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  1. #1
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    flow through chiller design



    Hi, I'm new to this forum. I'm in the wholesale bait busniess and I'm in the need for a large flow through chiller. Of course like most people I just can't see paying someone to prepackage a system for me. However not being familiar with refridgeration, I'm stuck. Hopefully someone here can help me out. I'm not trying to steel anyones designs and make money off them, just trying to save myself some $.

    the system I'm looking at is made by
    Aqualogicinc
    I've attached a picture.

    The system consists of a large air conditioner connected to a Tube-In-Shell titanium fluid heat exchanger. A digital electronic controller is used to regulate the temp. in the coil by turning on and off the unit. There also appears to be a flow switch that will shut down the system when water stops flowing.
    I have been able to find all these parts so far on the web. Many from this site.

    My question is, Am I missing anything? any help would be greatly appreciated.

    thanks!
    Attached Images Attached Images



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    Re: flow through chiller design

    Hi, sucker_dave, welcome to RE

    Quote Originally Posted by sucker_dave
    Hi, I'm new to this forum. I'm in the wholesale bait busniess and I'm in the need for a large flow through chiller. Of course like most people I just can't see paying someone to prepackage a system for me. However not being familiar with refridgeration, I'm stuck. Hopefully someone here can help me out. I'm not trying to steel anyones designs and make money off them, just trying to save myself some $.

    the system I'm looking at is made by
    Aqualogicinc
    I've attached a picture.

    The system consists of a large air conditioner connected to a Tube-In-Shell titanium fluid heat exchanger. A digital electronic controller is used to regulate the temp. in the coil by turning on and off the unit. There also appears to be a flow switch that will shut down the system when water stops flowing.
    I have been able to find all these parts so far on the web. Many from this site.

    My question is, Am I missing anything? any help would be greatly appreciated.

    thanks!
    Maybe you can say little more what for you need it?

    It is not a good way to save some money using titanium HE.

    Believe that some other guys here can give you a better practical advice

    Best regards, Josip

    It's impossible to make anything foolproof because fools are so ingenious...

    Don't ever underestimate the power of stupid people when they are in large groups.

    Please, don't teach me how to be stupid....
    No job is as important as to jeopardize the safety of you or those that you work with.

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    Re: flow through chiller design

    A titanium plate heat exchanger may be more cost effective, since you want to use titanium.

    We need some guys who work on fishing boats to comment here, but I'll add my two cents...

    The use of titanium is recommended for fish. Apparently, if you use stainless steel or copper the fish are sensitive to those metals. Titanium is basically inert as far as the fish are concerned.

    I seem to remember this from a project for lobsters. It should be similar for other fish, unless, if you will pardon the pun, I'm all wet.

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    Re: flow through chiller design

    Ice,
    Exactly right. Not only are copper, stanless steel and aluminum toxic to fish, they also react badly to the salt we use in recirculating aquaculture. While titanium is expensive, it's the most readly available material for aquaculture chillers.

    Josip,
    I hold bait fish in a recirculating water system. Water temp is very important to the health of the fish. I'm currently using a small imported in room chiller but want to increase the size and move the condensor outside to minimize the heat in the room.

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    Re: flow through chiller design

    Hi Sucker dave

    I have built a few of these units in the past. Mine were for sardine freezing. We normally had a bulk salt water tank, with the titianium shell and tube chilling the salt water. We did not allow for pulldown of the initial water to freezing only maintaining the water at about a 5 degree range.
    the best chiller design is dx with salt water in the shell , add some cleanout holes, lots of trash will hold up in there and these allow for easy cleaning..

    I used a Kramer condensing unit for the refig sized to the calculated load. we were freezing not just holding.

    I would get the chiller from my old employer Isotherm in Texas
    they are experts in shell and tube espically titanium for sea water applications, they can size it for you ..
    plate and frame are excellent but titanium plate is about a 12 month lead time very hard to get
    tubes are easier to get but expensive.

    hope this is useful, glad to help

    It is more fun to do this then my day job of applications engr for AC with Trane now...

    bruceboldy

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    Re: flow through chiller design

    Bruceboldy,
    Thanks for the help, I've looked into the dx chiller barrels. I agree that for a very low temp application, it's the way to go. Because I'm looking for 58 deg. I can just use a house AC unit as shoun in the picture. Let me ask you this. Being an ac app engineer, could you look at the system I'm trying to build and tell me if I'm missing anything that will make the unit I've described not work? Because I'm trying to hold water at 58 deg. f. I have sized the system to require a 2hp unit. The system I've shown in the picture sells for $4500. I've priced out the individual parts for the system as I see it and cant see spending over $2500 with the titanium heat exchanger. Makes me think I've missed something (other than profit).
    Thanks!

