Looking For Expertise: Chiller Reservoir Issues

[The Happy One]

Not sure what I'm doing wrong, but I'm doing something wrong for sure. Here is our setup:
*We have four tables and each table has 32 plant sites set up on a constant drip recirculating system and each table has their own reservoir, with total water capacity of around 58 gallons per table. So total volume I am trying to chill (to about 68 deg) is under 250 gallons.
*The chiller we are using is a 1 hp capable of chilling 800-1800 liters.
*How I set it up: Chiller is located in our mechanical room outside of grow room, about 40 feet away from the grow room. The lines connecting the chiller are 1 inch diameter and all insulated. The chiller is mounted to a wall and under the chiller is a 55 gallon insulted plastic drum. The pump is in the reservoir and pumps directly into the chiller, through the chiller into fully insulated 1" diameter PVC lines into the grow room, both supply and return.

Once in the grow room there are four 1 inch to 1/2" T's, both on supply and return. (a reduced supply and return line going into each of the four table reservoirs. I'll post a few pictures for reference.

Anyway, water flow back to the chiller reservoir seems unrestricted, and I know each of the cooling coils in the table reservoirs are flowing as well as a 1/2" hose can be expected to flow. I've used several types of cooling coils from plate/fin to a Wort coil design, the latest being about 40 feet of 1/2" copper coiled up. I figured this would drop that reservoir a few degrees lower than the tranny coolers I am running is the other three reservoirs. It made no difference, and we are still hovering around 70 to 72 degrees in the reservoirs. I NEED 68 degrees or my symmetric OCD goes into overdrive. According to the chiller readout, it only has the capability to bring the water down to around 64 degrees shown at the chiller meaning there is around a 8 degree differential between the readout of the chiller and the actual temps in each of the four table reservoirs.

So..... I'm thinking two potential issues.
1. Is the 55 gallon chiller reservoir simply too small? I'm trying to cool over 200 gallons of nutrient solution, so do I need a LOT bigger chiller reservoir?
2. Should I run a pump in the chiller reservoir going to the chiller then back to the chiller reservoir and use another pump to pump from the chiller reservoir into the grow room instead of one pump as I have it currently set up?
I truly need to figure this problem out, as my lights aren't even up to 50% yet. I fear when I hit flower stage and full power I'm gonna be up sh*t creek.
HELP!

 

[bluenoserjoe]

No expert here but have run into this problem years ago. Solution was to chill the res. alone and use a different pump to circulate the now super chilled water through out the system. Hope this helps.

 

[The Happy One]

I'm with you on that. I'll add a pump. What say you about the 55 gallon chiller reservoir? You think 55 gallons is large enough?

 

[bluenoserjoe]

If memory serves me , I think the tank we were using was a 120 gallon watering trough. It was used to feed two systems and always in winter. Really helped keep it cooled down.

 

[TurboBucket]

Temperature differential plays a big role in liquid cooling. The higher the differential the faster the heat exchange occurs. You usually want 5-10°f temperature difference from your chilled solution to your product. So for your 68° Target your aiming for 58-63° chilled water source.

An air cooled 1hp chiller is roughly 10,000 btu/hr. A larger chiller size will reduce the equipment run time and in your situation would give you a lower source temp to get you in range faster.

 

[Chris Scorpio]

Or

Forget yer OCD

Always funny , to me, when supposed professionals, in whatever aspect in life, ask the general public for help

Makes me laugh

 

[Hydroholic]

Also your whole set up is trying to overcome all the head pressure. I would add check valves after all my pumps that are trying to move water uphill.

 

[The Happy One]

Or

Forget yer OCD

Always funny , to me, when supposed professionals, in whatever aspect in life, ask the general public for help

Makes me laugh

One thing I've learned in life, there's always going to be at least one. Today, it's you. Thanks for your contributions.

 

[The Happy One]

Temperature differential plays a big role in liquid cooling. The higher the differential the faster the heat exchange occurs. You usually want 5-10°f temperature difference from your chilled solution to your product. So for your 68° Target your aiming for 58-63° chilled water source.

An air cooled 1hp chiller is roughly 10,000 btu/hr. A larger chiller size will reduce the equipment run time and in your situation would give you a lower source temp to get you in range faster.

Turbo, thanks for your reply. I have a 7 to 8 deg temp differential between what is showing on the chiller vs what is reading in the 4 feed tanks. It simply won't pull down lower than 63 to 64. By reducing the return output, I was able to drop one more degree.
I'm going to try connecting a recirc pump to circulate from the chiller to the control tank in a loop by itself and another pump to circulate from the control tank to the four feed tanks and see if the 1 hp chiller can do a little better. I'm also thinking the 55 gallon control tank might not be large enough.
I'll chime it with the results

 

[The Happy One]

Picked up a 275 gallon IBC tote last night, and plan on replacing the 55 gallon reservoir with the 275 gallon.
With a larger pool to choose from, I'm hoping this will get us to our 68 deg goal. Wish me luck!

 

[The Happy One]

I have an update and found a solution.
Not sure which one did it, but I'd venture to say it was the 55 gallon reservoir. Even though a 1 hp chiller is pretty big, we had too much heat transfer to keep up.
I ended up removing the 55 gallon barrel and replaced it with a 275 gallon tote. We insulated the tote and insulated the four reservoirs as well.
This took us from 73 degrees down to around 66 to 67 deg in less than half an hour.
We also removed the waterfall direct drive pump that pushed water from the control reservoir into the four feed reservoirs in the flower room. I installed a 1254 GPU in place. This doesn't move the volume the pond pump did but this slower movement has improved heat transfer from the four reservoirs as well as being more efficient. Yay!

