The digging has begun - Go Marvin Go

[Greg Hiller]

Randy,

We posted at the same time.

>How fast were you thinking would be optimal<

I calculated it out, and it was much lower than most or all of the standard aquarium pumps would deliver, as I say, don't remember off the top of my head. Remember, low flowrate is going to also mean less backpressure, and there will be plenty of backpressure on a 300 ft lenght of 3/4 tubing.

 

[Greg Hiller]

Randy,

You used standard tap water from a cooling line running though your sump. Did the water come to equilibrium with the tank water by the time it left the sump? How long was the tubing, what diameter, and how fast was the flow. Any idea how much of the time (% time open) the valve opened to let the water flow?

 

[Chuck Spyropulos]

Good Luck

>I don't think the slow flow loop will be too efficient<

You are correct that slow flow will be less efficient, but it doesn't matter once you get to equilibrium. Yes it will matter in the sump not outside...but why am I wasting my time....you have it all figured out nicely

I'm guessing I took heat transfer more recently that you did, but I might be wrong. You have a ME degree right? WRONG ! Do you take heat transfer in that program?PLEASE ! Anyhow...I digress..... GOOD!

Bachelors in Physics
Masters in Electrical Engineering

I was just trying to give you advice ...I didn't realize that I needed to defend my degrees to you online or get into a pissing contest.

You are making this too complicated. If the flow is slow enough, and the loop is long enough (300 feet I think Marvin said, of specialized tubing to maximize heat transfer), and small enough diameter the water in the loop will come to equilibrium with the medium outside the loop. Therefore, you can assume that the water coming through the wall of the foundation (out of the ground) will be at ambient temp year round. I forget what it is here in the northeast, but 52F comes to mind for some reason.

From there it's a simple calculation to assume that the water temp of the tank without any cooling would reach some particular temp without any cooling (85F, or you could even assume 90), and then to calculate how much heat the 52F water warmed to about 80F would remove (that of course assumes that the loop in the sump is long enough to also come to equilibrium, but I'm guessing that also will not be a problem).

You are guessing here ?...this is the most critical part of the design...

I ran through these calculations a few months ago, and came to the conclusion that I would have far more than enough cooling capacity, and that I would only need a slow pump rate (cannot remember what it was)....I don't have time at the moment to run through them again.

You don't have do do the simple math for me......you were the one asking for advice, correct?

Good luck with your project.

 

[Tstone]

never mind

 

[Greg Hiller]

Chuck,

Sometimes it's easier for me to effectively communicate with someone if I know their background. I in no way ment to insult you, and after posting I immediately edited my post after re-reading it, removing the section that clearly touched a nerve. Unfortunately, you had already read the post and were working on your reply.

FWIW, although I in general appreciate advice, I was not actually asking for advice about the cooling system in this thread, I had already done the calculations. I was only asking if anyone knew of a very low flow pump that would be suitable.

As far as the calculations go, there are many ways to run them....let's look at it this way. I looked up the specs on a 1/2 HP chiller (I think I used the Aqua Medic brand). This chiller is supposed to be good for a 300-500 gallon tank. It is capable of 790 W heat removal. If on continuously for 1 hour that would be 0.79 kw.hr = 680,000 cal. My guess is that for a typical chiller the manufacturer would not want it running continuously, but never-the-less we can continue with the calculation. If I was running my cooling loop pump (low wattage, low flow pump) at about 1 liter/min (~1/4 gallon/min) the water would be coming into the sump at 52F and leaving at let's say 82F. As I say, I plan to use whatever length of tubing in the sump necessary so that the water is at or near equilibrium with the tank water on the way out (if necessary, a titanium heat exchanger could be used, but I really doubt it will be necessary). At this kind of flowrate (1/4 GPM) my engineering intuition (yes, I could have put 'I think' into that sentence! lol) tells me that this is a reasonable assumption. 1 liter/min cooled 30F converts to around 1,000,000 cal/hour. So the cooling loop running as I have estimated above would be about 47% more powerful than a 1/2 HP chiller running continuously, again using the assumptions that I have mentioned.

As you mentioned earlier, putting the sump in the basement helps considerably (as I did with my main tank years ago) with cooling. Also increasing the volume of the system helps as well to dampen out the temp swings. I plan to have a sump of at least another 200 gallons or so. I stopped using the chiller on my main tank about 4 years ago when I moved my sump to the garage, and installed a fan to go on occasionally.