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    Re: flow through chiller design

    Well,you can repair your teaths on dentist or you can go to blacksmith.Both use jaw.

    Renato

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    Re: flow through chiller design

    ????

    how about a thermostatic expansion valve. will I need one on this system?

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    Re: flow through chiller design

    For chillers they do indeed seem to be the best option, I have used one on my chilled water system and been loving it, not the exact same application as yours same function though, you'd be good with an internally equalized one me thinks

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    Re: flow through chiller design

    Check out Flat Plate if your interested in plate and frame, their lead times are much better. They deliver most in three weeks, the rest not far behind.

    Just make sure that all of the components are matched to work together, it is not worth it to save money just to have the chiller give you trouble.

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    Re: flow through chiller design

    Thanks. Last question. Can an air conditioner run outside during the winter? I live in minnesota and it get's damm cold here. Is there anything special I need to do to run this system year round?

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    Re: flow through chiller design

    If the unit does not come with one, a crankcase heater may be needed to maintain oil temperature on the off cycle. These can be purchased in the form of a band that is strapped to the base of the compressor.

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    Re: flow through chiller design

    Were getting somewhere. Now my last question has to do with wireing the sytem. I believe in order to make my system function correctly I need to more things. 1 a water flow sensor ( so if the pump should stop pumping, the coils don't freeze up). 2, a temp controller.

    temp controller. I've picked a Ranco electronic temp controller to monitor the water temp. turning on and off the AC unit as required. question here is, 2 ton ac units are generally 220 v 20amp systems. the electronic controller is 110v 10 amp. therefore I'll need a relay to turn on and off the system. Can anyone reccomend a relay? and where in the electrical system of the AC unit should it be wired? Can I just switch it at the incoming power?

    Flow sensor is Rated at 50 psi, 125VAC to 25 A (1 hp motor) or 250VAC to 25 A (2 hp motor). Switch is single pole single throw (one wire in, one wire out) with 1/2" FNPT conduit connections on both sides.
    I assume I can wire that the same way. Not needing a relay just tieing into one leg of the power.

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    Re: flow through chiller design

    Quote Originally Posted by sucker_dave
    Is there anything special I need to do to run this system year round?
    Besides a cranckcase heater, you will also need some version of head pressure controls. If you do not have any, the system will not develop sufficient head pressure to feed the expansion valve in the winter time.

    Since you mentioned you wanted to move the condenser outdoors to remove the heat from the indoors, I'm assuming you are using an air-cooled condenser.

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    Re: flow through chiller design

    Quote Originally Posted by sucker_dave View Post
    Were getting somewhere. Now my last question has to do with wireing the sytem. I believe in order to make my system function correctly I need to more things. 1 a water flow sensor ( so if the pump should stop pumping, the coils don't freeze up). 2, a temp controller.

    temp controller. I've picked a Ranco electronic temp controller to monitor the water temp. turning on and off the AC unit as required. question here is, 2 ton ac units are generally 220 v 20amp systems. the electronic controller is 110v 10 amp. therefore I'll need a relay to turn on and off the system. Can anyone reccomend a relay? and where in the electrical system of the AC unit should it be wired? Can I just switch it at the incoming power?

    Flow sensor is Rated at 50 psi, 125VAC to 25 A (1 hp motor) or 250VAC to 25 A (2 hp motor). Switch is single pole single throw (one wire in, one wire out) with 1/2" FNPT conduit connections on both sides.
    I assume I can wire that the same way. Not needing a relay just tieing into one leg of the power.
    All of the above controls need to be wired in series into the control circuit - not the compressor power circuit, so you shouldn't need any extra relays

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    Re: flow through chiller design

    iceman, yea i'm just going to be using a 2 hp centeral A.C. unit. Can you reccomend a head pressure contiol for an ac unit?

    Frank, so all the control circuts on an ac unit are already 110 v?

    Thanks guys!

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    Re: flow through chiller design

    Quote Originally Posted by sucker_dave
    iceman, yea i'm just going to be using a 2 hp centeral A.C. unit. Can you reccomend a head pressure contiol for an ac unit?
    If you are using a central A/C unit you only have one option; to use fan cycling with a pressure switch to control the discharge pressure.

    Unfortunately, the winter weather in Minnesota may not really allow this. It can get too cold for a fan cycling control to work well in very cold weather.

    For this reason you would probably need to use a method called "condenser flooding". This uses several pressure regulating valves to hold liquid in the air-cooled condenser. In cold weather, the liquid backs up into the condenser and blocks off the heat transfer surface available for condensing.

