Goodman A-coils

[bb]

Is anyone running into problems getting replacement a-coils for the Goodman A-XX series airhandlers or the U-XX coils in particular ?

[cehs]

They have made some changes and are using different model numbers. The dementions have changed somewhat, but I can still get MATCHING coils for the condensing units I want to install.
I just have to ask to be sure I am getting a coil that will fit the plenum I am working with...

[BaldLoonie]

Got a A18 coil in couple months ago, no delay. Did have a hard time getting a CPKE outdoor coil in. About the time the customer was faint with heat stroke we ended up replacing the unit and hoping that Goodman will give us credit on the bad coil towards the unit. Supplier said they would if they got credit from Goodman. I can't believe Goodman wants to see the old unit. Must cost a fortune in shipping.

[RoBoTeq]

You'd be surprized at the equipment that the quality control at Goodman wants to see in person. There is a massive drive to prevent coil leaks and the best way to know what happens down the road is to test the equipment after it has failed.

About 95% of the coil leaks I invetigate can be attributed to other than manufacturing issues. This is consistant with all four brands I have repped over the past decade.

Evaporator coils for cooling only develope pinhole leaks at the brazed joints because of moisture that was not properly evacuated from the coil during installation. An hour pump down means nothing. Lines and coils need to be evacuated to under 500 microns and then then gauges shut off to see if the evac holds to below 1000 microns for at least 15 minutes. If the vacuum rises above 1000 microns in 15 minutes there is still moisture in the system.

That moisture mostly collects at the braze joints and being in the low side of the system does not get flushed through the system to the filter/drier. It just sets there eating away at the joint.

The best indication of this having happened is there will be a green coloration at the inside of the coil joints and at the joint where the copper lineset attaches to the suction side of the coil.

Other coil leaks are due to shipping. If there is any physical damage to the coil that has created a leak, that is not a manufacturing issue. There should always be a quick check for copper tubing rubbing against anything that will wear a hole in the tubinb through vibration.

I have had misdiagnosed claims of leaks due to not being able to build the pressures up. These mostly result in finding low or no indoor air flow that was missed by the technicians. Frozen coils, bad blower motors and in one case where the installer cut the return through the side of an "A" coil air handler so the air never went through the coil. This replaced a unit that had a slant coil in it so the installer put the new unit in the same way and claimed the unit must be leaking because the pressures would not go up.

[bb]

That's very usefull information Robo. I had no idea that it was moisture causing the return bend leaks. I always thought it was due to rapid brazing during the manufacturing process.

Give it to me straight though, "Is Goodman not making the U series coils anymore? I have recently come across several attic air handlers with leaky U-48 and U-60 coils. There is not enough clearance from the top of the coil to the blower housing to accept the "new" coils that we have gotten when ordering a U-xx.

Some of these airhandlers don't seem to be too old. Maybe 5-6 years.

It just struck me as odd that Goodman would dis-continue these as replacements.

[Swampfox]

The old style coils are still available, they have just changed the model numbers, My supplier stocks both so I can get you the model numbers tomorrow and post back here

[midhvac]

Originally posted by RoBoTeq
This replaced a unit that had a slant coil in it so the installer put the new unit in the same way and claimed the unit must be leaking because the pressures would not go up.

I think I was there! Couldn't get it to take no freon

[RoBoTeq]

Originally posted by midhvac

Originally posted by RoBoTeq
This replaced a unit that had a slant coil in it so the installer put the new unit in the same way and claimed the unit must be leaking because the pressures would not go up.

I think I was there! Couldn't get it to take no freon

Before we all laugh too hard at this, is there any of us who have not done really stupid things before? I certainly have

[RoBoTeq]

The "U" series coils are no longer being manufactured. The replacement coils of the same capacity may be a different width to accomodate the standardized widths for both Goodman and Amana brands to use the new corporate coils and the height/length may be greater due to the change in row design. So yes, the new coils may require some sheet metal changes when changing out a "U" style coil.

The upside is that the new corporate coils are better fitting to the new shorter series of both the Goodman and Amana brand furnaces.

[RoBoTeq]

Originally posted by bb
That's very usefull information Robo. I had no idea that it was moisture causing the return bend leaks. I always thought it was due to rapid brazing during the manufacturing process.

Manufacturing defects in brazing usually show up on startup or even installation. Think about how many indoor coils used with heat pumps develope leaks as compared to how many indoor coils that are strictly low side coils with condensing units develope leaks. By becoming the condenser coil in the heat mode with a heat pump the moisture in the indoor coil is usually absorbed by the hot saturated gas and flushed into the filter/drier.

[fastfred]

roboteq:

That moisture mostly collects at the braze joints and being in the low side of the system does not get flushed through the system to the filter/drier. It just sets there eating away at the joint.

Would you please explain how, "It (moisture) just sits there".
Thanks

[RoBoTeq]

When we refer to moisture in an HVAC system we are usually talking at the microscopic level. A few atoms of hydrogen with twice as many atoms of oxygen stuck in a microscopic cavern within a braze joint will not come out easily. A long enough deep vacuum will allow it boil out or liquid refigerant, being very absorbant, will most likely flush it out, but low pressure vaporizing refrigerant just keeps passing by as the corrosive oxygen molecules eat away at the braze.

[Edmund Forsthe]

i hate it when they do that.