A/C Basics?

[greenmaji]

single stage -evap +oil seps +tank
youll have it in the worklog?

anything helps the noobs Im sure

actually the double oil seps was new to me.. I havnt seen a work log for a recovery unit.. so that would be cool to see

 

[XeonStrikeForce]

well we don't want the recovery compressor to flood with oil from the unit we are taking the refrigerant from! so the intake sep is a fail safe.

 

[greenmaji]

well we don't want the recovery compressor to flood with oil from the unit we are taking the refrigerant from! so the intake sep is a fail safe.

thanks for the reply, and yes that makes sence, but seriously, Ive read TeamPuss and XtreemSystems and I have not seen someone post a thread on building a recovery system.. I guess If I joined up at TP I would be able to ask someone, but most of them I would think (with the exception of maybe Kal) wouldn't be using a DIY machine (I may be way off base in this assumption )

 

[MarkS]

Well, I'm begining work on this. For better or for worse, this is what I will be using to cool my system. This project will take me months, but I am going to have fun doing it.

Here are some pics of the heat exchanger parts:

The main body (6" Sch. 40 PVC),6" PVC cap and coil.


These are the blanks for the flange. Both are 12" dia x 3/4" thick type 1 grey PVC plate. Tomorrow I'll machine them and mount them on the body.


And a couple of close ups of the coil.



Tomorrow I'll post construction pics.

 

[MarkS]

Construction Pics...

Applying glue. This stuff is NASTY! It's heavy duty grey PVC cement and stinks. Raw sewage smells better. But, it makes a very strong bond.



Here you can see the fillet of cement oozing out of the joint. The joint will now be able to withstand the full pressure that 6" PVC pipe can withstand, 90 PSI. I'll never get the pressure that high.


One 7 1/2" OD x 3/16" deep o-ring groove for a 1/4" Viton o-ring.


With o-ring.


Secong o-ring grrove cut. This one is for an 8 1/2" OD o-ring.


Both o-rings installed.

 

[MarkS]

6 5/8" ID hole cut for the heat exchanger body.


And a test fitting.


Here the two flange halves are mounted together along with a 1/4" acrylic template. This template allows me to drill 12 - 1/2" holes with near CNC precision.


Drilling the holes.


All holes done. This is a very long process.


Here, the body is glued to the flange. I could not cut the body perfectly flush (VERY hard to do with a hand saw on 6" PVC), so after the glue dries, I trim it.


This is the top plate. The face is coincidental These are where the holes will be located for all of the bulkheads. I'm going to use two 1/2" cord grips to mount the evaporator to the flange. There will be a third located at the 1/8" hole for a temp probe from the temp controller.


That's all for now. I still have a little more work to do on the heat exchanger and then I'll start with the A/C unit. More pics to come.

 

[XeonStrikeForce]

looking very good. awsome job mate.

 

[MarkS]

looking very good. awsome job mate.

Thanks!

 

[Pf.Farnsworth]

fabrication is the best part of the prossess to look at pictures of. Very satisfying.

 

[greenmaji]

Did you build a quad-becket skimmer?

Nice work as usuall

 

[MarkS]

Did you build a quad-becket skimmer?

Nice work as usuall

Yep. That was me. My machining skills have progressed greatly since then. The skimmer is still at Aquatic Warehouse. I need to upgrade the pump and have not had the time or the money. I'm not sure what to do with it. I might sell it.

 

[MarkS]

OK, a few crazy questions...

First, most of the A/C units I've seen use R22. I was planning on using R134a, just because I can buy it legally. Will a compressor rated for R22 function with R134a? I know that there are car A/C conversion kits that change a R22 system to R134a, but will this work in this case?

Second...

I was thinking about how to cool the Iwaki pump I will be using for this system. I thought about wrapping a 3/8" copper tube around the motor and connect this either in series or parallel to the evaporator. Iwaki's run real hot and they have a very noisy fan. I wanted to remove the fan and bring the pump temp down to the point where it will not influence the coolant temp. Will this work?

