Condenser coils going bad

DCHVAC

Have any of you guys ever had this happen? The first time it happened it took four years to get to the point of failure. All the refrigerant and oil leaked out and the compressor seized. The manufacturer wouldn't give me a new unit so I had to rebuild the old one. They gave me a new coil and compressor. After just one year, it happened again. The original installer didn't use pump ups so I put them on when I rebuilt the unit. This is a heat pump installed in northern Pennsylvania. I'm at a loss to explain this and so is the manufacturer.

Attached Images

Goodman HP 1_0001.jpg (86.2 KB, 18 views)

Swampfox

Do they have a dog?

he might need to find a new spot to go potty

DCHVAC

Nope....no dog. The manufacturer was thinking along the chemical erosion theme as well. Exterior corrosion doesn't seem likely as there is another identical condensing unit 50 feet away at the in-law unit that has been issue free since installation.

Swampfox

something corrosive is getting to it, well water maybe? if it has a high sulpher content it will eat up the copper

scooter

Are those fins corroded?
The pixs look to me like phsyical damage to the aluminum fins?
Did the oil in the bottom come from the coils in the pictured area rotting through?
410A or 22?
Is this the only spot in the condensor or does this line go all the way around?
Scooter

RoBoTeq

That my friends is what happens when a heat pump does not have enough drainage to keep the bottom row(s) of copper from being crushed by ice.

What happens is that the condensate that drains from the unit during defrost refreezes around the bottom of the heat pump. As the ice builds up, it eventually gets to the bottom row of copper in the finpack.

Now, think about the ice forming around the copper tubing. Water expands as it turns to ice (the only liquid that does so, by the way).

As each defrost cycle adds more ice around the coil, the next defrost cycle turns the ice directly on the coil into water, which drains away until it can not do so any longer due to the ice buildup. This can occur in above freezing conditions because the heat pump coil in the heat mode is extracting heat from the outside ambient air.

Once the area around the tubing fills up with defrosted condensate that cannot drain away from the copper tubing, that amount of condensate...trapped by an outer casing of ice, itself freezes when the heat pump goes back into heating mode.

When that condensate freezes, it now cannot expand outward because of the encasement of ice. So, it expands to point of least resistance, which is the wall integrity of the copper tubing. The copper tubing crushes in on itself as the ice expands. When the copper tubing crushes in on itself, it becomes distorted which wrinkles the aluminum fins that are attached to it.

If you remove the aluminum fins you will find the copper tubing has been crushed into a "C" shape with one side of the tubing crushed into the inside of the other side of the tubing.

Sometimes the crushing of the tubing will create a crack leak and sometimes it will just cause a severe restriction in the coil.

If you are real careful, you can remove the crushed section of tubing and braze in a piece of copper. Remember that finpack tubing is very thin and will burn through with too much heat.

I like to teach what I call the VIAGRA method of remembering to "get your heat pumps up" using pump ups or other means of getting heat pumps up off or pads;
Very
Important
Application
Greatly
Reducing
Aggrevation

mechanicalDvr

I have seen thousands of heat pumps over the years and have yet to see one that would hold 2+ inches of condensate in the bottom, let alone a coil that would be so clogged it holds back water all the way around.

RoBoTeq

Sorry you didn't understand my post. I tried to make it as clear as I could.

I did not say that that much condensate builds up. What I said is that an ice dam forms around the bottom of the unit due to there being no where for the condensate to drain off properly.

My guess is that you have simply misdiagnosed a lot of heat pumps that had crushed coils from ice. My comments were not up for interrogation. What I posted is what happens and the only way what caused the problem in that photo to occur.

mechanicalDvr

I have 20+ years doing this stuff and have yet to see a heat pump coil damaged like that. And yes as this is an open forum anything posted here is up for debate, isn't that the reason for a forum discussion? Get out and read in some of these forums, it gets nasty at times.

RoBoTeq

You again misunderstood my post. The reason that this particular issue is not up for debate is because there is only one thing that causes what that photo shows. That one thing is ice damming around the lower coils that eventually crushes those coils.

Just because you have not been aware of this phenomenum does not mean it does not occur. There are no other occurances that will produce what has happened to that coil. I have been over this over and over in the years I have investigated field issues on equipment and I have run into too many techs who refuse to believe what is a fact and the only fact in this particular failure.

As for my getting out and reading some of the other forums, those who know me know that I am at least in the top ten posters on HVAC forums with over 48k posts on one site alone. I also teach technical troubleshooting and this particular instance is one that has no variation of causes. It is ice, and only ice that causes this problem.

The Dangling Wrangler

Yes he is. I'm surprized none of the guys, that post here, (from that site) have said anything.

RoBoTeq

You're a brave soul DW. No one else wants to admit knowing me

The Dangling Wrangler

And that was only my second post.

beenthere

I would, but I'm shy.

__________________
How many times must one fix something before it is fixed?

The Dangling Wrangler

DVR, rest assured, Robo's played in this ball game a few times.

So has beenthere.

We're mostly on another site, just ran into these guys by accident.
If they tell ya something,it's the truth.

Yuri

Must be as old as Moses if he has that many posts. LOL
Now sock it to me:

The Dangling Wrangler

Some folks get offended by Robo. Mostly because he uses facts to back himself up. Go figure

RoBoTeq

No backing out by pleading ignorance

RoBoTeq

Oh, I'm sorry, I mistook you for some other guy on another forum. We don't call him shy at all. Sometimes we call him a !

beenthere

Lots of heat pumps that are set directly on the pad. have that kind of damage done to them.

__________________
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