CArrier Aquasnap 30RAP015 Head Pressure fault

[isr410ashotgun]

I have a Carrier (customers) Aquasnap 30RAP0156DAF00 (R-410A) and Digital Scroll Serial# 2310Q39728 that is in a process application with a 58 degree F set point for fluid cooling
It is faulting off on a T126 Alert code active. This is Circuit A High Discharge Pressure (650 psi). It is a shutdown that occurs after three automatic resets
The unit readings were with a 81 degree F outdoor ambient and a 66 to 67 degree return liquid temp.
As the unit lines out when it loads, the discharge pressure was 410 PSIG
Suction was 170 PSIG + or – 5psig until the scroll unloads
16-17 degrees SH
19-20 degrees sub-cooling
TXV at 100%
No temperature delta across the liquid line filter taken with a 2 channel thermometer with line clamp sensors (calibrated to each other)

When it loads the compressor the discharge pressure was spiking to 520+ PSIG

Afternoon temperatures have been hitting triple digits and that is when it faults out

All the obvious, plugged condenser, set so it re-breaths its own hot discharge (not the case), condenser fan speed (one fan) are OK

The loop has about a 30% concentration of glycol to water.

The system was helped a little when I adjusted the MAX T on the scroll solenoid from the factory default of 7 seconds to 6 seconds. The head pressure doesn’t spike so bed when it re-loads
I’ve got another like model (it is a 50 ton) so it has multiple compressors/circuit so (I don’t know if this counts) that doesn’t spike when it re-loads.

Anybody have any thoughts ?

[Dallas Duster]

Is the 50 ton chiller newer?

[isr410ashotgun]

The 15 and the 50 ton are within a few months of each other serial number wise and installation wise.
They both have the same firmware rev.

It is in a different process but loads and unloads the digital compressor about the same.

[Dallas Duster]

The 15 and the 50 ton are within a few months of each other serial number wise and installation wise.
They both have the same firmware rev.

It is in a different process but loads and unloads the digital compressor about the same.

Put an email address in your profile .

[Six]

Where is it located? Roof ? Is there a fence around it ?

Having to adjust rate of load and unload to try and mitigate head pressure doesn't address the issue of why its running over 600 psi.

[isr410ashotgun]

there is an email address in my profile

[isr410ashotgun]

Six,
I agree that adjusting a parameter doesn't address why the pressure 'spikes' over 500psi when it re-loads and ultimately higher based on ambient conditions. It is an adjustable parameter (from 1 to 15 seconds) and that is why I adjusted it...I really adjusted it to keep the process on line and the customer off my a_ _ until I can find out why it is doing what it is doing.

There is no fence around the unit located adjacent to the building on the ground, approximately 8' from the building. It is not re-breathing it's own air.
The unit will line out when it is operating loaded, at operating pressures and temperatures one would expect for a properly operating/charged unit based on operating guidelines in the Carrier manual.

The problem is that when the digital compressor re-loads the discharge gauge on my service manifold jumps several hundred psi higher and just as fast settles back to the operating pressure. That very rapid jump and return is what I am referring to as a 'spike' that I believe ultimately faults the unit off on high head.