Polyscience Chiller 6800 Low Temp Alarm

Help Support and Requests
1

Hello,

We have a couple of the 6800 models and the low temp alarm keeps going off when using our booster coils with dry ice.
I’ve got it all the way dialed down to the max which is -14 I think. But once we get past that it shuts off

Does anyone know how to bypass this? Either through software or hardware mods. . ?

We are in SoCal.

Thanks!

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2

Stop using dry ice. It’s telling you there’s ice forming inside the pump and thermal exchanger. Wich means your about to crack your core if you keep doing it.

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3

Highly doubt it.

4

Are you running that dry ice coil after the outlet or before the inlet?

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5

Hi,
your main issue is the units are not meant to be run that low.You could bypass it, but you may also damage the unit as well. Beyond that fact that you may surpass the minimum operating temps of certain plastics/ components within the chiller, you may end up freezing the oils inside the refrigeration compressor. In addition the refrigeration cycle may stop all together in your chiller due to the evaporator being colder than anticipated, if you cant boil the refrigerant inside the evaporator nothing will happen.My .02 is to get a larger/ more suited chiller, anything less will be disappointing. What process are you using this with?

6

After the outlet.

7

Rotovap. 50L Dual condenser.

8

Let me ask you this, in normal operation (no coil) does the chiller maintain its low set point?

9

The lower limit setting is meant to shut off the chiller if it goes below that. It is saying there is no way the temperature should be at this temperature (i.e. -14c) if your set point is at -5c. Something must be wrong (the cooling is not cycling off on it’s own) and it must shut down to prevent excess damage to the chiller. On the opposite end, the high limit is triggered if there coolant reaches a temperature a certain degree above the setpoint (thermal load is too high or compressor /pump failure).

With additional programming, the alarms can also be used to trigger other shut offs (heating) if necessary.

Also, they didn’t design/test these models with coolant colder than what it can achieve on it’s own. Best not to do it.

10

Thanks for all the responses. The question wasn’t “why is this happening”. I’m aware of the reason why. I was curious if anyone knew how to bypass it.

Thanks!

11

Bypass it by removing the coil from the dry ice.

If, while running the 50l roto at full speed, the chiller isn’t able to keep up, then put coil in dry ice bath.

Maybe a just few rings deep at first, see how it does, a little deeper if the temp is still high