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Water Cooler

So I got a free outside unit for a spit cycle air conditioner/heater.
It looked something like this before I assaulted it.

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My plan was to hard wire up the fan so I could just plug it in and pump my condenser cooling water though the coil.
I think the idea still has a lot of potential but of cause it wasn’t going to be as simple as that.

First the fan.

So l was hoping I could just hot wire the power supply that was in there so all I had to do was plug it in but looking at the wiring diagram for the motor (MF) it looks like there’s too many wires. Somethings not right. Brushless DC?

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It looks like DC going into IC932 then three wires coming out to the motor, like three phase??

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I don’t want to replace the motor but if there’s no easy fix I might have to.

Second the coil.

This isn’t as simple as I thought it was going to be either.
Originally I just wanted to tie into the brass fittings that are already there and gut out all that stuff between them and the coil but the ID of the liquid fitting is only 4mm. My flow rate should be under 2 l/min, but still.
Just walking it out it looks like the larger diameter, hot gas line comes from the compressor through a few bits and pieces which I guess are tiny knockout pots or coalescers for the oil, then what looks like a divert valve for the cooling/heating function (the round brass thing with the coil and blue wires on it).
After all that is where I wanted to cut in but what I assumed was going to be one coil is actually two in parallel and a third in series.
I don’t think I can follow the same path anyway as the first two are falling because they were designed for gas.
Now I’m wondering the best way to go about this. Cut off the tees to make it one long one flowing from bottom to top?

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All the lines in the coil look to be 7.5mm OD but the ones that tie up are bigger or smaller depending on whether they’re gas or liquid.

Anyone done something like this? Anyone want to?

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Comments

  • I should probably add, the RHS of the coil that you can't see in the pic is all just 180° bends all the way down.
    No weird tees or anything. They just snake down like the orange bit you can see.

  • that is an 'inverter' unit (says it on the schematic if you want proof) , best thing would be to scavenge the control from the inside unit... if you don't have at least the outside control board, it is not worth the effort.. if you do, blue-230, white Nuetral, red try 12-24vdc (with white as gnd) to see what it does....

    Here is what motor that type is.

    you may be able to find some other controller, but not likely any easier or cheaper than the mitsibushi one, after all, they made millions of em...

    all else fails, it is a nice housing for a radiator and fan to place to outside to cool your RC water from 150 or whatever down to near ambient...

  • @CothermanDistilling said: that is an 'inverter' unit (says it on the schematic if you want proof) , best thing would be to scavenge the control from the inside unit... if you don't have at least the outside control board, it is not worth the effort.. if you do, blue-230, white Nuetral, red try 12-24vdc (with white as gnd) to see what it does....

    I realise it’s an inverter unit but I always assumed the ‘inverter’ bit was referring to a variable speed compressor, not the fan.
    The fan on the unit I have on the house seems to only go one speed.

    I only have the outside unit like in the picture. The electrical board for it is there but I don't have any of the inside unit.
    Wiring it up like you suggested sounds a bit scary. Are you talking about powering the motor or the board?
    Are you saying the fan motor is next to useless without the controller on the board?
    I’ll go through the link and look into it in a bit more detail tomorrow. Thanks for putting it up.

    @CothermanDistilling said: all else fails, it is a nice housing for a radiator and fan to place to outside to cool your RC water from 150 or whatever down to near ambient...

    That was my intention?!? I just want to utilise the fan on a single speed and the coil.

  • Looks familiar

    Mine had 4 separate radiators when I cut the manifold.
    2 run the PC and RC the other two run parallel on my pump bypass.
    The fan in mine was 3 speed and I found that it had 3 speed control wires. I connected medium to an on/off switch.
    This system has worked flawlessly for a couple of years and can handle everything I can throw at it (4800W) without heating the tank, with as little as 80L.

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  • I was going to suggest that meathead had done the same thing very successfully.

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  • MHI, it was your fantastic system that convinced me to give it a go.
    It looks like you've got a bit more going on than what I was planning though.

    @meatheadinc said: 2 run the pc and rc the other two run parallel on my pump bypass.

    So the RC and PC come together at the still then the single line runs though 2 of the coils in series? The other two coils just circulate the tank water and are in parallel?
    The small copper manifold I can see in the pic is where all four gas line come together, I guess that came off? I'm just trying to work out what all four bulkhead fittings are for, 1 from the still, 1 from the tank then 2 returning to the tank? I'm trying to have the flow going up through the lot so it stays flooded but in yours it looks like the the coils flow up and down in the same coil, it's a bit hard to make out in the pic though.

    It also look like yours has the same small gauge liquid lines as mine. What flow rate are you getting through these and what's your pump head to achieve it?

