Ability to reach set point vs Glycol Mix

[Bluepants]

I've got a 10 HP unit that seems to be unable to keep up with the Alabama heat. However, based on the loading calcs it should be able to handle it.

Background: 2 30 bbl fermenters and a 30 bbl brite. Currently fully loaded.

I used the unit in the 2nd stage of the heat exchanger to drop beer temp, resulting in the temp of the reservoir (3 bbl) running up to about 28 C. Since then I've been struggling to drop the temp back down without the thermal overloads on the unit tripping. We burnt up one of the thermal overloads trying to drop it down. They are both replaced now and the unit still won't drop the reservoir down to the set point unless I'm actively misting the coils of the unit and that's not running the loop that is intended to cool off the beer.

Anyone got any ideas on what I need to work on? One thing I"m worried about is that Glycol Water Mix actually affects the performance of the unit rather than just the freeze point of the liquid. In other words, I'm not worried about freezing it but should I be worried about the chilling being less effective.

My other idea is just to change out the circuitry since it seems to be undersized.

[greenmtnbrewer]

I am not positive but I think that glycol mixture is less conductive and so you would want to run only the amount of glycol required for your required temperature range, otherwise deionized (distilled) water. I found this chart, but I am not sure how that would affect real performance . What does the chiller manufacturer recommend?

https://dow-answer.custhelp.com/app/...-english-units

some other info
http://www.lytron.com/Tools-and-Tech...Liquid-Cooling

[lhall]

What are your suction and outlet pressures on your compressor? Is that is what is tripping? It sounds like your outlet pressure on your compressor is getting too high. An HAVC tech could make sure your refrigerant charge is right and that your fan cycle switches are set at the right pressures.

[jimvgjr]

When you combine the summer heat and operating at glycol temperatures in the mid 80 F (28 C) Range- you will have trouble keeping the system online.

Essentially as you increase the glycol temperature above 45-50 F Range, your condenser is likely becoming very undersized and unable to keep up. This will result in system overload due to high operating amps and also high head pressure alarms.

A short term "band aid" would be to mist down the air cooled condenser to assist as you are bringing the glycol temperatures back into the systems design operating range. Be careful to not introduce water into the fan motors and cause motor damage. It is also a good idea to clean the condensers to get maximum airflow across the condenser.

Many brewers will also dedicate all of the cooling capacity to wort cooling during the wort transfer period, this will reduce the total load on the chiller system and might help also.

We have a video posted on our support website here that covers how to clean and treat condenser that might be helpful. http://www.prochiller.com/Support.html

Good luck,

Jim
Pro Chiller Systems.

[Starcat]

Electrical fusing and overloads are sized by the equipment nameplate data strictly and in case of HVACR devices the maximum nameplate figure should always be used. Overloads are not to be over sized beyond the design of any load. Any compressor that is operated in a return gas pressure range that takes it into an overcurrent condition is going to have a radically shortened service life. If there is no redundancy in the plant, this is a risky way to operate.
I would install a CPR valve on the compressor and simply not allow overcurrent induced from that angle.
There are several ways to help the condensers effect with some easy home cooked devices that will desuperheat the discharge gas and then enhance subcooling if possible. The plant described needs more capacity and redundancy when possible.
We have a method of chilling a large vessel of water for the cool down heat exchanger that also has a city water feed for blended operation. This type of method takes much of the hard slamming load off of the glycol loop.

Warren Turner
HVACR-Engineering Tech
Moab Brewery
5 July,12

[tom@arcadia]

I'm having trouble justifying more glycol percentage in my chiller.

My chiller is located in the cellar area of the brewery and the ambient temperature in there is around 60F all year.

Do I need to run my glycol at 35% glycol 65% water if my glycol tank is not exposed to winter freezing temperatures. I know that more glycol in the system than is needed reduces the heat transfer coefficient.

I'm running at about 20% glycol now which was increased from 8% glycol earlier but I am not sure I need to go to 35%.

I am a little confused because Pro Refrigeration says that most systems run at 35% glycol and that you need your glycol freeze temperature to be about 20-25 degrees F below your system set point. We run our set point at about 24 degrees F normally but have had to lower it to 14F lately due to some issues.

Any suggestions?

[Bluepants]

Yeah, I need a different Chiller. Gotta love the summer. Ive discontinued use of the glycol for chilling wort. Its unfortunate but we still seem to have good cooling times. Thanks to everyone for the notes. Guess I'll have to figure out when I can start shopping for a larger unit.

Electrical fusing and overloads are sized by the equipment nameplate data strictly and in case of HVACR devices the maximum nameplate figure should always be used. Overloads are not to be over sized beyond the design of any load. Any compressor that is operated in a return gas pressure range that takes it into an overcurrent condition is going to have a radically shortened service life. If there is no redundancy in the plant, this is a risky way to operate.
I would install a CPR valve on the compressor and simply not allow overcurrent induced from that angle.
There are several ways to help the condensers effect with some easy home cooked devices that will desuperheat the discharge gas and then enhance subcooling if possible. The plant described needs more capacity and redundancy when possible.
We have a method of chilling a large vessel of water for the cool down heat exchanger that also has a city water feed for blended operation. This type of method takes much of the hard slamming load off of the glycol loop.

Warren Turner
HVACR-Engineering Tech
Moab Brewery
5 July,12

[lhall]

Tom @ Arcadia,

Your glycol freeze point is not based on the ambient temperature, but on the temperature of the refrigerant in your heat exchanger on the chiller unit. Depending on the suction pressure and the type of refrigerant, that temperature will be 10-20 F. You will get ice buildup on the heat exchanger which will slow heat transfer and cause all kinds of problems, even damaging the heat exchanger, if your glycol percentage is too low.