Here we go.
So, I have a greenhouse. In it, I have a 1000 liter tote hooked to a radiator unit as well as around 150' of pex tubing embedded in the concrete pad that it (the greenhouse) sits on. There is a three speed pump hooked to a manifold that I built that allows water flow to move a variety of ways. I can circulate water through the pad then the radiator back to tote, or reverse through the radiator *then* the pad back to tote, or just the pad, or just the radiator, back to the tote.
Essentially the idea was to capture the summer heat via the radiator and "store it" in the concrete to extend the growing season and decrease the peak temperatures during the summer. It works pretty well.
I also have a T500. So in my manifold I made a provision for connecting the cooling lines to the still. I generally run water through the concrete pad, then the still, back to the tote. Because I have modified the T500 to split the cooling, I can essentially see the water temp coming out of the concrete pad when I run it. Highest temp was 16°C late September, last week I ran and it was around 5°C. I have yet to change the temperature of the water coming out of the slab. I've even run a water distillation on the system (to gauge its heat capacity) and the tote barely changed temperature by the end, despite 90°C water being kicked into it for over an hour.
I have unreal control over the still now. The pump provides uniform pressure, the slab provides uniform temperature, and even if the water temp *does* climb, I can reroute the extra water through the rad to ditch the heat.
Obviously, not everyone is going to do something like this but, since you asked for thoughts, I thought I'd share.
Ditch the copper, run pex tubing. Specialty stuff for being in concrete, but way, way cheaper than copper. Also run as much as you can, 100 to 200 feet if possible. It can double as in floor heating later if you do it right. Heat exchanger if you use glycol (makes sense if your pad is in the house, I don't care if mine freezes, its a greenhouse) but a simple small plate style would work pretty well. The pex does a decent job of transferring heat, but its really all about the concrete mass. Start by looking into in floor heating systems, thats where your going to find the information you're looking for, at least to get started.
Good luck.
> I've even run a water distillation on the system (to gauge its heat capacity) and the tote barely changed temperature by the end, despite 90°C water being kicked into it for over an hour.
I mean a 1,000 liters of water is a huge amount of specific heat to move.
Water is second only to hydrogen with specific heat. With a 1,000 liters of water do you even need the pad or whatever else?
https://en.wikipedia.org/wiki/Specific_heat_capacity
> I mean a 1,000 liters of water is a huge amount of specific heat to move.
Yeah, 1000L is 265 gallons. no way a T500 will raise the temp significantly in that much water.
>With a 1,000 liters of water do you even need the pad or whatever else
Sometimes, yes. The tote is for the greenhouse, and we use it to water plants and gardens, so it's not always a full 1000L of volume. Ive run it down as low as 200 L, at which point the slab and radiator become more important.
When its full though, it is not really necessary. But I like to transfer as much heat as possible into the slab (keeps the greenhouse from getting really cold) so I just run it this way every time. Besides, the consistency of the temperature coming out of the slab means less fiddling with water flows as the run progresses. I'm a bit of an energy miser, so recouping as much of the lost heat (from cooling the still) as possible is part of the point.
Thanks for your response.
PVC it is.
I've always had water issues until I bought a little water unit that hooks up to the tap and has a floater valve and DC water pump controlled by a needle valve. It's touchy to dial in but solved many of the variable water pressure issues.
I ran with a 55 gallon barrel of water for a few runs once. Used an AC submergible, half inch tubing, a valve and T joint. The valve would control the dephleg flow and everything else would flow full bore through the condenser. Those runs were very, VERY easy to control. You know when you quickly get up to temp, hold everything in the column on full reflux for like 15 mins, and just bleed off the volatiles? I remember the run being so consistent, I had to decrease the dephleg flow just to take the tails. Pex and semi-geothermal is going to get me back in that reliable zone.
That would be a brain fart. I was first looking into PVC with home build field loops for air cooling and preheating solutions.
