On Jan 21, 7:05*pm, Ed Pawlowski wrote:
On Mon, 21 Jan 2013 05:52:09 -0800 (PST), andyeverett

wrote:
A manufactured home has a compact oil fired forced air furnace in one
corner oc a 40x28 manufactured home. A large central duct runs down
the middle of an unfinished basement and perpendicular ducts run in
the joist spaces. The joist spaces in the basement are insulated with
faced fiberglass. The home is in south eastern PA. Seemed like a lot
of heat was wasted because the central duct was not insulated. The
owner of the home complained of cold and one heating contractor
installed a larger central duct (slows down flow further increasing
heat loss?)

Should the duct work be insulated and if so roughly how many years to
payback?

Thank you for any help!

The heat loss is keeping the unfinished basement from freezing.
Insulating the ducts is probably not the problem. Installing a larger
duct is not a cure either, unless it was too small to begin with.

What is cold? *The entire house or just a room or two? *Does the
furnace run constantly when it is cold? *Sounds like a good evaluation
is needed to find what the real complaint is and to find if the
furnace is working properly.

That's my take too. Too little info to even guess what is
really wrong. But as you say it isn't likely the uninsulated duct.
You would lose some heat from those ducts for sure.
But it should manifest itself in slightly higher energy
bills, not a cold house. If the cold problem only happened
on the coldest day and the furnace was running all the
time, then that small loss could explain it. Or if it's
only cold in the room farthest from the furnace, then
insulating the duct would help some.



Right sized return duct s are a must, clean filters, proper blower
speed, balance by partly closing some of the vents, thermostat
setting, should all be looked at.

He said in one of his posts that he thinks the system
uses the house as a return? That would imply that there
isn't a return duct system and it's just sucking air from
the basement. If that's how it's installed, then it's a big
energy loss, because you're sucking cold air from the
basement into the furnace and constantly drawing air
from the heated house down into the basement, as well
as from outside.



What is the thermostat set for and what is the actual temperature? *.

Right, we don't even know if the thermostat set temperature
is reached or not. I would assume it must be, at least most
of the time or there would be one hell of a bill.


I'd also insulate the basement. There is a lot of loss on concrete
walls.