Liquid receiver level switch

[Gary S]

I am havinga problem with a small pack system with 2 compressors(1 inverter and 1 DOL)
there is a level switch in the liquidreceiver that is alarming out even tho the system is fully charged and all 6 coldrooms are reaching set temp of 2 degrees celcius. Anyone have this before?
The system is running ok from what I can see. The switch in receiver is making and breaking a lot. There is a timer and once it times out it creates an alarm.
Thanks in advance
Gary

[Grizzly]

If the level switch is isolatable?
It might be worth draining it to remove any oil accumulation.
I have seen level controls play up like this when system is reaching it's satisfied state.

You can get a "Ghosting" of the level alarm.
Or your working levels could just be a tad to near the high level set point.
Do you have the option of adjusting it.

My initial guess would be that you are actually operating the level switch as you mention all evaps being satisfied.
As I say check your working levels and high level set points.
Grizzly

[Gary S]

Cheers man
I don't think it's possibe to isolate the switch. The system has worked ok for a long time so can't understand why this is happening now. Maybe the switch is faulty? It's located at low level in a vertical receiver on R404a system.

[Grizzly]

Oil could be causing an issue, a build up of oil could raise the working level to create a problem.
It sounds as if some detective work may be necessary.
But obviously check out the switch itself first as you suggest.

Is this switch for low level, to fill vessel or to shut of ie at working level.

If it is at low level I assume it's not for high level indication?


So is the alarm a low level one?

Something missing so far Gary.
Grizzly

Good Luck Grizzly.

[Gary S]

The alarm is just labelled on panel as "plant alarm" which is ridiculous. It has to be low alarm due to it's location. It takes out the direct on line compressor but the inverter one still operates. Then it automatically resets itself but alarms out on a remote monitoring system. It did this 70 times over a weekend and Monday. But the coldrooms temperature was never affected so presumably the liquid level in receiver must be ok. Are these switches a float type mechanical switch?(paddle) or a presssure switch??
Work for HVAC company so don't come across these often.
Thanks for ur help much appreciated

[Grizzly]

Without seeing a picture Gary your guess is as good as mine,
Without some more info I am not sure what you have there Gary.
I could start guessing but that would be foolish!

If you can post some more info then someone may well be able to help.

This is definitely the receiver?

Plant Alarm would make me think it is a high level but this delay timer is the problem?

Can you check out just how this switch is wired up?

Meaning is it connected to a fill valve or purely a "Plant Alarm"?

Grizzly

[Gary S]

Definitly the receiver. There is no fill valve. It brings on a timer and according to the setting of that timer will bring on an alarm. I temporarily adjusted timer from a 1 minute delayto a 3 minute delay. This means that the switch has time to go open circuit(fault) then go back close circuit and because of 3 min delay doesn't alarm out.
Has on the drawing/wiring diagram that this switch is optional. It's a 230v switch. When everything is ok it's closed circuit.
I'll try get info off it. The terminals look like a solonoid valve with the pins and t box.
The receiver is a german brand called Klarin and the compressors are hitachi.

[Gary S]

Sorry receiver is klimal

[cool runings]

.

3 Min delay for low level liquid is for too short.

Give it 15 or 20 mins.

If it alarms out after 20 mins you have a problem if it is just
a fluctulating switch then it will give it time to reset.

All the best

coolrunnings

.

[Gary S]

It was on 1 minute and been set that way for some time I increased it to 3 mins and is ok now but wondering what's caused the sudden problem.

[cool runings]

It was on 1 minute and been set that way for some time I increased it to 3 mins and is ok now but wondering what's caused the sudden problem.

Bad contacts.........
Vibration............
Worn float.........
Float covered in stuff.......

Lots of possible reasons, but the only sure way of knowing is to remove it...

All the best

coolrunnings.

.

[Gary S]

Thanks for ur input cool runnings

[joe-ice]

the liquid level is normally used to monitor the gas charge of the system.The level itself will constantly be moving up and down but if you have to extend the time delay on a plant that has been running ok for a long while it is possible you have a leak.Normally there is a fair amount of liquid to be lost between an alarm and it actually affecting the cases.Agree with the op 1minute very short delay doesnt allow for normal system fluctuations

[cool runings]

Dependant on the make the electrical contact is seperated from the float,
so you should be able to remove the contacts side and test to see if the
problem is that part.

All the best

coolrunnings

.

[Gary S]

Thanks for info lads