View Full Version : Tank coolers
This is something I have started to use this summer and works really well........and keeps the family happy also.
Rather than invest in £400+ aquarium coolers, why not install air-conditioning in the room where your tank is kept.
Besides keeping the tank temperature down in the hotter weather (about 1 day in 365), it will also make your own "climate" more pleasant to live in. It will also stop all this evaporated water from raising the humidity levels in your room, this could lead over time to damaged furniture, wallcoverings etc.
Moveable ones are available from B&Q for about £200, fully installed ones shouldn't be more that £700 including fitting.
Last edited by Paul B at Aug. 05 2002,00:25
Depends on how much heat you need to remove from the water. The heat exchange between the ambient room temperature and the tank is not very efficient. Even on the coldest days my tank is still too hot without additional cooling - and running the fan in the winter is not a good idea as the doors/windows will be shut and condensation can be a problem.
Depending on the tank's location - may be there's a cheap method of cooling down the tank by running a small pipe up to the loft where the cold water cistern is, and pass through a
coiled pipe inside the cistern, and return back to the tank.
You simply have to provide a pump just powerful enough to overcome the pipework friction as no head pressure will be involved.
</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (tlp @ Aug. 05 2002,10:35)</td></tr><tr><td id="QUOTE">Depends on how much heat you need to remove from the water. The heat exchange between the ambient room temperature and the tank is not very efficient. Even on the coldest days my tank is still too hot without additional cooling - and running the fan in the winter is not a good idea as the doors/windows will be shut and condensation can be a problem.
Depending on the tank's location - may be there's a cheap method of cooling down the tank by running a small pipe up to the loft where the cold water cistern is, and pass through a
coiled pipe inside the cistern, and return back to the tank.
You simply have to provide a pump just powerful enough to overcome the pipework friction as no head pressure will be involved.[/b][/quote]
A few good points, perhaps it would have been better if I had pointed out that this method only applies to those people who have temperature problems in the summer months, in which case air conditioning would be an ideal solution. It would also eliminate the problem you have raised of condensation in winter months as it would act as a dehumidifier (in much the same way as modern cars automatically run the aircon in winter to demist the windscreen.
Your idea about running a cooling coil in the loft tank is a good idea, however there are 2 problems.
1 Modern houses, (since about 1966) due to the design of the loft, tend to have very hot lofts in summer and the loft tanks can get warm (infact a friend of mine markets a product specifically to reduce the temperature of tap water in summer due to this problem........alas the coils used are copper)
2 You are not quite correct in that there will be no head pressure on your pump. Whilst this is true for the system when static, once the pump starts up, *things like NPSH (Nett Positive Suction Head), friction losses and cavitation at the pump suction start to come into effect, and you may find that you need a pump 20x larger than you thought to overcome all of these...........
You are nearly correct though, just you have gone in the wrong direction, if you were to dig a relatiely deep hole in the garden and put a PVC or ABS coil underground then fill the hole in, that would work better than the loft idea.
Last edited by Paul B at Aug. 06 2002,09:07
I agree that to startup the pump would have a hell of a lot of work to do. But you can always prime the whole system first - say take a bucket up to the loft and fill the pipes up. Once the whole thing is filled, i would have thought there is only 'friction' from the pipe work, as the falling water in the output would counter-act the water going up, hence I said no head pressure. Providing ofcourse this pipe is sealed.
The idea of a hole in the garden have been discussed (and proven before) - and I'm not disputing that. However, IIRC, you would need a very deep hole, preferrably down to the water table level (ie. a well! ) to get the temp drop. Then you would have about the same amount of work for the pump to do.
I agree about the loft being insulated and can get warm in the summer, but, at least for my house anyway, we tend to get quite a reasonable usage of water and therefore the cistern seem to be refilled all the time with relatively cold water, even in the summer. Effectively you have cold water from below the water table stored up there already - and its very cold in the winter.
