How to Extract Water from Reef Tank without drillings of holes

29 March 2017


Reef tanks will  need fairly high water flow rate and an external pump sump is usually required so as to install a large water pump as well as other equipment such as chiller,  filter medias etc.  Large amount of water  will have to be extracted from the tanks.  The conventional way is to drill larger holes on either the top side of the back glass panel or the bottom of the tank.   This article will try to introduce another method.

What's Needed?

1.   1/2 piece of 4 feet x 2 feet perspex sheet available from any shop that sells lighting diffuser for the lighting fitting;

2.   2 numbers of 15" 20 mm diameter PVC tube

3.   2 numbers of straight joint for aquarium air distribution pipe

4.   Industrial Liquid Thinner

How to Construct?

 a.  Overflow box 

1.  Cut the perspex sheet to form a box of about 10" x 3"; make sure one of the back sheet of the box is long enough for a bend to be formed to hang over the edge of the water tank;

2.  Use heat gun or oven to soften the perspex of the longer back sheet with heat good enough to bend the perspex to form the hanger;

3.   Cut the front piece to form a row of grooves or small opening to allow overflow water to flow into the box;

4.   Assemble and join the 4 piece together using the industrial thinner.  Allow enough thinner to run to and fro at the joint so as to seal the joints properly;

b.  Over Flow Pipes

1.   Heat bend the 20 mm PVC pipe in the center enough to form a U-shape tube as shown in the picture;  The U tube should have a bend radius large enough for it to be placed over the hanger of the box;

2.   A flexible spring or PVC tube is necessary to ensure a smooth bend.  I used one piece of chest expander spring;

3.   Drill a hole large enough to insert the air tube straight joint at the top of PVC bend to form the air nipples

How It works?

When water is pumped into the tank,  the excess water will overflow into the overflow box.  It will be sucked up through the U-tube continuously.

But before any water can flow through the U tube,  the tube must be primed and fill the entire tube with water.

Water priming is make simple by plugging up the open end of the U tube and then suck the air out from the air nipple.  As soon as the water has filled up the U tube,  plug the air nipple and water will flow continuously and naturally.

 Other Relevant Sites
tinyurl  :https://tinyurl.com/ydfaloww

Lower Reef Tank Temperature Without Chiller

28 March 2017

One forumer in the Singapore Reef Forum asked how to lower the water temperature in a reef tank without using a chiller.   Another forumer asked for a picture of such construction.  The article will tell how.

What's Needed?

a)   To form a Cooling Tower

1.  2 pieces of 4 feet x 2 feet plastic sheets that are  available from the shop that sells office light fittings.  I got mine free when my office was under renovation.
2.  One pump sump of about 1.5 feet x 3 feet or other dimension to suit requirement
3.  Industrial liquid thinner

b)  To construct a dry filtration media within the tower

1.   About 3 rolls of twine string paper

2.   1/4" plastic tubing or plenty of plastic straws

3.    Few pieces of  10 mm diameter PVC pipe each cut to about 10" length

How to Construct?

a)   Description

As I have  retired the cooling tower a long time ago. The following sketch will give some idea on how to construct the cooling tower which was located at the back of the reef tank with a pump sump below the tank.

The tower was about 4 feet tall and filled with loose packed dry media made from flatten twine paper string that has gaps to allow air and water to pass through them.  


Water is fed into the top section using 2 Nos of 20 mm U shape plastic tube and overflow reservoirs without drilling any hole in the reef tank (link) The water is then allow to go through the rain shower plate, which is basically a plastic sheet full of small holes.

 b)  Constructing the Tower

1.  Cut plastic sheet into 10"x 4 feet strips and glue them up to shape using the industrial thinner.  As thinner will normally dissolve the surface of the plastic,  it will provide a good joint without using any other glue.  To form a good seal at the joint,  run a little amount thinner alongside the joint,  to and fro several times.  Allow  the plastic joints to dry over night.

2.  Cut a piece of plastic sheet and drill as many holes of about 1/8" to form the rain shower plate to be inserted on the top section to form the rain shower.  Allow at least 6" clearance between the fan and the rain shower plate.

