Improving efficency of a Chiller

[beerbaronaaron]

I have a few questions regarding our chiller system that I was hoping someone could help me with.

first a little background--
We bought a used 7.5 ton chiller (a bit oversized i think) that was originally set up to cool a laser at high pressure. Like everything else in our brewery, we did the piping and insulation ourselves with a 3/4 inch main line with pressure reducers to about 12 PSI (pump is running at about 70 PSI) and 3/4 inch drops for the tanks. We have 3 7bbl fermentors running off it with additional room to expand. I just got our first electric bill and it looks like it cost $600 to run the chiller for a month (ouch!). Something seems to be wrong.. The piping has the first in last out principle and there is no connection between the supply and the return lines (glycol would have to run through a tank to return to the unit)

The pump seems to cycle on and off a lot and the compressor seems to be running much more than I would think it should. Did we set up the piping wrong? Should the glycol be constantly circulating? I've had the local AC guys out here a couple times but they seem to mostly just stand around in awe because they haven't working on/designed a chiller system before. They know how to adjust the compressor and fans, but don't know how the overall system should be working.

Does anyone know a chiller expert in the orange county area of CA? I called PRO Refrig, but they said just to call a local company since it isn't a PRO system.

Any help would be greatly appreciated.

Thanks,
Aaron

[lhall]

The glycol should be circulating. Is there a seperate pump circulating the glycol within the reservoir? The dead-headed pump you have now is generating a lot of heat!

[beerbaronaaron]

The glycol should be circulating. Is there a seperate pump circulating the glycol within the reservoir? The dead-headed pump you have now is generating a lot of heat!

I am pretty sure there is a different pump for circulating the glycol in the reservoir. Although, I am by no means a refrig expert...

[BrewinLou]

It does sound a lot like you may not be getting enough flow. We have a valve at the end of the line (from send to return). I had to tune our old chiller with the bypass valve because it was not getting enough flow, the only thing it now runs to is our walkin cooler. I set the valve about half way open and the chiller does not cycle nearly as much. We have plenty of tanks on the new chiller and leave the bypass closed.

[Moonlight]

As I watch my refrigeration guy at work, I see there is quite a bit to "balancing" the equipment that he does after changes to a system. It involves setting the compressor to cycle off in the most efficient cycle to fit your loads. I am in no position to advise how to do it, but maybe a service call to a refrig guy could pay for itself easily.
It also looks to me that you have an over-sized compressor for your load. Kinda like having an 18-wheeler deliver one pallet of malt. It may even be cheaper to buy a smaller compressor that fits your load correctly (like a pick-up truck for that one pallet.) For example, my 5 HP unit handles three 20bbl fermenters and a 500 sq ft. cold box, and is mostly not running. Summer electricity bill for the whole brewery is high 500's, winter in the high 200's.

[beerbaronaaron]

As I watch my refrigeration guy at work, I see there is quite a bit to "balancing" the equipment that he does after changes to a system. It involves setting the compressor to cycle off in the most efficient cycle to fit your loads. I am in no position to advise how to do it, but maybe a service call to a refrig guy could pay for itself easily.
It also looks to me that you have an over-sized compressor for your load. Kinda like having an 18-wheeler deliver one pallet of malt. It may even be cheaper to buy a smaller compressor that fits your load correctly (like a pick-up truck for that one pallet.) For example, my 5 HP unit handles three 20bbl fermenters and a 500 sq ft. cold box, and is mostly not running. Summer electricity bill for the whole brewery is high 500's, winter in the high 200's.

I agree, it does seem a bit oversized at the moment, but my thought when purchasing is that I will quickly need the extra capacity as I add more tanks and I didn't want to go through the downtime, hassle, and cost of switching one out right as I am hitting critical mass. Although...with $600 electric bills, I am starting to second guess my logic...lol. Hindsight is 20/20 I guess..

[jimvgjr]

I have a few questions regarding our chiller system that I was hoping someone could help me with.

first a little background--
We bought a used 7.5 ton chiller (a bit oversized i think) that was originally set up to cool a laser at high pressure. Like everything else in our brewery, we did the piping and insulation ourselves with a 3/4 inch main line with pressure reducers to about 12 PSI (pump is running at about 70 PSI) and 3/4 inch drops for the tanks. We have 3 7bbl fermentors running off it with additional room to expand. I just got our first electric bill and it looks like it cost $600 to run the chiller for a month (ouch!). Something seems to be wrong.. The piping has the first in last out principle and there is no connection between the supply and the return lines (glycol would have to run through a tank to return to the unit)

The pump seems to cycle on and off a lot and the compressor seems to be running much more than I would think it should. Did we set up the piping wrong? Should the glycol be constantly circulating? I've had the local AC guys out here a couple times but they seem to mostly just stand around in awe because they haven't working on/designed a chiller system before. They know how to adjust the compressor and fans, but don't know how the overall system should be working.

Does anyone know a chiller expert in the orange county area of CA? I called PRO Refrig, but they said just to call a local company since it isn't a PRO system.

Any help would be greatly appreciated.

Thanks,
Aaron

Hi Aaron,

I'm not sure who you talked to here at Pro, I've tried to help many brewers with competitor's systems- sorry you didn't get any help.

Right off the bat it sounds like the glycol piping is undersized at 3/4", even for just 3 Fermenters I would guess you will need 12-15 GPM (plus you mention a plan to expand). The most I would try to push through 3/4" pipe is 5-8 GPM.

From your description, I think it will really take someone onsite to get a handle on what is going on. If you have a dedicated pump to circulate to the Fermenters, this should run all the time. A bypass (either pressure or manual) between the main supply and return headers will keep circulation going even when your tanks aren't calling for cooling and prevent a dead head situation on the glycol pump. I'm puzzled when you say the pump cycles off and on a lot, are you referring to this glycol pump? Do you know what controls this pump?

If you don't receive any names of refrigeration contractors from other breweries in the area, I can send you the names of some people we have worked with. We often will have technical sales people in your area too, I would be happy to have one stop in when in this area.

Good luck,

Jim
jimvgjr@prorefrigeration.com

[beerbaronaaron]

Jim,

Thanks for your response. I would be interested in any local referrals you can provide (please PM me)

I'm not sure what it is called, but there is a little switch in the unit that tells the pump to turn off when fluid is not moving in the line, and tells it to turn on when the fluid starts moving (i.e. a solenoid is opened). I suppose it is designed to prevent the deadhead situation, but it seems to cycle on and off a lot.

The system chills the fermenters fine right now, and given our budget, we arent going to rip the whole system apart and start over, so I guess we'll just install a gate valve between the supply and return for now to help minimize this situation...

Thanks,
Aaron

[Moonlight]

Is it possible that that this is a glycol pump and it contributes the turbulence to get good heat exchange from the refrigerant to the glycol? How about some photos? This could be causing your symptoms and your compressor will have a short life span. I say this from expensive experience. Get a good technician to check it out really soon.
Call nearby successful food processing companies and see who they use.