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Member Post posted an update
YK centrifical surge warning
I have a 15 year old YK I have inherited 3years back on an account for a highrise. I cannot locate a true medal nameplate but have written on the door of the optiview a model number: YKCCCQQ4-EKG and a charge written in multiple spots of 819lbs of R-134a.
I recently replaced a leaking valve and pulled out charge and after repair weighed in what I can only assume is start-up charge of 819lbs.
In low load conditions I routinly get excessive surge warning messages, before repair and now in start of season. The surge window is 3mins and the max I have seen the count get to is 11 surges in the 3min window. Lockout happens at 20 so I am below that threshold and havent had a surge shutdown in last 3 years.
I punchs tubes yearly and have eddy current every other year. Tubes looked great so I am confident not fouled HX. Without knowing tonnage not sure how to ensure proper flow.
I read that YKs can operate at really low EWTs for condenser bundles so I started by lowering tower setpoint from 80 to 75 to see whst type of effect it has.
Does anyone have a way to identify tonnage? Is this the path to counter the surge or is it just the way these YKs operate at low load conditons?
Appreciate any feed back.
Member Post, Member Post and 2 others6 Comments-
@time yes, they can operate at low condenser water temps.
It’s pretty common that the level sensors act up, those butterfly (variable orifice) valve’s can act up, low flow, etc.
We can help you narrow it down if you grab us the following:
1. set the tower to 60F leaving water ( it may stop surging, but still get us the rest of the info).
2. some photos of the levels in the sight glass levels at 100%, and low load. If you can’t get it loaded, stable conditions is more important.
2. a log sheet with operating data,
3. what’s the liquid level setpoint in the condenser and the actual reading?
If you get this info, we can narrow you down pretty quick.
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Unfortunatly I am not on site and not sure when I will be next. Operating tower at 60⁰ setpoint is not something I can do long term as tower rejects heat for condenser loops for building as well. When I was last onsite during surge event the liquid level was 0% with a 30% setpoint.
Once surging subsided the level did start to rise back towards the target.
The actuator was an issie for a previous high oiltemp issue. Found it in mounted improper so valve was 100% open with actuator in 100% closed position.
Changing this stopped high oil temp. The chief was checking that when he sent me pictures of the excessive surgr warnings. I changed setpoint remotley for tower from 80-75⁰ and am now waiting to see what typenof message I get this morning.
I can probably bring it down to 70⁰ but wanted to start with smaller adjustments.
As you can see from picture unit has a history of surging. Talking to previous tech he just chalks itnuo to low load….
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if Bldg has MEP drawings with a schedule that will tell you tonnage if the chiller is original for bldg. 0% in condenser hmm that is not good where was approach and discharge SH at the point the level was built up?
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According to the manual PG 22 for a C-C shell code and Q4 Comp it says its a 1240 Refrigerant charge. unless noted incorrect in a service bulletin (Looking now). Like John said if we could get more information on machine at the point of the events we can narrow down quickly.
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I read same like system way under charged at 819lbs. When I am on site next ill definetly look for schedule for designed size.
I did find actuator slipped on liquid valve causing high oil temp alarms. Fixing valve allowed liquid level to be obtained givong very tight oil temp not coming close to high temp alarm.
I changed CHW LWT setpoint to 50⁰ and tower setpoint to 70⁰ this gave me a tighter saturation window and surging is basically non existant. No warning alarms since change.
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