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#4480389 - 08/06/17 01:53 AM Split A/C unit - Missing something
Nick1994 Online   content


Registered: 02/19/13
Posts: 9820
Loc: Phoenix, AZ
Random off topic post. My grandmother bought a 1400 square foot manufactured home last winter, it's a nice house but the A/C is a bit off. It's got a split A/C unit, the last time the outside condenser part of the unit was replaced the inside evaporator part was not. This summer it's been a bit rough as far as temps in the house, most days it can only cool the house to about 81-82 degrees and the A/C runs all day long, finally kicks off at 74 late at night. She's also had pretty high energy bills. The outside A/C is a 3-1/2 ton Goodman but the inside is a Coleman. We had an A/C guy come out that I trust to look at the unit, he spent most of the time outside checking it out and the pressures which were perfect, he said the unit was working as good as it possibly can, that possibly the problem is leaking ventilation or lack of insulation, but the unit itself is fine, I believe he just overlooked the following problem as I had several times. The house is tightly sealed, light colored roof, large patios that shade the west walls, dual pane windows and window coverings etc.

Then I took a closer look at the inside unit. There's a 4"x15" gap with no panel. It's sucking in air that has not passed through the evaporator and blowing it directly into the vents! So only about 1/2 the air coming out of the vents has actually been cooled. I couldn't believe my eyes. Today I picked up some sheet steel and made my own small panels. They're not pretty but they work. I also used some tape to tape off the water lines and seal it up and put a little expandable foam to seal it all up. Now, 100% of the air coming out of the vents has gone through the evaporator and it does feel a little colder, we'll see how it works out in the days to come. It does have a large cover over the front of the whole thing.

I've cleaned the coils, I will soon clean up the rest of the unit, the tape will be removed, I just didn't want the foam to make a mess and if I need to remove it in the future it'll be easy. The expandable foam has formed a perfect fit against the front cover. Just wanted to get this together to get the house cool for now.

Top pic is sideways for some reason. Second picture shows the view from where the filter goes straight down the front in a passageway to the blower motor. Last pic is how it is now with my ghetto shelf and foam.







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#4480398 - 08/06/17 02:55 AM Re: Split A/C unit - Missing something [Re: Nick1994]
Merkava_4 Offline


Registered: 01/30/07
Posts: 17501
Loc: Clovis, CA
That third picture down is what mine looks like with the furnace off. My furnace sits on top of the evaporator and sits inside an elevated closet on the side of the house which I call the furnace room. Immediately outside the closet is the condensing unit. All the air flows downward from the roof and into the crawl space below the house. From there the ducts carry the air upward into the floor vents. The original GE condensing unit was attached directly to the side of the house. Now there's a plywood blank-off panel that covers the original opening. Immediately above that opening is the furnace room. The new condensing unit sits about 24 inches from the house on a concrete pad. I've been watching a lot of HVAC videos on YouTube. Those guys rake in the money.

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#4480399 - 08/06/17 02:57 AM Re: Split A/C unit - Missing something [Re: Nick1994]
Colt45ws Offline


Registered: 08/15/06
Posts: 9612
Loc: Central Washington
I have a very similar unit and that gap isnt a problem once the front panel is installed with it's filter. The panel is solid except for where the filter is which is in front of the evaporator.
If I take the front panel off while its running, the evaporator will begin to freeze up quickly from lack of air flow across it.
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2002 Ford Crown Vic PI 207k, Ex-Kootenai County, ID Unit #42
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#4480524 - 08/06/17 08:13 AM Re: Split A/C unit - Missing something [Re: Nick1994]
JHZR2 Offline



Registered: 12/14/02
Posts: 41410
Loc: New Jersey
That doesn't look like a split system to me...

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#4480525 - 08/06/17 08:14 AM Re: Split A/C unit - Missing something [Re: Nick1994]
zrxkawboy Offline


Registered: 11/30/04
Posts: 1748
Loc: SD
3.5 ton seems large for 1400 ft2, but maybe that's typical in your climate.
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#4480532 - 08/06/17 08:20 AM Re: Split A/C unit - Missing something [Re: JHZR2]
HerrStig Offline


Registered: 08/24/11
Posts: 9560
Loc: Boston, MA
Originally Posted By: JHZR2
That doesn't look like a split system to me...

