Material for keeping DWC bucket temperatures low

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medicine21

Active Member
As we all know one of the challenges in DWC is keeping the temps in the rez/buckets low. A chiller is an expensive option. Insulating buckets and reservoir will only help keep the temps that are already in the containers . Having a concrete floor and placing a large, relatively flat reservoir directly on it also helps the cause.

Due to the overflow height I have to raise the DWC buckets off the floor to be above the rez but I do want to leverage the cold concrete floor to cool the buckets.

The question is what material best to use to raise the buckets (i.e. between the concrete floor and the buckets)? Should it be flat stone slabs or a more insulating type material? Should this material have high or low thermal conductivity? http://www.engineeringtoolbox.com/thermal-conductivity-d_429.html

I am guessing high thermal conductivity would be the way to go as it would transfer heat from bucket to concrete more efficiently...
 
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mikadodarkside

Well-Known Member
If you want thermal energy to spread out and disperse you want something that has a high co-efficient of thermal conductivity. that being said its probably not going to matter a lot. Lets say you use copper( very high thermal conductivity) the interface between the copper and the concrete isn't going to be good, and neither is the area between the bucket and the copper. Do a test, see if your res is on the ground, measure the temp, then measure the temp when it is sitting on a chair or something. is there a difference? is that difference significat? if your buckets are close to your lights there might be a difference, but that difference is caused by proximity to your light and wont be easily solved using conductive radiation.

solutions:

increase water flow from your res to your buckets so the temperature doesn't raise too much, if your res gets too hot then make it bigger or limit your lighting by time reduction or wattage.

Insulate each bucket, This can easily be done in a variety of ways with insulation or orther buckets,

grow in an lst or SCROG method so that your buckets are totally shaded from the light and heat. try to make it so air intake goes up through the canopy and for the most part there is a temperature gradient across the canopy of your scrog or lst.



In conclusion, unless you have copper fitted heat sinks that radiate into your basement and the ground, its going to be hard conduct that heat downwards.
 
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medicine21

Active Member
Some good input, mikado! Increasing flow is an option indeed, assuming that the rez is cooler than the buckets. However this also raises the temp in the rez and consequently the water due to the pump generating heat when on. Airflow is beneficial either way, so good point.

Check out the definition of "conductive heat transfer": Energy is transferred from more energetic to less energetic molecules when neighboring molecules collide. Conductive heat flow occur in direction of the decreasing temperature since higher temperature are associated with higher molecular energy.

This tell me that if buckets are on the cold concrete floor, the heat would travel downward from the buckets thus cooling them. I do need to raise them about 3" off the floor so the overflow is above the rez. Copper would be great, unfortunately I think the cost of 3" thick copper slabs to put underneath each bucket would be prohibitive. From the chart I referenced in the first post looks like some type of rock slab would have to do due to cost reasons...

Other ideas?
 
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wiseguy316

Well-Known Member
I used to put my buckets in a cooler with water and put frozen bottles of water in the cooler, kept the buckets from sweating, some people just use coolers for the res. I got tired of always have to swap them out. Watched ebay for a used one for a while bought one chiller for 120 bucks, then bought another for a spare for 150 bucks. I will never look back. Was money well spent.
 
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mikadodarkside

Well-Known Member
medicine21 said:
Some good input, mikado! Increasing flow is an option indeed, assuming that the rez is cooler than the buckets. However this also raises the temp in the rez and consequently the water due to the pump generating heat when on. Airflow is beneficial either way, so good point.

Check out the definition of "conductive heat transfer": Energy is transferred from more energetic to less energetic molecules when neighboring molecules collide. Conductive heat flow occur in direction of the decreasing temperature since higher temperature are associated with higher molecular energy.

This tell me that if buckets are on the cold concrete floor, the heat would travel downward from the buckets thus cooling them. I do need to raise them about 3" off the floor so the overflow is above the rez. Copper would be great, unfortunately I think the cost of 3" thick copper slabs to put underneath each bucket would be prohibitive. From the chart I referenced in the first post looks like some type of rock slab would have to do due to cost reasons...

Other ideas?
Click to expand...


You fucking Dip Shit, "check out the definition of conductiver heat transfer" ... what an asshole response to a some good advice.
I Have studied Thermodynamics, heat transfer and fluid dynamics, as a systems engineer.

