Big problems please help, tinkering on this unit for 1 year and still wont work right

Hello every one I am finally at witts end with this project. I have been tinkering on it for over a year.
I have tried other forums for this cooler and the residential said to go to the commercial forums because I am using a 1/3hp compressor and the system is too large. The commercial forums tell me its too small and to go to the residential forums. Please help I am ready to shoot this thing.

Here is what I am trying to do. I have taken a 12CF chest freezer and installed a STC 1000 Digital controller in it to turn it in to a large refrigerator. Inside my modified freezer I am storing four 5 gallon kegs of home made beer at a temp of 35.5 degrees f. There is no problem with this part.

Here is the core problem.
On the lid I drilled a hole and put in a 4 faucet beer tower with the lines running down inside the refrigerator to the kegs. When I pull the beer from the tanks it gains heat from the tower and starts foaming like hell. On a 12 oz pour the temp of the beer climbs from 35.5F to 45 degrees F. So I am gaining 10 degrees, on successive pours it climbs to 42 degrees F so the tower cools down by 3 degrees on the second and third pour.

So I know that the metal of the tower is absorbing heat from the ambient temp of 90 degrees F. I have calculated that the brass in the tower retains 97 BTU's/hour ( I can show my metallurgical math if you desire).

The towers surface is 1.72 square feet yellow brass absorbs heat at 67 BTU's/ hr so if we take the surface area of the tower and multiply by 67. The surface of the tower is absorbing heat at 115 BTU's from the air per hour. (67.0 Btu · ft/(hr · ft2 ·°F) @ 68 F) Both Perlick and Micromatic seem to agree with this number based on 4 faucets they say heat load of 25btu per faucet. my unit is also a 4 faucet. erroring on the extream side of caution, 115 BTU's from the tower, and another 100 btu for the faucets.

Now the beer that runs thru the lines is at 35.5 degrees. I think I need to get the beer tower down to 32 degrees F. to prevent foaming for a proper pour at 35degrees F. So if I did my math correctly, 8.33lbs (weight of water/beer) X 3 degrees X 60gph = 1499 BTU/hour

So if I did my heat load correctly I have static heat load of 312 BTU's without any beer being dispensed. With beer being dispensed I have a heat load of 1811 BTU/Hour.

So to solve this problem (the beer tower is equipped with glycol cooling lines) to cool of the tower and the product. I have built a glycol cooler.
I purchased a 1/3 hp danfoss 103g5880 compressor that has a btu rating of 2555 btu's/hr @ 30 degrees F using lbp/hbp (what ever that does, low back pressure high back pressure)

I have purchased a commercial condensing unit that is rated for 2800 btu's that has a cooling fan that is adjustable speed.

I have taken 50' of 3/8 copper tube and made a double coil to use as my evaporator in my glycol bath. The glycol bath is 2.5 gallons circulated thru a Procor rotary vane glycol pump pushing 80 gph.

So to cool the glycol bath down from ambient temp my initial static heat load (no pumps on no product thru lines) from 90 degrees to 30 degrees is 60 degrees X 8.3lbs X 2.5 gallons = 1245 btu's hr.

Perlick says that an additional heat load for the lines is 25btu/yard (assuming it was carring a product line which mine is not, but I add it to be on the safe side), I have 2 yards going to and 2 yards coming from the tower. so 4X25=100 BTU + 1811 btu before, so now my total heat load is at 1911 btu's/hr

Once the bath is cold and the tower is working the heat load will then be at 1911 btu's/hr. so the compressor should be running at 75% or running for 45min/hr.

So the compressor should be able to handle the 1245btu initial cooling of the glycol without the pumps,
then the 315 cooling if the glycol pump is running,
and the 1596 btu's when the beer is running thru the lines.

Here are my current problems.
Now With my current set up I can get the glycol down to 32 degrees F but it takes about 3 hours to cool the bath. where by my calculations it should take only 30 minutes.
Once I turn on the glycol pump on to cool just the tower without beer, the bath jumps from 32 degrees to 48 degrees F and will not come down. Which I find is very strange since the heat load is only 315 btu's only 1/10 the btu's rated for the compressor.

I know that the diameter of the copper tube for the evaporator affects the heat absorption, and speeds used for cooling. is 3/8 X 50' too long or too small diameter?
I am also using a TXV inplace of the cap tube to make the unit more efficient. The TXV is of appropriate size and the orifice is also of correct size. The other problem is that with my current set up, the compressor gets HOT, hotter than I feel comfortable touching for more than a moment.

Can you please help me sort this out step by step starting with verifying the math in the heat load calcs. I am attaching photos of how I have set up the system.

Attachment 14985


Please help me out I am loosing my mind, thus far it has cost over $800 to build this with the pumps and trying to get it all up and working. Please any help will be greatly appreciated.