Now, another thing to mention, that chiller I spoke of uses 375 Watts of power while operating!!! The chiller also runs about $750! Ouch!! Also, all that heat is going to be dumped into your house, or basement in the summer rather than outside in the yard, making it that much more difficult for the chiller to operate during the course of a day.

Anyhow...time for some more pics!

 

[Greg Hiller]

The framing guys came today, you can see the extra supports they are installing for the area where the tank will be. The tank will be along the outer wall of the room. The room is 12x15 (was to be 12x12 but luckily Marvin overestimated while pouring the footer, good for me!). The tank will be using up 8 of the 12 feet along the far wall. I plan to keep it about 1 ft away from the left wall, and about 18 inched away from the outside wall. I will use that 18 inches to install a small catwalk behind the tank so I don't have to try and reach across the full 3 ft of the tank.

The basement section of the room was sealed, and the floor of the tank room was laid after I took these shots. The framers may be back tomorrow.

 

[denvig]

Greg looking good, glad to see the progress. It looks like you should have no problem holding up the tank with that framing. Keep the photos coming.

 

[Piscevore]

Specific heat eqn --> Q=cm dT
volume = (pi)(r^2)(h)

Chuck, i think there might be a few ways to look at the heat transfer problem. I see where you are coming from. If cashflow is no object, chiller plumbed into the garage or some other uninhabited space is probably the most labor efficient and reliable system. If the chiller breaks, you buy a new one. If it is hot in the tank, you turn the chiller on, and it will regulate to a degree of what you want. it is a high impact, high cost item however, and not something you just decided to go out and buy.

Greg-
I tend to agree with your Chiller comments. I'd rather run an A/C in the room and at least enjoy the benefit of the cooling as well...and I'd rather not pay for either a chiller or an A/C. The beauty of the geothermal loop is that it is essentially free once it is installed/running, except for the cost of pumping, which could be quite negligible with the right pump and controller. I'm a fourth year Mechanical Engineering student (Heat, Thermo, Fluids) and I think that given the High High High Specific heat (read: Q=cmdT) of water, given you've got a big enough gradient, 15+ degrees, you won't need a very high rate of flow. It takes a lot of energy to raise the temperature of water! Granted, that means you got to take a lot of E out to -lower- it too, as long as your ground is cold enough (plant some trees) you've got a limitless heat sink to chill with! You want as much contact time with the hot water and cold ground, to maximize your transfer of heat. This means less pumping, not more. You don't want miles of tubing in your house, or your lawn, so low flow maximizes transmission. I would be interested in what you are going to use -in- tank for tranferring heat. Big titanium radiators aren't cheap. Thin walled tubing maybe?

Consider:

Volume of h20 in 300 ft of 3/4" hose is about 175 gallons (volume = (pi)(r^2)(h) )


To raise that 175 gallons 5 degress takes around 285Kcal (roughly).

To raise 500 gallons 5 degrees takes around 770kcal(again, roughly).

175 gallons can give 800Kcal of energy to the ground, assuming a dempt difference of 15 degrees.

Basically what this means, with my crackpot reasoning, is at the very least the geothermal loop would reduce the tank temperature by a few degrees, for the cost of pumping the water. The hottest my tank has ever been, is around 84-85 degrees, and stress was evident. A reliable 5 degree temp drop from the Geo Loop basically means the difference between cooking your acros and having a nice comfy reef temp. Nevermind the cool factor. (pun intended).

All this said, my gpa stinks. Mr. Litman is more the academic sort. I'm more the dazzle them with power point while your buddy sneaks up and clobbers them from behind...

(a gallon of water is assumed to weigh 8lbs *light for salt i'm guessing*)
(i also suggest sp heat is 4.186 c in J/gm K for *which is probably low for salt water)
(and yes, a kg is 2.2 lbs, and i'm using Kcal)
(+/- 20% is acceptable for reef clubs)

 

[Randy Holmes-Farley]

You used standard tap water from a cooling line running though your sump. Did the water come to equilibrium with the tank water by the time it left the sump? How long was the tubing, what diameter, and how fast was the flow. Any idea how much of the time (% time open) the valve opened to let the water flow?