3.  Allow one empty section for air inlet as shown in the sketch 

c)  Constructing the filter media

1.  Unroll the twine paper string and flatten the string out so that it can be rolled loosely together again with plenty of  1/4" tube or the plastic straws inserted in between to form another roll of filter media that can be filled the inside of the entire cooling tower.   The tube or plastic straws should be as many as possible to ensure the papers will be  loosely packed and that air and water will be allowed to flow freely through the filter media.

2.  Place twine paper rolls inside tower horizontally with each roll separated by the 10 mm PVC pipe for proper air circulation in between the rolls.

Conclusion

This set up can cool the water  to about 27 C which is the average wet bulb temperature of our ambient air. Constant feed of light Limewater and kalkwasser is all that is necessary to replenish lost water.  I used the setup for about 2 years without any other filters although I stored some dead corals inside the pump sump.

Other Relevant Sites
tinyurl :  https://tinyurl.com/y994fau6

Aquarium Chiller Resun CL650- Erratic Temperature Readings

27 March 2017

The chiller  controller has erratic temperature readings.  It fluctuated between 3 to 4 degrees C erratically.  As a result,  the chiller did not start and stop properly.  Otherwise,  the Chiller worked normally.

What Could Go Wrong?

 1.  Dry Joints -  They are often responsible for erratic performance and often give erroneous readings;

 2.  Faulty Capacitors - They will lost the filtering and cause voltages to fluctuate;  thereby,  giving erroneous temperature readings.

How to Dismantle and Remove the Controller?

The controller is flushed mounted with a dust protective plastic cover in the inside of the chiller casing.  The cover is secured to the chiller casing by four clips evenly distributed around the peripheral of the plastic cover.

To remove the cover,  one will need to push the clip inwards using one finger and pull the cover down at the same time using another hand.  Releasing the clips will need some care and patients,  releasing the clips one at a time.  Some reported that there might be four screws securing the plastic cover and they must be removed first.

Once the plastic cover is removed,  one can pull up the controller from the top of the chiller casing.  Observe and make notes on how the wirings are connected.

What Went Wrong?

Bench inspection suspected that there are a few dry joints.  However,  resoldered those joints did stabliise the readings and prevent much voltage fluctuations in the supply line but the controller continued to give erratic readings.

Finally,  bench testing proved that one of the two capacitors shown below had a deteriorated capacitance giving only 15 uf instead of the 400 uf.  Replacing the 400 uf capacitor fixed the erratic reading.

Degree of Difficulty

It was  not difficult to replace the capacitors but the 2 tier circuit board arrangement made de-soldering and soldering pretty difficult to carry out to test and replace those capacitors.

What to get a Replacement?

For those who need a replacement for the controller,  they should be able to find it on TaoBao (link) for about RMB200.  Write to them make an enquiry at this website.  Alternatively,  one could replace the controller.  

 Other Relevant Sites
tinyurl : https://tinyurl.com/yae4zudq

What Size Aquarium Chiller?

11 April 2013

Introduction

Sizing a chiller for the Aquarium can be a difficult task as the tanks come with various dimensions and sizes;  also,  some aquarium set up can be so different that one would have to work out the detailed heat gain and loss to size a chiller.  This article will give 2 methods on sizing a chiller.

How to Select the Right Size Chiller

Many aqua and reef enthusiasts pick up some knowledge here and there. Some uses the one size larger rule and some just blatantly use figures provided by the manufacturers. Some suggested that chiller should be large enough so that it won’t run longer than half an hour on each start. Some preferred shorter operating time citing lesser wear on the compressor.

The correct chiller sizing should depend on heat loads transmitted into or out of the tank. There are basically the following heat losses/gains that can be found in an aquarium tank;

1) The heat gain from the light fittings
2) The heat gain from the pump or in-line filter
3) The heat gain transmitted through the exposed glasses
4) The heat gain from the occupants
5) The heat gain through surface and the heat loss from evaporation
6) Others heat gain such as those from internal circulating pumps, wave makers etc

As the calculation involves complicated thermodynamics and air conditioning engineering, it would not be discussed here. Those interested can read up this article.

Most enthusiasts just use rules of thumb. The thumb rule of using one size larger appear to be more appropriate because the manufacturer’s guideline often did not consider the extra heat load from the other equipment such as lights, pumps etc; also, the chiller will age and lost efficiencies. Then one might want to add more equipment such as more pumps in future. Some manufacturers could also over-rate their chillers.

