how to reduce heat loss in duct work?

[Speedy2222]

I recently bought a house and after sleeping there a few nights we have noticed that the rooms furthest from the furnace are extremely cold compared to the rest of the house. Its a single story ranch on a crawl space. Approx 1800 sqft. And has a 2 year old Lennox elite furnace.

So last night I looked a little further into the crawl space and found none of the joints in the duct work were taped off along with a few very poorly done joints. While also there the furnace kicked on and I noticed what seemed like alot of heat transfer through the main duct work. Is there anything that can be done economically to reduce this and help the hot air reach the back of the house?

 

[pseudorealityx]

Yes, seal and insulate the duct work. Foil tape or mastic, and then there are various insulation products out there.

 

[theoldwizard1]

First, find a good HVAC person and determine it the right size ducts were installed. Foil tape the joints and insulate. It might be cheaper/easier to replace what is there with pre-insulated ducts.

There is also a product now that can coat inside of heat ducts (after they are cleaned) that will seal all remaining holes. No added insulation value. Not cheap but effective.

 

[doctordirt]

Something else to look into, where is thermostat located. I venture to guess closer to the warm area and the furnace. Look at duct work close to furnace, you should have dampers that could be adjusted to provide less heat close to Tstat, thereby allowing furnace to run longer and warm distant rooms.

 

[bzinsky]

Yeah, insulating adds cost, and usually it can be fixed by taping the joints, and by adjusting the air flow. Most vents are adjustable so you could say slightly close the ones in the warmest rooms and open them in the coldest rooms.

 

[scoob8000]

I have one vent that passes thru our unheated "cold cellar". Air coming from that vent is significantly cooler than any other vents in the house.

We foil sealed the joints, then wraped the whole duct with the foil bubble wrap stuff, again sealing all the seams with foil tape. That made a day and night difference for that vent.

Pleased with the results I went ahead and wrapped the rest of the ducts in the basement. If it helps or not, the investment was pretty small.

 

[rlitman]

A few inches of fiberglass will work even better than the bubble foil, but that's a good start.

 

[bacr619]

I am an HVAC contractor close off some of the supply registers closest to furnace if air flow does not increase then duct is to small and needs to upsized. Home depot sells the duct sealent that is applied by brush comes in one gallon bucket. We use the cheap 3" brushes because we toss them when done. You will need to some FSK wrap FSK tape to wrap the ducts. Sorry I do not know were a DIY would purchase. Could try to see if HD or Lowes could special order manufactured by Mansville. The rolls are 48" wide 200 feet long. In PA I am sure it gets pretty cold so get the highest r value possible it will pay for its self in 3 to 5 years in energy savings.

 

[bacr619]

I am HVAC contractor close off supply registers close to the furnace if air flow does not increase to the room then duct is to small and needs to be upsized. The joints on the duct can be sealed with duct sealent they sell it at home depot applied with 3 inch brush. Do not use tape it will get brittle after a few years and the duct will start leaking air. We use the cheap brushes because we toss them when done. The duct needs to wrapped with FSK wrap and all seams on insulation needs to be taped with FSK tape. I do not know were a DIY would purchase I get it wholesale. Mansville has it may be able to special order thru HD or Lowes. Hope this helps.

 

[Speedy2222]

Talked with an hvac guy and was advised to ditch the metal ducting off the main trunk line in favor for flex line, aswell as wrapping the main line to try and keep as heat loss to a minimum.

 

[zmaxmotorsports]

Flex for a main trunk line huh? Time to call somebody else

 

[Dick in Wisconsin]

When you go to tape the joints, be prepared to clean the sheet metal of dust and stuff. I've found over the years that "stuff" sticks to the sheet metal and then tape sticks to the "stuff" and not the sheet metal and falls off. I stiff brush and/or a wire brush, some cleaning solution (like industrial strength 409 or Top Job or Green whatever), and elbow grease. Good luck!

 

[Speedy2222]

Flex for a main trunk line huh? Time to call somebody else

No just the lines coming off of the main line that run to the registers, he said to wrap the main line.

 

[acmikee]

seal and insulate the metal duct. keep the metal duct if its in good condition you will lose air flow with the wire flex.