Older mobile home ducts are pretty small. Air handlers for them are designed to handle the smaller ducts. When looking at the specifications on mobile home furnaces verses standard home furnaces, I notice they both show rated cfm's and temp rises at .1 to .5 wc. I would think the mobile home rated air handler would show a higher static pressure rating. What gives?

Actually if you are going to be replacing a gas or oil furnace in your mobile home you will need to obtain one that is approved for mobile home use since that is the HUD law/rule. The rule is there for your safety.

If you are going to be using a electric style unit then I suggest you talk to your local contractor that does such work. Many times the blower motor will need to be changed to compensate for the static pressure differential.

Another option for you is to use Google as a search engine. This will allow you to get as much information as you need on this subject as there is not enough room on this board to cover all the details about the question you are asking.

The s.p. ratings I referred to were from furnace spec's that I found on the internet. What I noticed was standard furnaces and mobile home rated furnaces were both rated from .1 to .5 s.p. I am looking for an answer as to why that would be.

i am looking for an answer as to why that would be.

The answer is real simple. That is what they tested out to be.

I agree that mobile home units are very restricted in the supply air department BUT the biggest problem is the return air department. When you get these unit up and running the return air makes so much more noise in a mobile home setting. Also most mobile home units are designed to run with very little restriction on the supply/return air side where as most residential stick built homes use a duct system for the return.

Do a Google search on static pressure as mentioned before there is just not enough room here to post all the possibilitys.

I have google'ld static pressure and did not come up with enough information to satisfy my curiosity regarding why the spec's on a mobile home unit are in the same range as a standard unit. Again, I would think the sp capability of a mobile home unit would be higher. The simple answer of "they tested out to be" still leaves me looking for additional information.

the simple answer of "they tested out to be" still leaves me looking for additional information.

You could always take a engineering course to satisfy yourself since I have no other information that I would post here in regards to this subject. I wish you luck with finding more info.