Attic Furnace & Insulation... (insulate, ceiling, rooms, pipe)

[ilmpk]

I have an older house that is in dire need of additional attic insulation. My issue is that the furnace for the house is located in the attic also. I am going to have a HVAC dealer come through and replace the soft duct work in the attic with hard ducting and flow rate everything because we have some rooms that are too hot and some too cold. After the HVAC dealer comes through, I would like to add additional insulation to the attic. My quandary comes with how do I insulate around the furnace? It is a newer furnace (manufactured within the last 3-5 years) and I would like to determine how close I can insulate to it to maximize my insulation performance. Thanks in advance.

[Charles]

Originally Posted by ilmpk

I would like to determine how close I can insulate to it to maximize my insulation performance.

I don't understand this. What do you mean by "how close" and "maximize my insulation performance"?

[Omaha Rocks]

Ask the HVAC guy when he's there to do your duct work.

My guess is that you'll only want to make sure you're not interfering with air movement.

[BigJon3475]

Originally Posted by ilmpk

I have an older house that is in dire need of additional attic insulation. My issue is that the furnace for the house is located in the attic also. I am going to have a HVAC dealer come through and replace the soft duct work in the attic with hard ducting and flow rate everything because we have some rooms that are too hot and some too cold. After the HVAC dealer comes through, I would like to add additional insulation to the attic. My quandary comes with how do I insulate around the furnace? It is a newer furnace (manufactured within the last 3-5 years) and I would like to determine how close I can insulate to it to maximize my insulation performance. Thanks in advance.

Hard duct is nice but it's not required. Flexible duct work works fine if it's sized correctly and ran securely and as straight as possible. Most flexible duct work looks like a octopus on the attack. The runs should be ight and straight. If you still want to get the duct work ran with hard pipe then make sure they do a Manual D calculation but to do that they need a Manual J calculation so they know the requirements for each room. A simple guess might work but there is no way to know till it's done. If they do the engineering calculations before hand they'll know before they ever do it and can assure you the fix they provide is exactly what you need.

[ilmpk]

Thanks for the quick responses! I'll make sure I query the HVAC installers when they are onsite about it.

[Ultrarunner]

The only thing problematic with "Soft" ducts is they are easier to damage... either by rodents or not being careful.

Often they are tighter because many times they are one piece or at least not segmented like hard ducts...

Part of my work responsibilities include Hospital HVAC... Whenever changes are made, we balance the air-flow using dampers... you can do the same thing by closing the ducts about 20% in the warm areas and leaving the cold areas wide open and check the temperatures and adjust by trail and error.

The first thing to check is that all ducting is air tight... no leaks.

I put in a complete new system in my brother's attic... the furnace was set on a platform raised 12 inches over the ceiling joists... plently of room to increase insulation depth... you could box in or use higher efficiency insulation just in the area under the furnace too..