Method 1:  Using JBJ Website

JBJ has a website that one can use to size various chillers.

Please note the following when using the website:-
a) For metric to imperial conversion, use the formula degree F= degree C * 9/5 +32 and 1 US gallon = 3.8 litres;
b) Remember that actual water temperature refers to maximum water temperature which should be around 30C or 87F for Singapore;
c) A 40 watts fluorescent fitting will give 50 watts of heat; 40 watts for the lamp and 10 watts for the ballast (25% for magnetic ballast, 20% for electronic ballast and 15% for LED driver);
d) Assume full tank volume and not actual water volume to be safe.
e) It is still good to up one size larger after the calculation.

The term horsepower (HP) is often used for sizing a chiller. One can take that 1 HP=2800 watts of cooling power. Divide that by COP of the chiller (1.3 for freon and 0.55 for Peltier), one should get roughly the power inputs in electricity watts.

Method 2:  Using Table Selection

The following were assumed when working out the table:

1.  The Bulkhead heat load is around 0.6 watts per US gallon;
2.  The pump heat load is around 0.5 watts per US gallon;
3.  The overhead lighting load is around 4 watts per US gallon;
4.  The maximum temperature across the glass is 5.5 degree C

The manufacturers appear to suggest the chiller should be sized such that the chiller should cycle on 15-20 minutes an hour for chiller to run about 6-8 hours per day. Depending on the setting of the temperature and the water flow rates, it may be normal for chiller to run for 1 hours and stay off for 2-3 hours before the next cycle.

Other Relevant Sites
tinyurl :  https://tinyurl.com/ybyepw7p

Insulation for Reef Tanks

2 December 2012

Introduction

Many reefers use chillers to cool their reef tanks to mimic the environment of the living corals and other ocean creatures. The tank is usually kept in temperature around 25-28C. This article will examine how much energy can be saved by insulating the tanks.

Heat Gains

One of the heat gains of the aquarium is through the glasses which have thickness varies according to the tank capacity. The thickness ranges from 5 mm for a 2 ft tank to about 12 mm for a 6 ft tank. The heat gains or energy losses will vary according to the thickness of the glass; the thicker the glass, the lesser the energy losses. The heat gain through the exposed glasses can be responsible for 50% of the energy losses for a 2 ft to about 12% for a 8 ft tank.

Energy Savings

As aquarium operates 24 hrs/day, the heat gains by the tank is non-stop over the period. These heat gains will have to be removed by chiller; otherwise, the cooling will not be effective. By insulating the tanks with ¼” thick polystyrene foam for all sides except the font viewing panel, as much as 30% of the energy can be saved and hence, the cooling bills.  The thicker the insulation, the more the energy or cooling bills will be saved.

How Much in $ and Cts?

Assuming one has a ¼ hp chiller and a 3 ft tank (36x24x24), the energy saving will be about 10% of the chiller running bills. If we further assuming that the chiller runs about 8 hour per day, the chiller kwh consumed will be about 370watts x 8 hrs/day x30 days = 88 kwh per month. With rate @ SGD$0.2727 per kwh, the cooling bill will come up to about SGD$ 24/=. The saving could be as high as SGD$ 2.50 per month.

Foam As Backdrop

This reefer uses foam to mimic the rocks as a backdrop. This arrangement will improve thermal insulation and reduce heat gains or energy.  It would be more effective if he can also seal the edges of the foam so that there will be no water movement in between the glass and the foam. 

 His tank finally looked like this

Other Relevant Sites 
tinyurl :  https://tinyurl.com/y9vs4pzx

Selecting Nano Aquarium Chillers

22 November 2012

Introduction

There is a choice when selecting chillers for nano aquarium tanks of  around 25 gallons or 100 litres or smaller. One can choose between a Peltier chiller or a Freon Chiller. This article will show the differences between the popular brands, using 1/20 hp range as examples.

What’re the Main Difference

Peltier chiller uses an electronic chip whereas Freon chiller uses mechanical compressor to generate the chilled water. The differences are discussed here in detail.

What're the Popular Brands?