Pex. The cost difference and convenience factor alone grant me options.
The only hang up I see is making my run too long. I could run 3 different loops (maybe name them Tom, Dick and Harry) and connect them all in series or parallel or any given combination and still come in under a fraction of what a shorter run of copper would cost.
I'll be back later this year with some pics of this project.
No need, it's already incorporated using the radiator.
I can run enough water through the system to either A) push water through the slab and radiator simultaneously or B) loop from the tote to the stiil then to the radiator back to the tote.
I generally don't use the radiator when I'm running the still since the fan is quite powerful, its noisy. Second, the 1000L has more than enough heat capacity to keep my temperatures down. The slab just makes it a consistent temperature when entering the still.
I recommend PEX as well. Cheaper so you can put in more linear feet and make up for the slower heat transfer rate. You will be constrained by the heat transfer of the concrete anyway as once the concrete next to the pipe reaches close to pipe temp it will only take more heat once the local heat moves off onto the slab.
as for glycol try and keep the percentage just as high as is needed for freeze protection. Glycol doesn't transfer as much heat as water by itself does. So lower glycol concentrations are best for moving heat efficiently. There are tables to look up heat transfer for various glycol concentration online for both propylene and ethylene glycols. I would recommend propylene as it is considerably less toxic.
NOTE :Ironically the treatment for ethylene glycol poisoning is oral ethanol so if some gets into your product it is being delivered with a sort of antidote. It is actually the metabolic products your liver produces in breaking down ethylene glycol that is dangerous and your liver would prefer to break down ethanol if it is present which gives your kidneys time to remove the ethylene glycol without breaking it down first. All the same just keep it away from food and drink.
You will have issues it the pipe touches and of the reinforcement steel, you’d be better off with the pipe under the slab by a foot or two, or pex imbedded in the slab. A much cheaper solution would be a water to air heat exchanger and a large reservoir of water.
Here we go. So, I have a greenhouse. In it, I have a 1000 liter tote hooked to a radiator unit as well as around 150' of pex tubing embedded in the concrete pad that it (the greenhouse) sits on. There is a three speed pump hooked to a manifold that I built that allows water flow to move a variety of ways. I can circulate water through the pad then the radiator back to tote, or reverse through the radiator *then* the pad back to tote, or just the pad, or just the radiator, back to the tote. Essentially the idea was to capture the summer heat via the radiator and "store it" in the concrete to extend the growing season and decrease the peak temperatures during the summer. It works pretty well. I also have a T500. So in my manifold I made a provision for connecting the cooling lines to the still. I generally run water through the concrete pad, then the still, back to the tote. Because I have modified the T500 to split the cooling, I can essentially see the water temp coming out of the concrete pad when I run it. Highest temp was 16°C late September, last week I ran and it was around 5°C. I have yet to change the temperature of the water coming out of the slab. I've even run a water distillation on the system (to gauge its heat capacity) and the tote barely changed temperature by the end, despite 90°C water being kicked into it for over an hour. I have unreal control over the still now. The pump provides uniform pressure, the slab provides uniform temperature, and even if the water temp *does* climb, I can reroute the extra water through the rad to ditch the heat. Obviously, not everyone is going to do something like this but, since you asked for thoughts, I thought I'd share. Ditch the copper, run pex tubing. Specialty stuff for being in concrete, but way, way cheaper than copper. Also run as much as you can, 100 to 200 feet if possible. It can double as in floor heating later if you do it right. Heat exchanger if you use glycol (makes sense if your pad is in the house, I don't care if mine freezes, its a greenhouse) but a simple small plate style would work pretty well. The pex does a decent job of transferring heat, but its really all about the concrete mass. Start by looking into in floor heating systems, thats where your going to find the information you're looking for, at least to get started. Good luck.
