Exposed flex ducts - Any tips?

[Phrancis]

Good evening!

I live in a manufactured home set on a slope, built circa 1995. The builder installed all the supply ductwork underneath the house, exposed to outside air, and it's all flex. The return is indoors just above the AHU. The heat in the house is uneven, it's several degrees warmer (or cooler in the summer) in the rooms closest to the AHU.

I have a feeling that a lot of heat is lost on the ductwork along the way, and possibly have leaks in it due to small animals as we live out in the country. I'm trying to think of ways this could be improved and was wondering if (after I patch any holes and looking for obstructions) there is a way to insulate flex ducts to reduce the amount of heat transferred to (or from) the outside air. If this is too DIY just let me know. Not planning on touching the equipment itself.

Thanks all!

[socotech]

I would suggest you replace the whole duct system with hardpipe and size properly for even airflow velocity. It will probably be cheaper and have better results in the end if you pay for a duct contractor to do this for you. You WILL continue to have problems with flex. I have never seen flex underneath a house last long.

[kdean1]

Flex duct is not intended for exterior use.

[Phrancis]

Flex duct is not intended for exterior use.

Looks like mfg housing builders like to cut corner don't they. Know anyone in the Southern Indiana area? I'm guessing any licensed contractor could handle this comfortably?

[mechanical'al]

also a good start is to shore up the skirting ,insulate it and isolate it as to keep out both the critters and old man winter
I do agree that the duct should be redone also though it is what all of them use those who dont know or maybe care about your comfort after the sale$$$$

[Sicofthis]

Get it done right with hard pipe. I have relatives that had flex under a manufactured home. They had to replace most of the first floor floor and spent tens of thousands of dollars on repairs due to supply leakage under their home.

[wahoo]

We replace a lot of "cross over" pipes under double wide homes with metal round pipe, covered with a slightly larger piece of insulated "flex pipe". Using the flex to insulate the metal inside is much simplier than trying to "wrap" that pipe! Even if the flex get torn, you'll still have heat or cool. And sealing up and insulating the skirting is a very good idea. Most homes have vinyl skirting which is totally useless except it covers up the mess underneath!

[jagans]

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[Phrancis]

We replace a lot of "cross over" pipes under double wide homes with metal round pipe, covered with a slightly larger piece of insulated "flex pipe". Using the flex to insulate the metal inside is much simplier than trying to "wrap" that pipe! Even if the flex get torn, you'll still have heat or cool. And sealing up and insulating the skirting is a very good idea. Most homes have vinyl skirting which is totally useless except it covers up the mess underneath!

Makes sense. Yeah the skirting is vinyl, I'll give that some thought. A coworker of mine who is in the field suggested I look into insulated flex, he said that would keep the expense minimal and pretty easy to do yourself. I haven't noticed what the crossover pipe is made of, I'll check on that later. Think this would yield some results?

Any suggestion on materials for the skirting?

[wahoo]

If you replace this flex pipe cross-over with flex by itself, then it will last about as long as it takes you to crawl out from under home. Waste of time to do flex only. On most manufactuered homes, the main ductwork is built into the floor and only the cross over is the flex. Is your home different?

[TwincamDave]

What color is the exhisting flex? If it is shiney silver that is for attics and basements only,if it is black that is for crawl spaces and designed for exterior use.If you can seal the crawl off completely,insulate it and put a vapor barrier down on the ground and add a dehumidifier in the crawl that will protect it and keep it dry.Just my $.02 ,PS I have done this in Ga. to my old home and it worked like a dream.

[Phrancis]

What color is the exhisting flex? If it is shiney silver that is for attics and basements only,if it is black that is for crawl spaces and designed for exterior use.If you can seal the crawl off completely,insulate it and put a vapor barrier down on the ground and add a dehumidifier in the crawl that will protect it and keep it dry.Just my $.02 ,PS I have done this in Ga. to my old home and it worked like a dream.

I'll check on all that tonight

[Phrancis]

We replace a lot of "cross over" pipes under double wide homes with metal round pipe, covered with a slightly larger piece of insulated "flex pipe". Using the flex to insulate the metal inside is much simplier than trying to "wrap" that pipe! Even if the flex get torn, you'll still have heat or cool. And sealing up and insulating the skirting is a very good idea. Most homes have vinyl skirting which is totally useless except it covers up the mess underneath!

Wahoo, it looks like you were right on target. I crawled down there tonight and to my surprise I found the crossover pipe to have... one of our cats, laying there nonchalantly among some mangled insulation. I went back inside and turned on the blower, and went by each register. All those on the furnace side of the home blow fine, but those across have barely any air coming out. Any suggestion on replacement crossover materials? Got Lowes & THD nearby but not sure if they carry that. Also got a Johnstone Supply and Berkheimer pretty close by.