Oh dear, DIY R&D at it best...

So to start with,
You have a system with a TXV as the metering device, is there a receiver in the liquid line to ensure the TXV got a true liquid supply of refrigerant?
I can see from the picture that you got a drier but I can't see a receiver. Assuming that the system not got a receiver, the easiest way to overcome the issue of varied refrigerant demand on a small system like yours (OK, I'm going to be shot down now...) is to replace the drier with a one that is one or two sizes larger, for example; if yours is a 308 go for a 508. When you install the new drier install it vertically with the inlet at the top and the outlet at the bottom, this way it will act as a receiver as well as a drier. Also do install a sight-glas either at the outlet of the drier or after the drier so that you can judge the amount of refrigerant in the system.

To be able to assist you further we do need running data from your cooler.
- Refrigerant type?
- Running pressures?
- Running temperatures? (Of the fridge system's pipework as well as the glycol mixture an surrounding air)
and so on.

Happy hunting.

:cool:

Hello Viking.
May I first ask is my math and heat load calculations look correct? Also Is the 3/8" X 50' suitable. I want to verify this before anything else.

As per your inquirey, The system is using R134 A. I have not got good readings on the temps as I only have a digital meat thermometer but the pressure was running at 30psi on the low side and 140 on the high. This was getting the glycol down to 5 degrees after about 4 hours. correct there is no sight glass nor receiver.

Also the TXV bulb is mounted in a vertical position just out of the box on the return line just befor the compressor. I was using a 01 orifice, when I tried to use a 00 orifice it would not take a charge.


Check receiver and sight glass, will have to modify the system again.

Quote:

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Originally Posted by The Viking

Oh dear, DIY R&D at it best...

So to start with,
You have a system with a TXV as the metering device, is there a receiver in the liquid line to ensure the TXV got a true liquid supply of refrigerant?
I can see from the picture that you got a drier but I can't see a receiver. Assuming that the system not got a receiver, the easiest way to overcome the issue of varied refrigerant demand on a small system like yours (OK, I'm going to be shot down now...) is to replace the drier with a one that is one or two sizes larger, for example; if yours is a 308 go for a 508. When you install the new drier install it vertically with the inlet at the top and the outlet at the bottom, this way it will act as a receiver as well as a drier. Also do install a sight-glas either at the outlet of the drier or after the drier so that you can judge the amount of refrigerant in the system.

To be able to assist you further we do need running data from your cooler.
- Refrigerant type?
- Running pressures?
- Running temperatures? (Of the fridge system's pipework as well as the glycol mixture an surrounding air)
and so on.

Happy hunting.

:cool:

---

At this moment the system is off line, I tried switching from a 01 orifice which Danfos said was to large to a 00 orifice, when I did this it would not take a charge. and I had a problem with my filler gauge leaking Blowen o ring. with the compressor running it would not put r 134 into the evaporator I am wondering if the 00 is too small for the 3/8 x 50' tube. the evaporator would not get cool, I could not get a charge above 50 psi high side, so I aborted the fill and reclaimed the r134 in the system. I want to verify the math and the pipe size before I go back to trying to change anything more.

Quote:

---

Originally Posted by The Viking

Oh dear, DIY R&D at it best...

So to start with,
You have a system with a TXV as the metering device, is there a receiver in the liquid line to ensure the TXV got a true liquid supply of refrigerant?
I can see from the picture that you got a drier but I can't see a receiver. Assuming that the system not got a receiver, the easiest way to overcome the issue of varied refrigerant demand on a small system like yours (OK, I'm going to be shot down now...) is to replace the drier with a one that is one or two sizes larger, for example; if yours is a 308 go for a 508. When you install the new drier install it vertically with the inlet at the top and the outlet at the bottom, this way it will act as a receiver as well as a drier. Also do install a sight-glas either at the outlet of the drier or after the drier so that you can judge the amount of refrigerant in the system.

To be able to assist you further we do need running data from your cooler.
- Refrigerant type?
- Running pressures?
- Running temperatures? (Of the fridge system's pipework as well as the glycol mixture an surrounding air)
and so on.

Happy hunting.

:cool:

---

Would a simpler solution be to install a small pump and run glycol lines in the freezer box itself, the additional heat load should be minimal. Pubs here take a loop off the water cooler that cools the beer, this is fed to the taps.

It might have been nice if you had responded to the answers given in your first thread covering this problem before starting a repeat thread.

One point, if you only cool your glycol down to 30°F you will never get your secondary circuit down to 30°F unless you eliminate all heat losses.

If your compressor is hot to the touch, as you say you can't touch it for long, then I would suggest that the compressor is lacking sufficient suction gas cooling. This indicates that your home made evaporator is undersized.

With an undersized evaporator, the heat absorption from the tank will take longer, as you note with the amount of time it takes to cool the reservoir.

