, the small access door above the ladder is where I took the pic of the crawlspace ductwork. I'll avoid saying anymore at this point as I'm sure I'm being clear as mud. Lol. Thank you for your feedback on helping me think this thru.

 

[3fordasho]

View attachment 175095 View attachment 175093 View attachment 175094 im new to the world of indoor furnaces and am doing my due diligence to see if my system is a good candidate for an add on furnace. I have a partial basement and all my ductwork in either on the basement ceiling or under the floor of the upstairs in the crawlspace. (Please see pics). If I understand the piping correctly, the hot air from the furnace would come out of that and into the return air supply before the indoor air handler, correct? Now, the return air set up in my home is set up using a void in the walls as part of the enclosure. It's covered in metal on the face and aluminum tape has it sealed. One of my questions is is that type of set up, with the exposed wood inside part of the the return air is a problem for an add on furnace. My other question is what are your thoughts on my set up that you see in the pics. Basically the air handler pushes air up to the trunk and it runs 60' to the other side of the house with flex ductwork shooting off to supply the registers in the floor along the perimeter of the home.

The wall to the left of the water heater is where I plan to core drill a hole and go out and up above the eve with high temp pipe. For reference, the small access door above the ladder is where I took the pic of the crawlspace ductwork. I'll avoid saying anymore at this point as I'm sure I'm being clear as mud. Lol. Thank you for your feedback on helping me think this thru.

Sounds like you are describing a series install (hot air from wood furnace feeding into cold air return and then thru your gas furnace and A/C coil)
This is typically not a good idea especially for the a/c coil. Also does not work for gravity flow in case of a power failure - unless you want all that hot air gravity flowing to the exposed floor joists that have been panned shut for your return ducting.

I believe you want to look at a "parallel" install where the output of the wood furnace ties into the plenum of the gas furnace above the a/c "A" coil.
back draft dampers are necessary to prevent the hot air from short circuiting through the gas furnace back to the wood furnace instead of making out to the far reaches of your warm air ducting. I would suggest downloading the manuals from what ever wood furnace manufacturers you are considering and see their recommendations for duct connections and clearance to combustibles.

EDIT - hmm after reviewing your pic some more that's not a gas furnace is it? Electric? which way is the air moving through that unit? down or up?

 

[tlhfirelion]

Sounds like you are describing a series install (hot air from wood furnace feeding into cold air return and then thru your gas furnace and A/C coil)
This is typically not a good idea especially for the a/c coil. Also does not work for gravity flow in case of a power failure - unless you want all that hot air gravity flowing to the exposed floor joists that have been panned shut for your return ducting.

I believe you want to look at a "parallel" install where the output of the wood furnace ties into the plenum of the gas furnace above the a/c "A" coil.
back draft dampers are necessary to prevent the hot air from short circuiting through the gas furnace back to the wood furnace instead of making out to the far reaches of your warm air ducting. I would suggest downloading the manuals from what ever wood furnace manufacturers you are considering and see their recommendations for duct connections and clearance to combustibles.

EDIT - hmm after reviewing your pic some more that's not a gas furnace is it? Electric? which way is the air moving through that unit? down or up?

I was about to clarify and saw your edit. Yes, it's an electric heat pump. The air is flowing up from the air handler and branches left to the basement vents and bedroom above what you see here, and right thru the block wall and into the crawlspace trunk. Does that change your advice?

Thank you for the reply.

 

[STIHLY DAN]

You want an add on that has its own fan tied into the supply of existing. Placement of unit would be best to the right of the existing. You WILL need to get rid of the flex and use metal take offs. Also will want to drop main trunk 2 inches.

 

[tlhfirelion]

You want an add on that has its own fan tied into the supply of existing. Placement of unit would be best to the right of the existing. You WILL need to get rid of the flex and use metal take offs. Also will want to drop main trunk 2 inches.

Crap......that's a massive headache. Looks like I'll need to go another direction. Thank you for the help.

 

[DoubleB]

On the other hand, can you just add new dedicated ductwork that is connected only to the wood furnace? A large supply duct and register to the floor above. Might not even need a return duct if your basement door is open.

Advantage is super simple and robust and gets lots of wood heat in your house.

Disadvantage is might not distribute heat as evenly as your heat pump ductwork.

Doesn't work in all houses, but it's what I did, and works great for me.

 

[STIHLY DAN]

You want an add on that has its own fan tied into the supply of existing. Placement of unit would be best to the right of the existing. You WILL need to get rid of the flex and use metal take offs. Also will want to drop main trunk 2 inches.

Other than laying on your back in the crawl space should be relatively easy to drop the main a bit. They sell metal flexible round duct and you seem to have straight runs. I think it will be easier than you may think it is.

 

[JRHAWK9]

IMO, I wouldn't install any wood furnace when there is ducting going through an unheated space. Using air as a carrier for heat is inefficient as it is and dragging it through unheated ducting will make it that much more inefficient. This is where those boiler guys and their many gallons of storage have a huge benefit over us furnace guys. They are capable of burning as efficient as we are but they are transferring/storing the heat produced more efficiently/effectively.

 

[Armaton]

It looks like you could do it, just depends on the details. You could use series, put the add on in front of your electric furnace, remove duct from just above your AC coil and run it to the intake of your add on. Connect the output of the add on to the main trunk and use the electric furnace blower to move the air through both. You would need a limit switch for the add on to make sure the blower would kick on for residual heat. The problems with this are, 1) Blowing the coldest AC air through your wood furnace in the warm months, (might cause condensation in furnace), and 2) having approximately a 10 foot horizontal chimney run to get to your vertical chimney. Doable, but not ideal. OR, you could have a heating and cooling indivdual move the AC coil to above your add on and still use series, (better option I think), but will still have that horizontal run. The second option is exactly like my fathers set up, (accept he has a fuel oil furnace), that he used for 20 years. The only problem he had was his chimney was an 8 inch masonary beast that he couldn't keep hot enough with the 12 foot horizontal run, so always had creasote problems. With the newer double and triple wall piping you may not experience that.

 

[tlhfirelion]

I appreciate everyones feedback but with the need to drill a hole thru the block and ductwork modifications, etc, I don't think it's my most cost effective approach. I'm going to use some inferred heaters in the basement this next winter and see how that works. I also plan to redo my upstairs stove with a newer stove.......which stove is the question, but it's it always? I like the thermostat controlled wood burners but man are they proud of them! My 10 year old century stove has soldiered on valiantly and was $300 new on clearance. It's a tough pill to swallow dropping 2 grand an up. Longer burn times, cleaner burns and reduced wood usage are important tho so I guess you gotta pay to play.