I also should have clarified that I'm looking at a system to provide cheap cooling all year round. During the summer people can rig up extra cooling fans/chillers etc... which should not need to be used for very long given the typical British summer we have http://www.ultimatereef.net/ibv3/iB_html/non-cgi/emoticons/sad.gif
simon garratt
06-08-02, 23:48
Hi Guys.
</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote </td></tr><tr><td id="QUOTE">you would need a very deep hole, preferrably down to the water table level (ie. a well! ) to get the temp drop[/b][/quote]
In fact you only need to go down to about four feet to get a stable temp of about 7-10degc all year round. Ive seen this system in operation using 50ft of hose. an MJ1000 PH and a thermostat to control the pump. its very effective and really reliable. the tank in question never deviates more than about 1 deg at any time, all year round.
Cheers
Si.
</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote </td></tr><tr><td id="QUOTE">you only need to go down to about four feet [/b][/quote]
Only four? Cool. Thanks for the correction!
Now where's that spade?
Yeah Si.
I am seriously thinking of doing same.
Anyone else tried this method ?
Brian.
Some good points here.
Tlp.
Please trust me on the pump losses other than just friction point. 3 weeks ago I would have agreed with you but a recent project at work (Pumping 38, 880 lph) has now proven otherwise.
Also, if you are interested in alternative forms of cooling systems for year round use, try typing "passive cooling systems", passive cooling media" or "chilled beams" into a search engine, you may find some useful info
Simon
You are correct in that you wouldn't have to dig down very far. When design Cold Store systems in the UK (I'm a refrigeration consultant) we tend to use a maximum summer ground temperature for heat gain calculations as being in the region of 15 degC. Also I took the kids to some caves in Yorkshire yesterday and the temperature went down from 23 degC to 8 degC almost as soon as we started to decend.
I must admit to only having got into Reef systems very recently, so it has never ocurred to me to apply my work to my new hobby until recently
Glenn'n'Emm
19-08-02, 13:07
Interested in the pumping question and comments
When lifting water the atmosphere does all the work, the max theroretical lift available is ~10m.
Energey is used in getting water to move from the supply, the work done in raising the water mentioned above, frictional losses due to the desing of the inlet to the pump/pipe and temperature of the water being moved.
In practice the maximum lifts is 8m, however, this wouldnt be a problem with the right pump and primer assuming ideal conditions.
When considering the outlet side frictional losses are incured due to the lenght of the pipe, the bore of the pipe and the velocity of the water. To all intents and purposes frictional losses are independant of pressure.
What this amounts to is that in order to move a good flow of water from a ground floor lounge to a loft and back would require large bore piping and a decent pump. just look at the central heating pipes fro the main supply and return to a how ater tank up stairs as an example.
Hope this info helps a little
Regarding the tank of cold water in the loft, no pump would be required at all!!. Gravity will do the work for you, the outlet to the aquarium must leave the loft tank at a lower point than the inlet. The effect of this will be that when the water cools in the coiled pipe it will become more dense and will want to sink, in order to sink it must pull the warmer water out of the aquarium and a cycle will occur. The head loss due to friction is a function of water velocity and a balance will be reached where the energy lost will equal the potential energy gained due to the increase in water density. The flow rates will be fairly low but the water will not exit the loft tank untill it is adequately cooled. Increasing the pipe size will reduce the head loss. A pump may be the easiest way to prime the system but once it starts it will keep going. An alternative to increase the flow is to draw the water from the aquarium, to the loft and return it to the sump. The water will then syphon via the loft at a good speed. Im not suggesting anyone try it as I would not expect the temerature differential to be worthwhile in the summer.
What about a similar setup with a fridge in the loft and the coil inside the fridge. This would work on the same principal as above, the big advantage being that the nuisance heat output from the fridge is in an uninhabited region. A simple solenoid valve and a teperature controller and you've got an automic temperature control system for about £100 (cheaper if you have a spare fridge).