Me either. Splits have a evap unit hung on a wall with the rest of the works outside. The evap unit looks like the front of a large window unit but it doesn't go through the wall.

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#4480565 - 08/06/17 08:57 AM Re: Split A/C unit - Missing something [Re: HerrStig]
JHZR2 Offline



Registered: 12/14/02
Posts: 41410
Loc: New Jersey
Originally Posted By: HerrStig
Originally Posted By: JHZR2
That doesn't look like a split system to me...

Me either. Splits have a evap unit hung on a wall with the rest of the works outside. The evap unit looks like the front of a large window unit but it doesn't go through the wall.


That's my understanding too, though I know some call those "split ductless", so perhaps this is split ducted... could be regional naming differences too, who knows...

Key thing is if a manual j was performed to define sizing of the system. In AZ, I suspect dehumidification is less of an issue (perhaps even driving designs to cool but leave what little humidity there is in the air). Its all about solar radiation and generally warm ambient temperatures, I'd guess.

Duct losses and sucked air that is not part of the conditioned loop is exactly why most all central air systems except ductless mini splits are lousy and highly inefficient.

Assuming that the whole evaporator system is in an attic or crawl space which in AZ I assume could be >100F (in a crawl space) and >150F (in an attic), ducting insulation is a major issue and consideration, as is the leakiness of that system.

While generally an advocate of ain't broke don't fix it, if the system is old, unmatched, and not working to par, why not get some quotes for a proper calculation, tear out and install of a complete new system once summer is over?

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#4480566 - 08/06/17 08:57 AM Re: Split A/C unit - Missing something [Re: Nick1994]
Reddy45 Offline


Registered: 08/15/08
Posts: 2728
Loc: USA
Nick you said this is a manufactured home. Is there still an attic where the ductwork runs?

Also, next time you are over there, see if you can take measurements at the warm air return, and at the cold air supply vents. Let us know the temp difference.

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#4480604 - 08/06/17 09:35 AM Re: Split A/C unit - Missing something [Re: Nick1994]
vwmaniaman Offline


Registered: 04/18/13
Posts: 100
Loc: Kevil,Ky
I live in KY and the climate here is hot and humid most of the summer. We have 2 homes and one is a manufactured home that is just a little bit larger than your mothers. We have a 2&1/2 ton split system with floor vents. It uses R22 but I have gone to R22A on ours. When it is a day that will be in the mid to upper 90's we can only cool to the upper 70's in the house. I am getting a 20-22 degree drop from air in to air out. It is mainly that mobile homes lack insulation. Our other home is 3900 sq feet that uses a 4 ton unit and cools to any temp you desire with ease but has 12" of attic insulation and thermostatic vent fans. The electric bills are nearly identical for both homes. Electric company rates are higher at the larger home. We even added the blue foam insulation under the vinyl siding on the mobile home and dual pane windows which helped a lot. Only relief you may get is to add a white metal over roof with a space between the 2 roofs for air circulation. Hope this helps you out.
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#4480625 - 08/06/17 10:01 AM Re: Split A/C unit - Missing something [Re: Nick1994]
bubbatime Offline


Registered: 03/18/08
Posts: 5456
Loc: South Florida
I would honestly turn that thing off and run 2-3 window units until you can afford to replace it. Would probably work much better and would probably save energy.
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#4480635 - 08/06/17 10:17 AM Re: Split A/C unit - Missing something [Re: Nick1994]
laserred96gt Offline


Registered: 03/03/13
Posts: 861
Loc: Florida
Everything that has a condenser and a furnace or air handler is called a split system. The ones you hang on the wall are called ductless mini splits. You also have package units which are more common on rooftops of commercial buildings and mobile homes. There's bard or leach units for some rare application that mount on the side of the building.
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#4480754 - 08/06/17 12:37 PM Re: Split A/C unit - Missing something [Re: Nick1994]
Colt45ws Offline


Registered: 08/15/06
Posts: 9612
Loc: Central Washington
I know with my manufactured home is a double wide, and the air handler (Yes, that is a split A/C air handler; I have the exact same unit.) pushes air down and through a duct on the same half of the home it is located on, but there is a large flexible duct that drops down into the crawl space under the home and goes over to the other half. You might crawl under there and make sure that duct is intact so you are not cooling the crawl space.