It is a long coil of thin PE tubing. About 1/4"OD. Maybe 200 (100?) feet long. I bought a big coil from Home Depot, and used part of it. The water exits at close to tank temp. That's how I decided how much to use. The flow is fairly low, one the order of a gallon in a few minutes.

The cooling is best in the early summer and less later when the tap water warms. I run the flow out to the yard to water plants. At the worst, it is still only on a fraction of the time. Certainly always less than half the time. Maybe 10% at most.

I sometimes use full house pressure up to the solenoid, but early in the year I valve it back to limit the pressure on the tubing and risk of accidents. I don't know how far back it is valved in terms of pressure.

 

[Yaktop]

....all that heat is going to be dumped into your house, or basement in the summer rather than outside in the yard, making it that much more difficult for the chiller to operate during the course of a day.

glad this was mentioned. I have a chiller and glad I do but it does counter itself by blowing heat back into my cellar. I am planning a move and redesign of my system and have this question. I plan on putting the chiller unit in the window and providing a cabinet that will blow the heat outside. Is there any reason why I couldnt leave the unit in the window through the winter like a regular air conditioner by just covering it?? There's no difference is there? And, if not, why arent other people doing it. Seems to me thats the answer to the biggest negative of the chiller besides the initial cost and wattage use. Which I'll trade for piece of mind.

nice set up Greg. gonna be great.

 

[Yaktop]

oh by the way, if I had the bucks Greg had I'd do the underground loop, a bigger addition, a bigger big tank, and a chiller as another backup

way to go Greg!

 

[Aquaman_68]

oh by the way, if I had the bucks Greg had I'd do the underground loop, a bigger addition, a bigger big tank, and a chiller as another backup

way to go Greg!

You got the money....Break down

 

[Greg Hiller]

Ed,

>Is there any reason why I couldnt leave the unit in the window through the winter like a regular air conditioner by just covering it?? <

I don't see why not. Just remember that when not using a chiller for a long time when you first fire it up you will want to flush the line a bit. Any water in the loop will have a lot of hydrogen sulfide built up in it.

>if I had the bucks Greg had I'd do the underground loop<

I had to take out a loan for this project!!! I'm hoping in the LONG run the cooling loop will be a lot cheaper. Since we were already digging, it was no big deal to install it.

 

[Greg Hiller]

>Volume of h20 in 300 ft of 3/4" hose is about 175 gallons (volume = (pi)(r^2)(h) )<

Seems like a lot more than I had thought.

I like to do everything in metric until the last second. Assuming the tubing is ID 3/4" = 1.9 cm. 300 ft = 9144 cm. 1.9/2 = 0.95 cm = radius. 0.95 x 0.95 X 3.14 = 2.83 cm2. 2.83 x 9144 = 25,912 cc or ml. 25.9 liters or 6.8 gallons total in the loop, not including the expansion vessel and the loop in the sump. If I assume another 2-3 gallons in the loop in the sump, plus 2-3 gallons in the expansion vessel I come up with maybe 13 gallons total. I will use this number for some calculations on what concentration of salt I can use in the loop and still be safe if it were to all dump into the sump.

 

[Greg Hiller]

More recent photos. We finally had the windows delivered, but the framers never seem to show to put them in. Now the snow is coming!!

Anyhow.....From the outside:

From the inside, tank will be against the back wall. Bay window behind and to the left of the tank. Sliding glass door to the right. French doors will separate this room from the rest of the house.

 

[Greg Hiller]

Oh, and here's a shot of the roof of the room showing the skylight:

 

[Moe_K]

Looking good!

 

[MickyB]

Greg,
Hows the Room Going, interested in the Geothermal setup PartSummer is coming soon, is it up and running?

 

[Greg Hiller]

Nothing is up and running. I cannot get the contractor to come back to do any of the work. The tank has been sitting in my living room now for 2 months. The corals in my main tank are either growing out of the water, or all over the glass, it looks like $#%$.

The thing that's really annoying is that all I need in the short term is a bit of trim put up in a few places and I could at least put the tank into position and start plumbing it.

 

[NateHanson]

That's aggrevating Greg. Sounds like you need to organize a little work party. Getting some trim up shouldn't be too hard with this group of folks.

Just about everyone here will work for beer and/or frags!