HTH
Paul
Interesting.
Thinking about the piping ungerground theory.
An idea to enhance the cooling, might be to sink a container into a hole, say 4' deep, fill with water, and then run some coiled flexible hosing through it.
Theory being that the water in the submerged vessel will dissapate the tankwater heat quicker.
Prolly would be more efficient at cooling the water, and as stated previously, run a pump working off a thermostat to activate this circulation when a designated temp range had been reached say , pump on when 83F has been reached.
Think I will try this.
Cheers
Brian.
Glenn n Emm,
Where do you get the maximum head as being 10m from ?
Pavlo
The diameter of the pipe has no bearing on the static head Static Pressure (fluid)= rgh where r = m/V = fluid density
g = acceleration of gravity
h = depth of fluid
You are correct about a gravity/convection circulation system working in theory but the temperature gradient would be too small in practice. However, as you rightly suggest, put the water tank in a fridge so you have a bigger temperature gradient and that would work (depending on how big your heat load was of course.)
Irishreefer.
You would be better off with just the coil buried in the ground (backfill with sand) as putting it in a tank then adds another mass to be cooled (The tank water will be warmer than the cool tank water than the ground). The best pipe material to use would be Hep2O, as it can be easily formed into coils.
You are correct, the diameter has no effect on the static head, but we don't want static water we want moving water and the diameter of the pipe has a significant effect on the dynamic head. Even the smallest temperature gradient will cause flow, the question is if there would be a significant cooling effect on the tank.
Glenn got the figure of 10m from the equation you quoted to me
10m head is approximately equal to 1 atmosphere and is therefore the height water may be forced to if the air above it is evacuated. It's worth noting that when this is done the water boils in the top of the pipe at ambient temperature and can lower the oxygen content.
</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (pavlo @ Aug. 19 2002,23:29)</td></tr><tr><td id="QUOTE">You are correct, the diameter has no effect on the static head, but we don't want static water we want moving water and the diameter of the pipe has a significant effect on the dynamic head. *Even the smallest temperature gradient will cause flow, the question is if there would be a significant cooling effect on the tank.
Glenn got the figure of 10m from the equation you quoted to me
10m head is approximately equal to 1 atmosphere and is therefore the height water may be forced to if the air above it is evacuated. It's worth noting that when this is done the water boils in the top of the pipe at ambient temperature and can lower the oxygen content.[/b][/quote]
Understand now, what you meant to write in your original statement was that increasing the diameter reduces losses due to flow restrictions, not head losses.
On the 10m thing, I must have missed something here though, when did evacuation come into it ?
You are correct about water boiling, we used to make fresh water from seawater by running hot water (about 60 degC) through a heat exchanger, with the sea water surrounding it. We then dropped the pressure around the outside of the HX by using an water powered educter (orfice) so that the seawater boiled at a lower than normal temperature. Used to make 30 tonnes of almost pure water everyday with it.
Also, we lifted water (well 30% glycol + 70%water) 18m last month when filling a new cold store cooling system using only a 1/2hp vac pump, quite incredible really
The 10m thing only comes into play when you are trying to 'suck' water up a pipe. ignoring capilliarity which only affects small bore pipes, 9.81m is the maximum height to which water can be drawn. If you have a pump at the bottom, pushing the water up then the 10m thing has no significance. I have seen pumps that can pump to several hundred metres in one stage. multistage pumping is used in high rise buildings etc. When you think of the problems of raising water to reasonable heights, it is amazing how much water a tree can get to the leaves right at the top, the worlds tallest tree is 367.5 feet!! (Amazing fact number 232).
Regards
Paul
Glenn'n'Emm
20-08-02, 11:46
Pavlo is partly right and partly wrong.
In a closed loop circuit it is a combination of effects not only gravity but the heat energy from the aquarium also.
If it were gravity alone then we would have a perpetual motion device and we all know how well they work don't we.
