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Old 07-02-2011, 08:31 PM   #1
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New Heat Pump for Double Wide MH


Hi,

I'm purchasing a 28X76 2128SF double-wide mobile/manufactured home and the AC/Heating has been vandalized and is in need of replacement. I got a local HVAC firm to give me an estimate and there's no way I can afford to have them do the job.

I've since begun looking at trying to size and purchase the equipment myself and hire a local independent HVAC person to do the install. I'm running into conflicting information and finding it hard to decide what to do.

The HVAC salesman quoted prices for a 5-ton system, citing that mobile homes are poorly constructed and that was what I needed after he measured the SF of the home. Everyone I've talked to says that is too big even for a 2100 SF MH. The house we live in now is very near that large and also has an add-on sunroom with seven huge windows and a large french door...it stays comfortable with only a 3.5 ton unit.

I know that each structure is has its own unique heat loss/gain factors, so I purchased the HVAC-Calc software and did my own calcs. I get a borderline requirement that could go either 3.5 ton or 4 ton, depending on how poor I think the "tightness" of the structure is. But I am a bit hesitant to rely on my own inexperienced calculations (no reflection on HVAC-Calc's excellent program!) over the words of a "seasoned professional who's done this for 15+ years."

Another issue is one of the guys giving me an estimate (not complete yet) for the install asked if I was aware the ducts were undersized and that if I went with a non-mobile home type of system, the air handler would not work against the high static pressure. So naturally, all the "mobile home" equipment is more expensive and not as plentiful as standard units.

So...my dilemma is... do I need to search for mobile home rated equipment and keep the duct work as is? Or do I wreck out the ducts and install larger ones so I can use a "regular" split unit system? I am also hearing that my home owner's insurance company may not like me installing equipment that is not specifically rated for use in "mobile/manufactured homes". Yet, I know there has to be MANY folks out there who have had to replace their mobile home heat pump/air conditioner systems before me....so what did THEY do? What do I do?

Also, this home is located near Greenville, SC. I think the installation would be a fairly straightforward hook-up, duct-work aside. The lot is flat and there is 30" of crawlspace access underneath. I will be installing brick underpinning, so I will have all the old vinyl crap wrecked out. Inside, there is an existing working blower and heat strip in down-flow configuration in an easily accessible hallway space, but the evap coil has been stolen. The old outside unit has had all the lines and wiring cut. I will remove the old air handler cabinet myself and the installer would just have to place the new air handler, evap coil, and hook it up to a new outside unit. The only surprises I can envision are maybe having to upgrade the wiring from the service panel and/or upgrade the two trunk line ducts and crossover. Assuming no extra wiring or duct-work, what fair price should I expect to pay for an installation like this? I can't see this job taking more than 4 hours MAX without needing to rewire or upgrade ducts. Is that realistic?


Last edited by MrPisky; 07-02-2011 at 08:56 PM.
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Old 07-02-2011, 09:29 PM   #2
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Why don't you contact the manufacture and ask what tonnage they recommend for the duct system that they installed.

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Old 07-03-2011, 07:53 AM   #3
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The furnace/air handler portion of the system has to be rated for mobile home use. The AC/heat pump portion is the same as a conventional home. Four hours is not realistic to replace a system and set it up correctly.
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Old 07-03-2011, 08:00 AM   #4
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Originally Posted by Artco View Post
Why don't you contact the manufacture and ask what tonnage they recommend for the duct system that they installed.
Yes, that's one option. Thanks for suggesting. I guess I'm really leaning towards converting the air handler over to more standard equipment. Would reworking the ducting allow me to install a lower static air handler? I can get a complete Goodman system with inside/outside units, evap coil, heat strip, TXV and lines at a very affordable price. Just not sure about the cost/issues with reworking the ducts.

What about going with a package heat pump unit? Is that possible/doable after there's been a downflow split unit originally installed?

I'll stick with mobile home rated equipment if it's my only option, but I want to know what the options are first. Thanks for the reply!
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Old 07-03-2011, 08:09 AM   #5
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Originally Posted by Marty S. View Post
The furnace/air handler portion of the system has to be rated for mobile home use. The AC/heat pump portion is the same as a conventional home. Four hours is not realistic to replace a system and set it up correctly.
Hmm...the air handler blower is working fine, just no evap coil. Not sure about the heat strip, but that's not an expensive item from what I can tell. From what I've read so far, I keep seeing phrases that say "the air handler and outside heat pump must be matched correctly". Does that only refer to the tonnage output? Or are there some other factors that must be looked at in the specs to match an air handler to the outside compressor/heat pump?

