THPRE

**THPRE** · 01-28-2013, 04:51 PM

Coil placement. The coil is definately in the top cabinet - and I feel fins like when I reach in there but I have not gotten a mirror to actually look at the coil. It feels like the top of an "a" coil with the legs coing to the sides of the cabinet. That might not jive with the tx valve placement But I was not looking or really trying to asertain the configuration - just know there were fins in the middle. I have 15 or 16 out lets and thet have modified the air ducts three times - maybe I actually do have reasonable air flow?

**THPRE** · 01-28-2013, 04:57 PM

So do you think I need a smaller air handler? That would lower the static even below the .3 total I have now. What would that do to the high side pressures? Then would I need a smaller outside unit too? So is the entire unit too big for a 2500 sq. ft. home? No one else has suggested this but the unit sure does not work!

**crmont** · 01-28-2013, 05:47 PM

Originally Posted by THPRE

Coil placement. The coil is definately in the top cabinet - and I feel fins like when I reach in there but I have not gotten a mirror to actually look at the coil. It feels like the top of an "a" coil with the legs coing to the sides of the cabinet. That might not jive with the tx valve placement But I was not looking or really trying to asertain the configuration - just know there were fins in the middle. I have 15 or 16 out lets and thet have modified the air ducts three times - maybe I actually do have reasonable air flow?

Are the coil doors facing front? The pictures are too close up to tell.

Who knows about the air flow. You'd think after 3 tries they'd have corrected the problem.

I personally have a rule of not installing anything bigger than a three ton heat pump on any manufactured home because of the inherent duct work limitations.

A 4 ton seems a bit large unless there is 6 skylights and vaulted ceilings. I don't suppose that there has been a load calculation done?

**Shophound** · 01-28-2013, 05:51 PM

Originally Posted by THPRE

So do you think I need a smaller air handler? That would lower the static even below the .3 total I have now. What would that do to the high side pressures? Then would I need a smaller outside unit too? So is the entire unit too big for a 2500 sq. ft. home? No one else has suggested this but the unit sure does not work!

No, what folks are saying is that the blower itself is not a high static rated blower. It's a blower designed to go on a standard stick-built residential house, not a mobile home.

As to whether or not your system is sized properly for your house, only a heat load calculation can help you determine that.

**beenthere** · 01-28-2013, 06:19 PM

Originally Posted by Shophound

No, what folks are saying is that the blower itself is not a high static rated blower. It's a blower designed to go on a standard stick-built residential house, not a mobile home.

Lots of stick built homes have statics of .7 to .8", really makes no difference that its a mobile home. A 4 ton Coleman air handler made for a MH doesn't deliver anywhere near 1600 CFM at 7" static.

**garyed** · 01-28-2013, 07:16 PM

If I'm not mistaken this unit has a VS motor that's capable of pushing 2000 cfm at .8 total static. Assuming the jumpers or dip switches are set for 1600 cfm & it is anywhere near .3 tsp there should be plenty of air flow. The problem from what the OP is describing though sounds like a classic low air flow problem so it doesn't make sense. No tech rep is going to be able to help over the phone without a lot of specific technical info from an HVAC tech. The problem could be anywhere from a bad outside TXV to miswired system & a lot of other possibilities in between. My recommendation would be to invest a little more money with a pro that might be more familiar with the equipment.

**beenthere** · 01-28-2013, 07:36 PM

Originally Posted by garyed

If I'm not mistaken this unit has a VS motor that's capable of pushing 2000 cfm at .8 total static. Assuming the jumpers or dip switches are set for 1600 cfm & it is anywhere near .3 tsp there should be plenty of air flow. The problem from what the OP is describing though sounds like a classic low air flow problem so it doesn't make sense. No tech rep is going to be able to help over the phone without a lot of specific technical info from an HVAC tech. The problem could be anywhere from a bad outside TXV to miswired system & a lot of other possibilities in between. My recommendation would be to invest a little more money with a pro that might be more familiar with the equipment.

Does Goodman include the coil PD in their static rating for that blower.

**garyed** · 01-28-2013, 09:34 PM

Originally Posted by beenthere

Does Goodman include the coil PD in their static rating for that blower.

That's a good question. The technical literature is a little ambiguous but the way I interpret it I think it does. Here's a quote from the technical literature:

The MBVC blower cabinet uses a variable speed motor that
maintains a constant airflow with a higher duct static. It is
approved for applications with cooling coils of up to 0.8 inches
W.C. external static pressure and includes a feature that
allows airflow to be changed to + 10%.

It sounds like the coil alone can have up to .8 inches of static & that's a pretty good amount of allowance. It doesn't say anything about tsp but my understanding is that most VS motors max out around .8 to 1.0 tsp on AH's with coils. That cabinet can be set to put out anywhere from 800 to 2000 cfm so its possible the system is just not setup right.

**beenthere** · 01-28-2013, 10:18 PM

Originally Posted by garyed

That's a good question. The technical literature is a little ambiguous but the way I interpret it I think it does. Here's a quote from the technical literature:

It sounds like the coil alone can have up to .8 inches of static & that's a pretty good amount of allowance. It doesn't say anything about tsp but my understanding is that most VS motors max out around .8 to 1.0 tsp on AH's with coils. That cabinet can be set to put out anywhere from 800 to 2000 cfm so its possible the system is just not setup right.

I think thats up to .8" - the coils PD. Since the coil is actually external to the blower. But I could be wrong.

**Shophound** · 01-29-2013, 12:17 AM

Originally Posted by beenthere

Lots of stick built homes have statics of .7 to .8", really makes no difference that its a mobile home. A 4 ton Coleman air handler made for a MH doesn't deliver anywhere near 1600 CFM at 7" static.

I stand corrected.

**crmont** · 01-29-2013, 02:55 AM

Originally Posted by garyed

I........The problem could be anywhere from a bad outside TXV.....

Nope. Take that off the list.

**THPRE** · 01-29-2013, 01:38 PM

Yeah pictures are hard -- not enough room. I think think there are no doors on the side facing the room. A load calculation was done and 4 ton recomended. Actually 4 1/2 ton but I guess no such thing exists. The ceilings are mostly ten feet and big skylights and lots of windows. Three sliding doors. No shade , placed on a sunny knoll. Load calculation was done by the testing company not the installer.

**THPRE** · 01-29-2013, 03:26 PM

Gary - I have had supposed experts out -- I should not say supposed - they impressed me with their knowledge and equiptment. The problem was that Goodman would not discuss much with anyone except the original installer. The only thing they would do was to verify that the units should work together. So if I want any warranty I have to go through things with my original installer. Thus the phone conferences. And since they just stonewall me I'm on this site to gain knowledge. And I am learning form all these answers. So Thanks to all! THPRE

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