    The down side is during the summer, you need a receiver to store the liquid. A cheap commercial refrigeration unit may be a better choice as these usually have receivers built into the unit.
    Last edited by US Iceman; 29-08-2006 at 02:16 PM. Reason: spelling corrected

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    Re: flow through chiller design

    iceman, check out the ICM326hon
    icmcontrols.com would this work for my head pressure and fan cycling??


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    Re: flow through chiller design

    How about fan speed control to control head presure. Don't know how well it would work in a minnesota winter. Alco make one which senses head pressure and varies fan speed between 0 and 100% to keep it constant, you need the correct one to suit your chosen refrigerant. Edc (in the uk) make one that senses temperature (probe cable tied to condesenser coil) and varies fan speed to kep it constant. I'd like to see an anti cycle timer to stop teh (damn dyslexia) the compressor starting and stoping too frequently, might be a programable function of your ranco thermostat. Only american stuff i've worked on is Surge dx milk tanks so may be talking out my a*se. Also some overloads on your compressor relay/contactor would be cheap insurance against power problems.

    cheers Jon

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    Re: flow through chiller design

    Quote Originally Posted by sucker_dave View Post
    Frank, so all the control circuts on an ac unit are already 110 v?

    Thanks guys!
    Thats not what I meant. Any control device like the one's you mentioned should be installed in the control circuit - not the main power supply to the compressor. Basically, in the line that switches on the contactor that supplies power to the compressor.

    It could be 240v, 110v or even 24v

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    Re: flow through chiller design

    Quote Originally Posted by sucker_dave
    ...would this work for my head pressure and fan cycling??
    I don't think so. Fan cycling controls or fan speed control is only effective down to about 20F (-6.6C) or thereabouts.

    When you are trying to operate a DX system during very low ambients, you need to resort to more drastic measure for head pressure control, .i.e., flooded condenser control.

    I'm sure the Minnesota winters get a lot colder than that!

    I have seen some systems where they use a low-pressure switch with a time delay built-in. This allows the system to try to build up discharge pressure before the system shuts down.

    Fan cycling or speed control might be cheaper, but for very low ambients you would be taking a risk in my opinion.

    BTW, I have been looking for some controls like you directed me to for some other purpose. Thank you for the link.

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    Re: flow through chiller design

    I agree with US Iceman. On the larger chillers we use a receiver along with fan cycling to flood the condenser in low ambient temperatures. This requires that enough refrigerant is available to flood effectively along with leaving enough in the receiver to allow the system to start up again. This also requires a few other items such as a means of maintaining discharge pressure along with a means of maintaining receiver pressure.

    The other down fall of chillers is they are prone to floodback. Superheat needs to be carefully set and the use of a pumpdown solenoid before the expansion valve is a good insurance policy on liquid slugging at start-up. This would then require a low pressure control to allow the system to shut down. This control will also protect the compressor in the event there is not enough pressure in the receiver. I would then operate the solenoid by the temp control.

    The more I think this through the more I am reminded why each component is so important.

    Is it best to build something yourself to just save money? Or should the goal be to build a better quality system that will last longer and work more effecient?

    I have seen too many systems hacked together and are better used as boat anchors.


    I use Harwil flow switches and have found them to be top notch.

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    Re: flow through chiller design

    Thats how I built mine was with a pump down solenoid with a receiver.

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    Re: flow through chiller design

    Perseus raises some very good points which I had neglected to mention. I highly recommend the use of the liquid line solenoid valve controlled by a thermostat for the pump down cycle.

    Here is a link that provides more detail on the use and requirements for head pressure control:
    http://www.sporlan.com/90-198.pdf

    I think if you investigate the use of a commercial refrigeration unit with the receiver and head pressure controls factory assembled you will be much better off in the long run. You can add the receiver and controls to a residential AC unit, but by the time you get done it may cost you more money.

    Just some thoughts to consider...

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    Re: flow through chiller design

    Man, who thought it would get this complicated.

    Perseus. Where can I find a low pressure control?


    Iceman, I was just thinking the same thing. I may save a thousand bucks to loose $3000 + fish this winter when the whole this freezes up.

    Here's 2 last options I'll throw out. don't laugh.

    I get a comercial AC unit. Add a low pressure control, pumpdown selenoid, ( which I attach my temp gauge to) crankcase heater. Run it untill the ambiant temp reached 30 deg f. and shut it off till next spring. Or (here's where I dont want you to laugh at me) cover 3 side with 2" insulation foam and add a small heater to the system to keep the everything above freezing) run year round.