    Do you have the elec drawing under the lid too. Does the fan look the same as mine? If so what kind of power are you actually giving it (AC240/DC280/DC24) and are you using anything off the board to supply that power?

    I was also going to solder the bits in but I think hose and clamp like yours is a much smarter/easier way to do it.
    At the moment I'm thinking the easiest way might be to not utilise the bottom coil and run backwards through the rest coming in and out at the tees that are there. Nice even, parallel flow.
    If pressure isn't an issue I could even add the small bottom one as a pre cool step.

  • I visited a pharma facility recently and they used the same system as MHI, just a 22kW system designed for swimming pools connected to a 300L reservoir tank. Cooling from >180oC to ambient without issue. I do enjoy seeing technology being used in different ways from that intended, and saving the person responsible a shit load in the process.

  • I'd love to see the machine that manufactures those coils. How do they thread the tube through and keep the fin spacing so perfect, with the bend and everything?

  • edited July 2015

    I don't get it, you are pulling the compressor out and just using it as a air-water heat exchanger?

  • @jacksonbrown said: I'd love to see the machine that manufactures those coils. How do they thread the tube through and keep the fin spacing so perfect, with the bend and everything?

    No machine. Very small hands

  • @grim said: I don't get it, you are pulling the compressor out and just using it as a air-water heat exchanger?

    That's it :D Get the fan running and pump hot water through it. That's all I want.

  • Hi Jacksonbrown.

    @jacksonbrown said: So the RC and PC come together at the still then the single line runs though 2 of the coils in series? The other two coils just circulate the tank water and are in parallel?

    Yes.

    The 4 bulk heads are:

    1. combined RC ,PC flow from still to cooler
    2. return to reservoir
    3. bybass from reservoir to cooler
    4. bypass return

    @jacksonbrown said: It also look like yours has the same small gauge liquid lines as mine. What flow rate are you getting through these and what's your pump head to achieve it?

    The lines are 3/8. ( inside is rifled/spiralled) flow is great. the bypass (2 radiators in parallel ) flows around 4L + per min.
    the RC PC line runs abot 2-3L per min. 3L on reflux, hard to measure flow when in operation due to solenoid valve controller RC

    I also have another BY pass running within the reservoir at around 3l per min.

    The Pump is a 550w "izito"submersible pump. 3 years old with no dramas.

    @jacksonbrown said: Do you have the elec drawing under the lid too. Does the fan look the same as mine? If so what kind of power are you actually giving it (AC240/DC280/DC24) and are you using anything off the board to supply that power?

    No elect drawing under the lid. sorry.
    Fan appears to be different - I am running 240vac using original relay for start up..

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    @jacksonbrown said: I was also going to solder the bits in but I think hose and clamp like yours is a much smarter/easier way to do it. At the moment I'm thinking the easiest way might be to not utilise the bottom coil and run backwards through the rest coming in and out at the tees that are there. Nice even, parallel flow. If pressure isn't an issue I could even add the small bottom one as a pre cool step.

    Hose clamps work well for me.
    I had to cut the manifold on mine as some of the entry lines on the manifold were 1/4" although the rad is 3/8.

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  • Thanks for the info mate, appreciated. I guess this is your pump.
    If so then no wonder you've got all those diverts and bypasses :) That's a whole lot of flow.

    I think getting the fan going is going to be the tricky bit so any outside input there would be fantastic.

  • yep that's my pump.. the extra flow is handy for priming a dry system.

    When stripping out the box, keep EVERYTHING. I had to go through my garbage to find the control relay for my fan.

    Being DC I am guessing there will be a DC speed controller somewhere, probably mounted on the shroud between fan and compressor.

  • I haven’t turfed anything yet but I probably should have taken a few more photos when I was demolishing it. Especially when yanking out connectors. Lucky for me most of the plugs seem to be different sizes to make it a bit more idiot proof when reassembling.

    I can’t see why a fan motor would need so many wires. Someone suggested it might be a weird stepper thing.

    image

    I’d love to get it going but if the existing motor ends up in the too hard basket maybe the next best option is a $30 exhaust fan with custom shroud to fit the existing 400m hole in the panel (just a doughnut made out of plywood).
    Getting the power supply/controller, motor and fan blade already mounted on a keyed shaft makes a bit more sense I think.
    This one seems nice, very low power and I’m thinking the air flow will be enough.
    The coils are about 90cm x 50cm which should mean air speed through the fins at 235m3/hour will be a bit over 13cm/s if I worked it out right. This should be good enough to flush out the hot air but I’m curious how much less it will be with the resistance cause by the fins. As long as the hot air is flushed out, I don't think it needs to blast.
    The main thing I want is low power and quiet.

