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Commentator

Join Date: Oct 2010
Posts: 65

Chiller Problem

08/25/2012 11:21 AM

We recently McQuay chiller plant in our power house.But as soon as it is started alarm for suction pressure low appears.Before starting the pressure is 244 kpa but assoon as the chiller starts it drops to 150 and it trips.can some one help

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Guru

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#1

Re: chiller problem

08/25/2012 11:32 AM

Yes! Got the installers back out to fix the problem!

This is different than finishing one of Bill Gates incomplete software designs for him.

Would you push start a new car everytime you wanted to go somewhere?

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Anonymous Poster #1
#3
In reply to #1

Re: chiller problem

08/25/2012 5:34 PM

check for the evaporator temp. sensor

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#2

Re: Chiller Problem

08/25/2012 5:22 PM

Make sure the water pumps are turned on. Also check the refrigerant charge.

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Power-User

Join Date: Jun 2012
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#4

Re: Chiller Problem

08/26/2012 3:38 AM

Sounds like problem with refrigerant charge. You don't say which refrigerant is used in this chiller. or what is ambient temperature in the room?

Pressure of 244 KPa for R-22 corresponds to only about -11 degrees Celsius.

Maybe there is no refrigerant in the machine, only a dry nitrogen holding charge?

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Guru

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#15
In reply to #4

Re: Chiller Problem

08/29/2012 5:38 AM

agreed. maybe a the wrong size expantion valve, mis-matched pump, and dozens of other possibilities.

i think your in way over your head.

it would be cheaper to hire an expert.

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Guru

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#5

Re: Chiller Problem

08/26/2012 3:50 AM

Is it a DX type of chilled water type?

Causes for low suction pressure are :

Shortage of refrigerant

Blower belt slipping on indoor or outdoor blower

Defective check valves

Clogged expansion valve

Wrong super heat setting

Check the contactor contacts

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Commentator

Join Date: Oct 2010
Location: Bangladesh
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#6

Re: Chiller Problem

08/26/2012 4:29 AM

Look, we need details information.

is it R22? Chiller type and controlling system is important. different brand controlling system is different and as different the suction pressure is! Check from the manual, what is the recommended pressure at that stage. Give us as much data you can.

Suc Pr, Dis Pr, Sub cool & super heat temp, water in & out temp & dP, condenser air inlet and out let temp? Finns condition? starting Amp and on load Amp etc!

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#7

Re: Chiller Problem

08/26/2012 7:50 AM

244 kPa =~ 36 PSI or 2.44 bars

The pressures would have been much higher in the range 1500 kPA (15 bar).

It looks like what ZVI said (#4): Maybe the unit has not been charged with any refrigerant but was shipped filled with Nitrogen.

This is done frequently as a safe gas during transit.

Check with the supplier and if it is the case, they will give you the instructions on how to fill it AND BETTER, STILL, DO THE JOB THEMSELVES!

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Power-User

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#8

Re: Chiller Problem

08/26/2012 1:49 PM

I would also recomend to ask your Technician to check electrical variables in The compressor volts, amps against plate data Also use a megger to check electrical resistan ce on windings

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Commentator

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#9

Re: Chiller Problem

08/26/2012 2:09 PM

Hello jan63,

As per the other posters advice to you, I would also urge you to give full details when asking for help with a problem.

Was this installation carried out by yourselves, by a competent contractor (refrigeration mechanic) or perhaps by the equipment suppliers/agents?

Was this a new or second hand chiller?

Normal practice when installing water chillers is to carry out a full commissioning procedure during which the installation would be checked electrically and mechanically, water flow would be checked plus confirmed that the flow rates complied with design, interlocks and safety circuits should be checked and proved, oil levels and crankcase heaters checked, valve positions checked etc etc - the list is quite extensive but should be available in the 'Installation and Start up' instruction manual that was supplied with the machine. Not only should these checks have been carried out and logged, but it should have also been confirmed that the plants that this chiller was supplying were operational and providing a load for the chiller.

I would agree with the majority of the comments and advice given as answers to you but add one more suggestion - the fact that the chiller trips immediately on LP may indicate that a valve has not been opened prior to start up. If the correct gas charge has been charged into the chiller (not the shipping charge of nitrogen) then, if the system was in fact low on refrigerant I would expect to see the LP gauge pressure dropping down until the LP trip point is reached and not an 'instantaneous' LP safety trip!

I believe the answer for you is to carry out the proper commissioning procedure as per manufacturers instructions and 'good practice' before attempting to commission the chiller into operation or get the manufacturers agents to carry out this commissioning for you.

Hope this helps you.

Regards,

Keith

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Guru

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#10

Re: Chiller Problem

08/26/2012 6:25 PM

Jane63::::: I think that you are supposed to REPLY to the questions and comments you received here.

If you found out that the chiller was not charged with the refrigerant and or it was still having its Nitrogen charge, then report back! this is part of the deal to help others diagnoze similar cases... etc.

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Active Contributor

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#11

Re: Chiller Problem

08/27/2012 6:25 AM

Echo Post #9 !!!!

What happened at the startup commissioning ?

Large McQuay chillers come in sections, what size "chiller" is this ?

Second; McQuay transducers routinely fail, is this indication only, or is it actually been verified through the good old fashioned, tried and true method of hooking up gauges ?

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Participant

Join Date: Jul 2012
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#12

Chiller Problem

08/27/2012 6:34 AM

check solenoid valve and check the filter for the freon system and make a visual inspection on sight glass be care full

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Commentator

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#13

Re: Chiller Problem

08/28/2012 9:20 AM

thank you all.One problem solved.there was gas leakage and after stopping gas leak gas added.Now chiller does not trip immedietly but still trips after 5 minutes.This time contractor says the cooling water into the chiller is too cool(20 degrees C).They say it should be 25 or above and we have to install some sort of cooling tower

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Guru

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#14
In reply to #13

Re: Chiller Problem

08/28/2012 9:41 AM

This seems a bit confusing to me!

The chiller is supposed to cool the water and the cooling tower also cools the water!? SO they are telling you that you should heat the water back to 25deg C using a cooling tower???

There is some missing information here: What does the process requires in terms of chilled water temperature and volume?

You might have misunderstood the contractor's reply.(Or else ...?)

The chiller should be able to cycle without tripping off. It will cool the water to the desired setting temperature (outlet probe or inlet probe - ~ 5deg C). When the returning water (Inlet) reaches the desired temp, the compressor(s) will stop (Unless this model has a variable speed drive etc.).

WHAT is tripping the chiller after 5 minutes running?

- High pressure , Low pressure,

- Freezing temperature,

- Water pump failing or not enough circulation....

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Users who posted comments:

Anonymous Poster (1); bashir01219 (1); durtieduck (1); Frank-Jazz (1); HBR thechnique (1); jan63 (1); Keith Grewar (1); LAA_Lucke (3); lyn (1); Moparmyway (1); mrswamy (1); Tornado (1); Zvi (1)

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