Increase the evaporator size, i.e. more turns of copper tube required.

Not the smartest thing to do by blowing hot air onto your box, install baffle deflect air.
80-100 btu/F2/f
4.9f2 * 80 * 10 =3920btu, more than big enough, split will reduce to reach equalibrium.
Suction pressure to high.
Install receiver and sight glass.
Adjust superheat setting increase (clockwise) all the way. Suction pressure should drop. If so start to adjust slowly, slowly.

Ok with all your help guys here, I think I am honing in on some key problems with my setup

First
Mad fridge. A similar Commercial cooling unit as mine is using a condenser that is 10.5" wide X 9 tall, it is using 1/4" copper tube and has 24 passes back and fourth, totalling 24' of copper tubing inside. It is using a 8" fan, fan speed unknown. this unit is capable of cooling down glycol at a rate of 2500btu/hr.

So I am guessing that the condenser I am using will be ok? all the dimensions are larger than the commercial one. My condenser is 12" X 14" using 3/8 copper tube, has 30 passes, back and fourth, totalling 33.5' of copper tubing. Mine is also using a 8" fan spinning at up to 1550 rpm.
I think my unit has 8530btu unit based on the surface dimensions???

Can having a condenser too large be detrimental?

Mad you mentioned something about adding a split? to balance the pressure?
I think I know what you mean, Correct me if I am wrong, on the liquid side at the top, you take the tube coming in at the top and place a t on it to the first coil bank, at the other end of the t you solder an elbow which feeds the second bank. and does the same thing at the bottom. The pipes make an F correct?

like this unit? Attachment 14995

I think I understand what is being done, but can you please explain the advantage of this? vs 1 long line?

Is it necessary or will the 1 line work for my purposes.

Concerning blowing the heat into the box, I agree, the fan is reversible so I will change that later. On the current setup, (the cowling has a side vent for the air to escape) comes in from condenser, past the compressor and goes out the side. air Temp inside the unit by the motor only gets 3 degrees above ambient (running hot) But a change to be made, duly noted.

Quote:

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Originally Posted by mad fridgie

Not the smartest thing to do by blowing hot air onto your box, install baffle deflect air.
80-100 btu/F2/f
4.9f2 * 80 * 10 =3920btu, more than big enough, split will reduce to reach equalibrium.
Suction pressure to high.
Install receiver and sight glass.
Adjust superheat setting increase (clockwise) all the way. Suction pressure should drop. If so start to adjust slowly, slowly.

---

I thought about that and tried it al, there is still too much heat load coming in from the tower, the freezer cant keep up.

Well I found out from micro matic you are correct, they are using a copper coil 50' X .5" where I was using a 50'X3/8"

So this is my next step to do. The reason they are using a .5" is cause the r134 moves more smoothly and looses less velocity with the increased diameter? which inturn produces lower temps do to less friction?? does this make sense to any one?

Quote:

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Originally Posted by frank

If your compressor is hot to the touch, as you say you can't touch it for long, then I would suggest that the compressor is lacking sufficient suction gas cooling. This indicates that your home made evaporator is undersized.

With an undersized evaporator, the heat absorption from the tank will take longer, as you note with the amount of time it takes to cool the reservoir.

Increase the evaporator size, i.e. more turns of copper tube required.

---

I am going to create version 2 here. implementing some new found information, and suggestions that were made here. as you said install a sight glass, a resivour, replace the valve with a new one or with a cap now I know the size of the glycol coil., and put a larger diameter glycol coil in.

I will get the changes made and will give you the numbers after I get it up and running again shortly.

Quote:

---

Originally Posted by The Viking

Oh dear, DIY R&D at it best...

So to start with,
You have a system with a TXV as the metering device, is there a receiver in the liquid line to ensure the TXV got a true liquid supply of refrigerant?
I can see from the picture that you got a drier but I can't see a receiver. Assuming that the system not got a receiver, the easiest way to overcome the issue of varied refrigerant demand on a small system like yours (OK, I'm going to be shot down now...) is to replace the drier with a one that is one or two sizes larger, for example; if yours is a 308 go for a 508. When you install the new drier install it vertically with the inlet at the top and the outlet at the bottom, this way it will act as a receiver as well as a drier. Also do install a sight-glas either at the outlet of the drier or after the drier so that you can judge the amount of refrigerant in the system.

To be able to assist you further we do need running data from your cooler.
- Refrigerant type?
- Running pressures?
- Running temperatures? (Of the fridge system's pipework as well as the glycol mixture an surrounding air)
and so on.

Happy hunting.

:cool:

---

I think maybe an ice bank cooler might have been a better idea for head cooling, or better still go to the pub and let them have the problem and you do the drinking, works for me

hi for the glycol you have to multiply your calculation by 1.5+20% and most important is metering device try to use 404 instead 134