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  • Folks might have an easier time converting traditional AC condenser units. The electronics on the motor are pretty simple and most times the coils are perfectly fine, but the compressor is shot.

    Usually you can find nice units on Craigslist for similar for a few bucks more than scrap value.

    Nice thing there is that you can sometimes find the larger units, couple of tons at least.

    Nice to use as a cool season drycooler. Recirculate into a reservoir when it's cool out.

  • While I agree with the Master of All Trades @grim ;-)

    I want a mini-split housing for a strictly passive cooling of the RC - it is just a nice, attractive small package...

    Then do a write up on converting a brand new standard outside unit that you can get nearly anywhere along with a readily available heat exchanger into essentially what I have in the video above, and look 'neighborhood-legit'... next plumb it to an old, but non-leaking water heater for an insulated, and innocuous looking cold liquor tank setup... use this for the Product Condenser, beer making, etc...

    edit - the key for the above regular outside unit is to start with something clean, has a TXV, and is good for a write-up... anyone can get something like this in the US, and they don't need special inverter driver stuff or controllers... The mini-split would be better but you have to buy inside and outside sections to control the things... well, at least until until the dragonchiller(tm) is made...

  • I have an identical looking unit in operation to heat and cool my garage. I confirm that the ventilator is of the variable speed type. I think that C932 on the diagram controls the ventilator motor with a variable frequency through the 3 wire connector and that the other connector is used to measure the speed and provide control signals for C932.

    I just wonder if you could convert an indoor unit by swapping the condenser with a plate heat exchanger and connect the temperature sensor to the outgoing water line to make a 6 kW water chiller :-) I have been looking into aquarium chillers ( a 1/2 hp can cool 2kW) but they all seems to be of the on/off type.

  • I have a 3 ton unit that I'd like to convert over to use a plate type exchanger. Not sure I really want to become and hvac expert too though.

    We are going to dig out the floor and bury the 1500g tank.

  • I can take a bunch of pics of how my one in the video is wired and plumbed.... I think as long as it has a TXV to vary the flow according to temp, you are fine... the chillers sometimes seem to have a bypass solenoid that is normally open for a loop when press/temp are out of spec.....

  • @EdwinCroissant said:

    I just wonder if you could convert an indoor unit by swapping the condenser with a plate heat exchanger and connect the temperature sensor to the outgoing water line to make a 6 kW water chiller :-) I have been looking into aquarium chillers ( a 1/2 hp can cool 2kW) but they all seems to be of the on/off type.

    yes, that would be the ideal way, but a complete mini-split is a lot more than a just the outdoor part of a conventional unit, especially when you go to 3-4 tons..

  • Yeah I'd appreciate pix

  • @CothermanDistilling said: Here is what motor that type is.

    So the description of a sensored brushless DC at - 2.2.1. Construction of motor - look about right.
    Three power wires and a shit load of feed back wires (+, -, and three sensor wires).
    Are all those feed back wires critical for use if I only want on/off with no speed control? I guessing that the power needs to switch coils at correct rotor positions, so they kind of are critical?

    @EdwinCroissant said: I have an identical looking unit in operation to heat and cool my garage. I confirm that the ventilator is of the variable speed type. I think that C932 on the diagram controls the ventilator motor with a variable frequency through the 3 wire connector and that the other connector is used to measure the speed and provide control signals for C932.

    This is what I was thinking. To you think it can be easily hacked?

    I'd like to wire 240v into the board and just plug it in for a single, fixed speed. If under $50 could I get a cheap brushless dc controller to work if I find an 8 pole, 280V one.
    I've also got some spare micro controllers with PWM output?? Truth is I'm not really sure what I'm dealing with on the original motor but I know I don't need to vary the speed.
    The inside unit is long gone but I've got everything on that elec drawing.

  • edited July 2015

    Really like where you are all going with this, I found this Window AC chiller. I am thinking it will work well to chill water

  • @vooharmy said: Really like where you are all going with this, I found this Window AC chiller. I am thinking it will work well to chill water

    That guy scored 5000 btu window units for $34 bucks each?

    That guy pisses me off.

  • I can't remember when I have seen so many pictures in one DIY. Really cool stuff, what those computer guys are doing.

  • The question is does it apply here? Could we use something similar to chill our cooling water?

  • I'm sure that you could but I don't think that the ice chest will work unless you have a very small still. Like Cotherman has previously pointed out, you could use it to pre-chill your reservoir. Maybe turn it on the night before you plan to do a run.

    Shit, anymore I wouldn't know how to run my system with sub 90F cooling water.

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