In the 1/20 hp range, the popular brands in Singapore are

1. Resun CL150

2. Hailea HC100a

3. Arctica nano DBI-038

Their specifications from the manufacturers are tabulated as follows:-

Brands	Resun	Hailea	Arctica
model	CL150	HC 100a	DBI038
Range (hp)	1/20	1/20	1/20
Type	Electronic	R134a Freon	R134a Freon
Power Input (watts)	200	1101	1651
Power Output (Watts)	150	150 (from a website)	200 (600 BTU/hr)
Ampere (230V)		0.6	0.9 (1.8 @ 115V)
Tank size (litres)	120	50-200
Flow rate (LPH)	1000	200-1000	400 -600
Weight (kg)	8.5	9.2	12
Water Connection (mm)			12 (1/2”)
Dimension (mm)	260 x 310 x 205	338x18x25	195x320x358
Estimated cost (SGD$)	170	300	800

1. Estimated from running current

The Coefficient of Performance (COP)

This figure is never available for the manufacturers. Although COP can tell if one chiller is more efficient than the other,  it will depend on the operating conditions, the cooling as well as ambient temperatures.  Also, most tests in factories are carried out under laboratory conditions where good quality water are often used.

From the manufacturers’ data and some estimation of  input power, one can tabulate the following table:-

Brands	Resun	Hailea	Arctica
model	CL150	HC 100a	DBI-038
Range (hp)	1/20	1/20	1/20
Power Input (watts)	200	110	165
Power Output (Watts)	150	150	200
COP (output/Input)	0.75	1.36	1.21
Performance	100	180	160

Assuming that the chillers are operating under the same conditions and factory tests carried are identical, Hailea 100a appears to be more energy efficient.

Inside the chillers

Stripping out the case, the insides of the chillers are shown as follows:- (click to enlarge)

Comparing the pictures, one can straightaway tell that Resun CL150 has a different configuration. It has no compressor. A refrigerating chip was named to provide the cooling. Also, it uses a plastic heat exchanger for the cool side and an aluminium heat sink with forced air cooling for the hot side of the chip. It is hard to tell from the picture if the  refrigeration chip is actually a peltier chip.

Working out COP for Peltier Chillers

Ultrasonic2 has posted in his webpage a TEC calculator to workout the COP for Peltier chiller.
Enter the various measured data such as hot and cool side temperatures and also the power input etc, the TEC calculator will be able to work out the COP.   As for the freon chillers,  some calculations will be required to work out the cooling power.

Heat Sink for Peltier Chillers

Someone in one of the forums pointed that the size of heat sink does not matter much in Peltier Chiller but this article about heat sink for Peltier will prove him wrong.

Ultrasonics2 and Shine7 have both provided TEC calculation results for their Peltier chips. Their webpages can be found here and here.   It is believed that Ultrasonics2 used the peltier for computer cooling whereas Shine7 used it for aquarium cooling.

As one can see from the following that the COP of peltier chip can vary a lot. In this case, Ultrasonic2’s 0.74 vs Shine7’s 0.54

Also noted that the Shine7’s peltier had a hot side temperature of 52C whereas the Ultrason2 had a temperature of 30C. Also,   the Delta T across the chip was lower in Ultrasonics’s case. The results  suggest that Ultrasonic2 has an extra efficient heat sink. But now, look at Shine7’s heat sink again and compare  to that of Resun CL150 chiller shown earlier (but the real one may be much larger though). 

How to Select the Right Size Chiller

Many aqua and reef enthusiasts pick up some knowledge here and there.  Some uses the one size larger rule and some just blatantly use figures provided by the manufacturers. Some suggested that chiller should be large enough so that it won’t run longer than half an hour on each start. Some preferred shorter operating time citing lesser wear on the compressor.

The correct chiller sizing should depend on heat loads transmitted into or out of the tank. There are basically the following heat losses/gains that can be found in an aquarium tank; 

1) The heat gain from the light fittings
2) The heat gain from the pump or in-line filter
3) The heat gain transmitted through the exposed glasses
4) The heat gain from the occupants
5) The heat gain through surface and the heat loss from evaporation
6) Others heat gain  such as those from internal circulating pumps, wave makers etc

As the calculation involves complicated thermodynamics and air conditioning engineering, it would not be discussed here. Those interested can read up this article.

