Aeremec chillers

[fridge_bloke]

Is there anybody who can help with this make of chiller. unfortunatly there is a lack of technical help from the manufacturer....basicaly within 60s of start up circ 1 goes i to fault, (low differential pressure alarm) .. no one can tell me what is causing this. at start up the operating pressures are the same as circuit 2. within the pco controller there is an option to disable the low diff alarm or alter its paramaters. if disabled then c1 fails to even try and start..your thoughts would be apreciated

[chillerman2006]

Hi fridge_bloke

low diff pressure - should be

pressure differential between water in/out of evap

Or possibly lp pressure from cut out to cut in if controlled via controller and transducer

Code for aermec carel is 0442 or some changed to 0666

If its the same ones I see, they are not bad bits of kit - Bitzer screws/carel controller

R's chillerman

[fridge_bloke]

chillerman thanks for the reply. yeah there not bad chillers. but nothing can beat the arabic made petra chiller, 6 bitzer recips and a microtech stage sequencer ,its a dream to work on :-) ... back to the aermec's ,i originaly thought it was a water issue as the same thing has happend to two identicle machines. 1 circuit out of the 2 has a low diff pressure fault. but there isnt anything on the plates or pipework to generate this fault so it has to be a pressure issue. all the pressures are read via transdusers.i have checked actual pressures against the carel digital read out. there basicaly the same. if the aermec manual was a bit more descriptive as to this fault and how its generated i maybe able to do somthing about it.

[james10]

PETRA you must be taking the p##s

[chillerman2006]

Hmmm

I wonder if there is poor connection to transducer (plug) or one is intermitently faulty

Cant think what else to check

[chillerman2006]

PETRA you must be taking the p##s

Hi James

Not seen one mate - are they like ''mercury climatic'' ???

[fridge_bloke]

thanks james, i wasnt expecting many responses to my petra joke

[james10]

Petra units in my opinion should be banned have a site with two of them and there nowt but a head
Ache designed to run in Saudi and situated at the side of the Tyne

[fridge_bloke]

Hmmm

I wonder if there is poor connection to transducer (plug) or one is intermitently faulty

Cant think what else to check

nor me mate, ive been through everything today,,well i think everything

[fridge_bloke]

i took the inverter out of mine,running all the fans of individual hp switches .the sequencer blew up in the summer, for a short time was running the thing of some eliwell 974ts and delay timers until i could get a replacment sequencer

[chillerman2006]

Petra units in my opinion should be banned have a site with two of them and there nowt but a head
Ache designed to run in Saudi and situated at the side of the Tyne

Oh great ... do they suffer low head pressure issues then

maybe bypassing part of the condensor would help

probaly cool nice in height of summer though

R's chillerman

[fridge_bloke]

Oh great ... do they suffer low head pressure issues then

maybe bypassing part of the condensor would help

probaly cool nice in height of summer though



R's chillerman

mine had low head issues,, it dosnt help when all the cond fans are on all of the time becaue of the inverter.when the inverter died on it i put in some hp switches and some additional contactors to modulate the fans based on pressure .works well now. no more over condensing or racking up the run hours on motors that arnt even required to run

[chillerman2006]

Nice one mate

back to your aeremec, dont suppose you could swap controllers to iliminate that

R's chillerman

[fridge_bloke]

yeah we did get sidetracked . if your talking about the circuit related controllers and not the carel head unit then i think thats my next job. ive checked everything else. its just odd that the same fault has happened on two seperate chillers. both loosing a circuit with the same fault. water is a common factor and somthing that has some mods latly.but im sure its not a water issue

[chillerman2006]

.the sequencer blew up in the summer,

if your talking about the circuit related controllers thats my next job. the same fault has happened on two seperate chillers. both loosing a circuit with the same fault. water is a common factor and somthing that has some mods latly.but im sure its not a water issue

Hi F B

'if' water flow and pd ok across the vessel - illiminate pd by linking out for the minute

and that only leaves the other common to both issue, that sequencer

was it a case these circuits were running at the time and has taken controllers out with it

a strange one but appears to be one or the other

R's chillerman

[fridge_bloke]

evening chillerman, i think iv confused the thread by talking about petra chiller.that beast had a sequencer fault,,but definatly somthing that could of happend to the aermec's..there isnt much to link out really.all we have is hp lp transducers,hp switch and an lp switch plus a common flow switch. il have to swap the controllers over and see if the fault shifts

[chillerman2006]

Hi fridge_bloke

my mistake mixing posts mate, should have read more carefully
as you say though looks like last choice - controller
surprised there is no differential pressure switch on evap in/out
as if flow drops, flow switch can still be made if set too harsh
and then your reliant on lp switch/setting only to protect evap

R's chillerman

[fridge_bloke]

chillerman

im suprised also mate, but also i dont know enough about this chiller.theres probably a formula programed in to the controller that makes a calculation based on water in and out plus the refrigerant pressure and temp to decide if theres a fault that its going to generate without any real after market help.. were talking about water now though,,the fault on the display is 'low differential pressure alarm' .theres no idication as to wether its water or refrigerant pressure

[chillerman2006]

Hi fridge_bloke

your last post has me wondering now too

Does this controller have the ability to monitor a logarothm based upon water temp and suction pressure - anyone ???