In practice the temperature gradients would, i suspect, be small in the summer, thereofre the flows would be relatively small. If you look at 'gravity' fed central heating systems the temp gradients are large and the diameter of the pipes typically is 22mm.
I reckon that to be effective you would need to pump a system such as this.
Unless your heat exchange mechanism was quite efficient, i.e. typically small bore piping or similar method the rate of flow through the loft tank would need to be very slow to be effective. There could then be significant heat gains whilst the water returned to the aquiarium.
LOL perhps we should do some experimentation, cause at the moment were all beating our gums (keyboards) on a nice little problem which is all very theoretical.
Of course I'm not suggesting a perpetual motion scheme. Energy is required in order for the water to circulate. This energy comes from the water in the fish tank and the result is a drop in temperature which is exactly what we are trying to achieve. You are correct that the energy from the heat is powering the system but it is gravity that is actualy making the water move.
Any way I've had enough of this now, I think the hole in the ground idea is a much better one.
Gonna go polish my shovel.
Paul
CodeMonkey
22-08-02, 14:37
How about the use of heat sinks? Attach them to the side of the glass and then blow the air across them - they would cool down and in turn draw heat from the tank via the glass?
Not sure on how big a heat sink you'd need though
ps anyone tried modifying a small fridge to do the job?
eg 2 holes - 1 large coiled pipe - seal holes with sealant once pipes are in place - pump water round. not too sure where the CFC angle comes into it all with fridges though
Hi All,
I don't know to much about cooling or head pressure etc, etc but I cant understand why Paul B has gone for a work around to the problem of cooling his tank when as he informs us "I'm a refrigeration consultant", I would have thought Paul that you of all people would have access to all the proper kit to cool fluid?
Just my opinion.
Phil K
Phil,
In all fairness, "Paul B" fitted an air con unit to cool the house, and hence the fish tank too.
'Tis was I who started debating on the passive cooling (and how I'd rather not have the air conn on in the winter) - and usage of naturally cold things like a wet cod. http://www.ultimatereef.net/ibv3/iB_html/non-cgi/emoticons/biggrin.gif
Quite a few interesting ideas have developed - like Paul (pavlo) suggestion that no pump would be required and convection would do all the work. Which might just work as the temp gradient would be 10-15degC in the loft header tank, and my tank temp of 28-30degC (if not more if wasn't running a chiller).
Poking a couple of whacky big holes through upstair into the loft may not please the wife though. http://www.ultimatereef.net/ibv3/iB_html/non-cgi/emoticons/laugh.gif
</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (Phil K @ Aug. 22 2002,16:16)</td></tr><tr><td id="QUOTE">Hi All,
I don't know to much about cooling or head pressure etc, etc but I cant understand why Paul B has gone for a work around to the problem of cooling his tank when as he informs us "I'm a refrigeration consultant", I would have thought Paul that you of all people would have access to all the proper kit to cool fluid?
Just my opinion.
Phil K[/b][/quote]
I'm a consultant not a supplier/installer (also I work mainly in industrial, so I doub't very much the neigbours would be impressed if I brought home a 3.2mW chiller that needed it's own substation to drive it and 1500kg of ammonia refrigerant http://www.ultimatereef.net/ibv3/iB_html/non-cgi/emoticons/biggrin.gif , I therefore would have to pay the same price for a cooler as you.
Also, as Tuan has pointed out, this all started from me pointing out that simply putting a/c in your room would provide not only room cooling and dehum but also keep your tank temp down
verytricky
27-08-02, 16:05
Buy a copy of loot. Look for a chest freezer, use this as the sump, or part of the sump. The freezer can be controlled via the temperature gage. I used a timer so it is off when my lights are off, as the minimum temperature is too minimum when there is no heat from the lights.
It cost me £50 for the freezer, and 2.50 for the timer.