Edited by Colt45ws (08/06/17 12:39 PM)
_________________________
-Colton
2002 Ford Crown Vic PI 207k, Ex-Kootenai County, ID Unit #42
Down for engine swap
2003 Ford Crown Vic PI 75k
Castrol EDGE HM 5W30, Fram XG2

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#4480870 - 08/06/17 02:15 PM Re: Split A/C unit - Missing something [Re: Colt45ws]
Nick1994 Online   content


Registered: 02/19/13
Posts: 9820
Loc: Phoenix, AZ
Originally Posted By: JHZR2
Originally Posted By: HerrStig
Originally Posted By: JHZR2
That doesn't look like a split system to me...

Me either. Splits have a evap unit hung on a wall with the rest of the works outside. The evap unit looks like the front of a large window unit but it doesn't go through the wall.


That's my understanding too, though I know some call those "split ductless", so perhaps this is split ducted... could be regional naming differences too, who knows...

Key thing is if a manual j was performed to define sizing of the system. In AZ, I suspect dehumidification is less of an issue (perhaps even driving designs to cool but leave what little humidity there is in the air). Its all about solar radiation and generally warm ambient temperatures, I'd guess.

Duct losses and sucked air that is not part of the conditioned loop is exactly why most all central air systems except ductless mini splits are lousy and highly inefficient.

Assuming that the whole evaporator system is in an attic or crawl space which in AZ I assume could be >100F (in a crawl space) and >150F (in an attic), ducting insulation is a major issue and consideration, as is the leakiness of that system.

While generally an advocate of ain't broke don't fix it, if the system is old, unmatched, and not working to par, why not get some quotes for a proper calculation, tear out and install of a complete new system once summer is over?
It's got the compressor and condenser coils with a fan outside, the evaporator coils (pics above) are kind of in a closet in the laundry room. The ducts run under the home, which is actually probably better since it isn't too hot under there compared to attics in homes here. The home doesn't have an attic and the ducts run underneath.

Replacing right now isn't in the budget. The unit runs fine, I'm thinking this was the missing piece to the puzzle but we shall see. It had a HUGE gap sucking in uncooled air into the ducts.

Originally Posted By: Reddy45
Nick you said this is a manufactured home. Is there still an attic where the ductwork runs?

Also, next time you are over there, see if you can take measurements at the warm air return, and at the cold air supply vents. Let us know the temp difference.

Ducts are under the home, no attic space. I will take measurements next time I'm over there.

Originally Posted By: Colt45ws
I have a very similar unit and that gap isnt a problem once the front panel is installed with it's filter. The panel is solid except for where the filter is which is in front of the evaporator.
If I take the front panel off while its running, the evaporator will begin to freeze up quickly from lack of air flow across it.
Looking from the top of this unit shows the 4"x15" gap where air is just sucking right down directly to the fan that pushes it through the ducts. This is with all panels connected, I think this one is missing something.
_________________________
2015 Hyundai Sonata 2.4L 76k PU 5w30 & OEM
2000 Toyota Camry 2.2L 227k M1 AFE 0w30 & Wix
1996 Jeep Cherokee 4.0L 145k M1 HM 10w40 & Fram Ultra

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#4480896 - 08/06/17 02:42 PM Re: Split A/C unit - Missing something [Re: Nick1994]
mk378 Online   content


Registered: 09/27/15
Posts: 1327
Loc: USA
The TXV bulb should be fully covered with insulation so it only sees the temperature of the line it is clamped to. How cold does that suction line get? Also measure the temperature of the air leaving the indoor unit. Like others said, you need to look under the house and make sure the ductwork is intact.

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#4481199 - 08/06/17 08:20 PM Re: Split A/C unit - Missing something [Re: Nick1994]
Nick1994 Online   content


Registered: 02/19/13
Posts: 9820
Loc: Phoenix, AZ
I still need to measure the vent temps, but I talked to my mom and it's 75 in the hallway, it was 79 yesterday (only 105 or so outside) and it is much more comfortable in the house.
_________________________
2015 Hyundai Sonata 2.4L 76k PU 5w30 & OEM
2000 Toyota Camry 2.2L 227k M1 AFE 0w30 & Wix
1996 Jeep Cherokee 4.0L 145k M1 HM 10w40 & Fram Ultra

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