 

[greenmaji]

Mixing those gasses, Xenon has a thread not to long ago that he was talking about that.

And I'm thinking you are not going to get the Iwaki's heat out of the loop unless its air cooled, then vented away from the loop. That idea takes all the motors heat and puts it directly into the loop (and do you know the operating temeratures?)

 

[MarkS]

Mixing those gasses, Xenon has a thread not to long ago that he was talking about that.

I'm not planning on mixing the gases. I'm going to recover the R22 and replace it with R134a, assuming this will work. Of course, if I recover the R22, I could just reuse it.

And I'm thinking you are not going to get the Iwaki's heat out of the loop unless its air cooled, then vented away from the loop. That idea takes all the motors heat and puts it directly into the loop (and do you know the operating temeratures?)

I'm not sure about the Iwaki's temp, but if it feel warm, it's over 98.6 and it feel hot so it has to be higher. I'm talking about making that loop part of the evaporator. It would not be much different than placing the evaporator on a CPU. However, after the refridgerant leaves the motor loop, it enters the heat exchanger loop to cool the coolant. I don't see this being a big problem. I am only cooling the CPU and GPU's. As I understand it, the 5250 BTU A/C I'll be using will be far overrated for this purpose, so adding the pump's heat should not be an issue. But I'm new to this so please correct me if I'm wrong.

 

[XeonStrikeForce]

*Hits head on wall* you HAVE to mix Gases to get the right capacity out of the compressor!, if you don't you can use Propan as it is the next closest.

But to make an azeotropic replacment you need a 55/45% Mix of R-134a & R-290 by weight.

 

[MarkS]

*Hits head on wall* you HAVE to mix Gases to get the right capacity out of the compressor!, if you don't you can use Propan as it is the next closest.

But to make an azeotropic replacment you need a 55/45% Mix of R-134a & R-290 by weight.

There is a smiley here that will save you fingers some extra effort:



OK, I did not understand that. Thanks. You did answer my question, albiet indirectly. I'm really starting to like the propane option. It's cheap, legal and is supposed to work well. Just got to make sure there are no leaks.

 

[Pf.Farnsworth]

First, most of the A/C units I've seen use R22. I was planning on using R134a, just because I can buy it legally. Will a compressor rated for R22 function with R134a? I know that there are car A/C conversion kits that change a R22 system to R134a, but will this work in this case?

Second...

I was thinking about how to cool the Iwaki pump I will be using for this system. I thought about wrapping a 3/8" copper tube around the motor and connect this either in series or parallel to the evaporator. Iwaki's run real hot and they have a very noisy fan. I wanted to remove the fan and bring the pump temp down to the point where it will not influence the coolant temp. Will this work?

If you want to use other refrigerants thent he compressor is meant for or mix, you have to change the oil in it as different refrigerants use different oils.

...not sure what you mean, pumps dont have "fans". Do you mean an "impeller" ? And they are not that noisy, it depends on the model and impeller housing. The japanese made once are quieter.

Dont bother will cooling it, you will just be wasting your chiller capacity. They do just fine with air cooling. These are aquarium pumps and are made to run for years in a fairly small poorly ventilated area. Get some airflow across it that and it will be enough. I just use a few 120mm yate loons. You cant hear them when they are on, and they push a nice flow.

 

[MarkS]

...not sure what you mean, pumps dont have "fans". Do you mean an "impeller" ? And they are not that noisy, it depends on the model and impeller housing. The japanese made once are quieter.

Many pumps do have fans at the back of the pump that are covered by a shroud that directs the air over the pump's housing. My Iwaki looks like this is the case, but I'll need to take it apart to make sure.

Here is a thread at ReefCentral where some people have scrapped the stock fan for a CPU heatsink and fan: RC Pump Mod

 

[greenmaji]

Mark.. whats the model of your pump? Can you dig up a link to were they are selling it on Marinedepot?

 

[MarkS]

Mark.. whats the model of your pump? Can you dig up a link to were they are selling it on Marinedepot?

Mine is a WMD30RLT. I bought mine used and it does not have the starter capacitor on it.