 

[TurboBucket]

It's the insulation. Slower heat transfer to the air now. The bigger reservoir just gives your equipment more buffer/time to pull down to temp. Without it you've been using your reservoirs to help cool the rooms they're stored in.

 

[bluenoserjoe]

Glad you got it figured out.

 

[Manny D]

I love all of this sharing of info that I'm seeing here. I'm in the process of designing a similar set up myself, by using one chiller that will cool a main rez, and that chilled water (solution) will be pumped into 2 flower rooms which are on alternate light schedules. Each room will have 2 SEPERATE 12 buckets, 12gallon rdwc set ups. The chilled water will flow from the "chilled Rez" to the first flower room then into a stainless steal wort chiller coil for Rez #1,,then from there, piped into rez #2 (steal coils),,,then into flower room #2, ect. The total estimate round trip travel is 33-37feet back to the chiller. Similar to this photo I've attached. I'm I crazy? I know it would be easier to consolidate the sites instead of having 4 SEPERATE gardens, but I'm trying for a Perpetual system. Do you guys see any holes in my theory? Thanks for your input..keep in mind, I'm not very mechanically inclined. I'm more of a visionary. Lol

 

[The Happy One]

I love all of this sharing of info that I'm seeing here. I'm in the process of designing a similar set up myself, by using one chiller that will cool a main rez, and that chilled water (solution) will be pumped into 2 flower rooms which are on alternate light schedules. Each room will have 2 SEPERATE 12 buckets, 12gallon rdwc set ups. The chilled water will flow from the "chilled Rez" to the first flower room then into a stainless steal wort chiller coil for Rez #1,,then from there, piped into rez #2 (steal coils),,,then into flower room #2, ect. The total estimate round trip travel is 33-37feet back to the chiller. Similar to this photo I've attached. I'm I crazy? I know it would be easier to consolidate the sites instead of having 4 SEPERATE gardens, but I'm trying for a Perpetual system. Do you guys see any holes in my theory? Thanks for your input..keep in mind, I'm not very mechanically inclined. I'm more of a visionary. Lol

Well, the good news is you aren't crazy. If you are, we both are.
This said, here is what I have came to know.
In our 1st flower room dubbed GR1 there are four rows with one reservoir per row. Each reservoir has about 46 gallons of nutrients on a perpetual loop. Each reservoir has it's own chiller loop.
So I am trying to chill these four reservoirs using a 1 hp (12,000 btu) Echo chiller.
I went from a 55 gallon reservoir to a 175 gallon reservoir. The unit runs 24/7 to keep the reservoirs below 70. I'm guessing I'm closer to needing 1.5 tons per room. The 4 ton chiller I am making SHOULD take care of two flower rooms, however this is new territory to me. I should have the 4 ton unit up and going within a week and will know a lot more.
There just isnt a lot of info out there on this subject....yet.

 

[Manny D]

Well, the good news is you aren't crazy. If you are, we both are.
This said, here is what I have came to know.
In our 1st flower room dubbed GR1 there are four rows with one reservoir per row. Each reservoir has about 46 gallons of nutrients on a perpetual loop. Each reservoir has it's own chiller loop.
So I am trying to chill these four reservoirs using a 1 hp (12,000 btu) Echo chiller.
I went from a 55 gallon reservoir to a 175 gallon reservoir. The unit runs 24/7 to keep the reservoirs below 70. I'm guessing I'm closer to needing 1.5 tons per room. The 4 ton chiller I am making SHOULD take care of two flower rooms, however this is new territory to me. I should have the 4 ton unit up and going within a week and will know a lot more.
There just isnt a lot of info out there on this subject....yet.

Rt on. You said you now have a 175gal Rez,,Now us that for each row or total?

 

[The Happy One]

Rt on. You said you now have a 175gal Rez,,Now us that for each row or total?

The 175 gallon is only for the chiller reservoir, and it only consists of h20. I may add a glycol mix later. Inside the 175 gallon reservoir is a pump that distributes this chilled water into the flower room and hits a 4 way manifold, each of the 4 feeds go into one of the four nutrient reservoirs, into a 50 foot coil loop that sits in the nutrient reservoir. There are four of these. Chilled water circulates through these 4 loops, then is carried back into the 175 gallon reservoir.
With the 4 ton chiller I've built, I should be able to cool 8 of these 46 gallon reservoirs, if not 12. Least that's the plan.

 

[Manny D]

Very cool. I'm anxious to see the results. Here's an idea of what I'm trying to build for my two flower rooms.

 

[The Happy One]

I did some research on this. They are basically doing the same thing. It looks like they use a stainless steel wort chiller in each reservoir.
I want to take it a step further, mainly because the chiller evaporator. Instead of a chiller loop coil, mine in rated at 5 tons, is a brazed plate coil with a footprint of about 4"×12"×4" and it doesn't even need to be in the reservoir.
The ones for the chiller loop replacement are about 75 bucks each, and have 4 1/2" nipples for easy connection. I'm gonna get one and compare it against the 1/2" loops we are running. If the improvement is notable, I may do all reservoirs with brazed plate chillers.

 

[iNeedMeds]

You have many problems with your system. I would first start by insulating your reservoirs, especially between the tanks and the concrete. I would buy some reflective bubble wrap insulation, and wrap all the irrigation pipes. Submersible pumps are cooled by the water that surrounds them. I would swap out the submersible pump for an external pump. External pumps should be used for your irrigation too. The tank only serves as a sump, and should be minimally sized to maintain enough water to keep the pump supplied. 10 gallons should be enough. If this doesn't work, add another water chiller in series.