Carrier 19XR loading fault

[bunglebear]

Anyone had any problems with a Carrier 19XR. This one refuses to load fully past 75-80% or so because of an approach temperature problem. All I can think is either refrigerant charge, flow rates incorrect, fouled tubes, faulty sensor.

I was just thinking that someone may have a different take on it....

Thanks

[nyrb]

Assuming you have the IOM this is what Carrier says to check.
Some operational data readings would also be helpful.

162 SENSOR ALERT EVAPORATOR
APPROACH
162→Evaporator Approach
[VALUE] Exceeded Limit of
[LIMIT]*.
Check that refrigerant charge level is adequate,
waterbox division plate gaskets are sealing,
evaporator tubes are not fouled and that oil
reclaim system is working.
Check sensor resistance or voltage drop.
Check for proper wiring.
Check Evap Approach Alert setting in SETUP1
screen.
163 SENSOR ALERT CONDENSER APPROACH 163→Condenser Approach
[VALUE] Exceeded Limit of
[LIMIT]*.
Check sensors resistance or voltage drop.
Check for proper wiring.
Check Cond Approach Alert setting in SETUP1
screen.
Check for noncondensable gas in the
condenser.
Check that the condenser tubes are not fouled.

[klove]

The obvious first question is "What's your approach temp?"

[bunglebear]

Actually it had been manually limited to 80% by someone else.

I noticed the oil level was just to the bottom of the second sight glass. No flashing in the motor cooling line sight glass. Refrigerant temp 2.7 degrees leaving water was 8.9 degrees so 6.2 degrees approach (sorry these are celcius) approach alert 162 triggers at 2.8 degrees C.

After running for a while at 95% approach was slightly decreasing so perhaps some oil logging in the cooler ??

[Davids1964]

I just placed two brand new 19XR"s into service and I am receiving alarms on one of them. I too have seen in the alarm history warnings of approach problems. I have placed a service call too Carrier about this since it's under warranty by the contractor. I will let you know what they find.

[DITAW]

approach is high, do you have oil issues or have you had to add oil, need a full set of readings to really tell you more load pressures , drops etc... water and refrigerant side plus deesign if you have it.

[Shophound]

In I-P terms you are speaking about an 11 degree approach on the evap side.

Regardless, when someone says "I can't get a chiller to load past such and such %", the follow up sentence I want to read is "and the chiller isn't meeting the load" but for some reason that follow-up wording is often missing. If the chiller meets the load at all times but never loads past, say, 80%, could it mean the chiller is a bit oversized for its given "full load" condition?

Or are you speaking about not being able to manually open the guide vanes to get the chiller amps to go past, say, 80%? Are we speaking about % of vane opening or % of full load amps?

The more precise information you give, the more precise answers you will receive.

[PSI]

Assuming:

1- your refrigerant charge is correct
2- tubes are clean
3- GPM flow is correct
4- evap transducer is calibrated

I'd say your float may require attention if your (evap) approach is still high.

[Randy S.]

Got leaks?

[bunglebear]

high cooler approach which at near full load is around 8-10 degrees F (5-6 degrees C) the oil level looks low in the compressor as well. The skimmer line sight glass was clear. At part load 60% amps and 30% guide vanes the appraoch is much lower (1.3 degrees C or 2.5 degrees F) there is liquid flashing in the skimmer line sight glass and the alert is gone. I checked the resistance of the thermistors which seem OK. The flows are near enough, only marginally low. My deduction is that there is a refrigerant shortage, as at fuller load the liquid in the cooler is below the skimmer line, which leads to poor oil return (the level is lower). Another identical chiller runs mormal oil levels, and a 0.2 degree C approach, with flashing in the skimmer line.

I couldn't pick up any obvious leaks, but that doesn't mean they aren't there. It's a reasonably new machine 3 or so years old. I screen printed all the figures from my service tool but they are on my other computer..

[19C]

Assuming:

1- your refrigerant charge is correct
2- tubes are clean
3- GPM flow is correct
4- evap transducer is calibrated

I'd say your float may require attention if your (evap) approach is still high.

Go with PSI. Float may be sticking. Check bubbler line/service valve open.

[bunglebear]

The condenser approach is OK 0.3 degrees. Maybe on further reflection it is the float. I was hoping that it wouldn't be the float, which is going to be a bit more involved...

The end plates have never been taken off the cooler, the GPM flow is OK, the evap temp sensor seems OK. Approach alarm is set to 2.8 degrees C. The load is met on slightly cooler days as the machine will run at part load. At full load on a warm day the machine will almost but not quite meet load, that however being the lower level in the cooler I imagine

[Randy S.]

Try playing with the condenser temp before you give up and take it apart.
Maybe you don't have enough bubbles to float the float.


Another idea might be to go around the float with a hose and some fittings to try to figure out what's going on.