Cold Weather and Maintenance Visits!

[Grizzly]

Hi Guys.
How many of you are starting to get problems now the cold weather is here like:-
Chillers overrunning their temp/ pressure controls due to overcondensing.
An even bigger problem is convincing the customer that I can't do a full maintenance log because the chiller won't load up. ( no point doing superheat readings or looking for flash gas) if the system isn't fully loaded.
I had a visit, I had to abandon the other day because the BMS System would not allow the chiller to run.
It wanted heating in the building and not cooling!
And NO I was not prepaired to override the BMS.
I was called to a system recently where a pair of
chillers were in alarm due to no water flow through them. It transpired that the BMS. Had a chiller lock out which was set to 5c. Which allows either of the 2 pumps to run or not!
As the ambient was nearer 2c the chillers were in alarm. A cup of tea and a biscuit with the facilities Enginner later the ambient temp had risen above 5c.
The BMS said pump 1 was running but the chillers were locked out on alarm. I went down several floors to get my Electrical test Kit. Upon arrival back on roof space found chiller 1 running with 2 available.
Confused I was but happy to leave it running.
I was subsiquently told that 1 of the 2 pumps had it's 3 fuses removed. Hence showing as running but chillers locked out. When I arrived back the second pump had been selected by the BMS and "all was well".
When I asked "what was wrong with the pump" I was told " Don't know just put the fuses back in"!!
Cheers Grizzly

[hendry]

Grizzly,

1] your 1st point should not exist knowing the plant is in 4 seasons weather. something is not right in the design from day one.
2] maintenance monitoring should be drafted to suit the operations. why you need to load chiller in cold weather just to take readings?
3] i feel you have some ctrl & instrumentation issue in your refrigeration system; you need to synchronize all parameters within the system.
4] typical of any plant operator to remove fuse or isolate circuir breaker as and when they like!

our system design will consider HAZOP of each item installed and each situation it is in.

Hope that helps.

[Brian_UK]

Grizzly,

1] your 1st point should not exist knowing the plant is in 4 seasons weather. something is not right in the design from day one.This depends on the original designer and the amount of money he was prepared to pay. Sometimes equipment has to operate with less than ideal controls.


2] maintenance monitoring should be drafted to suit the operations. why you need to load chiller in cold weather just to take readings?How else to you acheive full load readings as required by customer if the machine will not load? Or do you subscribe to the method of copying the last report sheet figures?


3] i feel you have some ctrl & instrumentation issue in your refrigeration system; you need to synchronize all parameters within the system.Design and operation of the BMS is separate from the mechanical items of plant normally; us poor techs have no control over such things.


4] typical of any plant operator to remove fuse or isolate circuit breaker as and when they like!Might be your way but not around here.


our system design will consider HAZOP of each item installed and each situation it is in.HAZOP does not really apply in this instance, we are not manufacturing chemicals etc.


Hope that helps.No, not a lot to be honest.:(

[hendry]

[quote=Brian_UK;86364]This depends on the original designer and the amount of money he was prepared to pay. Sometimes equipment has to operate with less than ideal controls.

:)we have plants coming from US & Europe to Asia with winter designs. how do you name that?

How else to you acheive full load readings as required by customer if the machine will not load? Or do you subscribe to the method of copying the last report sheet figures?

:)i still do not understand why you need toload up the machine just to get readings. each record represent hte response of the machine at that particular time. why loading up? clear my doubts, please.

Design and operation of the BMS is separate from the mechanical items of plant normally; us poor techs have no control over such things.
:)it is our duty to inform. it has nothing to do with your authority. not telling what is necessary to ctrl the plant efficiently will induce higher liability unless that is your intention/s all the while.

Might be your way but not around here.
:)yeah ... may be your location do not have bad apples!

HAZOP does not really apply in this instance, we are not manufacturing chemicals etc.
:)HAZOP has nothing to do with type of industry but safe operation & maintenance design.

No, not a lot to be honest.:(
:)well ... thank to be honest!