Say with R407c it will alarm at 3.6bar.g 0*c

But does it have the ability to look at say 15*c water outlet temp with a 4.0bar.g suction pressure and alarm on diff pressure to high and say 15*c water outlet temp and 6.0bar.g suction pressure being to low - anyone ???

To illiminate mate, if no-one does give a definitive answer prior to your return, I would check suction pressure and superheat on both circuits - against the same water leaving temp and look for a rather large difference

If not I would still be inclined like yourself to suspect the controller

R's chillerman

[james10]

Not wanting to but in, but surely if if it was a flow issue then you would have a fault on circuit2,
Could the low diff be oil-suction pressure the older carrier units have a simmlar alarm

[chillerman2006]

Hi James

would think fridge_bloke would be glad of ''but in'' as we not getting far

we are just clutching at straws, so far

post #18 does not mention oil pressure is monitered, but could be an oversight mate

R's chillerman

[fridge_bloke]

Hi fridge_bloke

your last post has me wondering now too

Does this controller have the ability to monitor a logarothm based upon water temp and suction pressure - anyone ???

Say with R407c it will alarm at 3.6bar.g 0*c

But does it have the ability to look at say 15*c water outlet temp with a 4.0bar.g suction pressure and alarm on diff pressure to high and say 15*c water outlet temp and 6.0bar.g suction pressure being to low - anyone ???

To illiminate mate, if no-one does give a definitive answer prior to your return, I would check suction pressure and superheat on both circuits - against the same water leaving temp and look for a rather large difference

If not I would still be inclined like yourself to suspect the controller

R's chillerman

hiya chillerman

i will be doing that mate, iv got a few things to check..the only problem is the compressor barley starts ,,there is less than a minute run time before faulting out .they havnt really run long enough to stabalise enough to get any readings that could be used for diagnosis.the initial readings are good but need that additional bit of time to load up .

[chillerman2006]

Hi fridge_bloke

I dont expect it to be that then as these sort of moniterings have a time delay to alarm

As you say for system to stabalise

R's chillerman

[thebigcheese]

I would check oil, most aermecs are set to not fault on pressures for first 3 minutes of start up.
Also it usaly gives a fault code as well. Low oil diff pressure alarm i think from memoryis al 07 or al 08

[1torr]

Hi, low pressure diff alarm that ive had in the past is low diff between suction and discharge pressures. On screw comps not pumping properly or not loading, or liquid flooding back to compressor. Cheers

[thebigcheese]

Yes 1torr your on the money there

[chillerman2006]

I would check oil, most aermecs are set to not fault on pressures for first 3 minutes of start up.
Also it usaly gives a fault code as well. Low oil diff pressure alarm i think from memoryis al 07 or al 08

Hi thebigcheese

good point mate but fridge_bloke has not responded to James on that yet

and have seen a number of aeremecs with screws not monitering oil for some reason

R's chillerman

[fridge_bloke]

Not wanting to but in, but surely if if it was a flow issue then you would have a fault on circuit2,
Could the low diff be oil-suction pressure the older carrier units have a simmlar alarm

hi james ,,but in as much as you like .i just need to sort these poxy chillers out..there is no oil pressure monitoring on these chillers. within the the controller there is a setting for this alarm which is set at 3 Barg.

[fridge_bloke]

Hi thebigcheese

good point mate but fridge_bloke has not responded to James on that yet

and have seen a number of aeremecs with screws not monitering oil for some reason

R's chillerman

evening gents, got a manual. yes the fault code does indicate an oil diff alarm .008 on an aermec,,this alarm is activated if the diference between high and low pressure is less than the setting. it faults out soon after starting up,,im talking less than a minute.i have checked readings as much as possible during this short time and there is nothing that stands out as being odd, there is nothing differant to the other operating circuit.there are two machines doing the same thing just to make matters worse.