What i was trying to convey is that your heat sink will have fuck all of an effect compared to other factors in your grow.
If you consider the surface area of your bucket there is the top the bottom and the circular side. based on the average temperature of the water in the bucket, the ambient surrounding temperature and the ambient temperature of the bottom of the bucket. If you were to model this under the assumption that air temp>water temp> ground temp.

heat is radiated from the sides top and bottom of the bucket. the amount of energy radiated is proportional to temperature and surface area. ( you can model these using resistor like in electronics, more insulation is more resistance, better thermal conductivity is lower resistance ) you want high resistance on top and sides and low resistance on the bottom.

then depending on the dimensions of your bucket around 70% would be exposed to air, water temperature would be governed air temp, ground temp, factos such as air pump mass flow rate and temp (heat transfer of bubbles in water ), water mass flow rate and temp ( from res).

IT DOESNT MATTER WHAT YOU DO TO PROP UP YOUR BUCKETS.

next time you ask for help try not to tell people to " check out the deffinition " you fucking terd.

PS. if your floor is decently colder the the air temp in your grow. ( like say your ground temp is 60) then based on the fact that adding a pump to increase circulation increases entropy ( make heat ) in the system, then depending on your pump power rating, and the size of your res, and the heat transfer between the floor and the water, you could still lower the temperature if you heat transfer is greater then your pumps' entropy heating.
 
Banditt

Banditt

Well-Known Member
mikadodarkside said:
You fucking Dip Shit, "check out the definition of conductiver heat transfer" ... what an asshole response to a some good advice.
I Have studied Thermodynamics, heat transfer and fluid dynamics, as a systems engineer.

What i was trying to convey is that your heat sink will have fuck all of an effect compared to other factors in your grow.
If you consider the surface area of your bucket there is the top the bottom and the circular side. based on the average temperature of the water in the bucket, the ambient surrounding temperature and the ambient temperature of the bottom of the bucket. If you were to model this under the assumption that air temp>water temp> ground temp.

heat is radiated from the sides top and bottom of the bucket. the amount of energy radiated is proportional to temperature and surface area. ( you can model these using resistor like in electronics, more insulation is more resistance, better thermal conductivity is lower resistance ) you want high resistance on top and sides and low resistance on the bottom.

then depending on the dimensions of your bucket around 70% would be exposed to air, water temperature would be governed air temp, ground temp, factos such as air pump mass flow rate and temp (heat transfer of bubbles in water ), water mass flow rate and temp ( from res).

IT DOESNT MATTER WHAT YOU DO TO PROP UP YOUR BUCKETS.

next time you ask for help try not to tell people to " check out the deffinition " you fucking terd.

PS. if your floor is decently colder the the air temp in your grow. ( like say your ground temp is 60) then based on the fact that adding a pump to increase circulation increases entropy ( make heat ) in the system, then depending on your pump power rating, and the size of your res, and the heat transfer between the floor and the water, you could still lower the temperature if you heat transfer is greater then your pumps' entropy heating.
Click to expand...
Get bent out of shape much? :lol:
 
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mikadodarkside

Well-Known Member
I rage hard when people do dumb shit.

durrRRRRRRRrr lets ask questions then pretend we know everything....

fucking seriously . i have no patience for peoples feelings.
 
woodsmaneh!

woodsmaneh!

Well-Known Member
Must have missed that day in school where they taught you how to get along with others, Mother issues??? "A" personality types are all full of themselves and are condescending to those they feel are worthy of their scorn. Still good info and come on we don't want this to be Mr. Rogers ""Won't You Be My Neighbor?"" hood some flames keep it interesting.

Lighten up

1.jpg
 
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medicine21

Active Member
Haha, well thanks for the useful part of your post, anyway. I'll assume you had a bad day or something.

So assuming the concrete floor is about 60*, buckets are fully insulated, you are saying there would be NO difference in bucket temp if I propped it on a rock slab vs a raised 4-leg wooden table?
 
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mikadodarkside

Well-Known Member
I would never say that it has no effect, but based on the surface area your only dealing with 30% of radient heat. You would have more fruitful returns if you adressed other issues.
 