Nothing has to be done to the outside unit...it's been severed from the system and moved out of the way. The majority of the work would be installing either a new air handler and evap coil or just fitting a new coil to the existing handler. So what would be a reasonable expectation of time for setting up on a mobile home with the old system already removed? Thanks for your reply!
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Old 07-03-2011, 08:12 AM   #6
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The furnace/air handler portion of the system has to be rated for mobile home use.
Are you saying this from a legal/code requirement? Or from a practical application standpoint?
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Old 07-10-2011, 04:16 PM   #7
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Mr. Pisky, I first found you over on mobilehomerepair.com where someone said, I thought at least, that it didn't matter about the air handler, or at least if you're using the original one it would be rated for mobile home use. We actually have the opposite problem (maybe I need to start my own thread?); we don't have the original air handler, or at least I don't think; I think maybe we did but now it's been taken out but maybe not since we're dealing with a package unit that I think has it included in the package. Otherwise I think you use the one in the mobile home but since I don't think we are I am wondering about ours being rated for mobile home use. Just noticed you hadn't gotten an answer; anybody still around or maybe they too are gone on a trip Hope we find some answers soon.
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Old 07-10-2011, 04:49 PM   #8
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Just had a new Ruud furnace and air conditioner put into my mobile home, it is not rated for mobile home use and is doing just fine! Forget about worrying about if it is certified, it doesn't have to be. Until just recently, it had to be rated, and coleman was the only choice. They lifted that regulation. So go ahead and pick any brand, it's up to you.
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Old 07-10-2011, 08:17 PM   #9
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Originally Posted by vln View Post
Just had a new Ruud furnace and air conditioner put into my mobile home, it is not rated for mobile home use and is doing just fine! Forget about worrying about if it is certified, it doesn't have to be. Until just recently, it had to be rated, and coleman was the only choice. They lifted that regulation. So go ahead and pick any brand, it's up to you.

Coleman was never the only company to make HUD approved units.

In many states, the state's HUD will still require that the unit be HUD approved.
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Old 07-11-2011, 11:57 AM   #10
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Coleman was never the only company to make HUD approved units.

In many states, the state's HUD will still require that the unit be HUD approved.
So what it sounds like is if I want my structure to be "HUD approved" then I'd need to stick with mobile home rated equipment? This will be my own private residence and I wanted to know if I am personally restricted by some restriction/regulation the governs the type of HVAC equipment I can install.

I guess it might be a consideration in the future if I try to resell the property or rent it out?
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Old 07-11-2011, 12:01 PM   #11
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Quote:
Originally Posted by vln View Post
Just had a new Ruud furnace and air conditioner put into my mobile home, it is not rated for mobile home use and is doing just fine! Forget about worrying about if it is certified, it doesn't have to be. Until just recently, it had to be rated, and coleman was the only choice. They lifted that regulation. So go ahead and pick any brand, it's up to you.
Well, I think there are two separate issues...one being the physics of using an air handler that is made specifically for "high static pressure" applications where the duct work is smaller versus regular framed homes where the duct work has been (hopefully) properly sized by a HVAC contractor.

Then there's the regulation/code issue that I was trying to get information on. It seems as if that might pose problems down the road for potential buyers or renters, should I choose to either sell or rent the home and HUD is involved.
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Old 07-11-2011, 12:03 PM   #12
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Thanks for all the responses. Fortunately for me, we have decided against purchasing this property and located a different one which doesn't need a new HVAC system. Maybe this information will be useful for someone in the future.
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Old 07-11-2011, 12:07 PM   #13
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Just ask the city if it is OK. That is what my HVAC guy did and everything checked out. As to the high static, my guy widened the return vent to 16" and cut out a large space under one of the existing returns and installed a bigger grille.

Everything is running fine and everything is up to code.

(Note this is California, which has some of the strictest code).
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Old 07-11-2011, 12:29 PM   #14
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Originally Posted by vln View Post
Just ask the city if it is OK. That is what my HVAC guy did and everything checked out. As to the high static, my guy widened the return vent to 16" and cut out a large space under one of the existing returns and installed a bigger grille.

Everything is running fine and everything is up to code.

(Note this is California, which has some of the strictest code).
Thanks for that information.
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Old 07-11-2011, 04:08 PM   #15
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Quote:
Originally Posted by MrPisky View Post
So what it sounds like is if I want my structure to be "HUD approved" then I'd need to stick with mobile home rated equipment? This will be my own private residence and I wanted to know if I am personally restricted by some restriction/regulation the governs the type of HVAC equipment I can install.

I guess it might be a consideration in the future if I try to resell the property or rent it out?
Thats always something that should be considered.


Good luck with the other property.

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