Most enthusiasts just use rules of thumb. The thumb rule of using one size larger appear to be more appropriate because the manufacturer’s guideline often did not consider the extra heat load from the other equipment such as lights, pumps etc;  also,  the chiller will age and lost efficiencies. Then one might want to add more equipment such as more pumps in future.  Some manufacturers could also over-rate their chillers.

JBJ has a website that one can use to size various chillers.    Please note the following when using the website:-
a)  For metric to imperial conversion,  use the formula degree F= degree C * 9/5 +32 and 1 US gallon = 3.8 litres;
b)  Remember that actual water temperature refers to maximum water temperature which should be around 30C or 87F for Singapore; 
c)   A 40 watts flourescent fitting will give 50 watts of heat;  40 watts for the lamp and 10 watts for the ballast (25% for magnetic ballast, 20% for electronic ballast and 15% for LED driver);
d)  Assume full tank volume and not actual water volume to be safe. 
e)  It is still good to up one size larger after the calculation.
 
The term horsepower (hp) is often used for sizing a chiller.  One can take that 1 hp=2800 watts of cooling power.  Divide that by COP of the chiller (1.3 for freon and 0.55 for Peltier),  one should get roughly the power inputs in electricity watts.

The manufacturers appear to suggest the chiller should be sized such that the chiller should cycle on 15-20 minutes an hour for chiller to run about 6-8 hours per day. Depending on the setting of the temperature and the water flow rates, it may be normal for chiller to run for 1 hours and stay off for 2-3 hours before the next cycle.

Flow Through Vs Drop-in Coils

There was a misconception that drop-in coils are much more efficient than the normal flow through type of chiller.  However,  this is not quite true as the chiller efficiency depend much on the coil design of the evaporator and the condenser.  The manufacturers can further improve the condenser designs to make chiller more efficient;  such as providing more condenser tubes and fins with improved fan design.  However,  for evaporating coils,  the manufacturers will have to weigh between cost and efficient design as titanium which is often used in aquarium chiller comes with a price.  It is for this reason that the COP of aquarium chillers are never better than window airconditioners.  The following manufacturer's data will show that the amperage drawn for both flow through and drop-in chillers are identical.

Conclusion

Peltier chillers are less efficient but they cost much less. An economic will have to be worked out before choosing the right chiller. On the other hand, Freon chiller may cost more but on the longer term, it will cost less because of higher COP.

Other Reference Sites
tinyurl : https://tinyurl.com/y7p6tev3

Freon Vs Peltier Chillers

21 November 2012

Introduction

There were some interesting exchanges in one local forum about the use of Freon chillers and peltier chillers for aquatic and reef work. Many experienced aquatic enthusiasts in the forum argued that peltier chillers will not work. Those used peltier chillers before was of the view that such chiller is not suitable for reef tanks and cold-stored the chiller. This article will present the differences between the 2 types of chillers and their applications in aquatic and reef work.

What is a Peltier Chiller?

Peltier chiller is often referred to as an electronic chiller because it uses a semiconductor chip that has hot and cold plates.

When there is a current passes through, the chip will transfer heat between the plates for heat to be rejected or produced depending on the polarity of the plates. Peltier chip was discovered by a French Physicist Jean-Charles Peltier in 1834 when he passed a current through to product heat and cold energy from a junction composed of two different materials.   The largest Peltier chip from ebay has a power input around 500 watts.  This has about 300 watts or 1/10 hp cooling power,  good enough just  for a 300 litre tank.  Larger and more efficient ones are being developed.

What is a Freon Chiller?

Freon Chiller uses a compressor to compress gaseous freon into liquid state, then the freon is allowed to be cooled in a condenser for heat to be rejected to the atmosphere. After that, it is allowed to be expanded into an evaporator chamber either by means of an expansion valve or capillary tube. In the process of expanding from liquid to gaseous freon in the evaporator,  it absorbs heat from its surrounding. The cycle repeats when the gaseous freon is returned back to the compressor.

What’re the Differences?