Doer

Doer

Well-Known Member
Back to the subject. A bucket sitting on a concrete floor has very little in contact with the floor. Just the rim. A few square millimeters, only. And the rim is 1/2 inch away from the water. It also has a 1/2 inch deep dead air space....a most excellent insulator.

So, I don't think you are getting an advantage. OTH, raise 3 inches it might be better since you disrupt the deal air space
and the cold floor is shaded by the bucket. Now the entire floor is a heat sink against the total environment.

I think of heat as a substance that has to be transported....out. The entire room, inside the house, inside the local weather is the environment. Heat transfers itself through the 2nd law if allowed.

And black buckets transfer heat, both ways, according to the 2nd law depending on gradient.

The set up needs environment control. Shedding heat. It's a real problem in the Space Station and in my bathroom. Every thing adds heat. Lots of stuff is working and Work is defined as heat. Watts are dissipated as heat. The Law.

The good thing is water is a most excellent transport, air is not so good. So, it is a full press to shed heat. But, we need the water colder than the air.

Insulate the buckets, paint the lids white.
A bucket in a bucket with a little bit of water between them is good insulation.
Add a chill down somehow
gain temp stability from more water
isolate the hot air outputs and take it out of the grow (I have it pushed outside thru the bathroom exhaust vent.)
Get cool air from under the house for intake air

Here, we fortunately get cool almost every night even in summer. So, I thought I didn't need a chiller. Had 40 gals, 12 buckets.

Nope lost it all to root rot.
 
G

gagekko

Well-Known Member
mikadodarkside said:
You fucking Dip Shit, "check out the definition of conductiver heat transfer" ... what an asshole response to a some good advice.
I Have studied Thermodynamics, heat transfer and fluid dynamics, as a systems engineer.

What i was trying to convey is that your heat sink will have fuck all of an effect compared to other factors in your grow.
If you consider the surface area of your bucket there is the top the bottom and the circular side. based on the average temperature of the water in the bucket, the ambient surrounding temperature and the ambient temperature of the bottom of the bucket. If you were to model this under the assumption that air temp>water temp> ground temp.

heat is radiated from the sides top and bottom of the bucket. the amount of energy radiated is proportional to temperature and surface area. ( you can model these using resistor like in electronics, more insulation is more resistance, better thermal conductivity is lower resistance ) you want high resistance on top and sides and low resistance on the bottom.

then depending on the dimensions of your bucket around 70% would be exposed to air, water temperature would be governed air temp, ground temp, factos such as air pump mass flow rate and temp (heat transfer of bubbles in water ), water mass flow rate and temp ( from res).

IT DOESNT MATTER WHAT YOU DO TO PROP UP YOUR BUCKETS.

next time you ask for help try not to tell people to " check out the deffinition " you fucking terd.

PS. if your floor is decently colder the the air temp in your grow. ( like say your ground temp is 60) then based on the fact that adding a pump to increase circulation increases entropy ( make heat ) in the system, then depending on your pump power rating, and the size of your res, and the heat transfer between the floor and the water, you could still lower the temperature if you heat transfer is greater then your pumps' entropy heating.
Click to expand...
Haha... I love it :)
 
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gagekko

Well-Known Member
Seems like it's all too complicated... Put ur buckets in a concrete mixing tray from Lowes or Home Depot and throw in a frozen water bottle to keep temps down... But heat sinks or whatever I guess is more fun :P
 
Doer

Doer

Well-Known Member
That's a good idea. And it is more fun to try stuff.

I just decide for $450, (a bag or so of weed) get a chiller. 1000 gph pump, 1/4 horse chiller, 22 gals. 63 F. I think I have enough power to run a heat exchanger for the water cooled light, also. I lost 12 fat colas to root rot last year. Surely much more than $450.

Highly recommended. All thumbs up!
 
Vasdef

Vasdef

Member
Doer said:
That's a good idea. And it is more fun to try stuff.

I just decide for $450, (a bag or so of weed) get a chiller. 1000 gph pump, 1/4 horse chiller, 22 gals. 63 F. I think I have enough power to run a heat exchanger for the water cooled light, also. I lost 12 fat colas to root rot last year. Surely much more than $450.

Highly recommended. All thumbs up!
Click to expand...
I hear those chillers are power hungry, any truth to that?
 
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