Hussmann 404a

[hvac248]

I'm more of a air/water guy who was thrown into a problem. I have a 5 & 4 door freezer case. 2 evaps 1 condenser numerous problems over a 4 year period. My question is can a slow leak in a 404a cause a intermittent high head trip-out (400psi) due to separation of ref.

:couchhide:

[icemeister]

Fractionation is unlikely and if it were the cause it would tend to be constant high head pressure and not just intermittent.

What's the condensing unit make/model? We've been seeing a lot of receivers with broken or leaking dip tubes which cause techs to overcharge units resulting in high pressure trips...usually coinciding with the first warm weather. ;)

[pdrake65]

I'm more of a air/water guy who was thrown into a problem. I have a 5 & 4 door freezer case. 2 evaps 1 condenser numerous problems over a 4 year period. My question is can a slow leak in a 404a cause a intermittent high head trip-out (400psi) due to separation of ref.

:couchhide:

No...not the problem. Have you checked the TRUE pressure yet? If so,what is it?

[hvac248]

Fractionation is unlikely and if it were the cause it would tend to be constant high head pressure and not just intermittent.

What's the condensing unit make/model? We've been seeing a lot of receivers with broken or leaking dip tubes which cause techs to overcharge units resulting in high pressure trips...usually coinciding with the first warm weather. ;)

That was my thought. Just not much experience with blends,

Funny you mention receiver I ordered new one last week due to it was the source of the leak. "Time for an autopsy." Once I get up running I'll have more info.
Thanks!

[thefreezerguy]

Fractionation is unlikely and if it were the cause it would tend to be constant high head pressure and not just intermittent.

What's the condensing unit make/model? We've been seeing a lot of receivers with broken or leaking dip tubes which cause techs to overcharge units resulting in high pressure trips...usually coinciding with the first warm weather. ;)

Ice, What manufacture and sizes of receivers are having these problems that you have found? Its good info to have. Thanks

[surenuff]

Fractionation is unlikely and if it were the cause it would tend to be constant high head pressure and not just intermittent.

What's the condensing unit make/model? We've been seeing a lot of receivers with broken or leaking dip tubes which cause techs to overcharge units resulting in high pressure trips...usually coinciding with the first warm weather. ;)

Serious question here. How could a loss a refrigerant of any kind cause our head to go high?? Even if it did fractionate(which is highly unlikely with 404 in a working unit) how would that cause high head pressure?? Never heard of that before. Any time I have seen a loss of refrigerant, It made the head go down instanly on a fixed meter, and once we go down very low on a txv.

[craig1]

Serious question here. How could a loss a refrigerant of any kind cause our head to go high?? Even if it did fractionate(which is highly unlikely with 404 in a working unit) how would that cause high head pressure?? Never heard of that before. Any time I have seen a loss of refrigerant, It made the head go down instanly on a fixed meter, and once we go down very low on a txv.

I'm pretty sure he meant if the system had a continuous leak, with multiple top offs. So now it has the right volume of refrigerant, but the wrong refrigerant due to fractionation

[icemeister]

Ice, What manufacture and sizes of receivers are having these problems that you have found? Its good info to have. Thanks

They're the tall shinny ones...about 6" x 30"...that come with outdoor units from Heatcraft and Russell.

Here's a couple of thread discussing it:
http://hvac-talk.com/vbb/showthread.php?t=321062
http://hvac-talk.com/vbb/showthread.php?t=291472

[TheWolfLA]

True pressure, what's that?

[surenuff]

True pressure, what's that?

I Think he means has he actually used a guage to see what the "true" pressure was, or if he is just assuming it is reaching the set point of the high pressure control.

[thefreezerguy]

They're the tall shinny ones...about 6" x 30"...that come with outdoor units from Heatcraft and Russell.

Here's a couple of thread discussing it:
http://hvac-talk.com/vbb/showthread.php?t=321062
http://hvac-talk.com/vbb/showthread.php?t=291472

Thanks Ice, I suspected you might say that. I have worked on a unit I believe had or has this problem. It explains a lot.
I will be checking into it.

Thanks again!