As far as the quality of cooling is concerned, there is no difference between the two. This is because water from aqua or reef tank will cycle through heat exchangers of the chillers. For freon chillers, titanium tubes are often used as cooling coil inside the evaporator whereas for peltier chillers,  polypropylene or stainless steel sections are used for heat transfer. No copper or aluminium materials will be used in the water heat exchanger unit.

Apart from this, peltier chillers are often smaller in size except for the electricity consumption.  They are not  as efficient as the freon chillers. Also, there is no difference in the inlet and outlet connection because there is no cooling coil used in peltier chillers.

One aqua enthusiast built this peltier chiller for his 20-litre tank.

What're the Pros and Cons For Peltier Chiller?

Pros

1. Can be easily DIYed. Multiple units can be cascaded to give the desired cooling;

2. Light weight and smaller in size;

3. Can use for both cooling and heating by just reversing the polarity of the peltier chips;

4. Lower capital cost

5. Easier to maintain; no moving parts except the cooling fan; spares are a plenty;

6. Peltier chip claimed to have a life expectancy of 200,000 hrs

Cons

1. Higher running cost ; Freon chiller is 75% more efficient than Peltier chiller;

2. The fans for aluminium heat sinks can be noisy unless a bigger heat sink with less noisy fans or remote cooling can be used;

Design Pitfalls for Peltier Chillers

 

Pitfall No.1

Computer Heat Sink

They are a plenty in the market and often being used wrongly for Peltier chips. A wrong selection of a smaller size not only affects the cooling performance but also results premature failure of peltier chips. Too big a heat sink will cost money although the chiller will run more efficiently.  An economic will have to be worked out for the selection. Water cooling is a better alternative than forced air cooling because more heat can be transferred when properly designed;  and also, cooling devices can be remotely located to minimise fan noises.

The following is a good article to learn more about peltier and the heat sink selection. Read here.

 

Pitfall No 2

Cooling blocks

There are a plenty also from the market but most are designed for computer cpu cooling where clean water are often used. They are either of copper or aluminium type which is not suitable for use in aquatic or reef tanks. They could be corroded or choked up easily after sometime.

It may be more appropriate to use stainless steel channel cut to form a box with both ends sealed for plastic inlet and outlet.  Corrugated stainless steel sheets such as the following can be DIYed to stuff inside the box and stick lightly with non-toxic thermal conductive expoxy glue to help heat transfer.

Polypropylene plastic can also be used as alternative.  The heat transfer characteristic of polypropylene plastic is about as good as stainless steel.

As stainless steel may also corrode over time,  the other alternative is to use titanium tubes either embeded in the holes of solid aluminum block or high thermal heat transfer epoxy which has thermal conductivity comparable to titanium.  Multiple passes can be arranged for better heat transfer.

Confusion about Cooling Efficiency and Coefficient of Performance (COP)

Someone claimed that Peltier has only 8% efficiency as compared to Freon chiller which has 50% when he searched the net and might have tumbled into the following Wiki site. The paragraph in the Wiki site read as follows.  He argued strongly that no chillers will ever have cooling efficiency higher than 100%.

Thermoelectric junctions are generally only around 5–10% as efficient as the ideal refrigerator (Carnot cycle), compared with 40–60% achieved by conventional compression cycle systems (reverse Rankine systems using compression/expansion). Due to the relatively low efficiency, thermoelectric cooling is generally only used in environments where the solid state nature (no moving parts, maintenance-free, compact size) outweighs pure efficiency

For cooling and heating purposes, the efficiency of cooling or heating device is often measured in terms of Coefficient of Performance (COP) and not the Carnot cycle efficient. This is because freon, when allowed to be expanded in the evaporator, absorbs free energy from its surrounding and therefore, the efficiency can be more than 100%. Peltier chiller,  on the hand,  has no such advantage of getting free energy from the surrounding and therefore,  its COP is much lower. 

COP is often expressed as

COP cooling = Qc/W_in

Where Qc is the cooling output and Win is the power input

Normally, freon chiller has a COP around 1.3 whereas Peltier chiller will have a COP around 0.55. Air conditioner has much higher COP around 2 to 2.5 because it has larger and more efficient condenser and evaporator. Commercial chillers would have COP more than 5.0 because they have super large condensers with multiple water passes in the heat exchangers.

Why no Large Peltier Chillers?

