Sizing packaged air in a manufactured home

Originally Posted By: mtomlinson
This post was automatically imported from our archived forum.



I inspect in rural Florida, and frequently this includes manufactured homes with a packaged air unit (usually Tempstar or Intertherm). The rule I use for sizing is living_square_feet / 500 = maximum tonage, living_square_feet / 600 = minimum tonage.


The rule always seems to work with block or stick homes, but always fails with manufactured. Typically the unit is sized 1-1/2 tons greater than I estimate. So instead of 3-1/2, I'd find a 5; and instead of 1-1/2 I'd find a 3.

Is there some unwritten rule that says heat loss/gain in a manufactured home is so great that you have to add 1-1/2 tons?


Originally Posted By: bking
This post was automatically imported from our archived forum.



I’m not an expert on this but I know that a difference of that magnitude would not be reasonable. The manuf. home still has to meet the same insulation requirements.


I would think the builder just got a quantity discount on those units and used them to actually save from buying more.


--
www.BAKingHomeInspections.com

Originally Posted By: mtomlinson
This post was automatically imported from our archived forum.



I’ve found the oversize units on all manufactured homes I’ve inspected. This is regardless of manufacturer, or age of the home. I’ve found this to be true on repo’s that investor’s have relocated, as well as new installations. I’ve found it on units manufactured in Georgia as well as Florida.


I've done about a dozen manufactured homes, and I have two more coming up in the next few days. Let's see what I find there.


--
Michael Tomlinson
At-Home Inspection, Inc
"The Knowlege to Protect Your Investment"

Originally Posted By: Gary Reecher
This post was automatically imported from our archived forum.



Sizing of heating and cooling units should be done by accomplishing ACCA’s ( Air Conditioning Contractors of America) Manual J procedures calculating the heat loss/gain for the structure. Manufactured homes have a special section for calculation in the manual.


The ductwork installed in mobile homes are typically undersized and require higher blower static pressures to move sufficient air flow.


--
Gary Reecher, CM
HVAC Service Technician

MechAcc's Carbon Monoxide Site Links