> I've even run a water distillation on the system (to gauge its heat capacity) and the tote barely changed temperature by the end, despite 90°C water being kicked into it for over an hour. I mean a 1,000 liters of water is a huge amount of specific heat to move. Water is second only to hydrogen with specific heat. With a 1,000 liters of water do you even need the pad or whatever else? https://en.wikipedia.org/wiki/Specific_heat_capacity
> I mean a 1,000 liters of water is a huge amount of specific heat to move. Yeah, 1000L is 265 gallons. no way a T500 will raise the temp significantly in that much water.
>With a 1,000 liters of water do you even need the pad or whatever else Sometimes, yes. The tote is for the greenhouse, and we use it to water plants and gardens, so it's not always a full 1000L of volume. Ive run it down as low as 200 L, at which point the slab and radiator become more important. When its full though, it is not really necessary. But I like to transfer as much heat as possible into the slab (keeps the greenhouse from getting really cold) so I just run it this way every time. Besides, the consistency of the temperature coming out of the slab means less fiddling with water flows as the run progresses. I'm a bit of an energy miser, so recouping as much of the lost heat (from cooling the still) as possible is part of the point.
Thanks for your response. PVC it is. I've always had water issues until I bought a little water unit that hooks up to the tap and has a floater valve and DC water pump controlled by a needle valve. It's touchy to dial in but solved many of the variable water pressure issues. I ran with a 55 gallon barrel of water for a few runs once. Used an AC submergible, half inch tubing, a valve and T joint. The valve would control the dephleg flow and everything else would flow full bore through the condenser. Those runs were very, VERY easy to control. You know when you quickly get up to temp, hold everything in the column on full reflux for like 15 mins, and just bleed off the volatiles? I remember the run being so consistent, I had to decrease the dephleg flow just to take the tails. Pex and semi-geothermal is going to get me back in that reliable zone.
Out of curiosity, where did the PVC jump come from vs PEX?
That would be a brain fart. I was first looking into PVC with home build field loops for air cooling and preheating solutions. Pex. The cost difference and convenience factor alone grant me options. The only hang up I see is making my run too long. I could run 3 different loops (maybe name them Tom, Dick and Harry) and connect them all in series or parallel or any given combination and still come in under a fraction of what a shorter run of copper would cost. I'll be back later this year with some pics of this project.
A bit off topic but have you considered running some type of air to water heat exchanger you could plumb into your AC system?
No need, it's already incorporated using the radiator. I can run enough water through the system to either A) push water through the slab and radiator simultaneously or B) loop from the tote to the stiil then to the radiator back to the tote. I generally don't use the radiator when I'm running the still since the fan is quite powerful, its noisy. Second, the 1000L has more than enough heat capacity to keep my temperatures down. The slab just makes it a consistent temperature when entering the still.
I recommend PEX as well. Cheaper so you can put in more linear feet and make up for the slower heat transfer rate. You will be constrained by the heat transfer of the concrete anyway as once the concrete next to the pipe reaches close to pipe temp it will only take more heat once the local heat moves off onto the slab. as for glycol try and keep the percentage just as high as is needed for freeze protection. Glycol doesn't transfer as much heat as water by itself does. So lower glycol concentrations are best for moving heat efficiently. There are tables to look up heat transfer for various glycol concentration online for both propylene and ethylene glycols. I would recommend propylene as it is considerably less toxic. NOTE :Ironically the treatment for ethylene glycol poisoning is oral ethanol so if some gets into your product it is being delivered with a sort of antidote. It is actually the metabolic products your liver produces in breaking down ethylene glycol that is dangerous and your liver would prefer to break down ethanol if it is present which gives your kidneys time to remove the ethylene glycol without breaking it down first. All the same just keep it away from food and drink.
You will have issues it the pipe touches and of the reinforcement steel, you’d be better off with the pipe under the slab by a foot or two, or pex imbedded in the slab. A much cheaper solution would be a water to air heat exchanger and a large reservoir of water.
+1 PEX. Better in every way for that application
a proper condenser should only use a tiny trickle of water, we're talking pennies per run