Ice Rink Sequence

[integrator]

Hello,
We are upgrading controls to an ice plant and have found this as the sequence, which might not be correct now a days.

1 Brine pump, 2 compressors (on\off), cooling tower with VFD condensor fan with pump (water).


The original sequence we found is to turn on the brine pump to maintain return brine temperature of 16F. The two compressors also turn on at 16F and then 17F. The cooling tower is controlled by monitoring the head pressure of the compressors. The VFD will modulate to maintain pressure of 165 PSIG. If the VFD is at 100% and the pressure goes above 180 PSIG turn on the pump. Then the pump remains on until 150 PSIG then turns off. The VFD still remains in control and will ramp down as the pressure goes down. The VFD never turns off - at 0% we have it at 20 hz.


I'm not sure if there's a better way to control this or even if the cooling tower part is correct.

Thanks for any input

[causa]

What’s the refrigeration? ammonia? Other?

NFL official size. With all the lighting?

Does the area have dehumidifier in the arena. Air ducting and it works and is set up?

Cooling tower? Evaporative. Properly maintained?

Or is this a community Ice rink?

What’s the operators, desired ice temperature?

Is there figure skating competition done on the Ice.?

I know it sound like a lot of questions but. Believe it or not it does matter.

[ehsx]

Type compressors?
Refrigerant?
Step or infinite capacity control?
Vfd on what component?
Brine constant or variable flow?
Condenser water flow constant or vfd?
Tower fan cycling? Vfd?
Setpoint? Control band?
…..

[pecmsg]

Honeywell Gray Manual will have your sequence of operation.

[integrator]

Please see below reply

Type compressors?
two(2) Reciprocating compressors
Refrigerant?
ammonia
Step or infinite capacity control?
Step
Vfd on what component?
VFD only on the condensor fan (cooling tower)
Brine constant or variable flow?
Brine constant
Condenser water flow constant or vfd?
Spray pump constant
Tower fan cycling? Vfd?
Condenser fan on VFD
Setpoint? Control band?
Now this is what I don't know based on new theory. 20F for return brine, Compressor 1 on at 16F and Compressor 2 on at 17F, Condenser Fan VFD maintained to setpoint of 165PSI, spray pump turns on at 175psi and turns off at ?
…..

[pecmsg]

What was the original sequence of operation?

[integrator]

What was the original sequence of operation?

Brine pump on hand, compressor 1 starts at 16F compressor starts at 17F, cooling tower condensor fan starts at 175psi and with a Diff of 40, and the spray pump turns on at 175psi with a diff of 10.

[pecmsg]

So why do you want to change it?

[Bob-Brr]

The rink plant I worked with here (about 50 miles south of Montreal) used condenser water temp to control the tower fans.
As long as the tower didn't have much splash-out, we didn't have much issues with icing in the winter.
The system (long before I started) had an event due to lack of maintenance, they had to shut the plant down and punch condenser tubes in the middle of the hockey season!
Our fans ran on an on/off temp control, I don't know how variable control, with not total off time would work when the temperatures dropped below zero.

[pecmsg]

So your concerned about tower freeze protection.

Tower make and model as well as piping design allmplay into it.

[Bob-Brr]

So your concerned about tower freeze protection.

Tower make and model as well as piping design allmplay into it.

I checked the gent's profile, he is a Canadian, western Canada is far more temperate then the east, I would think that info would pertain to his OP,
which I believe he alluded to condenser water issues.

[integrator]

I checked the gent's profile, he is a Canadian, western Canada is far more temperate then the east, I would think that info would pertain to his OP,
which I believe he alluded to condenser water issues.

Yes that's our concern with condenser - sorry if I wasn't clear. We are installing a VFD on the cooling tower and will be adding in controls replacing the old pressure units. So with that, how would you turn on \ off the spray pump with a VFD drive. We're turning on the Brine pump with a return of 16F, 1st compressor comes on at 18F, 2nd compressor on at 20F. The VFD will maintain the head pressure around 175Psi, so when would you turn on \ off the spray pump. Anything below 175psi the drive would be at 0%. With the old method, they both came on the same time with a 40 and 10 Diff. Also we plan to disable the spray pump at around 20F to prevent icing in the tower.

My original post was a spec we have at our other rink which might not be correct and we don't want to incorporate something which is 20 years old --> The original sequence we found is to turn on the brine pump to maintain return brine temperature of 16F. The two compressors also turn on at 16F and then 17F. The cooling tower is controlled by monitoring the head pressure of the compressors. The VFD will modulate to maintain pressure of 165 PSIG. If the VFD is at 100% and the pressure goes above 180 PSIG turn on the pump. Then the pump remains on until 150 PSIG then turns off. The VFD still remains in control and will ramp down as the pressure goes down. The VFD never turns off - at 0% we have it at 20 hz.

[Bob-Brr]

Yes that's our concern with condenser - sorry if I wasn't clear. We are installing a VFD on the cooling tower and will be adding in controls replacing the old pressure units. So with that, how would you turn on \ off the spray pump with a VFD drive. We're turning on the Brine pump with a return of 16F, 1st compressor comes on at 18F, 2nd compressor on at 20F. The VFD will maintain the head pressure around 175Psi, so when would you turn on \ off the spray pump.

I, personally, would NEVER consider interrupting, or restricting the spray (condenser) water flow, especially going out to the tower. Flowing water is hard to freeze.
Also by controlling condenser water temp, ensures you are always sending warm liquid through the tower, a redundancy to prevent icing.

[ehsx]

Staging based on return or supply? Big difference in control band setting.

Spray pump should start with the compressor.

Fan vfd best with direct pressure control with cooling enable.

Low ambient may require tower sump heater & tower dampers.
Flowing water still freezes below 32*f. Even Niagara falls has completely frozen over.

Main thing is to maintain system stability.

Equipment vendors should also list detailed sequences.

[Bob-Brr]

Staging based on return or supply? Big difference in control band setting.

Spray pump should start with the compressor.

Fan vfd best with direct pressure control with cooling enable.

Low ambient may require tower sump heater & tower dampers.
Flowing water still freezes below 32*f. Even Niagara falls has completely frozen over.

Main thing is to maintain system stability.

Equipment vendors should also list detailed sequences.

Our tower had piping sloped so it the event of total shut down the water would drain back to the holding tank inside the building.
I always thought when you ran by temp, you used the coolest potential temp (condenser supply).
If appropriate considerations are taken into account, a heater or piping insulation shouldn't be needed, never had an issue with ours.