Peltier chillers are limited to smaller sizes in the market. They usually have cooling power of less than 150 watts or 500 BTU/hr or 1/20 hp. It is not because larger one cannot be constructed or manufactured. It may be because the running cost may become more manageable for smaller sized chillers; moreover, Peltier chiller has a significant cost advantage in this range.

Why Peltier Failed to Work?

Some claimed that Peltier chillers not only failed to work but also tank temperature kept rising.  There are several reasons;  one of which may be there was not enough air cooling for the heat sink when it was placed in the cabinets.  The other could be due to over-rating by the manufacturers.  Some claimed Peltier chillers to have COP of around 0.75 with small heat sinks.

Economics

One can get a 1/20 hp Peltier chiller for about SGD$170/=  and will have to spend around SGD$300 for a similar size freon chiller.  Assuming the cooling power is around 140 watts, Peltier will need about 250 watts of electricity and Freon chiller around 110 watts. At current electricity tariff of 0.2727 per kwh and assuming 48 starts/stops per day with 10 minutes running and 20 minutes resting, the electricity cost will work out to be SGD16 per month for Peltier and SGD$8 for Freon chiller. With that difference in running cost, the straight payback for using Freon chiller will be around 14 months.

Conclusion

Peltier chillers are only good for those who have a smaller budget and not too worried about the higher running cost or for starters who just wanted to try nano reef keeping for a short period.  It is suitable for use as a backup chiller.


Other Reference Sites
tinyurl:  https://tinyurl.com/ybqva9ws

Servicing Resun CL650 Aquarium Chillers

18 November 2012

Introduction

Many reef keepers will have an aquarium chiller to keep the reef tank at temperature around 25C to 27C. Many complained about noisy chiller and insufficient cooling after sometime in operation. Some have problems maintaining proper temperature with chiller turning on and off frequently although it was working properly before. This article aim to introduce some basic about chiller operation and how to service them, taking Resun CL650 as an example.

What is in a Chiller?

Chiller has 3 components; the compressor, the evaporator and the condenser.

It works like a refrigerator. The chiller uses a compressor to compress gaseous freon into liquid state, then the freon is allowed to be cooled in a condenser for heat to be rejected to the atmosphere. After that, it is allowed to be expanded into an evaporator chamber either by means of an expansion valve or capillary tube. In the process of expanding from liquid to gaseous freon in the evaporator,  it absorbs heat from its surrounding. The cycle repeats when the gaseous freon is returned back to the compressor.

What can be wrong with the Chiller?

Like refrigerator, the chiller’s compressor is hermetically sealed.  Freon should never leak unless there is a piping leak which topping up of gas will not help. Most compressors can last more than 5 years. The evaporator has no moving part if they are the capillary type of expansion system as shown in the picture. The electronic controller is usually quite reliable and no servicing is usually required. Therefore, the condenser is often the cause of most chillers’ cooling problem.

What can be wrong with the Condenser?

The condenser has 2 components: the radiator and the cooling fan.
The radiator often gets air clogged with dust and dirt and the cooling fan will need oiling from time to time for efficient operation. Dirty condenser will cause high compressor ratio, thereby increases the amperage of the compressor, causing the motor protection thermal overload to come on and off and hence,  the complaint. This CL650 chiller has almost 40% of the condenser coil area clogged up with dust as shown.

 

How to Service the Resun CL650 ?

CL650 is a ¼ HP chiller capable of cooling 650 litres or 140 gallon reef tank. It has a cooling power of about 650 watts. To service, first make sure the electrical supply is off by unplugging the power supply plug. It is best to service in the toilet area as water flushing may be required.  

1. Removing the cover

Remove the 8 small screws at the bottom of the case,  4 on each side. Also remove the 2 big plastic nuts attached to the water inlet and outlet on the top of the case.

The case will not come off until one has also removed the right side recess handle bar because it is tucked underneath the evaporator box. To remove the recess handle, one must release it by pressing the 2 plastic catch on its sides. It can be difficult to access this catch as it is hiding inside the box.  Some patient will be required.

As the case is removed, make sure the cable connector to the case and the wiring connecting the control box are also removed.

2.  General

Check the compressor and its piping for visible oil leaks.  If there is,  most likely there is a freon leak somewhere.  Servicing the chiller by cleaning up will not help.  The leak must be found and repaired with the freon recharged.