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    Re: flow through chiller design

    My wallet sympathises with yours for the power that will suck up! durring the cold weather shut it down and use a direct air to water exchanger. then summer use valves to divert water through the chiller and break out the Air to water exchanger.

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    Re: flow through chiller design


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    Re: flow through chiller design

    use a direct air to water exchanger
    Now there's an original idea. What is going to keep the water from freezing in a Minnesota winter?

    Quote Originally Posted by sucker_dave
    Or (here's where I dont want you to laugh at me) cover 3 side with 2" insulation foam and add a small heater to the system to keep the everything above freezing) run year round.
    I won't laugh, but I think this is where I bow out of the conversation for now.

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    Re: flow through chiller design

    Iceman, I figured as much. sorry. Don't bail on me yet.

    mg, I really have considered that air to water exchanger. Here's why. My water is moving around 50 g/min. I think if I were to shut off my ac unit arounf 32 deg. f and divert the water thru a 1 1/2 dia pvc pipe outside the building for say 6' I think the water would chill. However if the pump shuts down or anyrhing else like a power outage happens I'm screwed. plus there's no way to accuratly control the temp.


    I had a engineer tell me he could wire in a small heater to turn on for a few min. before the compressor came on to warm up the system.
    does this seem like a possible approach?

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    Re: flow through chiller design

    Low pressure controls are available at local refrigeration wholesalers around town.

    Around here there are times in the spring and fall when the temperature changes from 30-40 degrees in the morning to 65 degrees or better during the day. You dont want to go there with foam and blocking airflow that situation will drive you nuts because you will have to monitor it constantly.

    We use evap condensers as well as air cooled up here. Here is the difference. With the evaps, we always use a remote sump for the water which is located in the mechanical room. When the pump shuts off all of the water runs back into the tank in the 70 degree room. We always run water first. This is better than running air first and cycling on water into a condenser that has metal at freezing temperatures. It doesn't take long to freeze up a tower this way.

    Water treatment is a must. The formula for figuring out the water usage on an evaporative condenser is 3GPM per 1 ton of refrigeration. This equates to a lot of water used and a lot of scale to deal with

    If it was me I would stick with air cooled and use a receiver large enough to hold enough refrigerant to allow for condenser flooding in the winter.

    I wish I could tell you this would have been easy. But the actual truth is that chillers look simple, when in fact they are quite complex. I think that you have already found that out.

    A good chiller tech is hard to find

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    Re: flow through chiller design

    Sorry, after I thought about it I realized where the air to water exchanger was going.

    Obviously not in the same direction as I went with the water cooled condenser.

    I do agree though there is too many variables to that situation. Would the water potentially freeze?

    Going back to my previous post on the temperature fluctuations during the month or so in the spring and fall...what do you do then?

    You don't have a large volume of water like a lake that can handle the temperature changes. A smaller volume is more susceptable to larger changes in the water temp.

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    Re: flow through chiller design

    UPS is your friend far as power outs go, they have never let me down to say the least just size it accordingly.

    Temp controll is actualy realitivly easy have a wrap around heater or submersed heater to nudge it to where you need it, or use a secondary loop.

    Loop one is a brine or glycol loop that circulates out side then to a secondary liquid to liquid exchanger this way you can control temp by controlling a valve on either loop to slow down or speed up flow. using a simple Temp to PWM system and a servo type control chip higher temp more open the valve lower temp more closed the valve. couple ways to do it, and this saves you much more in power to boot, the 2 loop system you have more parts with single loop heater you have less parts about same power usage so go with what fits and a UPS is a wonderfull insurance policy to have on any thing that will not tollerate a power outageand geting one that will handle up to 500watts is easy look up APC systems UPSs

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    Re: flow through chiller design

    As for the Veriabls with the two systems working togeather there isn't an issue that I can see, above a theshold a divert valve puts it through the chiller system below thresh hold a divert valve and switch kills the chiller and runs it though the Air to water exchanger and a make up heater fine tunes it.

    Sounds complex but can be implemented rather simply

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    Re: flow through chiller design

    Sounds complex but can be implemented rather simply
    Sorry but experience tells me otherwise.

    A chiller built correctly will work effeciently and give years of sound operation. Maybe I am wrong but I feel that alternative methods of cooling is another thread altogether.

    There is a lot of good advice on this thread but in my opinion I think that it is starting to push boundaries that the poster or his wallet may not want to cross.

    One thing that I have learned is that simple is better. Too many diverting valves and extras are just asking Murphy's Law to pay a visit.

