cutting a hole in the cold air ducts

[mlasko]

Here's my thought. You know how you have your cold air ductwork in the basement. I have my Englander in the basement. What if you cut two new cold air ducts in the bottom of the ductwork itself. So the cold air could actually fall out of the duct work. The way it looks now, the cold air is contained in the actually ductwork and cannot escape to the basement to be actually warmed. Anybody ever try this? Am I being too vague?

 

[Pagey]

What exactly is it you wish to achieve by doing this? Are you trying to use the duct work to circulate warm air from the wood burning stove? My understanding is that duct work for a central heat/air system is designed to "balance" the CH/A system. Doing what you are suggesting could serve to unbalance the system. But, I'm by no means even an HVAC novice, so take what I say with a grain of salt or four. Just something to ponder, though.

 

[LLigetfa]

That would short circuit the cold return for the furnace and/or air conditioner destroying the balance. It also can cause too much pressure drop in the basement when the furnace fan kicks in, sucking exhaust gas from several appliances and may well be against code.

 

[mlasko]

My thinking is that the newly installed ducts could be closed and opened depending on whether or not the furnace is running. For example, if the furnace is running when its really cold, then I could close the installed ducts so the cold air return functions as normal. However, when I'm attempting to let cold air falls from the second floor to the basement, I would leave them open.

 

[LLigetfa]

There would likely be fire code violations with that plan. A fire in the basement would use the cold return like a chimney accelerating the fire. You would have to put in fusible dampers.

What if you forgot to close the damper and the furnace came on? You could be sucking in carbon monoxide. There would have to be a damper that closes automatically when the furnace comes on.

 

[mlasko]

But would it work?

 

[LLigetfa]

But would it work?

It would depend on how your ducts are laid out, what natural convection would do. If you take the service door off the furnace blower what amount of air flow do you get? Is there a make-up duct also feeding into the return?

Don't forget that for convection to work, you need to be able to complete the circuit. What path would the warm air take? It's just like the two wires on your battery. They complete the circuit.

 

[mlasko]

I would be making these cold air ducts in the ductwork at the far end of the basement opposite the open stairwell, so I'm looking for my loop to work as follows: warm air naturally up the stairs, across the 2nd floor, and then cold air sinking from bedrooms at the far end of the house through the newly formed ducts, heated by centrally located stove, and then up the stairs again. Has anybody ever tried this?

 

[fossil]

I don't think you're going to accomplish anything other than hosing up what's probably a perfectly good central system. Rick

 

[LLigetfa]

My house is open concept with an open central stairwell. The natural convection causes the warm air to follow the ceiling up the stairwell while the cold air rolls down the stair treads. I can really notice it if I sit on the stairs.

That said, I have a centrifugal blower that takes cold air from one floor below my fireplace and blows it up inside the enclosure and out into the hearth room. Upstairs is cooler than the main floor but that's how we like it. I also have a vented chimney chase upstairs that scavenges some heat that would otherwise go out the chimney.