[chillerman2006]

evening gents, got a manual. yes the fault code does indicate an oil diff alarm .008 on an aermec,,this alarm is activated if the diference between high and low pressure is less than the setting. it faults out soon after starting up,,im talking less than a minute.i have checked readings as much as possible during this short time and there is nothing that stands out as being odd, there is nothing differant to the other operating circuit.there are two machines doing the same thing just to make matters worse.

Evening Fridge_Bloke

this being under a minute, as you seem to agree this sort of alarm should allow time delay for the system to settle

I am starting to wonder now if this alarm is a secondary alarm as the compressor has stopped and maybe its going out on something else

for instance does it monitor amp draw to confirm running and drops out contactor if it fails to recieve a reading

yorks for instance have an alarm that can mean half a dozen different faults, including this

does the alarm code come up prior/at shut down or after ?

That manual - PDF ? Any chance of a copy ?

R's chillerman

[fridge_bloke]

hi chillerman, you do have a point. you may be onto somthing.the alarm code comes up after shutdown.i havnt seen anything related to currant draw within the panel or in controller.ive got a efw more manuals now,you can have a copy of them all. not sure how else to get them to you except for email

regards fridgebloke

[chillerman2006]

Hi fridge_bloke

it does appear as this comes up after shutdown its a generic alarm

have pm'ed my email mate and will have a good read of what you have acquired

R's chillerman

[fridge_bloke]

hiya chillerman

ive sent you an email with the manuals that ive obtained

il have a flick through them later on ready for my return to site tommorow

keep well

fridgebloke

[chillerman2006]

Hi fridge_bloke

quick thought, are the crankcase heaters on the failing circuits working ?

have read through your pdf's and it appears it can only be one of a few circuit only faults

have listed them on attached

alarm 08 can have time delay set, maybe worth looking at adjusting this and see what happens

R's chillerman

[fridge_bloke]

chillerman how ya doing mate..i can confirm that the cch's are working .theres definatly no problem with oil temp. providing your talking about the low diff setting , ive tried altering it, both pressure and time setting . there is also an option to turn it off,,but if its off the problem circuit dosnt even try and run. its factory set at 3Bar with a 90s delay

[chillerman2006]

Hello Mate

ok so I think we can safely rule out 'low oil diff'

think it might be an idea to start linking out one at time to illinate

lp(id9) hp(id8) oil level(id12) & thermal cut out(id10)

they should though come up with their relevant codes

am i right in thinking the good circuit is running at the time

the failing circuit trips ?

definately not any loops of coiled wire or plastic rings around

any of the compressor contactor phases, monitering amp draw ?

R's chillerman

[fridge_bloke]

hiya mate

i cant confirm anything about current monitoring at the mo.but i dont remeber seing any i should be back on site tommorow to hopefully diagnose this fault. the linking out proccess was going to be part of my next step.the other circuit starts not long after the faulty one and continues to run. lets also not forget that whatever has happend to this machine has also happend to another in the same plant room


regards fridge_bloke

[james10]

This is a long shot, are there any auto leak detection systems on the units, the reason I ask is I once had a climaveneta unit tripping on hp tested the switch and the usual couldn't find anything wring
Then I found a little leak detector hidden under the compressor wired in series with the hp switch
Which had blown a fuse causing the hp circuit to break and showing a hp alarm

[chillerman2006]

This is a long shot, are there any auto leak detection systems on the units, the reason I ask is I once had a climaveneta unit tripping on hp tested the switch and the usual couldn't find anything wring
Then I found a little leak detector hidden under the compressor wired in series with the hp switch
Which had blown a fuse causing the hp circuit to break and showing a hp alarm

Hi James

thats certainly one to look out for that I have not experienced before, seen them on systems many a time now but never had an issue, so never needed to check wiring...will certainly remember that now and could be fridge_bloke's answer quite easily, as the fault code does not match the symptoms, nice one mate

R's chillerman

[fridge_bloke]

morning chillerman and everyone else involved
ok i had a brief bit of time on site last night . i can confirm that there is no form of current monitoring.

during my brief visit before being kicked of site i did link out everything possible and the fault still occurs . i was going to swap the carel controllers from chiller 2 to chiller 3 to see if the fault shifts but ran out of time.

[chillerman2006]

morning chillerman and everyone else involved
ok i had a brief bit of time on site last night . i can confirm that there is no form of current monitoring.

during my brief visit before being kicked of site i did link out everything possible and the fault still occurs . i was going to swap the carel controllers from chiller 2 to chiller 3 to see if the fault shifts but ran out of time.

Morning Mate

brief time/kicked off site, do they not want you to resolve this ? Oh well, if they will not leave you alone to work on it, what more can you do ?

R's chillerman

[james10]

Did this fault ever get resolved ????????