19xr carrier chiller

[billyp7999]

compressor surging-im new to this chiller what symptoms cause this fault, amp draw all over the place on compressor. Only runs for about 5 minutes then you can hear it start to surge. condenser water temp 77 in 88 out. also evap water temp is 88 in. any help would be great thanks

[nique]

whats your ref temps (approach) will need more info to really help. also what fault is it giving.

[Shophound]

If you understand what happens inside a centrifugal compressor when it is surging, you will also understand why the compressor motor amp draw fluctuates wildly during surge events. Surging is essentially the inability of the compressor impeller to overcome the pressure difference between the evaporator and the condenser. Gas flow momentarily reverses through the compressor, in effect attempting to stall the rotation of the impeller. The motor continues to push against this backward acting force, thereby drawing more power to do so...hence the spike in amps.


Surging is horrible for a centrifugal compressor; this is why chiller manufacturers often include surge count algorithms to shut the machine down after so many surge events. As to why your 19XR is surging? Start with the basics:

• Cooling tower sumps: are the strainers clean?
• Cooling tower: is the fill and drift eliminators scaled over?
• Strainers in condenser water pumps: are they clean?
• What is the approach temp on the condenser? When was the last time tubes were punched on this machine?
• What are the surge prevention settings on your 19XR?

With the chilled water loop as hot as you say (88 degrees? Really??), I would want to slowly load this machine and slowly pull the loop down. Easiest way to do that is bump up the chilled water supply setpoint and then slowly ease it down as the loop cools off. You may also need to adjust the surge prevention points (P1, T1, P2, T2) but I WOULD NOT do that before the condenser side of the plant is thoroughly checked out to ensure it is delivering the right amount of water to the condenser, and that you don't have excessive scaling in the machine or towers.

And most important of all, be sure all the strainers on the condenser side are clean!! Sometimes the simplest things get overlooked while we search for more complex solutions.

[mikeacman]

Go into status and look at heat exchanger screen ....scroll down to condensor approach....ill bet it's high ...normal is one or two degrees...ill bet you have 9 or higher..


If so your condensor tubes are fouled and need to be brushed with nylon brushes only and if there is scale you will have to chemically clean and rebrush...

9 degrees across the water side sounds normal so I would think your flow is ok....but you could have a combination of low flow and fouled tubes ...

We need to know your approach and gpm calculated from delta p across the water side and the tonnage of your machine ...


Soooooo...look for 1-2 degrees approach and around 3 gpm per ton

[mikeacman]

Oh crap ...88 chilled water in ...thats not helping...your machine should be configured for kilowatt loading or temp loading ...meaning the chiller loading is limited based on one of those configurations ....someone may have them disabled and your guide vanes are just going wide open

If your approach and gpm are in line look at configuring it for kw load limiting or temp load limiting ..... In other words ramp loading or soft loading

[pecmsg]

Oh crap ...88 chilled water in ...thats not helping...your machine should be configured for kilowatt loading or temp loading ...meaning the chiller loading is limited based on one of those configurations ....someone may have them disabled and your guide vanes are just going wide open

If your approach and gpm are in line look at configuring it for kw load limiting or temp load limiting ..... In other words ramp loading or soft loading

Or read the Manual

[mikeacman]

Or read the Manual

yes ... That info can be found in the manual.....

[Tech Rob]

An 11 degree delta on the condenser and crazy surging within 5 minutes of startup sounds like low/no condenser water flow to me. The vanes haven't even started to open by that time. Unless they are already open when the machine starts, which would be a big problem. If the water flow on the evaporator is right (it may not be), and the refrigerant charge is right (it may not be), a heavy load on the evaporator typically doesn't cause surging.

I am in agreement that you need to evaluate the condenser water side further before proceeding. Look for anything that would cause a decrease in water flow. It could be a dirty strainer, a cooling tower running low and sucking air, a pump that is air-bound, a closed valve, etc...

[billyp7999]

great info thank a million

[Tech Rob]

You're welcome. Let us know what you find so others can learn from the experience.