View Full Version : Need r134a charge help with a glycol cooler with a TXV

12-09-2017, 04:07 PM
Hello gentlemen,

I am in some need of help! I have built this glycol cooler to cool off my beer tower...14969149711497214973

The system is running r134a

The glycol cooler is built using a
1/3hp Danfoss 5880 compressor. the compressor has a btu rating at 32' of 2400btu or .2TR

Danfoss TXV TN2 valve part Number 068z3346 -40 to +10C temp range running a 01 orifice part number 068-2010 this combination should allow me to pull up to .80TR at -40 to +20 which is more than the compressor can pull down. (this was danfoss recommendation) the compressor has a 3/8" suction and a 1/4" fluid line.

the condenser is made of 3/8 copper tubes about 1' long consisting of 30 single passes, or 15 double passes. the condenser is rated for up to 3/8 hp so the 1/3hp motor is within its range. it is rated for 894w or 3053 btu or .25TR

the condenser is the same as this one http://purswave.en.made-in-china.com/product/IqZnjNzULXro/China-R404A-Embraco-Compressor-Condensing-Units-for-Commercial-Refrigerator-T2168GK-.html

The evaporator is connected to about 50' of 3/8 copper coil that is submerged in a 2 gallon glycol bath.

from the glycol bath there is a glycol pump is a 1/3hp with a proctor RV pump. pumping the chilled glycol about 6 meters one way, and up 1.5 meters to the tower, then returns 2 meters back to the glycol bath. the lines on the glycol pump are 5/16 lines that are just loose hanging in the box.

Now I know that I am running under the rated btu due to the fact that the commercial systems for this tower use 1/4hp compressor, and a 1/4hp glycol pump to keep the system cold.

If I did my math correct it takes 1 btu per degree per pound of water, so if I have 2 gallons in the box, that weighs 16.6lbs I want to bring down the temp from 90 degrees f to 30 degrees f so that is 60 degrees so if you take 16.6X 60 = 500 btu/hr so the pump cooling at 2400 btu/hr, it should take 12 minutes to cool down the 2 gallons of glycol to 32degrees... It is taking over 4+ hours to cool the system.

BUT when I get the system glycol down to 32 degrees F and turn the pump on the temp of the glycol climbs to 48 degrees F and will not come down even after running for 6 hours.
The compressor gets hot( not hot enough to trip the thermal switch but hot to the touch). The pressure is running at about 140 on the high side, and about 30psi on the low side. If I let the system run for 8 hours, the glycol bath will get to +6.5 degrees f

Can any one please help me out here to tune this in. I don't know if the system is over charged or under charged, I don't know if the TXV valve is open too wide or closed to little I can give you specifics on temps and pressures if you let me know what you need.

This is has been driving mad for the past 3 months.

I am not a technician so I do apologize if I do not know all the technical jargons so please forgive me.

12-09-2017, 06:57 PM
All systems need a certain amount of 'pull-down' time to get hold of the load and perform their work on it.

Until the system is at design conditions the operating temperatures will not be stable.

Try to measure things as temperatures not pressures and do check your calculations - 16.6 x 60 does not equal 500.

Measure your subcooling to ensure that you are getting liquid at the TXV, also check the superheat from the TXV.

As an aside, brewers reckon on 18 hours to cool things down.

13-09-2017, 07:10 PM
What is your flow rate on the glycol side to the evaporator?

20-09-2017, 01:12 AM
Hello Frank the glycol pump is pushing 80 GPH/ but the heat load If I have done my math right is 315btu with only the glycol pump running with out product coming out the taps. with product coming out the taps It jumps to 1911btu/hr.