 

3. Check the condenser fan

Check the fan for free rotation using fingers or else remove the fan which is held down by 2 bolts.

To remove the fan blade, first remove the circular spring clip coiled around the fan shaft leaves. If the rust prevents the easy  removal of the fan blade, use a small hammer to carefully knock the centre of the fan blade after having released the “leave” using a small screw driver.

Once the blade is removed, check for free rotation of the motor shaft and oil the bearings first with WD40. If the fan have been making noises during operation, it may be necessary to remove the shaft and oil the bearings and the shaft together with good quality grease such as lithium grease. Removing the shaft will require some patient and care so as not to break the bearing housing which can be quite brittle. Reassembling the motor rotor will require knocking the shaft of the rotor with a screw driver from side to side to centre the rotor for the screws to be tightened down.

When remounting the fan after cleaning the condenser coil, make sure the blade is free to rotate without touching any metal work.

4. Check  and  Clean the Condenser cooling fins

Make sure the fins are cleaned using a tooth brush, carefully brushing the fins in the direction of fins. If the dust is so built-up like it was shown in one of the pictures above for CL650, then spray cleaning chemical to loosen the dirt first. After that,  wait for about 10 minutes and then water flush out the dirt stuck in between the fins. Apply flushing water carefully ensuring that no water will wet the cooling fan motor or compressor motor or any electrical components especially the control board which should have been removed by now for safe keeping. Wrapping the electrical parts with plastic bags or even clothes will help.

If the cooling fan has not been removed and is still in position,  make sure the coil of the fan is properly covered with plastic bag to prevent water from shorting the coil.

5. Reassembling

Reverse the procedure just described above. It may be difficult to put back the control board when the case is in place as one can only access and place the box properly from inside the case using the feeling of hand and fingers.

Relocating the Internal Probe

One can relocate the internal probe by removing the plastic nut that holds down the sensor to the evaporator box on the top. To seal the hole, one can cut a small piece of rubber and use it as a seal before screwing back the plastic nut. Sometimes, the sensor may be stuck underneath the evaporator coil. A screw driver to shift the coil a little to the side will help to free the sensor.

Remember that once the sensor has been removed, the chiller will have no internal sensor to stop the chiller and it can work itself to freeze point if the external pumping system stops working.

Testing

Important Note:  The following test should be done only when you know what you are doing

Plug the chiller to the mains supply.  Connect the water tap to the inlet and the outlet to the drain.  Turn on the tap for moderate water running,  then start the chiller.   If the compressor motor is running, check for its proper working by hand feeling the temperature of the compressor's discharge (tube leaving the compressor and entering the condenser) and the suction tubes (tube entering into the compressor from the evaporator box). One should notice the discharge tube is always much warmer than the suction tube. If there is not much temperature difference, most likely the compressor is not working properly and it is time to repair or retire the chiller compressor.  

If the temperature sensor has been relocated,  make sure the chiller will not run for longer than necessary period to perform the test which should not be more than 15 minutes.    .

Start/Stop Problem

Chillers are usually sized such that they will cycle on 15-20 minutes an hour so that they will run about 6-8 hours a day.  When they start/stop too often,  it may be due to a water flow problem or there may be a faulty temperature sensor.   Improve the water flow by first cleaning the canisters that is used to filter the water.  Some chillers may have cooling fins at the coil to improve heat transfer.  They may trap debris.  In that case,  back flush the chiller (connecting water pump to the outlet of the chiller) may loosen up and flush away the trapped debris and improve the water flow.   Changing existing pump to a  bigger one may help.  Relocating the temperature probe or installing another temperature controller with probe in the  sump or the tank would definitely help. 

Conclusion

The servicing has cleaned out all the dirt stuck onto the condenser coil.  The fan also worked without any knocking or bearing grinding noise. Wattage measurement found that the chiller has worked within the specification of about 490 watts.

References
Selecting Nano Chillers for AquariumHow to Service Resun CL650 Aquarium Chillers
Freon vs Peltier Chiller for Reef Keeping
Cut Cooling Bills by 90%
Spot Cooling Cuts Aircond Bills by 50%

Other Relevant Sites
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