Carrier 30RA problems!

[Chil]

Hi, wonder if anyone can help. Been working on a Carrier 30RA-050-B0458-PEE, system runs for a few days and then shuts down with 'Alarm37' -Low suction pressure/faulty suction pressure tranducer/blocked drier! Have changed the suction transducer and the refrigerant charge seems fine, 3.75 bar suction, 11.5 bar discharge at ambient of 18'c. Not seen any bubbles in the sight glass either. Typically the unit shuts down in the night and calls out a member of the factory staff,
Any help or suggestions would be greatly appreciated, thanks guys.

[james10]

you have two possibilities
,1, low refrigerant charge, as this fault is genarated when the system sees 6 repeated faults on low sst overide, is the load on the machine significantly less at night when it trips?, if the water temperature is low then the sst falls with it causing the machine to trip,(charge is 13kg R407c)

2, water flow, either the flow rate drops or possible that the machine is over sized and runs past its setpoint
flow rates are
single pump 1.1 l/s min 4 l/s max

[Grizzly]

Hi James.
Would an exposed location with windy conditions give the same scenario?
Grizzly

[james10]

Hi James.
Would an exposed location with windy conditions give the same scenario?
Grizzly

I would hope not Grizzly, if the machine is sited as you suggest then in theory the condeser fans should go to low speed to maintain the correct condensing temp/discharge pressure, but these units only have high/low speed fans so i suppose in the wonderful world of refrigeation anything is possible , i do have one sited a few yards of the humber estuary and its never given me any issues as mentioned

[Grizzly]

Thanks for the explanation James.
The reason I ask is because some I have on the Bristol Channel shoreline. Do very occasionally suffer from poor lift across the comp on start-up.
Due to high winds through the exposed condenser.
Resulting in LP fault conditions.
Read and learn as they say!
Grizzly

[james10]

Thanks for the explanation James.
The reason I ask is because some I have on the Bristol Channel shoreline. Do very occasionally suffer from poor lift across the comp on start-up.
Due to high winds through the exposed condenser.
Resulting in LP fault conditions.
Read and learn as they say!
Grizzly

Once the machine gets under way does it run ok, maybe worth getting a wind break fitted
http://direct.tesco.com/product/images/?R=205-0258

[Grizzly]

It's a problem that occurs so infrequently that it's not really a problem.
There are three chillers and it's only the end one that has this issue. So there are 2 others to take up the load.
But thanks for the link, I will save it for future use.

The thought of a chiller kite surfing down the Bristol Channel would be something else!

Grizzly

[Chil]

Thanks James, I'll speak to my customer tomorrow and quiz them about the loadings overnite, I do however remember one of the guys saying that they have, over the last year or so been using more load on the chiller but it may still be unloading in the night.
Grizzly's suggestion may have some bearing on it too, we have had high winds over a few nights here and the chiller is fairly exposed but having said that, it would surely have done it before and like you said, the fan would ramp down to its low speed. The unit has run without a hicup, as far as I know since it was installed in 2006.