</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (verytricky @ Aug. 27 2002,16:05)</td></tr><tr><td id="QUOTE">Buy a copy of loot. Look for a chest freezer, use this as the sump, or part of the sump. The freezer can be controlled via the temperature gage. I used a timer so it is off when my lights are off, as the minimum temperature is too minimum when there is no heat from the lights.
It cost me £50 for the freezer, and 2.50 for the timer.[/b][/quote]
Using a chest freezer (ie something designed to freeze the contents) as a chiller is not a good idea as the compressor unit is not designed to operate continuously at "high back pressures" also the condensing circuit will be too small. You might get away with it though (the compressor not failing)if it is not having to run very often.
A chest chilller however would be more than suitable and I posted a similar suggestion to this on the reef section of the board.
i thought ov something similer but with an old fridge and running the coil through two holes in the door http://www.ultimatereef.net/ibv3/iB_html/non-cgi/emoticons/biggrin.gif
EnglishReefer
07-09-02, 18:20
Having used aircon to keep a tank room cool myself I would say dont bother if thats the only reason for buying it, if your chillin the family too then fine but the electrical running costs of an aircon are higher than a proper tank chiller - higher initial outlay but lower running costs.
FWIW
Unless you're on a water meter, what's wrong with a heat exchanger? A lot cheaper than a chiller and no electrics except a valve and stat. I must admit I like the hole in the ground idea too. Another idea I came across (similar to cleggg's) was to buy a cheap s/h small fridge with a temp regulator for around tenner, drill an inlet and outlet hole through the sides and starting on a rod, coil up loads of hose to fill the whole area inside the fridge. There are various ways to control the temperature. The fridge can be switched on and off via a stat. You'd probably need it to kick in and out early though. Or you could work a solenoid and stat on the hose. Voila! One cheap chiller. http://www.ultimatereef.com/ibv3/iB_html/non-cgi/emoticons/smile.gif Sounds too good to be true doesn't it? *http://www.ultimatereef.com/ibv3/iB_html/non-cgi/emoticons/smile.gif
How about using a peltier effect heat pump and a decent size heatsink? Not sure if they make heat pumps big enough though? http://www.ultimatereef.com/ibv3/iB_html/non-cgi/emoticons/confused.gif
D.
I'm going to go with a dual heat exchanger and a "cold store" for the next project. Basically the RO tank will act as a "cold store" - one heat exchanger circulates the flow from the tank controlled by a thermostat. All the house water usage will go through another heat exchanger sitting in this cold store as well.
The whole cold store will ofcourse be well insulated.
The idea is simple - any usage of water in the house will cool down the content of the RO store. The tank water will be chilled when it needs to by circulating through the other heat exchanger - using a solenoid valve or pump on the thermostat.
I don't waste any water (metered), and I store the 'cold' from the mains water and make full use of the lower temperature of the mains water. If there's more usage of mains water (ie. more "cold") than necessary, the "cold store", will act like a battery ready for later.
Mains water will also be heated up slightly from the energy transferred and therefore should save a little off the 'heating' that we generally have to do any way, not just for central heating, but for showers/washing machines etc...
A chiller will be on stand by to supplement if there's not enough cold mains water usage to cool the tank.
When water changes are done its even better - the RO water would already be warmed up from the tank's heat - and when the RO container is refilled alot more mains water will be used.
The main costs of at the outset would be the two titanium heat exchanging radiators - but in the long run I feel better being a little more eco-friendly.
Last edited by tuan at Sep. 26 2002,14:53
</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (diadema @ Sep. 26 2002,10:11)</td></tr><tr><td id="QUOTE">How about using a peltier effect heat pump and a decent size heatsink? Not sure if they make heat pumps big enough though? *http://www.ultimatereef.com/ibv3/iB_html/non-cgi/emoticons/confused.gif
D.[/b][/quote]
I posted about this elsewhere last month. The small fridges that you get for cars now run on Peltier devices and last month Tesco were knocking them out at £55 each
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