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    Re: flow through chiller design

    the cost of cheap is occasionaly complexity, but not to complex. build it modulerly and it will be simple to manage each section, you'd only need one divert valve on the out put line of the pump hard part is selectiong a valve technology.

    A chiller built correctly will work effeciently and give years of sound operation. Maybe I am wrong but I feel that alternative methods of cooling is another thread altogether.
    But this is NOT the issue we are talking of, we are talking about an issue of duty cycle during extreme cold periods and the chillers inability run in such do to the nature of refrigerant. Thus we either find an equaly complex system to over come it or add a more straight up design equal complexity but possibly cheaper.


    Like any thing it is an idea one can take or leave it

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    Re: flow through chiller design

    I thought I would stop by and see what is happening on this thread.

    Quote Originally Posted by Perseus
    Too many diverting valves and extras are just asking Murphy's Law to pay a visit.
    Yep. I agree completely. That's why I backed out of this initially. Either Mr. Murphy will visit you at the wrong time or you run the risk of the chiller winning a Rube Goldberg award!

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    Re: flow through chiller design

    Hi

    I agree with the other posts, controlling the fan will not do the job.
    You need the fan to be running at a constant speed whenever the compressor is running.
    Control the headpressure using a headmaster control. This will require a larger refrigerant charge, and a receiver to store it in the summer.
    I would use a semihermetic compressor for mid temp refrigeration application, preferably a Copeland. I would definitely install a suction accumulator(not a small one), and would consider a crankcase pressure regulator (when the water is changed on a hot day, probably overload the compressor without one).
    The compressor will need a heater if it is installed outside, but I would install the condensor outside and everything else inside...therefore no heater, or refrigerant migration issues.
    The flow control device I would use would be a tx, but I have seen flooded evaporators used in similar applications (to chill draft beer lines).

    I would abandon any idea of attempting to obtain free cooling in such a small application. The cost savings are tiny compared to the risks, and it will simply make the installation way too complicated IMO.
    For controls, I would keep it very simple....freeze stat on the chiller barrel, monitor entering fluid temp as your control point, do a pump down for the offcycle which will require a LL solenoid and a low pressure limit, constantly circulate water through the chiller barrel on the off cycle and allow the compressor to pump out the chiller from time to time if the pressure rises.
    If short cycling of the compressor becomes a problem, or too much temperature swing occurs in the tank, it might be worthwhile to consider capacity control of some kind..perhaps multiple refrigerant stages in the chiller with their own tx.

    As an afterthought you could cycle the condensor fan motor when it is very cold, but not necessary. I have seen similar installs run at -30f plus windchill, and the fan is running. Headmaster will keep your pressures right.

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    Re: flow through chiller design

    Sledge, Great information, thanks. It’s sounding more and more like a commercial refrigeration unit is the way to go. I have found that many ac manufacturers make a “low ambient kit” for there units. However most say they are good down to 32 deg f of 0 deg f. I suppose that’s because there is no way to add a receiver to them for the extra refrigerant. I haven’t completely discarded the idea of an AC unit. And just turning it off in really cold weather. I need to take a look at the cost of various options now.
    Last question, if I order a commercial refrigerant unit, is there any special hardware I need for year round operation, or will a low ambient unit work as is.

    Again, thanks to all for the help on this!!!!!!!!

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    Re: flow through chiller design

    We produce free cooling and ordinary chiller that can be installed in any climate. We have a bunch of installation in finland, which in the course of time were exposed to temperature as low as -30°C, and CCUs installed in Arkangelsk and Oymyakon in Siberia for temperatures as low as -60°C

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    Re: flow through chiller design

    NoNickName, Tell me more. Do you sell these in the U.S.?
    Are there any special controls you use for those cold climates???

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    Re: flow through chiller design

    Quote Originally Posted by sucker_dave View Post
    NoNickName, Tell me more. Do you sell these in the U.S.?
    No, we presently do not export to USA

    Quote Originally Posted by sucker_dave View Post
    Are there any special controls you use for those cold climates???
    Yes, condensing controls coupled with liquid bypass and pressure switches, check valves to prevent migration, and special fans with non-freezing bearings.
    Below -40°C we also use double-thick shells for evaporators, to prevent fragility.

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    Re: flow through chiller design

    One more question. It seem's I have 2 options for the compressor.

    1- central A.C. unit with low ambient controlls.
    2- copeland condensing unit with crank case heater and fan control.

    Looking for opinions. price is about $500 between them.

    Thanks.

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    Re: flow through chiller design

    Looks like you didn't pay attention. None will work.

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    Re: flow through chiller design

    I did pay attention. However because of what's available to me these are my 2 choices. I will more than likely have to shut the unit off when the temp nears freezing.

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